JPH023351A - Printer - Google Patents

Abstract

PURPOSE:To change printing speed by clearing a picture memory only to a section corresponding to the effective block of a virtual page corresponding to a data for printing. CONSTITUTION:In a printing control section 40, a memory block assigning control section 42 discriminates the effective blocks and null blocks of each virtual page, and stores information displaying storage into any block address of a picture memory 30 of the effective block 62 of any virtual page 61 in an address conversion section 44. The block of interest of the picture memory 30 is cleared at every mapping. When a data is read, the printing control section 40 forms a null data regarding the null block section, and only an effective data is read from the picture memory 30 at specified timing. A mapping flag, etc. are reset after the reading. Accordingly, a printing output corresponding to the virtual page 61 is acquired. The memory clear operation of the null block is removed, thus shortening the clear time.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a printing device that stores print data in an image memory and prints on paper while reading the data.

(Prior Art) Various devices are known for printing print data created by a host control device such as a computer or a word processor onto paper, such as electrophotographic printers, thermal printers, and wire dot printers. It is being

FIG. 2 shows a block diagram of a printing apparatus that employs a conventional electrophotographic method.

In this device, a processor 4, a program memory 5, a working memory 6, a font memory 7, an image memory 8, and a print engine interface 9 are connected to a system bus 3 connected to a host control device 1 via an interface 2. It is of composition. A print engine 10 is connected to the print engine interface 9.

The host device 1 is a device such as a computer, word processor, or image reading device that creates print data. The interface 2 is a known circuit composed of a so-called R32.32C interface, a parallel interface, or the like. The processor 4 is a circuit that controls the entire printing apparatus, and its execution program is stored in the program memory 5. The working memory 6 is a memory for storing and managing data transmitted and received by the interface 2. The font memory 7 is a memory that converts character codes and other codes sent from the host controller 1 into font data for printing.

The image memory 8 is composed of a random access memory that stores, for example, one page of print data that has been edited and turned into an image.

Printer 1 to engine 10 are devices that print on printing paper based on printing data stored in image memory 8, and include a paper transport system, an electrophotographic process, and the like. The print engine interface 9 receives print data 9a from the image memory 8 according to instructions from the processor 4.
This is an interface circuit that reads and transfers the signal to the print engine 10, or receives the print control signal 9b output from the print engine 10, and transmits it to the processor 4, etc.

The printing device as described above temporarily stores control commands, character codes, graphic commands, bit image data, etc. received from the host control device 1 via the interface 2 in the working memory 6 as necessary. Imaged print data is created on the image memory 8 under the control of the processor 4.

The print data in the image memory 8 created in this way is
It is processed as follows.

FIG. 3 is a conceptual diagram illustrating the operation of reading print output from a conventional image memory.

As shown in the figure, when the read address 8a is input to the image memory 8, each raster ■,
The data corresponding to ■, ■, ■... are read out in order,
This will be printed in that order (■, ■, ■, ■...)
A printout 20 is obtained. That is, the data read from the image memory 8 is converted into a bit stream for each raster and sent to the print engine 10 shown in FIG. is obtained. Note that data is normally read from the image memory 8 not in bits but in words.

FIG. 4 is an explanatory diagram showing more specifically a conventional method of reading print output from an image memory.

As shown in the figure, the image memory is divided into units of one word (for example, 8 bits) for each raster (2), (2), and so on. The data is written in this word order (1),
(2), (3), etc. are read out, and a printout as shown on the right side is obtained.

As can be seen from this figure, there is a complete one-to-one correspondence between the data stored in the image memory 8 and its print output 2o. Normally, the image memory 8 is set to a memory capacity that can print out about one page 20, and even if the information scene during printing is very small, the print data for one page is always stored in the image. The data was stored in the memory 8 and then printed. Further, when writing new print data to the image memory, due to the algorithm, the image memory is first cleared before writing.

(Problem to be Solved by the Invention) Incidentally, in an electrophotographic printing apparatus, a photosensitive drum having a photoreceptor layer formed on its outer periphery is rotated at a constant speed, and a static image corresponding to printing data is placed on the photoreceptor. It forms an electric latent image. The electrostatic latent image is developed with toner and transferred and fixed onto the paper, or the printing process is continuous and cannot be interrupted. Therefore, normally, after the printing data has been completely edited in the image memory 8, the conveyance of the paper is started and the printing process is started.

