US3620879A

US3620879A - Apparatus for continuously determining the diameter of mask apertures

Info

Publication number: US3620879A
Application number: US849695A
Authority: US
Inventors: Hitoshi Imamura; Hiroshi Ishino
Original assignee: Tokyo Shibaura Electric Co Ltd
Current assignee: Toshiba Corp
Priority date: 1968-08-15
Filing date: 1969-08-13
Publication date: 1971-11-16
Anticipated expiration: 1988-11-16

Abstract

Apparatus for continuously and successively determining the diameter of mask apertures in a plurality of masks formed in an elongated tape material which is moving at a substantially constant speed, the tape having a series of equally spaced perforated masks thereon and start- and stop-detecting apertures near the front and rear edges of each mask. The start aperture is detected and a slider device is operated to engage with the traveling tape to thereby travel with the tape. Upon detection of the stop-detecting aperture, the slider device is released from the tape and is quickly returned to its original position. While the slider is engaged with the tape, similar light beams are projected on corresponding areas of a mother or ''''master'''' mask and of a mask on the traveling tape. The light passing through the two masks is converted to electrical signals and the electrical signals are compared. The respective masks of the tape are either approved or rejected as a function of the magnitude of the difference between the output electrical signals.

Description

United States Patent lnventors Ilitoshilmamura Aug. 19, 1968, Japan, No. 43/58692 Oct. 3,1968, 43/71605 APPARATUS FOR CONTINUOUSLY DETERMINING THE DIAMETER 0F MASK APERTURES 13 Claims, 26 Drawing Figs.

US. Cl

73/432, 156/8 Int. Cl C231 1/02, GOln 21/00 Field of Search Primary Examiner-William A. Powell Attorney-Flynn & Frishauf ABSTRACT: Apparatus for continuously and successively determining the diameter of mask apertures in a plurality of masks formed in an elongated tape material which is moving 2 at a substantially constant speed, the tape having a series of I equally spaced perforated masks thereon and startand stopdetecting apertures near the front and rear edges of each mask. The start aperture is detected and a slider device is operated to engage with the traveling tape to thereby travel with the tape. Upon detection of the stop-detecting aperture, the slider device is released from the tape and is quickly returned to its original position. While the slider is engaged with the tape, similar light beams are projected on corresponding areas of a mother or "master" mask and of a mask on the traveling tape. The light passing through the two masks is converted to electrical signals and the electrical signals are compared. The respective masks of the tape are either approved or rejected as a function of the magnitude of the difference between the output electrical signals.

,4? 41 U 43 32 4.4 46 11 PROCESS OF 2 CONTINUOUSLY COATING OF A l EXPOSURE IDEVELOPIN'G] FHIN GW DETERMINING 9 SENSITIZER TO LIGHT THE DIAMETER EXCHANGE SPOOL OF MASK APERTURES EXCHANGE SPOOL PATENTEUuuv 16 I97! SHEU 5 OF 8 ago 22 28 FIG. 125

FIG. 12A

FIG. 13A FIG. 13B

FIG. 14A FIG. 14B

PATENTEDNUV 1s IHII SHEET 6 BF 8 SHEET 7 BF 8 Trw! PAIENTEUunv 1s IQTI APPARATUS FOR CONTINUOUSLY DETERMINING THE DIAMETER OF MASK APERTURES BACKGROUND OF THE INVENTION The present invention relates to an apparatus for continuously determining the diameter of mask apertures, and more particularly to an apparatus well adapted for use in continuously determining with high precision the diameter of apertures perforated in a shadow mask included, for example, in a color television set so as to match the manufacturing process of said mask.

For briefness, there will now be described the case where the apparatus of the present invention is employed in determining the diameter of apertures perforated in a shadow mask for a color television set. It will be apparent, however, that said apparatus is also substantially applicable in other devices comprising a member which has to be perforated with a large number of apertures as is the case with the aforesaid shadow mask. Obviously, the present apparatus can be used in determining the diameter of apertures provided, for example, in a perforated net of a mechanical roller razor or electrical razor.

As is well known, the manufacture of a color television set including a shadow mask demands from the standpoint of quality control that the diameter of apertures formed in the shadow mask be measured constantly with high precision.

However, the method of determining the diameter of apertures of a color television shadow mask as currently practiced in its manufacture only consists in visual observation through a shop microscope or projector of about 100:] magnification.

Shadow mask apertures perforated by photoetching (which generally have a diameter of about 0.2 to 0.3 mm. and are provided in a large number at an interval of about 0.6 to 0.8 mm. so as to be located at the apices of an equilateral triangle) do not assume the form of a true circle as microscopically observed, nor are of uniform diameter. Said apertures are progressively reduced in diameter from the central to the peripheral parts (the diameter is generally about 0.26 mm. in the central part and about 0.22 mm. in the peripheral part). Accordingly, the determined values of these diameters substantially vary with the part of the shadow mask where there are positioned the observed apertures or with the particular form of said apertures themselves. Also the individual difference of observers tends to result in variation in the determined values. Thus the prior art process has the great drawback that it actually presents extreme difficulties in effecting constant, high-precision determination.

Quite recently, therefore, there has been proposed a different principle of determination which consists in measuring an average light transmission in a certain area of the shadow mask and qualitatively computing from said measurement the diameter of equivalent true circular apertures in said area. This principle may be deemed to enable the diameter of shadow mask apertures to be determined constantly with high precision and reliability without being affected by errors resulting from the varying parts of the shadow mask to be determined or individual divergences of observers as is the case with the aforementioned visual determination. At present, however, there is not realized any practical apparatus embodying said principle which is considered suitable for use in the manufacturing process of the aforesaid type of color television shadow mask.

SUMMARY OF THE INVENTION It is accordingly the object of the present invention to eliminate the drawbacks encountered with the prior art and provide a novel apparatus of extremely great industrial merit for continuously and automatically determining the diameter of color television shadow mask apertures with constant high precision and reliability in a manner well adapted for the practical process of manufacturing said mask.

