JP3001081B2 - Printer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printer, and more particularly to a printer in which a buffer capacity of a print image buffer for storing dot image data of received print data is expanded in accordance with a load of the print data. .

[0002]

2. Description of the Related Art Conventionally, a laser printer capable of high-speed printing receives print data such as document data and image data from an external device such as a host computer or a personal computer, and prints a printable bit of the print data. While developing the image data, the developed bit image data is stored in a print image buffer, and bit image data for each dot line corresponding to one raster is sequentially read out from the print image buffer, and a laser system or the like is used. The printing mechanism prints characters and images on a printing medium.

When a dedicated buffer capacity for storing bit image data of one page is fixedly provided for the print data buffer, the buffer capacity of the print image buffer is large (for example, 1 megabyte). ), The provision of a memory chip for this large-capacity print data buffer increases the cost and
Recently, since the space for the memory chip is required, the buffer capacity of the print image buffer is
For example, various printers of a band buffer system designed to reduce the size to 1/10 pages have been proposed.

For example, Japanese Patent Laid-Open Publication No. Hei 2-30557 discloses a text memory unit (intermediate buffer) for storing received document data, and a 1/1 for storing bit image data obtained by expanding the document data in the text memory unit. n
(N is a positive integer) A video band buffer (print image buffer) for pages is provided in the same memory, and when printing print data, the size of the buffer capacity of the video band buffer depends on the data density of the print data. The buffer capacity of the video band buffer can be reduced to 1 / n pages and the occurrence of print overrun errors can be suppressed by arbitrarily setting each time by operating keys provided on the operation panel. A printing device configured as described above is described.

[0005]

However, as described above, in the printing apparatus described in Japanese Patent Application Laid-Open No. 2-305557, a band buffer system in which the buffer capacity of a video band buffer is 1 / n pages is used. By adopting the buffer capacity and making it possible to set the buffer capacity according to the density of the print data, the buffer capacity and cost can be reduced.On the other hand, the buffer capacity can be reduced by key operation each time the print data is printed. From setting,
There is a problem that the operation of setting the buffer capacity is cumbersome.

Further, since the buffer capacity of the print image buffer cannot be set appropriately and accurately in accordance with the data density of the print data, when the buffer capacity is set excessively, the text memory section coexisting with the print image buffer is not provided. The result is an inadvertent reduction in memory capacity. Conversely, when the buffer capacity is set small, there is a problem in that the bit image data creation processing speed for printing processing is lower than the printing processing speed, and a print overrun error is likely to occur.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems. The buffer capacity of a print image buffer can be optimally set in accordance with the load of data processing of print data. An object of the present invention is to provide a printer capable of preventing overrun as much as possible.

[0008]

In order to achieve the above object, a printer according to a first aspect of the present invention stores a reception data buffer for storing print data received from an external device, and stores print data received from the reception data buffer. A printer comprising: an intermediate buffer; a print image buffer for storing dot image data obtained by decoding print data of the intermediate buffer into a dot image; and a printing means for receiving dot image data from the print image buffer and printing it on a print medium. A load calculating means for calculating a load of data processing for decoding the compressed print data stored in each of the plurality of bands of the intermediate buffer; and an output from the load calculating means, and for each band of the intermediate buffer. ,
Determining means for determining whether the load is greater than a predetermined threshold, and receiving the determination result of the determining means, determining the number of bands for which the data processing load is determined to be greater than the predetermined threshold. Buffer expansion means for expanding the buffer capacity of the print image buffer by a proportional capacity.

Here, when the print data is document data, the load calculating means calculates the load based on the number of codes such as character codes and control codes. In a preferred embodiment, when the print data is image data, the load calculating means includes:
The load may be calculated based on the number of rasters in a direction orthogonal to the printing direction for printing for each dot line (claim 3 dependent on claim 1). it can.

[0010]

The print data received from the external device is temporarily stored in the receive data buffer, and the print data received from the receive data buffer is stored in the intermediate buffer. Here, in the printing process, first, the load calculating means calculates the load of the data processing for decoding the compressed print data stored in each of the plurality of bands of the intermediate buffer. Then, it is determined for each band of the intermediate buffer whether the load is greater than a predetermined threshold. The buffer expansion unit receives the determination result of the determination unit and expands the buffer capacity of the print image buffer by a capacity proportional to the number of bands for which the data processing load is determined to be larger than the predetermined threshold.

When the printing process is executed, the print data in the intermediate buffer is decoded into a dot image, and the decoded dot image data is stored in a print image buffer having an expanded buffer capacity. The dot image data stored in the print image buffer is sequentially read out and printed on a print medium by the printing means. At this time, since print data having a load greater than a predetermined threshold value is stored in the band of the intermediate buffer, even if the processing time required for the decoding process is long, the dot image data creation process is delayed. Since the dot image data for print processing is stored in the print image buffer expanded by the buffer capacity corresponding to the number of bands determined to be larger than the threshold value, the dot image data for print processing The occurrence of a so-called print overrun error in which no error occurs is minimized.