FIG. 5 is an explanatory diagram of the operation of the print engine that executes such a printing process.

In the figure, paper 12 to be printed is stored in trays 11a and llb. This paper 12 is pulled out by hopping rollers 13a or 3b and conveyed on a conveyance path 14.

In front of the conveyance path 14, a photosensitive drum 15 and a writing device 16 for writing an electrostatic latent image on the outer periphery of the photosensitive drum 15 are arranged. This writing device 16 is composed of, for example, a light emitting guide array or a laser head.

In this device, a sheet of paper 12 is conveyed through a conveyance path 14 to a transfer position W. When the toner reaches the position, the toner on the photosensitive drum 15 is transferred, fixed by a fixing device (not shown), and discharged. Normally, the conveyance of the paper 12 is temporarily stopped by a registration roller or the like (not shown) at one point Wp on the conveyance path, and then the sheet 12 waits, and conveyance is resumed at the same time as the writing device 16 starts writing the electrostatic latent image. That is, the photosensitive drum 15 is β. While the paper 12 rotates by an angle α
is ρ. ' has been conveyed exactly to the transfer position W. reach.

In order to control such timing, the timing at which print data is transferred from the image memory 8 to the writing device 16 in FIG. 4. This is after transporting by 10ρ2.

FIG. 6 is a time chart showing the timing of writing data to the image memory and the timing of reading data.

As shown in the figure, first, time t. The image memory for one screen is cleared between time t1 and time t1. Subsequently, writing starts from time tl, and when the writing of the first page print data to the image memory ends at time t2, the hopping roller 13a or 13b shown in FIG. 5 starts conveying the paper 12 at time t3. . Thereafter, after waiting until time t4, reading of the print data for the first page from the image memory is started. Between times t3 and t4, the paper 12 pulled out from the trays 11a and 11b shown in FIG. 5 is conveyed to one point Wp on the conveyance path 14. Then, the transfer position W is set at the same timing using a registration roller or the like. (Fig. 5). In this way, the printing process for the first page is advanced.

On the other hand, if printing data is written into and read out from the image memory alternately, the waiting time on the print engine side increases.

Therefore, in order to speed up processing, reading of the first page data is started, and before the reading is finished,
Writing of data for the second page is started. Time t4
The time from t5 to time t5 is the time from when reading of the first page is started to securing a certain memory area for writing data of the second page. Also, time t
5 to time t6 is the time for clearing the read memory area.

Therefore, the time tx from the end of writing of the first page to the start of writing of the next second page is from t2 to t6.
It will be between.

After time t6, the data of the second page is written while clearing the memory in order each time. Furthermore, when reading of the first page data from the image memory is completed at time t7, the final memory clear is performed until time t8, and writing of the second page data continues from time t8 to time t9. Printing of the first page is executed while the second page is being written, and this is completed at time t. The paper will be ejected.

Here, the time for clearing the memory performed when writing the second page is the time required to substantially clear the entire page, and is the same as the time for clearing the memory performed between time to and tl. It will be time. Since this memory clear time is a relatively long time that cannot be ignored compared to the data write time, some measure is required to shorten the data write time.

Therefore, it has been proposed to use a method called a read-modify-write method, for example, to clear the memory at the same time as reading the image memory. However, the time required to access the image memory becomes longer due to the data write time required to clear the memory, which hinders high-speed reading. In particular, as the resolution of the printed image increases, a larger capacity image memory is required, which increases the memory clearing time and significantly reduces the printing speed.

The present invention has been made in view of the above points, and it is an object of the present invention to provide a printing apparatus that eliminates the memory clear operation of unnecessary areas and achieves faster printing.

