JPH0236960A - Printer - Google Patents

Abstract

PURPOSE:To retain page data with a substantially minimum storage capacity and to contrive the improvement of a memory efficiency by mounting a means which converts input data to bit map image data per page, a compression means, a storage means, and a control means determining whether the compression processing is to be applied to the retained data on the basis of the result of detecting the modulus of compressibility of the respective data. CONSTITUTION:As a retention processing in a control operation in an LBP, by referring to each timer counter 401 in a page retention table 400, a unit of the page retention table 400 corresponding to a minimum counter value, i.e. the oldest one in a plurality of paper waste stagnated in the LBP, is detected. From this unit as a start point, past page data remaining in a retention memory 106 is reprinted in the order of the units in the retention table 400. The compressed data on the retention memory 106 pointed by a page pointer 403 is released from a compression form and restored on a page memory 107 in a previous form. After waiting an operator's removing action of stagnated paper, a printer prints the restored data on the memory 107. In this manner, a data retention area can be conserved, and a memory area for another information can be increased by the conserved amount.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a printing device that converts data to be printed into a bitmap on a memory.

[Prior Art] Conventionally, this type of printing apparatus processes data input from a data source, creates a bitmap image corresponding to a print image in a memory, and converts this into an image signal. It is then sent to the printing mechanism section and printed on the recording medium.

Moreover, some printing apparatuses of this type have a relatively long conveyance path for the recording medium, and it takes a long time to discharge the printed recording medium out of the apparatus. Furthermore, some of them have a structure in which a plurality of recording media exist in the conveyance path.

In such devices, if a jam (paper jam) occurs in the conveyance path, it is necessary to reprint the recording medium remaining in the conveyance path, so it is necessary to resend the print data for this purpose. In order to eliminate this error, there is a system that temporarily stores this input data in a storage means.

Furthermore, in a device that temporarily stores input data in a storage means when a jam occurs, the above-mentioned bitmap image is compressed once in order to prevent the storage capacity from increasing during this time. There are also things to save.

[Problems to be Solved by the Invention] However, when a bitmap image is compressed, the capacity does not necessarily become smaller, and depending on the contents of the bitmap image, the capacity may increase, leading to deterioration of memory efficiency. There is.

The present invention provides a printing device that temporarily stores inputted data in a storage unit when a jam occurs, which can store page data with a substantially minimum storage capacity and improve memory efficiency. The purpose is to

[Means for Solving the Problems] The present invention provides a printing device that prints characters and images corresponding to data input from a data source, including a conversion means for converting the input data into page-by-page bitmap image data; data compression means for compressing bitmap image data; storage means for storing the bitmap image data or data compressed by the data compression means; and detecting the data compression rate of the bitmap image data. The apparatus is characterized by comprising a detection means and a data processing control means for determining whether or not to perform compression processing on data to be stored in the storage means based on the detection result of the detection means.

[Operation] In the present invention, by detecting the data compression rate of bitmap image data, the bitmap image data and the compressed data, whichever has a smaller data capacity, is stored in the storage means, thereby achieving optimal memory efficiency. can be obtained.

Embodiment FIG. 1 is a block diagram showing the configuration of a control circuit of a laser beam printer (hereinafter referred to as LBP) according to an embodiment of the present invention.

This control circuit includes a CPU 10I, an input interface circuit 103, a ROM 104, a work memory 105, a storage memory 10B, a page memory 107, a page storage amount selection switch 108, a timer circuit 109, and an image signal generator 110. and output interface circuit 111
It is equipped with.

The CPU I0I controls the entire LBP and analyzes input data. Input interface circuit 1
03 receives data transmitted from the host computer 102 serving as a data source, and transmits it to CPU10I. R
The OM 104 stores the LBP control program shown in FIGS. 5 to 7, character dot pattern information corresponding to character codes in data transmitted from the host computer 102, and the like.

