WO1987006531A1

WO1987006531A1 - Envelope printing in dot matrix printer

Info

Publication number: WO1987006531A1
Application number: PCT/US1987/000788
Authority: WO
Inventors: Michael Joseph Piatt; Randy Kalani Ray
Original assignee: Eastman Kodak Company
Priority date: 1986-04-24
Filing date: 1987-04-09
Publication date: 1987-11-05

Abstract

A compact dot matrix printer having a paper drum (22) capable of handling 8 1/2 inch wide sheets of paper. Prints on 9 1/2 inch wide envelopes (34) by feeding the envelopes into the printer lengthwise, storing lines of character data to be printed on the envelope in an envelope print buffer (40), reading character data out one column at a time, and rotating the dot matrix pattern for each character by 90° before printing the character.

Description

E VELOPE PRINTING IN DOT MATRIX PRINTER Technical Field

The present invention relates to dot matrix printers and more particularly to printing on envelopes with dot matrix printers. Background Art

Small dot matrix printers for use with personal computers are gaining increasing commercial popularity. One such printer is the Think Jet Printer manufactured by the Hewlett—Packard Company which employs a drop—on— emand ink jet print head. The small personal printers handle standard 8 1/2 x 11 inch sheets of stationery or 8 1/2 inch wide fanfold tractor driven forms and are advantageous in that they take up very little desk space.

One draw back of the small personal printers is that they cannot print on a standard No. 10 size business envelope, since the envelope is 9 1/2 inches wide, too wide to fit in the paper drum of the personal printer. It is an object of the present invention to provide a compact personal printer that is capable of printing on envelopes that are wider than the paper drum of the printer. Disclosure of the Invention The object of the invention is achieved by feeding the envelopes lengthwise into the paper drum; storing the information to be printed on the envelope in a print buffer having a matrix of storage locations m rows by n columns for storing data representing up to m rows having n characters each of information to be printed on the envelope; addressing the print buffer one column at a time; and rotating the dot matrix patterns for each character by 90° before printing. In a preferred mode of practicing the present invention, the envelopes are temporarily fixed to an edge perforated carrier sheet for use with the tractor drive mechanism of the printer. Brief Description of the Drawings

Fig. 1 is a perspective view of the paper drum and print head of a dot matrix printer, shown printing on an envelope according to the present invention;

Fig. 2 is a plan view of an envelope attached to a carrier sheet according to a preferred mode of practicing the present invention;

Fig. 3 is a schematic diagram of the microcomputer control system of the dot matrix printer according to the present invention; and

Fig. 4 is a flow chart illustrating the operation of the control electronics shown in Fig. 3 for controlling the dot matrix printer according to the present invention.

Modes of Carrying Out the Invention

Referring now to Fig. 1, there is shown a dot matrix printer for printing on envelopes according to the present invention. A dot matrix print head 10, comprising for example, an ink jet print head having a vertical linear array of drop—on—demand type ink jets, is slidably mounted on a support 12. A stepper motor 14 is coupled to the print head 10 through a pair of pulleys 16, 18 and a cable 20 to advance the print head parallel to a paper drum 22. The paper drum 22 is wide enough to accommodate widths of paper up to 8 1/2 inches. A stepper motor 24 is coupled to the paper drum 22 and rotates the paper drum to advance paper in the paper drum line by line. Paper drum 22 is provided with tractor sprockets 26 for advancing edge perforated forms 28.

Control electronics 30 receives print data from a personal computer (not shown) and operator inputs from a control panel 32, and controls the operation of the paper drum drive motor 24, the print head advance motor 14, and the print head 10. In the normal printing mode, the dot matrix print head 10 is advanced in the direction of arrow A to print one line of characters. The paper drum 22 is then rotated in the direction of the arrow B to advance the paper one line, and the next line of characters is printed.

In the envelope mode of printing, an envelope 34 is fed lengthwise into the paper drum as shown in Fig. 1. Optionally, the envelope 34 is temporarily attached to an edge perforated carrier sheet 28, as shown in Fig. 2, to facilitate proper orientation in the dot matrix printer. The characters to be printed on the envelope are rotated 90° and printed one column at a time on the envelope. The operation of the control electronics 30 will now be described in more detail with reference to Fig. 3. The control electronics 30 includes a microprocessor 36, a read only memory (ROM) 38 for storing the control program for the microprocessor and the dot matrix patterns for the character fonts employed in the dot matrix printer, and a random access memory (RAM) 40 that functions as an input buffer for temporarily holding data representing the characters to be printed and a line buffer for temporarily holding one line of dot matrix patterns for a line of characters to be printed. In the normal mode of printing, the input buffer is configured to hold data representing one page of characters. In the envelope mode, the input buffer is configured to hold data representing lines of characters having n characters in each line, as shown in Fig. 2.