BRIEF EXPLANATION OF THE DRAWINGS FIG. 1 is a schematic block diagram illustrating the principle of an apparatus for continuously determining the diameter of mask apertures according to the present invention;

FIG. 2 shows the manner in which there is formed a mask hoop to be determined by the apparatus of the present inventron;

FIG. 3 is a schematic block diagram of the sequential processes of manufacturing an apparatus for determining the diameter of mask apertures according to the invention;

FIG. 4 is a fractional schematic plan view of an etching chamber included in the etching process of FIG. 3;

FIG. 5 is a fractional perspective view of an apparatus according to an embodiment of the invention for continuously determining the diameter of mask apertures so designed as to determine fully automatically and continuously the diameter of shadow mask apertures perforated in the mask hoop of FIG. 2 in line with the processes of FIG. 3;

FIG. 6 illustrates an equivalent arrangement as an aid to the understanding to the apparatus of FIG. 5;

FIGS. 7A to 7C indicate the wave forms of output signals resulting from determination by the apparatus of the invention for continuously determining the diameter of mask apertures;

FIG. 8 shows a fractional equivalent electrical circuit illustrating the operation of a means for correcting the vertical position of the travelling mask hoop as used in the apparatus of FIGS. 5 and 6;

FIG. 9 is a schematic diagram illustrating the operation of a suitable means for controlling the interior condition of apertures perforated by etching in manufacturing the apparatus of the invention for continuously determining the diameter of mask apertures;

FIGS. 10A to 10D are curve diagrams showing the relationship of the various treating conditions required for photoetching used in the perforating process which should be controlled from the results of determination conducted on each shadow mask by the means of FIG. 9 versus to the interior condition of shadow mask apertures actually perforated in the test mask hoop;

FIG. 11 illustrates a concrete arrangement of a magnetic chuck capable of being used interchangeably with the chuck operating air cylinder included in the slider of FIG. 5;

FIGS. 12A and 128 show modifications of apertures perforated by an analog means in the test mask hoop of FIG. 2 for correcting its vertical position;

FIGS. 13A and 13B illustrate further modifications of apertures perforated by a digital means in the test mask hoop and mother mask;

FIGS. 14A and 14B are schematic arrangements of both photoelectric converting systems disposed on the front and back sides of the test mask hoop and mother mask respectively which are perforated with the apertures shown in FIGS. 13A and 13B; and

FIGS. 15A to 15D illustrate schematic circuit arrangements of the main part of the present apparatus adapted for use in correcting the relative height of the test mask hoop and mother mask where they are perforated with the apertures shown in FIGS. 13A and 13B.

DETAILED DESCRIPTION OF THE INVENTION There will now be described by reference to the appended drawings the determining principle of the present invention and an apparatus based thereon for continuously determining the diameter of mask apertures manufactured in a manner well adapted for the practical process of preparing a mask.

There will be first explained by reference to FIG. I the determining principle of the present apparatus. Light beams projected from a light source I], for example, a lamp are first converted through a convex lens I2 into parallel beams having a uniform flux and then allowed to strike against a half mirror 13 transmitting, for example, 50 percent of the introduced light beams and reflecting the remaining 50 percent. The flux of light beams reflected from the half mirror 13 is projected on the predetermined plane of a mask 14 to be determined, whose effective area is perforated with a large number of apertures about 0.2 to 0.3 mm. in diameter disposed at a spacing of about 0.6 to 0.8 mm. in concentric rows at the apices of an equilateral triangle. On the other hand, the flux of transmitted light beams is projected on that plane of a mother mask 15 used as the standard for determination which corresponds to that of a mask 14 to be determined on which there are projected the aforesaid reflected light beams. Said mother mask 15 is perforated with ideal mask apertures with extremely high precision in the same number as those formed in the effective area of said mask 14. The reflected light beams passed out through the apertures of said mask 14 and the transmitted light beams passed out through the apertures of the mother mask 15 are conducted to the light-receiving sections of photoelectric converting elements 16 and 17 consisting of a solar battery or phototransistor which are disposed under the same condition at the back of the mask 14 and mother mask 15 respectively. Thus from the output terminals of these photoelectric converting elements 16 and 17 are issued photoelectrically converted signals in response to the amount of light beams introduced.

When said both output electrical signals are supplied to a known differential bridge circuit 18 comprising a differential amplifier, etc., said circuit 18 produces an output voltage corresponding to the difference between said both output electrical signals. To the output terminal of the differential bridge circuit 18 are serially connected in the order mentioned an amplifier 19 selectively actuated only when the output voltage from said circuit 18 has a level exceeding a predetermined threshold value, a meter relay 20 having a normally open contact to form a closed circuit only when it is supplied with signals from said amplifier 19 and an alarm generator 21 consisting of a lamp, buzzer or the like which is operated only when the contact of said meter relay 20 is closed to give an alarm. Then it is possible to approve a determined shadow mask whose apertures allow the output voltage from the differential bridge circuit 18 to have a lower level than the predetermined threshold value and inconsequence prevents an alarm from being given and reject another shadow mask whose apertures cause the output voltage from said circuit 18 to have a higher level than the predetermined threshold value and as a result an alarm to be given. To maintain the fully great stability of the aforementioned determining system, it is preferred that a power source 22 to operate an electrical circuit including the aforementioned light source 11 be a constant voltage type consisting of a standard battery, constant voltage diode or diode rectified bridge circuit. It is also desired that the aforesaid amplifier 19 be formed of a magnetic amplifier or the like which operates very stably independently of changes in environmental conditions, for example, ambient temperature.

There will now be described by reference to FIGS. 2 to 10 an apparatus according to an embodiment of the invention for continuously determining mask apertures according to the present invention, which is manufactured on the basis of the principle shown in FIG. 1 in a manner well adapted to the practical process of preparing a mask.

FIG. 2 is a concrete example of a test mask hoop 31 prepared according to the present invention. The material 32 of said hoop 31 consists of, for example, a very thin steel plate about 0. l 5 mm. thick formed into a long tape. The hoop 31 is stretched, as shown in FIG. 3, across a feed spool 41 and takeup spool 42 disposed at a predetermined spacing and allowed to travel from the former to the latter spool at a suitable speed. Along the route of the travelling hoop material 32 are provided a series of known perforating processes including the coating of a sensitizer 43, exposure to light 44, developing 45 and etching 46. Thus there is prepared a test mask hoop 31 by perforating the shadow mask area with a large number of

apertures

33,, 33 about 0.2 to 0.3 mm. in diameter at a spacing of about 0.6 to 0.8 mm. as described above within a frame having dimensions to fit the size of a predetermined color television picture and coaxially juxtaposing a series of test masks bearing such perforated shadow mask area at a substantially equal interval in the travelling direction of the hoop material 32, that is, in its longitudinal direction.

According to the experiments conducted by the present inventors which gave good results, a hoop material 32 for a 19- inch color television set was prepared from a low-carbon steel plate having a grade below SPC-3 about 540 mm. wide, 0.l5 mm. thick and about 1,000 meters (2 to 5 tons). Said hoop material 32 was allowed to travel at a constant speed of about 2 to 5 meter/min. in its longitudinal direction. And along the route of the travelling hoop material 32 there were provided a series of the undermentioned photoetching processes, that is, the coating of a sensitizer 43, exposure to light 44, developing 45 and etching 46 so as to perforate said hoop material 32 with predetermined apertures.