The work memory 105, storage memory 10B, and page memory 107 are constituted by general RAM. The work memory 105 stores counters and tables for control programs as shown in FIG. The storage memory 106 stores various types of registration information (download fonts, overlay page information) input from the host computer 102, and compressed data after printing in the page memory 107. The page memory 107 stores one page of bitmap images based on input data from the host computer 102.

The paper size handled by this LBP is fixed to A4 size, and therefore the memory capacity of this page memory 107 is also
A constant value. Hereinafter, the capacity of this page memory 107 will be referred to as page memory size.

The page storage amount selection switch 108 selects the storage memory 106.
This selects the upper limit of the compressed data capacity of the page to be saved in the page, and is made up of, for example, a rotary switch. This page storage amount selection switch 108 selects the page memory size X1 (one page of A4 paper), X2
(2 pages of A4 paper), X3 (3 pages of A4 paper)
, x4 (corresponding to 4 pages of A4 paper) are set.

The timer circuit 109 outputs a timer interrupt signal to the CPU 1ot every 100 m5, and the timer interrupt processing routine shown in FIG. 7 is activated by this timer interrupt signal.

The image signal generator 110 converts the image data prepared in the page memory 107 into an image signal, and transmits the image signal to the printing mechanism section 112 via the output interface circuit 111 in response to a synchronization signal from the printing mechanism section 112. It is designed to be sent. Output interface circuit 11
Reference numeral 1 controls the exchange of various control signals and image signals between the CPU 101, the image generator 110, and the printing mechanism section 112.

Further, the printing mechanism section 112 realizes a series of LBP printing processes such as paper feeding, laser beam generation, image transfer to paper, and fixing. Note that when a jam occurs, the printing mechanism section 112 detects the accumulation of paper and transmits this detection signal as a status signal to the CPUl0I via the output interface circuit 111.

FIG. 2 is an abbreviated side view showing the internal configuration of the printing mechanism section 112.

A circuit board 201 including the above control circuit is provided inside the main body 200 of the LBP. In addition, the laser driver 20
2 is a circuit for driving and controlling the semiconductor laser 203, and the semiconductor laser 203 is controlled according to the input image signal.
The laser beam 204 emitted from the laser beam 204 is turned on and off.

The laser beam 204 is swung left and right by a rotating polygon mirror 205 and irradiated onto the electrostatic drum 206.
A latent image of a character pattern or image information is formed thereon. This latent image is developed by a developing unit 207 around the electrostatic drum 206 and then transferred to the paper. A4 size cut sheet paper is used as the paper, and this cut sheet paper is stored in a paper cassette 20B attached to the LBP main body 200. Then, the paper is taken into the apparatus by the paper feed roller 209 and the transport rollers 210 and 211, and is supplied to the electrostatic drum 206.

The sensors 212 and 216 are for jam detection using general optical sensors. These sensors 211.21
6, the paper taken into the apparatus by the paper feed roller 209 reaches the jam sensor 212 within a certain period of time, or the paper is transferred to the developing unit 2 by the conveyance roller 211.
07 is fixed by the fixing roller 213 within a certain period of time, passes the jam sensor 216 by the paper ejection roller 214 and paper ejection belt 215, and is completely ejected to the external paper ejection stacker 217. Please check. If the paper becomes stuck somewhere, the printing mechanism is immediately stopped and the CPU 10I is notified. This L
In BP, if a jam occurs, the paper feed roller 2
There is a possibility that up to four pages of paper may stay in the conveyance path from 09 to the paper discharge stacker 217. If this jam occurs, the damaged paper is processed within the control program so that the information of the corresponding page always remains on the storage memory 106, and the data is not retransmitted from the host computer 102. It is possible to reprint the .

As described above, the data in the page memory 1071 that has been printed is compressed and stored in the storage memory 106. FIG. 3 is a schematic diagram showing this data compression format.

In this embodiment, a so-called run-length method is used as the data compression format, and the bitmap image on the page memory 107 is alternately counted and memorized as the number of consecutive "0"s and the number of "1"s. go. In Figure 3, Wl is r
QJ indicates the number of white pits, and B1 indicates "1" or the number of black bits. (i=1.2,...)
. Here, Wl and B1 each consist of one byte, and if the number of consecutive "0" or "1" exceeds 255, a dummy "1" or "0" byte is inserted. That is, for example, in the case of Wl, if Wi=255, then set B1 =0 and take the form Wi+1 =X.