The microprocessor 36 and RAM 40 receive printing instructions and character data from a microcomputer via a standard computer interface 42, and the operator panel 32. The paper drum stepper motor 24 and the print head stepper motor 14 are controlled by drivers 44 and 46 respectively. Motor phase information is latched into the drivers 44 and 46 by a latch 48, and then power is applied to the drivers by the microprocessor 36. The individual dots produced by the dot matrix print head 10 are controlled by a set of drivers 50, one driver for each dot generating location on the print head (e.g. one driver for each ink jet in an ink jet printer, or one driver for each pin inr a dot matrix impact printer) under control of the microprocessor 36. During printing, the microprocessor retrieves the data indicating the next line of characters to be printed from RAM 40. The microprocessor employs the character data to address the character font in the ROM 38 to retrieve the dot matrix pattern for driving the print head 10 and stores the dot matrix patterns in the line buffer. The dot matrix pattern for each character is stored in a rectangular _array having rows and columns of binary bits, each bit indicating whether or not a dot should be formed at a corresponding point in the array. The binary bits are supplied one column at a time to the print head drivers 50. As the columns of dots are being printed, the print head drive motor 14 is being advanced under control of the microprocessor 36 to space each column of dots by approximately one dot width. In this way, the characters are generated a column at a time.

In the envelope mode of printing, after the operator selects the envelope mode from the control panel 32, the print buffer in RAM 40 is loaded with m lines of character data from the personal computer. However, when the character data is retrieved from the print buffer for printing, the character data is retrieved a column at a time. The first character data that is retrieved is from the first column. Then, when the dot matrix print pattern is retrieved from the character font memory in ROM 38, for storage in the line buffer, the pattern is rotated 90° clockwise by storing the bottom row of binary bits from the array in the first column of the line buffer, the second from the bottom row in the second column, and so on. When the column of characters are printed on the envelope, they will appear rotated 90° from the normal printing orientation. Printing continues in this way until the first column of characters are printed on the envelope. The next column, column 2, is then printed in a similar manner, and the process is repeated until all the columns on the envelope 34 have been printed. A compact ink jet dot matrix printer according to the present invention was constructed. The printer employs a drop—on—demand thermal ink jet print head 10 having twelve jets arranged in a vertical line. The paper drum 22 is of width sufficient for printing on single sheets or tractor fed 8 1/2 x 11 inch paper. No. 10 size envelopes were fed singly into the paper drum for printing. Alternatively, the envelopes were also temporarily mounted on the 8 1/2 inch x 11 inch perforated tractor fed paper as shown in Fig. 2 with latex glue. The envelope print buffer was configured to store twenty lines of up to 100 characters each. The microprocessor 36 is a uPD 78C10-36 CMOS 8 bit microprocessor with an 8 port, 8 bit on board A/D converter, manufactured by the NEC Company in Japan. The ROM 38 is 256K of CMOS ROM and the RAM is 64K of 100 ns CMOS static RAM. The computer interface 42 is a standard Centronics parallel interface for personal computers. Stepper motors 24 and 14 are 4—phase stepper motors with 7.5 resolution (48 steps per revolution). The control panel 32 is provided with three input switches, an "on line" switch (OL), a "line feed" switch ( F), and a "form feed" switch (FF). The printer also includes a main power switch, not shown in the drawings. The "envelope mode" is entered by pressing the F switch while turning on the main power switch. In the envelope mode, the microprocessor 36 recognizes three escape codes and three commands from the personal computer that supplies data and control signals to the printer. The escape code ESCy, m, n sets a pointer in the envelope print buffer to the mth line from the top of the buffer and the nth character from the left side of the buffer. After setting this pointer, character data is entered into the envelope print buffer beginning at this location. Additionally entered character data is stored sequentially in the envelope print buffer, until the print buffer pointer is repositioned. As noted above, each line in the print buffer will accept up to 100 characters. Additional characters wrap around to the next line. The escape code ESCx, n selects a font style from the font memory in ROM 38 depending upon the value of n. The escape code ESCz, n where n is an integer between 1 and 255 specifies the number of copies to be printed. A request for n copies may also be made through the printer by tapping the LF switch n times while continuously pressing the OL switch. The command C/R returns the envelope print buffer memory pointer to the first column of the envelope field at the left margin of the envelope buffer. The command L/F automatically generates a line feed/paper drum return signal that returns the print head to the left margin of the envelope printing field. The command F/F is employed to start envelope printing after the envelope printing buffer is loaded with character data. This command can be issued either by the computer controlling the printer, or from the front panel. The envelope is advanced to the top of form upon completion of printing. In the envelope printing mode, the character pitch is fixed at 1/12 inch and the line feed pitch is fixed at 1/6 inch. Because the character pitch and the line feed pitch are fixed, only a limited set 5 of type fonts are available in the envelope mode. Fig. 4 illustrates a program routine in microprocessor 36 for carrying out the envelope printing operation according to the present invention. After entering the envelope mode, a