As described above, the dot image data for the printing process has a capacity proportional to the number of bands for which the load of the data process for decoding the compressed printing data stored in the intermediate buffer is determined to be larger than the threshold value. However, since the buffer capacity of the print image buffer is expanded, even if the load of data processing such as decoding slows down the dot image data creation process, the print image buffer The dot image data does not run out, the buffer capacity of the print image buffer can be set to an optimum capacity according to the load of the print data, and print overrun can be prevented as much as possible.

In the printer according to the second aspect of the present invention, when the print data is document data, the load calculating means calculates the load based on the number of codes such as character codes and control codes. The load of data processing such as decoding of print data of a document received from an external device can be grasped with high accuracy.

In the printer according to the third aspect of the present invention, when the print data is image data, the load calculating means determines the number of rasters in a direction orthogonal to a print direction for printing for each dot line. Since the load is calculated, the load of data processing such as decoding of image data received from an external device can be grasped with high accuracy.

[0015]

Embodiments of the present invention will be described below with reference to the drawings. In this embodiment, the present invention is applied to a laser printer (laser facsimile apparatus) that receives print data from an external device, stores the print data in a memory, and prints the print data. First, a printing mechanism PM provided in the laser printer 1 will be briefly described with reference to FIG. The laser printer 1 includes a laser scanner device 10, a process cartridge 20, a transfer / separation device 25 including a transfer charger and a static elimination needle, and a heating roller 3.
1, a fixing device 30 including a pressure roller 32 and the like, and a transport device 35 including a paper feed roller 36, a registration roller 37, a transport roller 38, a paper discharge roller 39, and the like.

The laser scanner device 10 includes a semiconductor laser 11, a hexahedral mirror 12, an imaging lens 13, a reflection mirror 14, a lens member 15 made of synthetic resin, and the like. Inside the process cartridge 20,
A photosensitive drum 21, a primary charger 22, a developing cylinder 23, an exposure lamp 24, and the like are incorporated therein. Then, the laser light LB emitted from the semiconductor laser 11 and incident on the hexahedral mirror 12 is deflected by a predetermined angle for each mirror surface of the hexahedral mirror 12 rotating at a constant high speed, so that the laser light LB extends over a predetermined angle range. The main scanning is performed, the light is reflected downward by the reflection mirror 14 via the imaging lens 13, and is irradiated onto the rotating photosensitive drum 21 via the lens member 15, thereby forming an electrostatic latent image.

The electrostatic latent image formed on the photosensitive drum 21 is developed by toner supplied from a developing cylinder 23, and the visible image is transferred from a paper feed cassette 5 to a transport device 35.
The recording paper P is transferred to and printed on the recording paper P conveyed by the printer, and the printed recording paper P is then conveyed onto the discharge tray 6 by the rollers 38 and 39 via the fixing device 30.

Next, the control system of the laser printer 1 will be described with reference to the block diagram of FIG. 2. Since this control system is basically the same as that of a general laser printer, it will be briefly described. And The video controller 50 of the laser printer 1 includes a CPU 51, a ROM 52 storing various control programs, and a reception buffer for receiving and storing transmission data transmitted from a data transmission device 80 such as a personal computer or a host computer. A RAM 60 provided with various memories;
A timing control circuit (TC) 53 for generating a timing signal for timing for writing / reading transmission data as reception data to / from a reception buffer, and a serial interface (S / S) for receiving data transmitted from an external data transmission device 80 (I / F) 54, a video interface (VI / F) 55 having two scan buffers of 4 Kbytes and sequentially outputting print information converted to bit image data to the DC controller 58, and an operation panel 57. Panel interface (P
(I / F) 56, which are connected to the CPU 51 via the bus 59, respectively.

The printing mechanism PM includes the laser scanner device 10 and the process cartridge 2 as described above.
0, transfer / separation device 25, fixing device 30, transport device 35
And a main motor for driving the photosensitive drum 21 and the conveying device 35, a fixing heater for the heating roller 31, and other electric component circuits.
The C controller circuit 58 includes a semiconductor laser 1 in addition to the main motor, the fixing heater, and various electric component circuits.
The scanner is configured to drive and control a scanner motor that drives the 1,6-hedral mirror 12.

In the ROM 52, a font memory, which stores printing dot pattern data relating to a large number of characters such as characters and symbols, in addition to various control programs provided in a normal laser facsimile apparatus, is used.
A memory management program for managing the memory capacity of each of the memories 61 to 69 provided in the AM 60 and the head address of each of the memories 61 to 69, and a control program for printing control specific to the present application described later are stored in advance.