A. Coating of a sensitizer 43 V i. A preparatory treatment to ease the application of a sensitizer consisted in spraying about 2 minutes a degreasing agent consisting of NaOH and an interface active agent heated to about 90 C. on to both sides of the hoop water 32.

ii. Both sides were washed about 0.5 minute by water spray.

iii. Both sides were subjected to acid washing otherwise known as preetching by similarly spraying an about 0.5 percent aqueous solution of HNO iv. Water washing was conducted about 0.5 minute in the same manner as in (ii).

v. Both sides were coated with a water-soluble organic sensitizer such as fish glue, polyvinyl alcohol or egg white by spraying about 1 minute with the density and temperature kept constant, thereby forming a dry film having a uniform thickness of about 1 to 2 microns.

vi. The hoop material 32 thus processed was dried about 2 to 3 minutes at as low humidity and temperature C. max) as possible with care taken to prevent the deposition of dust and the occurrence of dark reaction.

B. Exposure to light 44 i. There were prepared a pair of negative plates or films 0.19 to 0.21 inch thick and 32 inches X 28 inches in size, one side of each of which was coated witha sensitizer such as gelatine in a corresponding pattern to that defined by the predetermined perforated apertures. The hoop material 32, both sides of which were coated with a sensitizer by the process A was tightly sandwiched between said paired negative plates or films in such a manner as to allow both sensitized surfaces of said hoop material 32 to face those of the latter.

ii. Under the aforementioned condition, the assembly was exposed about 30 seconds to light beams of about 200,000 lux using a mercury, xenon or carbon arc lamp. in this case the sensitizer coated on the hoop material 32 displayed a most prominent decomposing property with respect to light beams having a wave length of smaller than about 4,000 A, indicating that light beams from a mercury lamp were most suitable. Further, to improve the close attachment of the paired negative plates to the hoop material 32, it was preferred that the interspace therebetween be evacuated to below about 10 mm. Hg. Adding such process, the process of exposure to light required about 2 to 3 minutes per mask.

C. Developing 45 i. When both sides of the hoop material 32 were washed about 2 minutes by spraying warm water at about 40 C. after exposure to light, the sensitizer coated on those parts of the hoop surface which were not sensitized was dissolved off due to its water solubility, thus effecting developing.

ii. The hoop material 32 thus processed was subjected about 2 minutes to baking (or burning) in an atmosphere at about 200 to 300 C., thereby forming in advance a protective film against the undermentioned etching agent on both sides of the hoop material 32.

D. Etching 46 i. As is well known, there are disposed, as shown in FIG. 4, in an etching chamber 53 a plurality of spray manifolds 521, 522 provided with nozzles 511, 512 of a predetermined diameter for ejecting an etching liquid (as illustrated, there are positioned said manifolds only on one side of the hoop material 32, but it is preferred in practice to provide them on both sides thereof). The hoop material 32 supported by a movable frame 54 is allowed to travel through the etching chamber 53 at a constant speed in a specified direction. Thus in each effective area of a series of

shadow masks

341, 342 juxtaposed at a substantially equal space 1 there are perforated a large number of

apertures

33,, 33 coaxially in the travelling or longitudinal direction of the hoop material 32. In this case there is applied an etching liquid prepared from FeCl to which there are added suitable amounts of C1 and, if required, HCl at a temperature of 60 to 80 C. with its specific gravity kept at about 1.4. The liquid is sprayed about 3 minutes per mask. Also in this case, the nozzels 511, 512 are mechanically oscillated so as to apply the etching liquid as entirely as possible over both sides (or one side) of the hoop material 32.

ii. Both sides of the hoop material 32 is washed about 0.5

minute with water spray.

iii. There is sprayed about 2 minutes an about percent aqueous solution of NaOH heated to about 90 C. to remove the protective film formed on both sides of the hoop material 32 during the developing process 45.

iv. There is conducted drying by irradiation of infrared rays. in this case it is preferred that said drying be carried out quickly so as to protect the

mask apertures

33,, 33 as much as possible from the occurrence of rust.

There have been described all the processes associated with the predetermined aperture perforating operation. What should be noted here is that since the time required for each process necessarily varies to some extent, the time and frequency of each process should be properly adjusted, if the hoop material travels at a constant speed. Where it is considered difficult to carry out such adjustment, it is desired to provide a bufler mechanism at an adequate point in the travelling route of the hoop material 32 in order to temporarily stock it.

According to the present invention, there are also perforated other apertures as mentioned below for use in the determination of the diameter of the later described mask apertures at the same time the aforesaid mask apertures are formed. Said other apertures represent, as shown in FIG. 2, start and stop

signal detecting apertures

35 and 36 and

position correcting slits

37a and 37b. The start and stop

apertures

35 and 36 are formed in the proximity of the front and end edges respectively of the

shadow masks

341, 342 as viewed in the travelling direction of the mask hoop 31 as indicated by the arrow of FIG. 2 where there are not provided any

mask apertures

33,, 33 either on the upper or lower transverse side of said mask hoop 31 (on the lower side is shown). The latter group of

position correcting slits

37a and 37b are intended to correct any positional displacement of the test mask hoop 31 during its travel. These slits are disposed at the front edge (permissibly at the end edge) of the

shadow masks

341, 342 in vertically symmetrical relationship with respect to the travelling or longitudinal axis of the hoop material 32.

After the process of perforating the

aforesaid mask apertures

33,, 33,, start and stop

signal detecting apertures

35 and 36 and

position correcting slits

37a and 37b, the present invention provides in the travelling route of the test mask hoop 31 a process 47 of continuously determining the diameter of mask apertures whose general arrangement is shown in FIG. 5 and further illustrated in FIG. 6 by a schematic equivalent setup as an aid for better understanding thereof.

There will now be described said determining process 47. There is provided a fixed bed 60 on the floor almost right under the travelling route of the test mask hoop 31. On the fixed bed 70 are securely disposed by bolts and nuts 62 two slider supports 61 (only one of them is shown) in a manner to face each other at a spacing of about 3 to 5 times the interval between the

respective shadow masks

341, 342 respectively in the travelling direction of the test mask hoop 31. Across these slider supports 61 are placed in the same horizontal plane two guide axles 63a and 63b for operating the sliders in parallel relationship to the travelling direction of the test mask hoop 31. Along both axles 63a and 63b are supported the later described slider 64 in a manner to reciprocate only for a distance corresponding to the longitudinal length of each shadow mask. Along one edge of the slider 64 right back of the indicated mask hoop 31 and the other edge in front thereof are integrally provided first and second substantially

upright projections

65 and 66 in parallel to the travelling direction of the mask hoop 31. In this case the first projection 65 has a height equal to or slightly below the lower edge of the