(Means for Solving the Problems) A printing apparatus of the present invention includes an image memory that stores print data, a print control unit that writes the print data to the image memory, and a print control unit that reads the print data from the image memory. and a printing section that performs printing, and the printing control section includes:
Divide a virtual page consisting of one page of images virtually set to correspond to print output into multiple blocks, and check whether each block is a blank block consisting only of blank data or valid data. a block determining unit that determines whether the block is a valid block containing the block; and a memory block allocation that selects only the valid block based on the determination result of the block determining unit and writes data to the image memory in units of blocks. A control unit associates the block address of the valid block in the virtual page with the block address of the image memory in which the valid block is written, and determines whether each block in the virtual page is the valid block or the blank block. and an address conversion unit storing a mapping flag for identifying the virtual page to which the valid block written in the image memory belongs, and a page identification flag for identifying the virtual page to which the valid block written in the image memory belongs, and the memory block allocation control unit: When writing data for printing, a mapping flag indicating the valid block is set, and after clearing the corresponding block of the image memory, the data of the valid block is written to that block, and the data of the valid block is written to the block. The present invention is characterized in that it operates to reset the mapping flag and page identification flag after reading the data of the valid block from the memory.

(For further information) Even if the above-mentioned apparatus has an image memory with a capacity for one page, for example, it is possible to store data for several pages depending on the content of the print data.

First, a virtual page is set on the processor side for each page to be printed. This virtual page is then divided into multiple blocks. Among these blocks, blank blocks consisting only of blank data are excluded, and only valid blocks containing valid data are written into the image memory.

For virtual pages with many blank spaces, this effective number of blocks will be very small. Therefore, it is possible to store several virtual pages in one page of image memory.

In order to store valid data in a predetermined block of the image memory in this manner, or to read and print data stored in the image memory, an address conversion section is provided.

In the print control unit, the memory block allocation control unit identifies valid blocks and blank blocks of each virtual page, and sends information indicating which virtual page's valid block is stored at which block address in the image memory to an address. Store in the converter. The address conversion unit also stores a mapping flag indicating which virtual page block is a valid block.

During this mapping, the corresponding block in the image memory is cleared each time. Further, when reading data, the print control section generates blank data for blank block portions, and only valid data is read from the image memory at a predetermined timing. After this reading, the mapping flag etc. are reset.

Thereby, a printout corresponding to the virtual page is obtained. Furthermore, since there is no memory clearing operation for blank blocks, the clearing time is shortened.

(Example) Hereinafter, the present invention will be specifically explained with reference to Examples.

FIG. 1 is a block diagram showing an embodiment of a printing apparatus of the present invention. The overall configuration of this device is similar to that shown in FIG. 2, but in this device, writing and reading of data in the image memory 30 is controlled by a print control section 40 as shown in the figure.

This device includes a block determination section 41 that receives print data 60, a memory block allocation control section 42 that assigns a write address for the data to the image memory 30, and an address generation section 4 that generates a block address.
3, and an address conversion unit 4 that performs predetermined address conversion, etc.
4, a connection switching circuit 45 for switching the input of write data to the image memory 30 or the output path of read data from this, and a printing section 50.

Before giving a detailed explanation of the operation of the apparatus of No. 1, first, the principle operation of the apparatus of the present invention will be explained using FIG.

In FIG. 9, this example shows a case where printing of two virtual pages (2) and (3) is requested.

First, the virtual pages ■ and ■ are each divided into a plurality of blocks 62 and 62'. For example, each block has a 128×128 bit configuration.

When a virtual page is divided into a plurality of blocks in this manner, each block is classified into a blank block 62' consisting only of blank data and a valid block 62 containing valid data. Then, the print control unit 40 shown in FIG.
Only the valid block 62 containing the valid data of (2) is written. If you do this, each virtual page
, ■ will be disassembled into pieces, but two pages worth of effective blocks 62 will be stored with sufficient margin in the image memory 30 with a capacity of one page.

After writing the print data to the image memory 3o in this way, print outputs as shown on the right side of FIG.
In order to obtain , the first block of virtual page ■ (
It is determined whether the block at coordinates (x, y)/(0, O)) is a blank block 62', and if it is a blank block, the memory block allocation control unit 42 of FIG. 1 generates blank data. If the block is a valid block 62, the data corresponding to the valid block is read from the image memory 3o and output to the print unit 5o.

This makes it possible to reproduce print outputs ■ and print outputs ■ corresponding to virtual pages ■ and ■.