Figure 4 shows the work memory 10 used by the control program.
5 is a schematic diagram showing the data structure of No. 5 and the relationship between the work memory 105 and the storage memory 106. FIG.

This work memory includes a page save table 400,
It has a next page pointer 410, a compression counter 411, a page capacity counter 412, and a capacity setting area 413.

The page storage table 400 is a management table for storing the data on the page memory 107 in the storage memory 106, and has four cheap units according to the maximum number of jammed sheets depending on the paper conveyance path. There is.

Each table unit has a time counter 401.
, a data length area 402, and a page pointer 403.

A time counter 401 indicates that when the image data in the page memory 107 is printed and its compressed data is stored in the storage memory 106, the paper is transferred from this point to the paper ejection stacker 21.
7 is set. This time counter 401 is periodically decremented in the timer interrupt processing routine and is used to know when the page storage ends.

The data length area 402 is an area for storing the data capacity when the image data on the page memory 107 is compressed.

The page pointer 403 is an address pointer indicating the start address on the storage memory of the compressed data compressed in the format shown in FIG. 3 and stored on the storage memory 106.

On the other hand, the storage memory 106 is divided into segments of a predetermined unit, and has a structure in which free segments can be used freely, and the compressed data in the page memory 107 can be stored in any empty area of the storage memory The page is saved at the location , and is connected to the page save table 400 by the page pointer 403 . In FIG. 4, the compressed data 420, 421, and 422 of the page memory 107 are represented by diagonal lines.

The next page pointer 410 indicates the unit of the page storage table 400 to be set next, and is 1
When printing of the page is completed, the image data on the page memory 107 is compressed and the next page pointer 4
Each parameter of the unit shown in 10 is set, and the next page pointer 410 advances to the next unit.

The compression counter 411 is a byte counter when the page memory 107 is compressed according to the compression format, and the final result is set in the data length area 402 as the compressed data length.

The page capacity counter 412 counts the total data length of the plurality of compressed data currently existing in the storage memory 106 in bytes.

The page capacity setting area 413 is for storing the upper limit of the storage amount of compressed data selected by the page storage amount selection switch 108, and converts the setting of the page storage amount selection switch 108 into the number of bytes and stores it. It is supposed to be done.

Next, control operations in the LBP configured as above will be explained.

FIG. 5 is a flowchart 1 showing the main routine of the control program of CPUl0I.

First, the entire LBP is initialized, tables and counters on the work memory 105 are reset, and the storage memory 106 is cleared (Sl).

Next, referring to the page storage capacity selection switch 108, the corresponding setting value is set in the page capacity setting area 413 (B2). Then, the CPU 101 repeats the steady processing from S3 onwards. This process begins with the host computer 102
It receives data from the ROM 1.04 via the input interface circuit 103 (S3), analyzes the received data, takes out the corresponding character dot pattern from the ROM 1.04, and develops the pattern in the page memory 107 (S4). Then, this page editing is performed until the data for one page has been received, and the bitmap image for one page is stored in the page memory 1.
07 (S5).

When the preparation of the page memory 107 is completed, it is then determined whether or not a jam has occurred (S6). If no jam has occurred, the image data in the page memory 1071 is sent to the image signal generator 110, and the printing mechanism unit 1
The image signal is output to 12 and the printing operation is executed (S7
). Then, upon completion of this image output, page memory compression processing is executed (S8), it is determined again whether or not a jam has occurred (S9), and if no jam has occurred, S3 is executed.
to continue processing the next page.

In addition, in S6, if a jam occurs before image output, page memory compression processing is performed without image output (S8), the process moves to image data storage processing, and in S9, image output If a post-jam occurs, the process shifts to saving image data that has already been compressed.

