JPS60160264A - Control system of bit map memory - Google Patents

Abstract

PURPOSE:To attain high speed printing without increasing the storage capacity by controlling the system so that the image storage start and end address of continued pages is made continuous and expanding sequentially the image of the next page to the read end area. CONSTITUTION:A bit map memory (BMM) 25 has a memory capacity of 1 page +alpha. When the image of the 1st one page's share is expanded to the area of addresses A-B-1 of the BMM25, a control section 22 sets a start address A to an address register (AR) 42, sets a page end address B-1 to an end address register (EA) 43 and also starts a printer 3. The control section 22 reads a character code of the next page from a RAM23 without awaiting the read of data from the BMM25 and expands it to an idle area (+alpha area) represented by the addresses B-C-1. In this case, when the control section 22 expands the area to the area of the address C-1, the section receives an address data represented in an AR42, identifies the read position and after the idle area cleared exists with the finished read, the image is expanded to the area.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a control method for a bitmap memory used in a printer.

[Technical background of the invention and its problems]

Conventionally, in laser beam printers, a photosensitive drum is rotated at a constant speed, and a latent image is formed on the drum in accordance with the print image in the bitmap memory, and printing is performed page by page. It is not possible to interrupt the printing operation in the middle of printing, so the bitmap memory has enough space to develop one page's worth of print images before printing. For this reason, a bitmap memory with a storage capacity of at least one page is prepared in the printer control unit, but since this type of memory is very expensive, it is usually configured with a storage capacity of one page. is called page memory.

In non-impact printers such as laser beam printers that have bitmap memory for one page, that is, page memory, all of the print image for one page developed on the page memory is sent to the printer mechanism. After that, the character generator was accessed based on the input character code, the next page's character image was generated at one character position, and the image was expanded into dots on the page memory.
It takes a long time from the end of printing the previous page to the start of printing the next page, making it impossible to increase the printing speed.

Therefore, when page printing is started and the images developed on the page memory are sequentially sent to the printer mechanism,
By clearing the memory area from which the output has been sent, that is, from which reading has been completed, and developing the print image of the next page in that area, the entire printing process can be performed efficiently and at high speed.

On the other hand, in recent years, non-impact printers with the above-mentioned page printing function have been designed to speed up the printer mechanism. There has been a need to shorten the time required for deployment.

Particularly in conventional laser beam printers, as mentioned above, once printing starts, the paper cannot be stopped midway, and the printer mechanism is activated only after one page's worth of print images have been developed in the page memory. Moreover, the data in the page memory is read out only after a predetermined period of time has elapsed after the printer mechanism has started and the positions of the rotating photosensitive drum and conveyed paper have been synchronized. From the time the mechanism is activated until the page memory is read, no free space can be created in the page memory, and therefore the image of the next page cannot be developed on the page memory during that time. This time usually takes about 1 to 2 seconds, and during this time the printer control unit cannot develop the image on the page memory.
This has been a problem in increasing the printing operation speed.

[Object of the Invention] The present invention has been made in view of the above-mentioned circumstances, and it is possible to print an image in a bitmap memory with a relatively inexpensive and simple configuration without significantly increasing the storage capacity of the bitmap memory. It is an object of the present invention to provide a bitmap memory control method capable of executing high-speed printing processing without affecting the time required for the entire processing.

CSummary of the Invention 7 The present invention comprises a bitmap memory having a storage capacity slightly larger than one page, and a continuous bitmap memory so that the image storage start address of the next page always follows the image storage end address of the immediately previous page. When performing page printing, the reading end area is cleared one by one, and the printer mechanism is activated to start printing, so that the empty area can be filled without waiting for the page to be printed. The structure is such that the print images of the next page are developed one after another. As a result, the image of the next page can be developed even during the time period from when the printer mechanism is activated until the image is transferred (read) from the bitmap memory, and the image is transferred to the bitmap memory. This eliminates the time impact that image development processing has on the entire printing process, making it possible to achieve high-speed printing processing.