Also, while printing the printout ■ of the virtual page ■,
It is possible to write the printing data of the virtual page (2) into the image memory 30 in parallel, and it is possible to speed up the processing.

Now, consider the image memory clearing operation.

In the conventional case, there was a one-to-one correspondence between the virtual page (2) and each block of the image memory 30, and writing was performed after all blank blocks were cleared. However, in the present invention, since blank blocks are not written, the corresponding memory clear operation is omitted.

That is, the apparatus of the present invention clears the memory of a valid block immediately before writing the data of a valid block into the image memory, thereby achieving a reduction in the number of memory clear operations.

Returning to FIG. 1 again, the specific operation of the apparatus of the present invention will be described.

In FIG. 1, print data 60 is configured by being divided into a large number of blocks 62 when looking at the virtual page 61 thereof.

When performing a write operation, the data is input to the block determining section 41 and the connection switching circuit 45 in units of one word (for example, 8 bits). The block determining unit 41 is a circuit that determines whether each block 62 constituting the virtual page 61 is a blank block or a valid block. That is, the comparator 41b provided in the block determination section 41 is manually inputted with the write data and the reference value 41a (data set to the level of blank data). After performing this comparison for one block of data, the determination result is output to the memory block allocation control section 42.

The memory block allocation control unit 42 controls the image memory 30
This is a circuit composed of a microprocessor and the like that controls writing of data to the computer. Based on the determination result output from the comparator 41b, the memory block allocation control unit 42 prevents the data from being written to the image memory 30 if all the blocks of the virtual page 61 are blank blocks consisting of only blank data. do. On the other hand, in the case of a valid block containing valid data, the write data input to the image memory 30 is controlled to be written to a predetermined address via the connection switching circuit 45.

The address generation unit 43 is a circuit that generates an address and outputs it to the memory block allocation control unit 42 in order to read data of the virtual page 61 word by word.

The address conversion unit 44 associates a mapping flag T for identifying whether each block is a valid block or a blank block with respect to all block addresses of the virtual page 61,
In addition, in the case of a valid block, it has an address conversion memory 44a that is associated with a block address RM of the image memory 30 in which the block is written. This address translation memory 44a has a capacity capable of storing flags and the like for a plurality of virtual pages. In addition, for all block addresses in the image memory 30, an empty block instruction is stored that stores page identification flags P1 to Px that identify which virtual page's valid block is written to that block address. memory 44b.

The memory block allocation control unit 42 writes the data of each virtual page to the image memory 30 in the manner described in FIG. This is a device for reading out the data toward the printing section 5o. The printing section 5o is
This is a print engine with a mechanism as explained in FIG.

The printing apparatus of the present invention having the above configuration operates as follows.

First, when the address generation unit 43 generates the address of the virtual page, the memory block allocation control unit 42 reads the data of the first block of the virtual page 61 in word units in the order of this address, and the block determination unit 41 reads out the data of the first block of the virtual page 61 in word units. Based on the determination result, if the data constitutes a blank block, it is not written to the image memory 30, and if it constitutes a valid block, it is written to the image memory 3°. When the determination result that the read data constitutes a valid block is input to the memory block allocation control section 42, the memory block allocation control section 42 refers to the address conversion memory 44a of the address conversion section 44.

FIG. 8 shows a detailed operational explanatory diagram of the address translation section.

In the figure, the address conversion memory 44a contains a mapping flag T indicating which block contains the data that has just been read out (whether a blank block is a valid block), and a block address RM of the image memory 30 into which the block is written.
is stored. When storing the first data constituting a valid block in the image memory 30, the mapping flag has an initial value of zero, and the block address RM of the image memory 30 is also undetermined. Therefore, in this case, the mapping flag is set to 1, the first block address of the image memory 30 is written to the block address RM of the image memory 30, and then the memory is cleared for the block at the block address RM of the image memory 30. Do the following.

Thereafter, the data for one word is written to the block address of the image memory 30.

Following the one word of data, one block of data that is successively read from the virtual page 61 is all included in the same valid block.