shadow masks

341, 342 and the second projection 66 is formed with a suitably lower height than the first projection 65. The second projection 66 is integrally provided with an upward projecting plateform support strip 67 in a manner to have substantially the same height as the first projection 65. Penetrating said support strip 67 is an air cylinder 69 integrally coupled with a feed chuck plate 68 in a manner to selectively reciprocate toward the first projection 65. The inner surface of the forward end of said feed chuck plate 68 facing the first projection 65 is smoothly ground. On the inside of the first projection 65 facing the feed chuck plate 68 of the air cylinder 69 is integrally fitted a stationary chuck plate 70 whose inner surface facing said feed chuck plate 68 is also smoothly ground. The air cylinder 69 normally assumes such a position as to allow the feed chuck plate 68 to be removed from the stationary chuck plate 70, namely, stands in a most retracted state. From the underside of the slider 64 disposed opposite to the travelling direction of the mask hoop 31 in tegrally extends outward a lug member 71 in the travelling direction of said hoop 31. With the teeth 72 of the lug member 71 is engaged a pinion 75 fitted to one end of the rotary axle 74 of a clutch and brake assembly 73. To the other end of the rotary axle 74 is connected a quick return motor 77 through a rotation pulley and belt assembly 76 so as to operate the lug and pinion assembly in a manner as described later. On both sides of the constantly travelling test mask hoop 31 perforated with start and stop

signal detecting apertures

35 and 36 are respectively positioned a light source 78 for projecting relatively narrow beams and a photoelectric converting means 79 consisting of a solar battery, phototransistor or the like for receiving beams projected from said light source 78 and taking out a photoelectrically converted output electrical signal. At a suitable point within the reciprocating range of the slider 64 is provided a lamp house 81 which comprises a light source 11 described by reference to FIG. 1, a convex lens 12 for transforming the beams from the light source 11 into parallel beams, and a half mirror 13 for reflecting 50 percent of the parallel beams obtained from the convex lens 12 to the predetermined surface of the test mask hoop 31 and conducting the transmitted light beams constituting the remaining 50 percent to the corresponding surface of the mother mask 15 through a full reflection mirror 80. Said lamp house 81 is supported in such a manner as to be slightly adjustable in vertical position through an arm 83 by a support stand 82 fixed on the bed 60. At the back of the test mask hoop 31 receiving the beams reflected from the half mirror 13 contained in the lamp house 81 and the mother mask 15 supplied with the beams transmitted through said half minor 13 respectively are disposed under the same condition photoelectric converting

means

84 and 85 consisting of a solar battery, phototransistor or the like. There is further fixed on the bed 60 another support stand 86 as is the lamp house 81 in opposite relationship to a photoelectric converting means 88. Said support stand 86 is located at a forward point suitably spaced from the lamp house 81 within the reciprocating range of the slider 64 in the travelling direction of the test mask hoop 31. There is supported by said stand 86 another light source 87 for projecting relative narrow beams in such a manner as to be slightly adjustable in vertical position by said stand 86. At the back of the test mask hoop 31 facing the light source 87 is located the aforementioned photoelectric converting means 88 which is formed of a solar battery or phototransistor. Where there occurs substantially no displacement in the travelling position of the test mask hoop 31, the photoelectric converting means 88 does not receive beams from the light source 87. Conversely where such displacement does occur either in the vertical position of the test mask hoop 31 or to a greater extent than predetermined as a result of exchanging the feed spool 41 or during the travel of said mask hoop 31, then the beams from the light source 87 are supplied to the photoelectric converting means 88 through either of the aforesaid vertical

position correcting apertures

37 a and 37b.

On the other hand, at the indicated rear part of the travelling route of the test mask hoop 31 on the opposite side of the slider 64 to that on which there is formed the second projection 66 there is fitted a mother mask support frame 92, which can be suitably adjusted in its fitted height by means of a feed screw 91 integrally coupled with the rotary shaft 90 of a motor 89 for correcting the height of said mother mask 15 which is rotatable in both normal and reverse directions as described later. In this case the mother mask 15 is perforated in'advance with accurate shadow mask apertures which are also desired to be formed the test mask hoop 31, as well as with other accurate vertical position correcting apertures (not shown). With respect to said vertical position correcting apertures, there are provided still another light source 93 and photoelectric converting means 94 under the same condition and with the same arrangement as the aforementioned light source 87 and photoelectric converting means 88 used for the test mask hoop 31. Here it will be noted that it is not always necessary to prepare the mother mask 15 in such form as covers the entire shadow mask area of each of the shadow masks formed in the test mask hoop 31. It will be sufficient to provide the mother mask 15 only in such size as corresponds to that part of the test shadow mask which it is required to examine.

There will now be described the operation of an apparatus for continuously determining the diameter of shadow mask apertures according to the present invention having the aforementioned arrangement. Initially the slider 64 assumes the rearmost position in the travelling direction of the test mask hoop 31. As the perforated test mask hoop 31 is carried along at a constant speed in the direction of the arrow of FIG. 5, there is performed the later described process of determining the diameter of shadow mask apertures.

First, the start signal detecting aperture 35 formed in the first shadow mask 341 is detected by a photoelectric converting system consisting of the light source 78 and photoelectric converting means 79. With the output used as a set signal the air cylinder 69 for operating the chuck pushes the feed chuck plate 68 toward the stationary chuck plate 70 to clamp the test mask hoop 31 therebetween by air chuck. The slider 64 travels together with the test mask hoop 31 along the two slide guide shafts 63a and 6311 by the drive mechanism of the mask hoop 31 for a distance substantially corresponding to the longitudinal length of the first shadow mask 341 in the direction of the indicated arrow. After lapse of a suitable length of time extending from the initiation of the travel until just before or after its end, the stop signal detecting aperture 36 provided in each travelling shadow mask (in this case the mask 341) is de tected by the photoelectric converting system consisting of the light source 78 and photoelectric converting element 79. With the output used as a reset signal, operation is continued as follows.

The feed chuck plate 68 of the chuck operating air cylinder 69 is moved apart from the stationary chuck plate 70 to release the air chuck and allow the slider 64 to be disengaged from the test mask hoop 31. At this time the clutch of the clutch and brake assembly 73 is so operated as to transmit the rotation of the quick return motor 77 from the pinion 75 to the lug teeth 72. As a result the slider 64 is instantly brought back to its initial position before the start by sliding along both guide shafts 63a and 63b. Upon completion of said return, the brake of the clutch and brake assembly 73 is actuated to release the clutch again. The slider 64 repeats the aforementioned operation for each shadow mask, and each time the fluxes of reflected and transmitted beams from the lamp house 81 are supplied to the photoelectric converting

elements

84 and 85 respectively. Accordingly, there are obtained from both photoelectric converting

elements

84 and 85 output electric signals which respectively correspond to the average light transmission through the apertures formed in the predetermined plane of the

test shadow masks

341, 342 and the corresponding plane of the mother mask 15 as shown in FIGS. 7A and 7B respectively. These output signals are supplied to the differential bridge circuit 18 described by reference to FIG. 1, from which there is issued an output signal as shown in FIG. 7C, each time the individual shadow masks of the test mask hoop 31 pass through the apparatus for continuously determining the diameter of mask apertures according to the present invention. If, the output voltage from the differential bridge circuit 18 associated with a given shadow mask has a level below a predetermined threshold value of :te or e, then there will not be actuated the meter relay 20 and alarm generator 21, proving that said mask is of good quality. Conversely, where the output voltage from said circuit 18 indicates a level exceeding said predetermined level, then there will be operated the meter relay 20 and alarm generator 21, indicating that the related shadow mask is of poor quality. As apparent from the foregoing description, the spacing P between the

shadow masks

341, 342 formed in the test mask hoop 31 in its longitudinal direction is only required to be so chosen as to allow the test mask hoop 31 to travel through said space in a time equal to or slightly longer than that which the slider 64 takes to quickly return.