[Embodiment of the Invention] An embodiment of the present invention will be described below with reference to the drawings. 1st
The figure is a block diagram showing the overall configuration of the device in one embodiment. In the figure, 1 is the upper processing unit at (H-CPU)
, 2 is the 7u computer system'1jNS, and 3 is the printer mechanism. 21 to 26 are printer control units 2, respectively.
21 is an interface unit (IF) that transmits and receives various information including commands, print data (character codes), etc. to and from the upper processing device 1 via the signal line 11; Each component (21 to 26) in the printer control unit 2 is executed under a predetermined microprogram.
23 is a RAM having a program storage area and a print data storage area; 24 is a control unit (CTL) that controls the print data (character code) stored in the RAM 23 under the control of the control unit 22; 25 is a character generator (CG) that is accessed when generating a character image according to the content; 25 is a bitmap memory (BMM) configured with a storage capacity of 1 page + α in which a print image is developed in units of 1 page; 26 is a control Under the control of the unit 22, the image data (dot pattern data) read out from the bitmap memory 25 is subjected to parallel-to-serial conversion, and sent as a video signal to the printer mechanism 3 via the signal line 12, as well as transferring the video signal. This is a video signal generation unit (VID) that performs management, address update control of the bitmap memory 25, and the like.

Further, 31 to 36 each constitute a component of the printer mechanism 3, and 31 is a mechanism control unit (MO) of the laser beam printer, 32 is a laser oscillation unit, and 33 is a mechanism control unit (MO) of the laser beam printer.
is a polygon mirror, 34 is a photosensitive drum, 35 is a paper cassette, 36 to 38 are paper transport rollers, and p is paper.

FIG. 2 is a block diagram showing the configuration of the bitmap memory 25 and video signal generation section 26.

In the figure, 41 to 52 are components of the video signal generation unit 26, and 41 is the first and second address registers (ARl, AR2) of the bitmap memory, and the bitmap memory 25 is They are used alternately each time one page of images is developed, and are incremented (+1) in accordance with the read operation of the bitmap memory 25 under the control of the memory read control section 41. 43,
and 45 are first and second end address registers (ERl, ER2) provided corresponding to the first and second address registers (ARl, AR2) 42, 44, respectively.
and the corresponding address registers (ARl, AR2)
Address (end address) data indicating the final address of the storage area for one page is set for the start address which is initially set to 42.degree. 44. A comparator 46 detects an address match between the first address register 42 and the first end address register 43, and a comparator 47 detects an address match between the second 7 address register 44 and the second end address register 45. 48 is the comparator 4
6 is a gate for invalidating the address of the first address register 42 when a match is detected; 49 is an inverter that inverts the match detection signal of the comparator 46; 50 is a gate for invalidating the address of the first address register 42 when a match is detected by the comparator 41; A gate for invalidating the address of the register 44; 51 a shift register (SHI FT) for serially converting the dot image data read from the pin 1 to map memory 25; 52;
is a video control unit that sends the serial data output from the shift register 51 onto the signal line 12 as a video signal and controls the memory read control unit 41. Also, the area indicated by address A-B-1 of the bitmap memory 25 is the image storage area for the first page, so here the area indicated by address B-C-1 is the area of +α, and the next page Image development will be performed in the area indicated by address BD-1.

The operation of one embodiment will now be described with reference to the drawings. When print data is sent character by character from the upper processing device 1 to the printer control unit 2 via the signal line 11, this print data is sequentially received by the interface unit 21 and processed under the control of the control unit 22. is stored in the RAM 23. Further, the control section 22 reads out the print data stored in the control section 22 in character units (in units of one character code), generates an address according to the code contents, and obtains character image data according to the address from the character generator 24. , and writes this image data into the bitmap memory 25. Here, image development (writing of image data) for the first page is started from address A shown in FIG.

In this way, the operation of expanding the image dots into the bitmap memory 25 continues, and the bitmap memory 25
When the image for the first page is developed in the area indicated by address A-B-1, the control section 22 sets the start address (see FIG. The end address of the page (address B-1 shown in FIG. 2) is set in the first end address register 43. Further, the control section 22 activates the mechanism control section 31 of the printer mechanism 3 via the memory read control section 41 and the video control section 52 in the video signal generation section 26 .