Then, when the mapping flag T is referred to each time it is read, it indicates that the month has passed and mapping has been completed, so the data is written to the block address RM already written in the address conversion memory 44a. . It is assumed that the image memory 30 is provided with an address pointer (not shown), which is incremented every time one word of data is written to control the write address.

On the other hand, when a predetermined valid block of the virtual page 61 is written to a predetermined block address of the image memory 30, the free block instruction memory 44b of the address conversion unit 44 stores information about which block address for each block address of the image memory 3o. A page identification flag is set to identify whether data for a virtual page has been stored. This page identification flag, like the mapping flag, has a content of 1 if it is mapped, and a zero if it is not mapped. Therefore, for each block in the image memory 30, if all the page identification flags are zero, it is known that the block has not been mapped to anything, and if any page identification flag is 1, the block has already been mapped. It turns out to be a block. In order to write a new valid block, the empty block designation memory 44b is referred to when determining an empty block address in the image memory.

In this way, when the address generation unit 43 in FIG. 1 supplies the address for one page to the memory block allocation control unit 42, the image memory 30 of the virtual page for one page
Data writing to is completed. Then, data for the next virtual page is written.

In parallel with this, printing of already written pages can be carried out. In this case, first, the address generation unit 43 in FIG.
direction). The memory block allocation control unit 42 uses the address conversion unit 4 based on this address.
The address conversion memory 44a of No. 4 is referred to.

Here, if the mapping flag T corresponding to the block address is 1, the valid data is read from the image memory 30 by referring to the corresponding block address RM of the image memory 30, and the valid data is read out from the image memory 30 via the connection switching circuit 45. The printing data is output to the printing unit 50. Further, referring to the address conversion memory 44a, if the mapping flag T is zero, the memory block allocation control unit 42 generates blank data by itself, and transfers this to the printing unit 50 via the connection switching circuit 45. Output to.

If you perform this operation one block at a time,
As shown in FIG. 9, the image on the virtual page 61 can be reproduced as a printout. When the reading is completed, the mapping flag T and page identification flag of that virtual page are all reset (cleared to zero), making it possible to write the next virtual page.

FIG. 9 is a flowchart showing the data write operation of the above-mentioned apparatus of the present invention.

In the figure, when a write operation is started, a virtual page is first read (step Sl). Here, it is determined whether the first read block is a blank block (step S2). In the case of a blank block, the T flag of the block of the corresponding virtual page in the address translation memory is set to 0° (step S3).

On the other hand, if the read block is not a blank block, it is determined whether the T flag is "°1°" (step S4). At the stage when the first data of the corresponding block is written, this T flag is Since it is °゛0°°, the T flag of the block of the corresponding virtual page in the address translation memory is set to "1" (step S5).Then, referring to the free block indication memory, the target of writing in the image memory is set. A block address is determined (step S6).

Next, the corresponding block address RM is written into the address conversion memory (step S7). Here, before writing data, one block of the corresponding block in the image memory is cleared (step S8). Then, the data of the virtual page is written into the corresponding block of the image memory (step S9).

Thereafter, it is determined whether the write operation for one virtual page has been completed (step 5IO). If one page has not been completed, the process returns to step S1. Also, after the first data of the valid block is written, the T flag is "°1".

Therefore, in step S4, the process directly proceeds to step S9, and the next data is overwritten in the corresponding block of the image memory. When writing the first data of a new effective block again, the process moves from step S4 to step S85.

The write operation is executed as described above.

Next, FIG. 10 is a flowchart showing a data read operation.

When a read operation is started, the mapping flag T of the address translation memory is first referenced (step Sl
). Here, it is determined whether the T flag is °O'° or not (
Step S2). If the T flag is "0", the block is a blank block, and one block of blank data is output (step S3). On the other hand, if the T flag is not '0', it is a valid block, and the corresponding block address RM is referred to (step S4).
. Then, one block worth of valid blocks at that address is read out from the image memory (step S5). After that, 1
It is determined whether reading of all pages has been completed (
Step S6), if not completed, return to step S1; if completed, proceed to step S7). When reading of one page is completed, all T flags of the address translation memory corresponding to the read virtual page are reset. Further, all T flags corresponding to the virtual page in the free block designation memory are reset (step S8).

In other words, the image memory is not cleared during the readout stage.