If, during the above-mentioned determining operation, the travelling position of the test mask hoop 31 should be displaced beyond a certain degree either upward or downward, with the resultant derangement of its relative position to the mother mask 15, then there will be presented difficulties in carrying out accurate determination in comparison with the mother mask 15. However, the determining apparatus of the present invention includes, as shown in FIGS. 5 and 6, two height correcting photoelectric converting systems using photoelectric converting

elements

88 and 94 disposed at the same height and with the same arrangement with respect to the test mask hoop 31 and mother mask 15 respectively. Accordingly, if the height of the travelling test mask hoop 31 should present any upward or downward disagreement with that of the mother mask 15, then there will appear a difference between the levels of output voltages from said photoelectric converting

elements

88 and 94 to an extent proportionate to said positional displacement.

lf output voltages from both photoelectric converting

elements

88 and 94 are supplied to drive the height correcting motor 89 through, for example, a servoamplificr 101 as shown in FIG. 8, then the originally set height ofthe mother mask 15 can always be adjusted by means of the feed screw 91 to an extent to match the varying height of the test mask hoop 31. Therefore, even if the test mask hoop 31 should display any vertical displacement during its travel, it is possible always to allow the determination of mask apertures to be carried out with high precision and reliability. In this case it is also possible, as shown in FIG. 9, to suitably amplify by the amplifier 19 an electric deviation signal corresponding to the difference between the output signals from both photoelectric converting

elements

84 and 85 of the differential bridge circuit 18 and feed them back to the various treating conditions of the etching 46 included in the aforementioned photoetching processes through an adjuster 111 so as automatically to control said treating conditions at all times. Then there will be great advantage in decreasing the occurrence of unsatisfactory shadow masks and preparing accurate ones. Said treating conditions associated with the etching 46 included in said photoetching processes which have to be controlled may include, as shown in FIGS. A to 10D, the specific gravity p of an etching liquid, temperature T, spray nozzle pressure P and the amount F of liquid jetted from a spray. Of these factors, the specific gravity p of an etching liquid and temperature T represented by FIGS. 10A and 10B respectively present relatively great difficulties in frequent adjustment and control and moreover make a slow response to control. Therefore, this example only relates to the adjustment and control of the spray nozzle pressure P and the amount of liquid jetted from the spray as illustrated in FIGS. 10C and 10D. Namely in the example, there is always automatically adjusted and controlled the pressure of the spray nozzles attached to the manifolds 521, 522 disposed in the etching chamber 53 as shown in FIG. 4 and the operation of valves 501, 502 (FIG. 9) for adjusting the jetted amount of etching liquid, according to the magnitude of the electrical deviation signal corresponding to the difference between output signals from the two photoelectric converting

elements

84 and 85 which are conducted in turn through the differential bridge circuit 18, amplifier l9 and adjuster 111. Numeral 112 of FIG. 9 is a tank holding a given etching liquid 113. The etching liquid 113 in the tank 112 is sucked up by a sucking pump 114 and then supplied to the spray manifolds 521, 522 and jetted through the corresponding nozzles 511, 512 on to the predetermined surface area, as shown in FIG. 2, of the test mask hoop 31 brought at a constant speed, to perforate mask apertures having a desired diameter.

FIG. 11 shows a concrete arrangement of a magnetic chuck member 120 interchangeably used with the aforesaid chuck operating air cylinder 69. This magnetic chuck member 120 comprises a stationary chuck plate 122 whose front plane 121 is smoothly ground almost in the same manner as the aforesaid chuck plate 70, a head 123 formed with a large diameter in a manner to face the stationary chuck plate 122, the top plane 124 of said head 123 being similarly ground, and the bottom plane 125 being sealed, a cylindrical guide wall 126 having a smaller diameter than said head 123 and a feed chuck 128 prepared from magnetic material such as iron which is integrally projecting from the head 123 along the inner surface of cylindrical guide wall 126 in the opposite direction to the stationary chuck plate 122 and includes a rodlike body 127 reciprocating in the axial direction of said cylindrical guide wall 126. The outer peripheral surface of the rodlike body 127 of the feed chuck 128 is wound with a magnetic coil 129 with said cylindrical guide wall 126 lying therebetween. Between the bottom plane of the rodlike body 127 and the sealed bottom plane 125 of the cylindrical guide wall 126 opposite thereto is interposed a compression spring 130. The magnetic chuck member 120 having the aforesaid arrangement cperates in the following manner. Normally, the magnetic coil 129 is energized to lock the feed chuck in the indicated state, namely, apart from the stationary chuck plate 122 in resistance to the resilient force of the compression spring 130. However, when the start signal detecting aperture 35 formed in the test mask hoop 31 as shown in FIG. 2 is detected by a photoelectric converting system consisting of the aforementioned light source and photoelectric converting element, then the magnetic coil 129 is demagnetized and instantly the feed chuck 128 is forced to the stationary chuck plate 122 by the resilient force of the compression spring 130 so as to chuck the test mask hoop 31 therebetween and in consequence allow the slider 64 and said hoop 31 to travel jointly.

On the other hand, when the stop-signal-detecting aperture 36 formed in the test mask hoop 31 is detected during its travel with the slider 64 by said photoelectric converting system, then the magnetic coil 129 is again energized to remove the feed chuck 128 from the stationary chuck plate 122 against the resilient force of the compression spring 130, and release the chucked condition, bringing the chuck member 120 back to a state shown in FIG. 11. Since this chuck member repeatedly performs the aforesaid operation, it

will be apparent that it can be used interchangeably used with the chuck operating air cylinder 69.

In the foregoing embodiment of the present invention, there is used a photoelectric converting element in common in detecting both start and stop signals. Obviously, however, there may be provided separate elements for this purpose.

There will now be described some modifications of a vertical position correcting mechanism. According to the aforementioned embodiment, there were perforated in the

respective shadow masks

341, 342 vertical

position correcting slits

37a and 37b in vertically symmetrical relationship with respect to the axial line of the travelling test mask hoop 31, with a substantially equal space allowed on both sides of said axial line. On both front and back sides of the travelling mask hoop 31 there were further disposed photoelectric converting systems each consisting of a lamp source and photoelectric converting element in the proximity of the axial line in a manner substantially to face each other. Also the mother mask 15 was similarly provided with vertical position correcting apertures and photoelectric converting systems. For the purpose of determination, there may be used any type of apertures, so long as they have the same shape and size for both test mask hoop and mother mask, obviously allowing determination to be carried out in the same manner as used in the foregoing embodiment and with the same effect. (Of course, it is important in this case that there be used under the same condition photoelectric converting systems of the same kind as described above and having the mutually equal arrangement). Further, it is not always necessary particularly to provide such vertical-position-correcting slits, but it is possible to use some of the shadow mask apertures as they are for this purpose. Nor there is any need to perforate said position correcting slits in the

respective masks

341, 342 but they may be provided intermittently, that is, for each group of a suitable number of shadow masks. What is important is that said position-correcting slits be formed at such a point as to allow the degree of displacement in the relative position of the mask hoop and mother mask to be detected by a photoelectric converting system as distinctly as possible.