Here, conventionally, data has not yet been read from the bitmap memory (page memory), and therefore, there is no free space on the page memory, so it is not possible to develop the image of the next page yet, but in the present invention. Then, when the mechanism control section 31 is activated, the image of the next page is developed in the free area (+α area) indicated by the address B-C-1 of the bitmap memory 25 by the same image development process as described above. That is, when the control section 22 activates the mechanism control section 31, the character code of the next page is read out from the RAM 23 without waiting for the data to be read out from the bitmap memory 25, and the character image data is read out from the character generator 24. Then, the image is developed in the free area (10α area) indicated by addresses B to C-1 on the bitmap memory 25. At this time, when the control section 22 expands (writes) the image data up to the area of address C-1, from then on, the address data indicated by the first address register 42 of the video signal generation section 26 is transferred to the memory readout control section 41. After reading the data and confirming that a cleared empty area exists, the image is developed in that area.

That is, after the control unit 22 develops the image of the next page in the free area (10α area) of the bitmap memory 25, it develops the image of the next page while monitoring the read address so as not to exceed the read end area. This prevents the data to be printed that has been expanded and not yet transferred to the printer mechanism 3 from being destroyed by the data of the next page.

On the other hand, when activated by the printer control section 2, the mechanism control section 31 drives and controls the paper conveying rollers 36 and 37 to start feeding the paper p. When the paper p reaches a fixed position in front of the paper conveyance roller 38, the paper feeding operation is stopped and print data is requested from the video signal generation section 26. This request signal is received by the memory read control section 41 via the shift register 51 in the video signal generation section 26. The memory read control section 41 is connected to the video control section 5.
When a data request is received from the mechanism control unit 31 via 2, the bitmap memory 25 is read and controlled by the address in the address register 42, the address register 42 is incremented (+1) L, and the read data is transferred to the shift register 51. After setting and performing parallel-to-serial conversion, it is sent to the mechanism control section 31 via the video control section 52. The mechanism control section 31 buffers this data and sends it to the laser oscillation section 32 at a predetermined timing. The laser oscillation unit 32 turns on and off the laser beam according to the input data. This laser beam is transmitted to a polygon mirror 33 that rotates at a constant speed in the direction of the arrow shown in the figure.
The light is emitted and reflected to draw a scanning line 1 on the photosensitive drum 34, and a latent image is formed on the photosensitive drum 34 by toner processing (not shown).

Here, after the printer mechanism 3 is activated, the paper p is conveyed to a fixed position, and the printer mechanism 3
Normally, it takes about 1 to 2 seconds for the data to be accepted. During this time, as mentioned above, conventionally, as there is no free space in the bitmap memory 25, the image of the next page cannot be developed. Although the next operation has not been executed yet, the operation according to the present invention is executed, and the bitmap memory 2 is
The image of the next page is developed in the +α area of addresses B to C-1 of No. 5.

On the other hand, the paper p, which had stopped before the paper transport roller 38, is moved by the drive of the paper transport roller 38 at a timing when the latent image position of the photosensitive drum 34, which rotates at a constant speed, and the transfer position of the paper p are synchronized. , is fed to a transfer position, and is transferred at a fixed position in contact with the photosensitive drum 34.

When such print processing operations are sequentially executed and the updated address of the first address register 42 matches the end address set in the first end address register 43, this address match is detected by the comparator 46. The detection signal closes the gate and invalidates the first address register 42, and also notifies the memory read control unit 41 that the transfer of one page of print image is completed, and starts the image transfer operation of one page. ends.

Also, during the above operation, the address register 4
Every time data is read from the bitmap memory 25 according to address 2, the read end area is cleared. When the data at address A is transferred, that area is cleared, and then the data at address A+1 is cleared. When the transfer is completed, that area is cleared, and similarly, when the data at address B-1 is transferred, that area is cleared. And in this cleared area,
The image data following the above +α area is expanded.