FIG. 11 shows two examples of actual virtual page configurations.

FIG. 2A shows a virtual page consisting of 80 blocks, of which 34 hatched blocks are valid blocks 62 and the other blocks are blank blocks 62'. On the other hand, the virtual page shown in FIG. 6B is composed of 80 blocks, of which 11 blocks are valid blocks 62 and the remaining blocks are blank blocks 62'.

When printing two types of virtual pages like this,
The memory clear time is as follows.

FIG. 12 is a graph comparing memory clear times.

In the figure, what is shown at the top of the graph is the total time for memory clearing using the conventional method, and that time is t3. However, when the present invention is implemented, the memory of the virtual page shown in FIG. 11(a) is cleared in a shorter time t2 as shown in FIG. 12. Further, the virtual page shown in FIG. 11(b) is cleared in memory in an even shorter time t1 as shown in FIG. 12.

In this manner, in the apparatus of the present invention, memory clearing of the image memory is performed only for the valid blocks when writing into the valid blocks, so that the memory clearing time decreases in accordance with the proportion occupied by the valid blocks.

Therefore, for virtual pages with few valid blocks,
Memory clearing time is significantly reduced.

The present invention is not limited to the above embodiments.

The configuration of the printing section is not limited to electrophotography, but may be of any type such as a thermal printer type or a wire dot type. Further, the printing control section may be replaced with various circuits having similar performance.

(Effects of the Invention) According to the printing apparatus of the present invention described above, the image memory is cleared only for the portion corresponding to the valid block of the virtual page corresponding to the print data, so it is more unnecessary than before. The rear operation can be largely omitted and the printing speed can be increased.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the printing apparatus of the present invention;
FIG. 2 is a block diagram of a conventional printing device, FIG. 3 is a conceptual diagram illustrating control of reading print output from a conventional image memory, and FIG. 4 is a specific example of the operation of reading print output from a conventional image memory. An explanatory diagram explaining an example, FIG. 5 is an explanatory diagram of the operation of the print engine, FIG. 6 is a time chart explaining the writing/reading timing of a conventional image memory, and FIG. 7 is an explanation diagram of the operating principle of the printing apparatus of the present invention. FIG. 8 is a diagram explaining the detailed operation of the address conversion unit of the device of the present invention, FIG. 9 is a flowchart explaining the write operation of the device of the present invention, and FIG. 10 is a diagram showing the data of the device of the present invention. FIG. 11 is an explanatory diagram showing an example of the configuration of a virtual page, and FIG. 12 is a graph comparing the memory clearing time when printing the virtual page. 30... Image memory, 40... Print control unit, 41.
...Block determination unit, 42...Memory block allocation control unit, 43...
Address generation section, 44...Address conversion section, 44a.
...Memory for address conversion, 44b...Memory for empty block instruction, 45...Connection switching circuit, 50...Print section, 60...Print data, 61...Virtual page, 62...・Block, T.
...Mapping flag, RM...Image memory block address, P,, P2...Px...Page identification flag. Patent applicant Oki Electric Industry Co., Ltd.

Claims (1)

[Scope of Claims] An image memory that stores print data, a print control unit that writes print data to the image memory, and a print unit that performs printing while reading print data from the image memory, The print control unit divides a virtual page consisting of one page of images virtually set in correspondence with print output into a plurality of blocks, and divides each block into blocks consisting only of blank data. a block determining unit that determines whether the block is a blank block or a valid block containing valid data; and a block determining unit that selects only the valid blocks based on the determination result of the block determining unit and stores data in the image memory in units of blocks. A memory block allocation control unit that performs writing, associates the block address of the valid block in the virtual page with the block address of the image memory to which the valid block is written, and each block in the virtual page corresponds to the block address in the virtual page. an address conversion unit storing a mapping flag for identifying whether the block is a valid block or the blank block, and a page identification flag for identifying a virtual page to which the valid block written in the image memory belongs; When writing print data, the allocation control unit sets a mapping flag indicating the valid block, clears the corresponding block of the image memory, and then writes the data of the valid block to the block; The printing apparatus further operates to reset the mapping flag and page identification flag after reading data of the valid block from the image memory.