There will now be described by reference to FIGS. 12A and 128 different modifications of such vertical position correcting slits. While these figures only represent those provided in the test mask hoop, it will be apparent that they may be formed likewise in the mother mask. FIG. 12A shows a stop signal detecting aperture 361 (or permissibly a start signal dctecting aperture) perforated in a substantially triangular form when the test mask hoop 311 is prepared in the manner as shown in FIG. 2. FIG. 12B denotes a group of a large number of small stop-signal-detecting apertures 362 whose diameter progressively varies toward the height of the test mask hoop 312. The aforesaid two kinds of stop-signal-detecting apertures are intended to be concurrently used in correcting the vertical position of the test mask hoop during its travel. Since these

apertures

361 and 362 used for the double purpose of detecting the stop signal and correcting the height of the test mask hoop are formed at a fixed distance d from the central axis 0 of the respective travelling

shadow masks

341, 342 they can obviously be utilized in correcting the height of the travelling test mask hoop.

All the foregoing embodiments relate to the case where the degree of displacement in the relative vertical position of the test mask hoop and mother mask while the former was travelling was detected and corrected by means of an analog. There is now to be described the digital detection and correction of such displacement.

As shown in FIG. 13A, there are perforated a plurality of small apertures of

equal diameter

131, 132, 13!: (where n denotes a positive even number) in vertical symmetry with respect to the control axis of the travelling shadow masks 34], 342 of the test mask hoop 313. These apertures are used as vertical-position-correcting apertures 373. On one side of the test mask hoop 313 facing one group of said symmetrical small apertures are disposed as shown in FIG. 14A photoelectric converting

elements

141, 142, 1411 which respectively correspond to the individual apertures. And on the other side of the test mask hoop 313 opposite to said photoelectric converting

elements

141, 142, 141i is provided one light source 163 which, while the test mask hoop 313 is travelling in the proper position, projects toward the proximity of the axial line a flux of beams having a width equal to or slightly narrower than the space between thetwo adjacent ones of the aforementioned

small apertures

131, 132, 13n. Also on the mother mask 153 are perforated, as shown in FIG. 138, a plurality of small vertical

position correcting apertures

171, 172, 17n of equal diameter in vertical symmetry with respect to the axial line 0 as in the test mask hoop 313. On one side of the mother mask 153 facing one group of said symmetrical small apertures are arranged as shown in FIG. 14B photoelectric converting

elements

181, 182, 18!: which respectively correspond to the individual apertures. And on the other side of the mother mask 153 opposite to said photoelectric converting

elements

181, 182, 1811 is provided one light source 193 which projects toward the proximity of the axial line of said mother mask 153 a flux of beams having a width equal to or slightly narrower than the space between the two adjacent ones of the aforesaid

small apertures

171, 172, 17n. FIGS. A to 15D present a most preferable concrete circuit of the main part of a vertical-position-correcting mechanism perfonning the aforementioned digital control.

There is provided, as shown in FIG. 15A a first DC source circuit 2061: wherein the AC voltage from a commercial AC source 201 is allowed to pass through a source transformer 202 and is impressed across the paired

input terminals

204a and 204b of the known source rectifying circuit 203 prepared by connecting four diodes in the rectifying bridge form and the resultant DC voltage is drawn out of the paired positive and

negative output terminals

205a and 205b of said bridge circuit 203.

Between the aforesaid paired positive and

negative output terminals

205a and 205b included in this first DC source circuit 206a are connected in parallel the later described circuit 207 for detectingthe vertical position of the travelling test mask hoop 313 including a plurality of photoelectric converting

elements

141, 142, 14n which respectively correspond to the individual

small apertures

131, 132, 13n perforated in said mask hoop 313 so asto correct its vertical position during its travel and another later described circuit 208 for detecting the vertical position of the mother mask 153 including a plurality of photoelectric converting

elements

18, 182, 18n which respectively correspond to the individual

small apertures

171, 172, 17n perforated in the mother mask 153. Since the circuit 207 for detecting the height of the travelling test mask hoop is of exactly the same arrangement as the circuit 208 for detecting the height of the mother mask, the following description only relates to the former circuit 207 and description of the latter is omitted with the numerals representing the same parts of the mother mask as those of the mask hoop given in parenthesis opposite to the numerals associated with the mask hoop.

Between the paired positive and negative

DC source terminals

205a and 205b are serially connected, as shown in FIG. 15A, a resistor R,(R,,) and a diode D,(D, disposed in the forward direction (said diode may consist of a resistor, but the use of a diode permits the automatic compensation of the temperature of the subject determining apparatus for the varying ambient temperature). To the contact 209 (229) of the serially connected resistor R,(R,,) and diode D D are connected in parallel the later described

circuits

211, 212, 21n (231, 232, 23n) for detecting the travelling height including photoelectric converting

elements

141, 142, 14!: (181, 182, l8n) which respectively correspond to the individual

small apertures

131, 132, 13n(171, 172, I7n). Since all these

circuits

211, 212, 21n are of exactly the same arrangement, there is only described the first circuit 211(231) and explanation of the other circuits is omitted with the same parts as those of the first circuit indicated by the same numerals. To

the aforesaid contact 209 (229) of the resistor R (R and diode DD is connected through the serially arranged photoelectric converting element 141 (181) the base of a first emitter-grounded-type NPN-transistor TR,,,(TR grounded through the emitter. Across said base input terminal and one 205b of the paired DC terminals which is used as a -B source terminal is connected a base biasing resistor R fll Further across the collector of the transistor TR,,,(TR and the other 205a of the paired DC source terminals used as a +8 source terminal is connected a collector resistor R R To the collector terminal of said transistor TR,,,(TR is connected the base of a second emitter-follower-type PNP-transistor TR (TR Between the DC source terminal 205a and the emitter of said second transistor TR ,(TR is connected in parallel a relay M,( K acting as later described and the known damping circuit provided, if required, to stabilize the operation of said relay K,(K,,) wherein there are serially connected, as shown, a resistor and a diode disposed in the backward direction to the power source. The indicated resistor Rd and capacitor Cd constitute the known source decoupling circuit provided, if necessary, and the indicated diode D2 is a constant voltage type similarly provided where required.