This saving process first refers to each timer counter 401 in the page saving table 400, and saves the page corresponding to the one with the smallest count value, that is, the oldest of the plurality of sheets that have accumulated in the LBP and been damaged. table 400
Find the unit of (S I Q). Then, using this unit as a starting point, the past page data remaining in the storage memory 106 is reprinted on the units of the page storage table 400. First, the compressed data on the storage memory 106 indicated by the page pointer 403 is decompressed and restored to the page memory 107 in its original form (S1
1). After waiting for the operator to remove the accumulated paper (S12), the restored data on the page memory 107 is printed (S13). Note that if a jam occurs again (S14), the process returns to S10 and the process is performed again.

Next, reset the time counter 401 of the unit of the current page storage table 400 to its initial value.S1
5) Confirm that all jammed pages have been printed (31B), and return to S3 to continue processing the new page.

FIG. 6 is a flowchart showing details of the page memory compression process in S8.

First, the value of the compression counter 411 is reset to O (S
21). Then, if the page capacity counter 412 has reached the value of the page capacity setting area 413 (S2
2)', wait for the storage memory 106 to become free before performing subsequent processing. Note that as time passes, the storage memory 106 is vacated by a timer interrupt processing routine to be described later.

Furthermore, if the page capacity counter 412 does not reach the value in the page capacity setting area 413 (S22), it is determined whether the compression counter 411 has reached the page memory size (S23). If the compression counter 411 has not reached the page memory size, the compression process continues;
The continuity of the white bit and black bit at the current position on the page memory 107 is counted, and the Wi
, Bi on the storage memory 106 (524),
The compression counter 411 is updated by 2 bytes (525), and the page capacity counter 412 is also updated by 2 bytes (525).
326). Then, this operation is repeated for all areas of the page memory 107, and when the processing for the epage is completed (S27), for the unit of the page storage table 400 indicated by the next page pointer 410,
Set the time for the compressed page to be completely ejected in the time counter 401, and
2, sets the start address on the storage memory 106 containing the compressed data in the page pointer 403, updates the next page pointer 41O to the next unit, and ends the page memory compression process. (
S33).

In addition, in S23, if the value of the compression counter 411 reaches the page memory size, this indicates that the data compression format in this LBP has no compression effect on the image data in the current page memory, so compression is stopped. Process.

First, clear the compressed data that has been partially created in the storage memory 106 at this point in time (528), store the page memory size in the compression counter 411 (529), and add the page memory size to the page capacity counter 412 (S30).
). Then, wait for free space in the storage memory 106 (S31)
, Copy the contents of the page memory 107 without compression to the free area of the storage memory [, (S32), Proceed to step 333 above to end the page memory compression process.

FIG. 7 is a flowchart showing a timer interrupt processing routine that is periodically executed by the timer interrupt signal.

First, make sure that the jam is not being processed (541), reduce the value of the time counter 401 of all units in the page save table 400 by one (342), and
If the value of 1 reaches 0 (S43), this means that the target page has been completely ejected outside the LBP main body and it is no longer necessary to save the page, so the storage memory 106
To release the memory area corresponding to the compressed data 420 occupied above (544), the number of bytes for the corresponding data length area 402 is decreased from the page capacity counter 412 (S
45).

Then, it is confirmed that all units in the page storage table 400 have been checked, and the interrupt processing is terminated (S46).
).

On the other hand, in S43, if the time counter 401 does not reach 0, the unit is left as is and the 346
Proceed to.

As described above, in this printing apparatus, the user can arbitrarily select the upper limit capacity value of page compressed data to be stored in the storage memory 106 using the page storage amount selection switch 108. In addition, if there is free space, the storage memory 106 is a registration area for not only compressed data in the page memory but also font download data input from the host computer, ruled line information used for overlapping pages, and page overlay data. It can also be used as a font cache when using vector fonts as downloaded fonts.

Therefore, when the capacity of the storage memory 106 is not sufficient, either data registration or page memory storage is prioritized to improve printing speed, or the storage memory 106 is selected depending on the purpose.
06 can be assigned.