In this way, when all image development for the next page is completed, that is, the address B-C-D of the bitmap memory 25 is
When image data for one page to be printed next is stored in the area indicated by -1, the control section 22 sets the address B1 in the address register 42 in the video signal generation section 26 and the address C1 in the end address register 43. After setting address A in the address register 44 and address D in the end address register 45, the video signal generation unit 2
The memory read control unit 41 in 6 is activated.

As a result, the memory read control unit 41 first sequentially reads data from the free area of the bitmap memory 25 indicated by the address register 42 and the end address register 43, that is, the area of addresses B-C, and transfers this data to the printer mechanism 3. It is sent to the mechanism control unit 31 of. When the address of the address register 42 matches the address of the end address register 43, that is, when the comparator 46 detects a match of the address C, the memory readout 1b IJI 11 section 41 is notified of this, and the gate 48 is closed and address register 42 is invalidated. When the memory read control unit 41 receives a match detection signal from the comparator 46, it stops updating control of the address register 42, and instead, from now on, the data is read according to the address data of the address register 44 in which address A is set as the start address. Data is sequentially read from the bitmap memory 25. At this time, it goes without saying that the address register 44 is updated (+1) each time data is read. When the address of the address register 44 matches the address of the end address register 45, that is, when the comparator 46 detects a match of the address D, this is notified to the memory read control unit 41, and the gate 50 is closed, the address register 44 is invalidated, and the image transfer of one page is completed.

By repeating such operations, page-by-page printing is performed continuously.

As described above, in the embodiment of the present invention, the printer mechanism 3 is activated from the printer controller 4 2, and thereafter the data is read from the bitmap memory 25 and transferred to the printer mechanism 3. Even during this period, the image development process for the next page is performed in advance in the bitmap memory 25, so the bitmap memory 25
It is possible to speed up image development processing on a page-by-page basis on the 5th page, and to speed up the overall page printing processing operation.

Although the above embodiment has been explained using a laser beam printer as an example, it is also applicable to non-impact printers having other configurations having a bitmap memory.

[Effects of the Invention] As described in detail above, according to the present invention, after developing a print image for one page in a bitmap memory, the printing mechanism is activated to position the paper, In printers that print continuously page by page, the bitmap memory is configured with a storage capacity slightly larger than one page, and the image storage start address of the next page is always the image storage end address of the immediately previous page. Continuous address control is performed as follows, and when printing a page, the reading end area is cleared in sequence, and the printer mechanism is activated to start printing, thereby starting the page printing. By configuring the printer to sequentially expand the print image of the next page into the free space without waiting, the transfer (read) operation of the image stored in the bitmap memory is executed after starting up the printer mechanism. Pit map memory control that enables high-speed printing processing by eliminating the time impact that image development processing in bitmap memory has on the entire print process. method can be provided.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the overall structure of an embodiment of the present invention, and FIG. 2 is a block diagram showing a partial structure of the printer control section in the above embodiment. 1... Upper processing device, 2... Printer control unit, 3
... printer mechanism, 21 ... interface section, 22 ... control section, 23 ... RAM, 24 ...
Character generator, 25... Bit map memory, 26... Video signal generation section, 31... Mechanism control section, 32... Laser oscillation section, 33... Polygon mirror, 34... Photosensitive drum, 35...Paper cassette, 36.37.38...Paper conveyance roller 41.
...Memory read control unit, 42...Address register 43...End address register, 44...Second address register, 45...Second end address register 46, 47...Comparator, 48.50...Gate, 51...Shift register, 52...Video control unit. Applicant's agent Patent attorney Takehiko Suzue

Claims (1)

[Claims] After developing one page's worth of print image in the bitmap memory, the printing mechanism is started, and the printing mechanism positions the paper and prints continuously page by page. The map memory is configured with a storage capacity of 1 page + 1/n pages, and when printing a page, the read end area of the bit map memory is cleared in sequence, and the print image for one page is stored in the bit map memory. After the expansion, the printing start is activated, so that the printing image of the next page starts to be expanded from the first address of the remaining 1/n page area of the bitmap memory without starting the printing of the page. A bitmap memory control method characterized by the following.