FIG. 153 shows the arrangement of a comparison circuit 240 operated as described later by the circuit 207 for detecting the height of the travelling test mask hoop 313 and circuit 208 for detecting the height of the mother mask 153 indicated in FIG. 15A. The comparison circuit 240 consists of a combination of exactly the same circuit arrangements as those of the test mask hoop 313 and mother mask 153, so that there is only given description of that component of said comparison circuit 240 which corresponds to the circuit of the test mask hoop 313 with the same parts of the other component of said comparison circuit 240 corresponding to the circuit of the mother mask 153 as those of the latter circuit denoted by the same numerals in parenthesis opposite to the numerals associated with the latter circuit.

The comparison circuit 240 includes a second DC source circuit 206b having the same circuit arrangement as said first DC source circuit 206a. Across the paired positive and negative output

DC source terminals

205a and 205b are serially connected in corresponding relationship to the

aforesaid dctecting circuits

211, 212, 21!: (231, 232, 23n) normally open first contacts K K K,, ,(K, K K,,,.,) selectively operated as described later by the relays K K K (K K K included in said detecting

circuits

211, 212, 2ln (231, 232, 23h) and two resistors consisting of one selected in turn from the group of R R R (R R R and another similarly selected from that of R R R (R R R respectively. To the contacts of the respective groups of the two resistors thus selected are connected the cathode terminals of the individual diodes D D D, (D D D The anode terminals of the diodes D D D,, (D,,, D D2,.) are collectively connected to one end of a resistor R,,(R the other end of which is connected to the +8 source terminal 205a and further to the -B source terminal 205b of a third DC source circuit 206c (a fourth DC source circuit 206d) having the same arrangement of the first and second DC source circuits through a serial circuit comprising a diode DMD of the indicated polarity and resistor R (R To the contact of the diode D -,,(D,,) and resistor R 01 is connected of the base of a first emitter-groundedtype NPN-transistor TR ,(TR grounded through the emitter using said third DC source circuit 206c (the fourth DC source circuit 20611) as a power source. One end of the collector rcsistor R R is connected to +8 source terminal 205a (205a) of the source circuit (206d) and the other end is connected to the collector terminal of the transistor TR,,(TR,,,). Said collector terminal is connected to the base of a second emitter-follower-type PNP-transistor TR tTR Across the emitter of said second transistor TR (TR and the +8 source terminal 205a (20511) of the source circuit 206c (206d) are connected in parallel the relay K3|(K-11) selectively operated as described later and a damping circuit provided, if required, for said relay K (K in which there are serially connected a resistor and a diode disposed in the backward direction to the power source.

FIG. 15C shows a source switching circuit 250 for controlling as described later the rotation of a motor 89 used in adjusting the fitted height of the mother mask 153 through the feed screw 91 in accordance with the set condition of the comparison circuit 240 of FIG. 158. This circuit 250 is formed by connecting in parallel second normally open contacts K to D,,, selectively actuated in interlocking relationship with the first normally open contacts K to K, shown in FIG. 15B by means of the relays K to K,, included in the circuits 211 to 21n of FIG. 15A for detecting the height of the travelling test mask hoop 313 and directly connecting the ends on one side of the normally open contacts K to K,,., to one end of the commercial AC source 201 and the ends on the other side of said contacts through a serially disposed relay K operated as described later to the other end of said AC source.

FIG. 15D represents a source circuit 260 for automatically controlling as described later the rotation of the vertical position correcting motor 89 capable of being rotated in normal and reverse directions according to the operating conditions of the circuits of FIGS. 15B and 15C, This circuit 260 is formed by serially connecting to one end of the commercial AC source 201 a fuse F, normally open contact K operated by the relay K, of FIG. 15C, normally open contact K operated by the relay D included in that component of the comparison circuit 240 of FIG. 158 corresponding to the test mask hoop 313, normally closed contact K operated by the relay K, provided in that component of said comparison circuit 240 corresponding to the mother mask 153 and one end of said height correcting motor 89, for example, one end of the field winding Wp thereof for normal rotation in the order mentioned. To the other end of the field winding Wp is connected the other end of the commercial AC source 20-1 and one end of the other field winding Wn for reverse rotation.

To the other end of the field winding Wn is connected t w Phase ad ust 2si 2n1essLat9 main a n a predetermined phase difference between said other end of the reverse rotation winding Wu and one end of the normal rotation winding Wpl Said other end of the field w(nding Wn is connected to the contact 26I of both normally open contacts Ksl-l and 3l-l through the serially arranged normally closed contact Kain operated by the relay K and normally open contact K4 is connected to the junction 263 of theaforesaid fuse F and normallyopen contact through a serially connected switch SW-l which normally remains closed while the determining apparatus of the present invention is operating. Also between the junction 263 and the junction 264 of the normally open contact K31] and the normally closed contact K414 is serially connected another switch SW-Z of the same type astheaforesaid switch SW-l.

There will now be described the operation of th'zfifi'cuitof FIGS. 15A to 15D. After being perforated with predetermined apertures as described above, the test mask hoop 313 is progressively introduced into the apparatus of the present invention for continuously determining the diameter of shadow mask apertures. Then according to the reciprocating movement of the slider 64, the average light transmission through the same areas of the

respective shadow masks

341, 342,

- 34" and the mother mask 153 are comparatively determined by photoelectric converting elements of the same arrangements thereby approving or rejecting each mask of the test mask hoop. If, in this case, there does not occur any displacement in the relative height of the travelling test mask hoop to that of the mother mask there will not arise any problem. HOwever, if there appears such displacement, the accuracy of determination will be remarkably decreased, because the apertures formed in the

individual shadow masks

341, 342, 34n vary in diameter from circular formation to another.

According to the present invention, however, there are provided correction circuits as shown in FIGS. 15A to 15D. If,

therefore, there takes place any disagreement between the relative heights of the test mask hoop 313 and mother mask 153, then there will result in the detecting circuits 207 and 208 a difference between the relative position of that of the detecting

circuits

211, 212, 2ln associated with the test mask hoop which is in a state to receive light beams and operate and the relative position of that of the detecting

circuits

231, 232, 23n associated with the mother mask which is similarly in a state to receive light beams and operate. This leads to the energization of relays K, to K and K to K at relatively different positions in each of said two detecting circuits brought to the aforesaid operating condition. Therefore in the comparison circuit 240 of FIG. 158, the closed one of the first normally open contacts K to K provided in that component of said comparison circuit 240 corresponding to the test mask hoop 313 lies at a different position from that assumed by the closed one of the first normally open contacts K to K formed in that component of said comparison circuit 240 corresponding to the mother mask 153.

