JPH04151270A - Image supply device - Google Patents

Abstract

PURPOSE:To carry out high-speed processing with less storage capacity by providing an information condensing device that condenses image data, a memory storing the condensed data, and an expanding device that expands the data read out of the memory and sends the expanded data to a recording section. CONSTITUTION:An information condensing device 34 reads out image data for one page developed in a bit map memory 23, and condenses the information by a specified information condensing method. The condensed information is temporarily stored in a memory 33. As time required for reading out and condensation of the information is normally short, image data for the next page can be developed in the bit map memory 25 after a short period of waiting time. The data stored in the memory 33 is read out and expanded with an information expanding device 32, and is sent to an I/F of a recording section 25. While expansion operation is being made to the data for the preceding page, the data for the following page can be developed in the bit map memory 23. Namely, processing for two pages can be made in parallel each other.

Description

[Detailed description of the invention] [Industrial application field]

The present invention provides an image provider that allows processing of the previous page and the following page in parallel without having to have bitmap memory for two pages.

[Conventional technology]

Some printers are equipped with an image supply device that constructs an image for one page in a bitmap memory using character images (fonts) and supplies the image to a recording section that executes printing. An example of such a printer is a laser beam printer. FIG. 6 shows a block diagram of a laser beam printer equipped with the above-described image supply device. In FIG. 6, 1 is a laser beam printer, 2 is a panel, 3 is a host computer terminal, 4 is a LAN terminal,
5 is a power terminal, 6 is an image supply device, 7 is a recording section, 8 is a power supply circuit, 9 is paper, and 10 to 14 are signal lines. Print data is transmitted from a host computer (not shown) to which the host computer terminal 3 is connected via a signal line 10.
The image is sent to the image supply bag f6 through the image supply bag f6. The laser beam printer 1 is not a host computer, but a LAN
(local area network), in which case it is sent through the LAN terminal 4. An operator can give various instructions to the laser beam printer 1 by operating the panel 2. One of the instructions includes an instruction for enlargement processing and an instruction for reduction processing. Instructions and responses between the panel 2 and the image supply device 6 are
Done through signal & ill. The detailed configuration of the image supply device 6 will be explained with reference to FIG. 5, and the image for one page created here is sent to the recording section 7 through the signal line 12. The recording unit 7 modulates the laser beam according to the image signal sent from the image supply device 6, and forms a latent image on the photosensitive drum irradiated with the modulated laser beam. Signals exchanged with the image supply device 6 during operation in the recording section 7 (for example, recording section 7 → synchronization pulse signal 2 to the image supply device 2, image supply device 6 → operation command to the recording section 7) signal) is sent through signal line 13°I4. Finally, the latent image on the photosensitive drum is transferred to paper 9, and printing is completed. FIG. 5 is a block diagram of the image supply device 6 described above. The symbols correspond to those in FIG. 6, and 20 is the host I/
F (1/F...interface), 21 is panel I/F, 22 is CPU bus, 231.23-2 is bitmap memory, 24 is bitmap controller, 25
is the recording unit 1/F, 26 is the CPU (central processing unit)
, 27 is PTC (programmable timer counter)
, 28 is a RAM (random access memory), 29 is a program memory, 30 is a character pattern memory, 31 is a removable memory section, 31-1 is a program memory, 31-2
is a character pattern memory. The program memory 29 stores programs for operating the CPU 26, and the character pattern memory 30 stores font data. The size of the stored font is one type @ (for example, 7.
In some cases, only 2 points), but in some cases, multiple types (for example,
There are also four types (7.2, 9.6, 10, 8, and 12 points). Program memory 31-1. Character pattern memory 31-
The removable memory unit 31 consisting of the program memory 29
It is connected when the capacity of the character pattern memory 30 is insufficient. The RAM 2B provides a working memory area, and for example, stores various data necessary for the operation of the CPU 26, or stores data input via the host I/F 20 or panel I/F 21. do. The bit map memory stores the printed image in a bit map (
It is a memory that provides a place to expand in the form of a map), and usually includes one bitmap memory for one page, and one page's worth of print Ml is formed there. However, with just one, even if the data for the next page is ready to be provided, the next page cannot be expanded until the previously expanded page has been read. Therefore, it has been proposed that the processing time is spent reading out the previously developed page from one focus map memory while the next page is being developed into the other bit map memory. In FIG. 5, two such bisotopic maps 1=I
The one equipped with J23-1.23-2 is shown. If the first page is expanded in the bitmap memory 23-1, the second page is expanded in the bitmap memory 23-1.
-2, and so on, the expansions are done alternately. While the expansion of the first page is being read from the bitmap memory 23-1, the expansion of the second page is performed in the bitmap memory 23-2, and the processing time is shorter than that of one buffer. The image signal read from the bitmap memory 23-1, 23-2 is sent to the recording section 7 in FIG. 6 via the recording section 17F25. The bitmap controller 24 is a bitmap controller. When accessing the bitmap memory 23-1.23-2, the bitmap memory 23-1.23-2 is
Controls data transfer to 5. Note that the PTC 27 is used to measure time, generate timing pulses, and the like.