In particular, the font cache has the function of converting a vector font into a dot pattern according to the frequency of use and preparing it in a working memory, thereby speeding up the creation of a bit pattern image on the page memory. In this case, the larger the memory capacity, the better, but even if the memory capacity is small, the operation can be performed accordingly. Also, if you erase the dot pattern in the font cache to use memory for other purposes, you can still replay it later. In this way, - When setting the storage area of page memory on the same memory as information that temporarily exists in memory or information that can be immediately regenerated even if deleted, the format of the user's print data Whether it is better to make the storage area of the page memory larger or smaller depends on the amount of storage, and in this sense, the effect of the page storage amount selection switch is extremely large.

Note that although the above embodiments have been described using a laser beam printer as an example, the present invention is not limited to this and can be similarly applied to LED printers, inkjet printers, and the like.

Further, in the above embodiment, data is compressed using a run-length method, but the present invention is not limited to this, and an MH method or the like may be used.

In addition, in the above embodiment, page data is saved for reprinting when a jam occurs, but page data is compressed and saved one after another even before the bitmap information created on the page memory is printed. Then, the compressed data may be expanded and the image outputted in accordance with the paper feeding speed of the printing mechanism section.

Furthermore, in the above embodiment, if the capacity of the compressed data exceeds the capacity of the original data while data is being compressed on the page memory, the compression process is immediately stopped and the original data is adopted as the saved data. However, another method of compression processing may be attempted at the time the compression processing is stopped.

For example, as another compression method, a format is adopted in which the bit pattern p is repeated n times, such as "number of repetitions n, repetition pattern p", and the compression process is performed again. In the case of such a compression method, compared to the compression method of the above embodiment, if the target bit pattern has many periodic repetitions, the compression ratio can be significantly improved.

Also, before data compression processing, that is, when analyzing input data or outputting an image, the image tendency of the bitmap image is checked, and the compression method is switched and set to one that is suitable for the bitmap image when compressed and saved. You can do it like this.

For example, in the case of a page containing only character data, the compression method of the above embodiment is adopted, and in the case of a large proportion of photographic data (image data), a method can be adopted in which compression processing is not performed because the compression efficiency is low.

[Effects of the Invention] According to the present invention, by detecting the data compression rate of the bitmap image data, the bitmap image data and the compressed data, whichever has a substantially smaller data capacity, is stored in the storage means, Optimal memory efficiency can be obtained. Therefore, the area for storing this data can be saved, and the storage area for other information can be increased accordingly, making it possible to make the most of the limited storage area.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of a control circuit of a laser beam printer according to an embodiment of the present invention. FIG. 2 is an abbreviated side view showing the internal configuration of the printing mechanism section of the same embodiment. FIG. 3 is a schematic diagram showing the data compression format in the same embodiment. FIG. 4 is a schematic diagram showing the data structure of the work memory used by the control program and the relationship between the work memory and the storage memory in the same embodiment. FIG. 5 is a flowchart showing the main routine of the control program in the same embodiment. FIG. 6 is a flowchart showing details of page memory compression processing in the same embodiment. FIG. 7 is a flowchart showing a timer interrupt processing routine that is periodically executed by a timer interrupt signal in the same embodiment. 101...CPU, 102...Host computer, 105...Work memory, 106...Save memory, 107...Page memory 108...Page storage amount selection switch, 112...
Printing mechanism section, 400... Page storage table, 401... Time counter, 402... Data length area, 403... Page pointer, 410... Next page pointer, 411... Compression counter, 412 ...Page capacity counter, 413...Page capacity setting area.

Claims (1)

[Scope of Claims] A printing device that prints characters and images corresponding to data input from a data source, comprising: conversion means for converting the input data into bitmap image data in units of pages; data compression means for performing data compression processing; storage means for storing the bitmap image data or data compressed by the data compression means; detection means for detecting the data compression rate of the bitmap image data; A printing apparatus comprising: data processing control means for determining whether or not to perform compression processing on data stored in the storage means based on the detection result of the detection means;