If the voltages generated at the contacts of every two resistors consisting of one selected in turn from the group of serially disposed R to R (R to R and that of similarly serially arranged R, to R (R to R which are provided in corresponding relationship to the two groups of normally open contacts K to K,, and K to K are previously so designed as to have suitably different values, then only one of the two diodes D and D, will he obviously biased in the forward direction. Accordingly there will be turned on only the first and second transistors 'I'R and TR corresponding to the diode (D taken at this time) which has been thus biased in the forward direction so as to energize the relay K;,,. In the circuit of FIG. 15D, therefore, the normally open contact K and normally open contacts K associated with the relay K will respectively present a different condition from that shown in said FIGURE namely, the contact K is closed and the contact K is released. As a result, the position correcting motor 89 with the normal rotation winding Wp energized and the reverse rotation winding Wn deenergized, will rotate to a predetermined extent in a given direction namely, in a normal rotating direction. This makes the mother mask 153 vary its position through the feed screw 91 according to the rotating direction of said motor 89 and the amount of said rotation. When the displacement in the relative height of the travelling test mask hoop 313 and mother mask 153 is fully corrected, those figure, the two groups of detecting circuits of 211 to 21m and 231 to 23n which received light and operated at different positions now assume the same position. This means that there is no such displacement, so that the correcting operation is brought to an end at this moment.

What we claim is:

1. Apparatus for continuously and successively determining the diameter of mask apertures in a plurality of masks formed in an elongated tape material comprising:

drive means for feeding said elongated tape having a predetermined width at a substantially constant speed in the longitudinal direction of said tape;

said tape having a large number of mask apertures within predetermined equally spaced areas of said tape, thereby providing a series of perforated masks having a substantially equal spacing therebetwcen in the traveling direction of said tape, said tape having start and stop dctecting apertures near the front and rear edges of each of said masks as viewed in the traveling direction of said tape;

means for detecting said start and stop detecting apertures;

a slider device including means for fixedly engaging said slider device with said traveling tape responsive to detection of said start detecting aperture to thereby travel with said engaged tape for a distance substantially corresponding to the longitudinal length of each mask, means for releasing said slider device from said tape responsive to detection of said stop detecting aperture and means for quickly returning said released slider device to its original position before detection of the next start detecting aperture;

a mother or master mask mounted on said slider device and perforated with predetermined accurate mask apertures;

means for projecting similar light beams to corresponding areas of said mother mask and of a mask on said traveling tape while said slider is fixedly engaged with said tape;

photoelectric converting means receiving the respective light beams transmitted through each of said masks and for generating respective output electrical signals corresponding to the light received; and

an electric circuit device for comparing the magnitudes of said output electrical signals from said photoelectric converting means and detecting the difference between said output electrical signals, whereby the respective masks of said tape are approved or rejected as a function of the magnitude of the difference between said output electrical signals.

2. Apparatus according to claim 1 wherein said means for fixedly engaging said slider device to said tape includes an air cylinder.

3. Apparatus according to claim 1 wherein said means for fixedly engaging said slider device to said tape includes a magnetic chuck.

4. Apparatus according to claim 1 wherein said tape has first vertical-position-correcting apertures at predetermined points therein for use in correcting the vertical position of said tape during its travel, and wherein said mother mask has second vertical-position-correcting apertures in those parts thereof which correspond to the locations of the first verticalposition-correcting apertures in said tape, further including:

a first light source and photoelectric converting element respectively disposed on the front and back sides of tape in registration with said first position correcting apertures;

a second light source and photoelectric converting element respectively positioned on the front and back sides of said mother mask in registration with said second position correcting apertures; and

control means responsive to the difference between the magnitudes of output signals from said first and second photoelectric converting elements associated with the mask on said tape and with said mother mask for adjusting, while said tape is traveling the height of said mother mask according to the value of said difference, to thereby locate the mother mask relative to the mask on said tape.

5. Apparatus according to claim 4 wherein said first vertical-position-correcting apertures perforated in said tape are concurrently used for detecting either a start or stop signal and for vertical position correction.

6. Apparatus according to claim 4 including analogoperated perforating means for forming said first vertical-position-correcting apertures in said tape.

'7. Apparatus according to claim 6 wherein said first vertical-position-correcting apertures are triangular in form.

8. Apparatus according to claim 4 including digitally operated perforating means for forming said first vertical-position-correcting apertures in said tape.

9. Apparatus according to claim 8 wherein said first vertical-position-correcting apertures comprise a plurality of apertures of the same diameter arranged with an equal spacing therebetween in a line perpendicular to the traveling direction of said tape.

10. Apparatus according to claim I further including perforating means for forming said apertures in said tape.

11. Apparatus according to claim 10 wherein said perforating means includes photoetching means.

12. Apparatus according to claim 10 including means for feeding a control signal corresponding to the output signal from said electric circuit device back to said perforating means to alter the perforating operation.

13. Apparatus according to claim 12 wherein said perforating means includes spray nozzles discharging an etchin li uid under pressure and wherein said contro signal IS fed ac to control the pressure of the spray nozzles and the flow rate of the etching liquid discharged from said spray nozzles.

Claims

2. Apparatus according to claim 1 wherein said means for fixedly engaging said slider device to said tape includes an air cylinder.
3. Apparatus according to claim 1 wherein said means for fixedly engaging said slider device to said tape includes a magnetic chuck.
4. Apparatus according to claim 1 wherein said tape has first vertical-position-correcting apertures at predetermined points therein for use in correcting the vertical position of said tape during its travel, and wherein said mother mask has second vertical-position-correcting apertures in those parts thereof which correspond to the locations of the first vertical-position-correcting apertures in said tape, further including: a first light source and photoelectric converting element respectively disposed on the front and back sides of tape in registration with said first position correcting apertures; a second light source and photoelectric converting element respectively positioned on the front and back sides of said mother mask in registration with said second position correcting apertures; and control means responsive to the difference between the magnitudes of output signals from said first and second photoelectric converting elements associated with the mask on said tape and with said mother mask for adjusting, while said tape is traveling the height of said mother mask according to the value of said difference, to thereby locate the mother mask relative to the mask on said tape.
5. Apparatus according to claim 4 wherein said first vertical-position-correcting apertures perforated in said tape are concurrently used for detecting either a start or stop signal and for vertical position correction.
6. Apparatus according to claim 4 including analog-operated perforating means for forming said first vertical-position-correcting apertures in said tape.
7. Apparatus according to claim 6 wherein said first vertical-position-correcting apertures are triangular in form.
8. Apparatus according to claim 4 including digitally operated perforating means for forming said first vertical-position-correcting apertures in said tape.
9. Apparatus according to claim 8 wherein said first vertical-position-correcting apertures comprise a plurality of apertures of the same diameter arranged with an equal spacing therebetween in a line perpendicular to the traveling direction of said tape.
10. Apparatus according to claim 1 further including perforating means for forming said apertures in said tape.
11. Apparatus according to claim 10 wherein said perforating means includes photoetching means.
12. Apparatus according to claim 10 including means for feeding a control signal corresponding to the output signal from said electric circuit device back to said perforating means to alter the perforating operation.
13. Apparatus according to claim 12 wherein said perforating means includes spray nozzles discharging an etching liquid under pressure and wherein said control signal is fed back to control the pressure of the spray nozzles and the flow rate of the etching liquid discharged from said spray nozzles.