[Problem to be solved by the invention]

However, the above-mentioned conventional image supply apparatus requires a bitmap memory for two pages, so there is a problem in that the memory capacity is large and the cost is high. The present invention aims to solve these problems.

[Means to solve the problem]

In order to solve the above problems, the image supply device of the present invention includes:
An image supply device that expands received print data into a bitmap memory and supplies the expanded image data to a recording section includes an information compression device that compresses the image data, a memory that stores the compressed data, and an information compression device that compresses the image data. The information decompression device decompresses the data read from the memory and supplies the data to the recording section.

[For production]

The information compression device compresses the image data developed in the bitmap memory, and functions to make the capacity of the memory for storing the compressed data smaller than the capacity of the bitmap memory. Once the image data from the bitmap memory is read into the memory, the data for the next page can be expanded to the bitmap memory, so while the data for the previous page is being read from the memory and expanded, the data for the next page can be expanded to the bitmap memory. Parallel processing such as page expansion becomes possible. Therefore, the overall processing can be performed at the same high speed even though it does not have two bitmap memories.

【Example】

Embodiments of the present invention will be described in detail below with reference to the drawings. (First Embodiment) FIG. 1 shows an image supply device according to a first embodiment of the present invention. The symbols correspond to those in FIG. 5, 23 is a bitmap memory, 32 is an information expansion device, 33 is a memory, 3
4 is an information compression device. The first difference in configuration from the conventional example shown in FIG. 5 is that the bitmap memory is reduced from 2 pages to 1 page. The second difference is that a mechanism is provided to compress and expand (restore) information read from the bitmap memory. The operation of printing data received from a host computer (not shown) via the host I/F 20 into the RAM 28 and developing it into the bitmap memory 23 is the same as that of the conventional example, so a description thereof will be omitted. The present invention is characterized by the configuration and operation up to sending the data developed in the focus map memory 23 to the recording section I/F 25, so this point will be explained in detail. Hinoki tJ1r"dl Sovenge Tsu J l+ L-,,,L-
? One page's worth of image data is read out and compressed using a predetermined information compression method (for example, the method used in facsimile). The compressed information is temporarily stored in the memory 33. Image data related to the next page is stored in bitmap memory 2.
Once the image data has been read from page 3, development of the image data for the next page may be started. However, in general, the time required to read and compress the information is much shorter than the time conventionally required to send the information from the bitmap memory to the recording section 17F. Therefore, the image data of the next page can be developed in the bitmap memory 23 with less waiting time than before. The data stored in the memory 33 is an information expansion bag! 32, expanded (restored), and stored in the recording section T/F2.
Sent to 5. While this expansion operation is being performed on the data of the previous page, the data of the next page can be expanded into the focus map memory 23. That is,
Processing is performed at high speed, similar to when two page bitmap memories are provided. Note that the information decompression device 32. The bitmap controller 24 also controls the memory 33 and the information compression device 34.
will do. There are various methods for storing compressed information in the memory 33, examples of which are shown below. FIG. 3 is a diagram showing a first storage method in the memory 33. The rectangle 33 indicates the memory capacity, Ao indicates the first address, A, , A, the address, and A1 the final address. In this storage method, compressed data of any page is always stored starting from address A0. In the figure, 1
Address A is used to store the first page. This is the information decompression device 3.
2, the compressed data for the first page of the second page is first stored from address A0. The figure shows that this storage required up to address At. The memory capacity of the memory 33 must be prepared to be able to store even the page with the largest amount of information, but since a normal page has a smaller amount of information than that, the memory near the final address AE is used. Opportunities to do so are rare. FIG. 4 is a diagram showing a second storage method (ring buffer method) in the memory 33. The symbols correspond to those in FIG. 3, A is an address, A 1 H is a write address for writing compressed data into the memory 33, and AOtlT is an address for reading from the memory 33 to the information decompression device 32. This is the read address being performed. This storage method stores the compressed data of the next page in the area following the area where the compressed data of the previous page is stored. In this case, the area following the final address A7 is treated as an area starting from the first address A0. If the compressed data for the first page of the first page is stored up to address A, then the compressed data for the first page of the second page is stored from address A onwards. If the compressed data for the first page of the second page is stored up to address A3, the compressed data for the first page of the third page will be stored from the next address. If the data cannot be stored even after reaching the final address A, the data is stored back to the first address A0. However, the write address A is the address that is being stored, or the read address A is the address that is currently being read to the information decompression device 32. It is controlled by the bitmap controller 24 so as not to overtake ul. This is because if the data is overtaken, data that has not yet been read out by the information decompression device F32 will be lost. With this storage method, if the amount of information in the previous page is small and the remaining area of the memory 33 is large, there is no need to wait for the compressed data of the previous page to be read to the information decompression device 32.
The next page of compressed data can be stored. Therefore, the processing speed can be made faster than that of the first storage method. (Second Embodiment) FIG. 2 shows an image supply device according to a second embodiment of the present invention. The numbers correspond to those in Figure 1, 33-1.3
3-2 is a memory. This example is an example of an image supply device of a printer (eg, duplex page printer) that performs double-sided printing. For both the front page and the back page, compressed data is formed through the bitmap memory 23 and the information compression device 34, but the memories that store the compressed data are different. The compressed data for the front side is stored in the memory 33-1, and the compressed data for the back side is stored in the memory 33-2. As the storage method in these memories, the method shown in FIG. 3 or FIG. 4 is adopted as appropriate.