10⁾ counter for the number of copies is initialized, the envelope buffer is cleared, and a character font is selected. The envelople buffer pointer is set by the computer sending the print data to the printer. The print data is received and stored in the envelope

15 buffer starting at the location indicated by the envelope buffer pointer. When all the data is received, and a print command is issued, the envelope buffer pointer is set to the bottom character in the first column (location 20, 1) and the character data

20 for the first column is retrieved from the buffer. The character data is used to retrieve the dot matrix patterns for the first column of characters from the font store, and the dot matrix patterns are rotated 90° by storing the bottom row of dot commands from

25 the character font in the firstcolumn of the line buffer, the next row up second, etc. and stored in the line buffer. The first column of characters is then printed.

Next, the print buffer pointer is

30 incremented by one column and the process is repeated until all the columns are printed. At the end of each column, the envelope buffer pointer is advanced to the next column. After the entire contents of the envelope print buffer have been printed, the printer

35 advances to the top of form, the copy counter is decremented by one, and the copy count is checked to see if all the required copies have been made. When all the copies are made, the printer returns to standby status.

Although the invention has been described with reference to printing on envelopes in a personal printer for personal computers, it could also be applied to a dot matrix portable electronic typewriter. Industrial Applicability and Advantages

The present invention is useful in compact dot matrix printers of the type used with personal computers. The invention is advantageous in that envelopes wider than the paper drum can be printed in the compact printer, thereby making the printer more versatile.

Claims

Claims :

1. A dot matrix printer having a paper drum (22) of width w, a dot matrix print head (10) for printing characters a line at a time on a page in the paper drum, a print buffer (40) for holding data representing a page of characters to be printed, a font store (38) for holding data representing the dot matrix pattern for an alphabet of characters, and control means (36) for reading the data in the print buffer, retrieving the dot matrix pattern from the font store in response thereto, and applying control signals to the dot matrix print head according to the retrieved pattern, characterized by: means for printing on envelopes (34) of widths greater than w, but heights less than w, including means for feeding an envelope lengthwise into the paper drum; said print buffer means inbluding an envelope print buffer (40) having an m row by n column matrix of storage locations for storing data representing up to m lines of n characters each, to be printed on the envelope; and said control means (36) including means for addressing the envelope print buffer one column at a time, and means for rotating the dot matrix pattern retrieved from the font store by 90°.

2. The dot matrix printer claimed in claim 1, characterized by means for feeding an envelope lengthwise into the paper drum (22), which comprises a rectangular carrier sheet (28) of paper having the envelope (34) temporarily affixed to the sheet with the long dimension of the envelope parallel to the long dimension of the sheet, and having the bottom left corner of the envelope arranged near the top left corner of the sheet.

3. The dot matrix printer claimed in claim 1, further including a tractor feed mechanism (26), characterized in that the rectangular carrier sheet of paper (28) is provided with edge perforations for cooperating with the tractor feed mechanism (26).

4. The dot matrix printer claimed in claim 1, characterized in that the printer is an ink jet printer.

5. A method for printing an envelope (34) in a dot matrix printer of the type having a paper drum (22) narrower than the envelope, a dot matrix print: head (40) for printing characters a line at a times σn a page in the paper drum, a print buffer (40) for holding data representing a page of characters to be printed, a font store (38) for holding data representing the dot matrix pattern for an alphabet of characters, and control means (36) for reading data in the print buffer, retrieving the dot matrix pattern from the font store in response thereto, and applying control signals to the dot matrix print head according to the retrieved pattern, characterized by the steps of: feeding the envelope (34) lengthwise into the paper drum (22); loading an envelope print buffer (40) having m rows by n columns of storage locations with data representing up to m lines of n characters each; reading the data from the print buffer one column at a time; and rotating the dot matrix pattern for each character by 90° before printing.

6. An article of manufacture, characterized by a rectangular carrier sheet (28) of paper having a rectangular envelope (34) temporarily affixed thereto, with the long dimension of the envelope parallel with the long dimension of the carrier sheet, and with the lower left corner of the envelope arranged near the upper left corner of the carrier sheet.

7. The article claimed in claim 6, characterized in that the carrier sheet (28) of paper is provided with edge perforations for cooperating with a tractor feed mechanism (26).