【Effect of the invention】

As described above, the image supply device of the present invention has the following effects. ■ High-speed processing can be performed with less memory capacity. In the present invention, data developed in a bitmap memory is compressed, temporarily stored in another memory, and then decompressed and sent to the recording unit I/F. Once the data of the next page is read from the bitmap memory for compression, the data of the next page can be expanded. It can be expanded. In other words, parallel processing can be performed for two pages. The time required for compression is much shorter than the time required to read data directly from the focus map memory to the recording section 17F, so the waiting time to develop the next page of data in the bit map memory is shortened, and two bit map memories can be used. As with the case where it is equipped, the overall processing speed is increased. Such high-speed processing is achieved with less memory capacity than when two bitmap memories are provided. This is because the memory capacity required to store one page of compressed data is greater than the memory capacity required to provide one more bitmap memory for expanding uncompressed data.
This is because less is enough. Along with this, cost increases can also be kept low. ■ Reduce host computer time constraints. When the reception buffer of RAM 2B becomes full, the host computer is made to temporarily stop transmission and resume transmission when a free space becomes available. However, in the present invention, the memory 33.
33-1.33-2 temporarily stores the data and functions as a buffer, so the received data is stored in RAM.
28 to the bitmap memory 23, and is unlikely to become full. Therefore, there are fewer opportunities to stop the host computer, and the time required is reduced.Therefore, the host computer can be used for other tasks.

[Brief explanation of drawings]

Fig. 1: A diagram showing the first embodiment of the present invention Fig. 2:
・While illustrating the second embodiment of the present invention, FIG. 3...Memory 3
Figure 4 shows the first storage method in 3...Memory 33
Fig. 5 is a diagram showing the second storage method (ring buffer method)... Fig. 6 is a block diagram of the image supply device...
・Block configuration diagram of a laser beam printer equipped with an image supply device In the diagram, 1 is a laser beam printer, 2 is a panel, 3 is a host computer terminal, 4 is a LAN terminal, 5 is a power supply terminal, 6 is an image supply device, 7 is the recording unit, 8 is the power supply circuit, 9 is paper, 10 to 14 are signal lines, 20 is host ■/
F, 21 is a parallel I/F, 22 is a CPU bus, 23 is a bitmap memory, 24 is a bitmap controller,
25 is the recording unit 1/F, 26 is the CPU, 27 is the PTC12
8 is a RAM, 29 is a program memory, 30 is a character pattern memory, 31 is a removable memory unit, 301 is a program memory, 31-2 is a character pattern memory, 32 is an information expansion device, 33.33-133-2 is a memory, 34 is an information compression device. Figure 4 Figure 6

Claims (1)

[Claims] An image supply device that expands received print data into a bitmap memory and supplies the expanded image data to a recording unit includes an information compression device that compresses the image data, a memory that stores the compressed data, and an information compression device that compresses the image data; An image supply device comprising: an information decompression device that decompresses data read from a memory and supplies the decompressed data to a recording section.