Further, the ROM 52 stores a threshold value K for setting a buffer capacity to be extended as an extended print image buffer 68 described later. When the print data is document data, since the load of the print data stored in each band of the intermediate buffers 63 to 65 is large, the threshold value K is the data of the bit image data developed in the print image buffer 69. If the amount alone is used, a print overrun error may occur.
When "0 code" is set and the print data is image data, "100 raster" which may cause a print overrun error is similarly set. Here, the raster is a scanning line that is printed one dot line at a time by one scanning of the laser beam LB.

In the RAM 60, as shown in FIG.
A control memory 61 having a predetermined capacity;
Data buffer 62 for storing print data received from the printer, three intermediate buffers 63 to 65 for storing one page of compressed print data received from the received data buffer 62, and data transmitted from the data transmitting device 80. Load font memory 6 for receiving and storing font data
6, a created font memory 67 for storing font data received from the font memory of the ROM 52 or created font data created by transforming font data from the load font memory 66; an extended print image buffer 68; For example, 100 KB)
Is provided. Here, the control memory 61 is provided with a pointer, a buffer, and the like for temporarily storing the calculation result calculated by the CPU 51.

That is, a control memory of a predetermined capacity is provided from the start address A0000 of the RAM 60, and the address B0000
From the address C0000 to the end address Z0000.
The three intermediate buffers 63 to 65, the load font memory 66, the created font memory 67, and the extended print image buffer 68 are provided coexisting in an adjacent state. Here, these intermediate buffers 63 to 6
5. The load font memory 66, the created font memory 67, and the extended print image buffer 68 are configured such that their buffer capacities and memory capacities can be changed at any time according to the type and amount of received print data. Similarly, the head addresses of the buffers and the memories 63 to 68 are similarly changed at any time in accordance with the change in the buffer capacity or the memory capacity.

Next, the first to third intermediate buffers 63 to
65, the first to third intermediate buffers 63 to 65 have the same configuration, so the first intermediate buffer 63 will be briefly described with reference to FIG. The second intermediate buffer 64 is a spare for storing the print data of the next page when the print data of one page is stored in the first intermediate buffer 63, and the third intermediate buffer 65 is a second intermediate buffer. This is a spare for storing the print data of the next page when the print data of one page is stored in 64. The first intermediate buffer 63 is for storing one page of compressed print data received from the reception data buffer 62. As shown in the figure, 70 first bands to 70th bands are used. Is divided into

In each of these 70 bands, for example, a character code and a control code to be printed in a divided area corresponding to one block obtained by dividing a print area of one page into 70 blocks are stored. , About 1 KB. That is, when the document data is received, each band is provided with various control codes and character codes, such as a character size and a modification required for printing control, of about one.
When the print character size is 0 pt (points), 120 codes corresponding to about two lines of the document are stored.

However, when the print character size is smaller than 10 pt, the buffer capacity is appropriately expanded to 1 KB or more, and three or more lines of code data are stored. When image data is received, image data for about 100 rasters is usually stored. However, in the case of overprinting with a position command, the buffer capacity is appropriately expanded to 1 KB or more, and this Bit image data for more than 100 rasters is stored. The control memory 61 has a band counter that counts a count value I that sequentially designates each of the 70 bands provided in each of the intermediate buffers 63 to 65, and an extension when extended as the extended print image buffer 68. An extended band number memory for storing the number N of bands is provided.

Next, the print image buffer 69 and the extended print image buffer 68 will be briefly described with reference to FIG. First, the print image buffer 69
A buffer capacity of 100 KB having a basic capacity of 10 KB is fixedly provided.
If the data processing load included in the print data for one page stored in 6 is appropriate, store the bit image data without causing a print overrun error in the print processing. Can be.

The extended print image buffer 68 expands the storage area of the bit image data in order to suppress a print overrun error when the load of the print data stored in each of the intermediate buffers 64 to 66 is large. This is for expanding the buffer capacity of the print image buffer 69 so as to obtain it, and can be expanded by an expansion band having a basic capacity of 10 KB. Here, in FIG.
This shows a state in which a buffer capacity of 50 KB corresponding to five extension bands is set. That is, the total buffer capacity of the print image buffer storing the bit image data
100K of extended print image buffer 68 of 50K
This means that 150 KB obtained by adding B is set. still,
The free memory 70 is an unused area of the RAM 60,
It is used as an extended print image buffer 68 as needed.

Next, a printing control routine performed by the video controller 50 of the laser printer 1 will be described with reference to the flowcharts of FIGS. In the drawing, Si (i = 10, 11, 12,...) Indicates each step. When this control is started upon turning on the power to the laser printer 1, first, the buffers and memories in the RAM 60 are cleared, and the printing mechanism P
Initial setting processing for initializing M is executed (S10). Next, when received data is detected based on a data transmission start signal transmitted from the external data transmitting device 80 (S11: Yes), the received print data is first temporarily stored in the received data buffer 62. (S12), the print data stored in the reception data buffer 62 is stored in the first intermediate buffer 63 (S13). Next, when the reception of the print data for one page is not completed (S14: No),
S12 to S14 are repeatedly executed, and the received print data is sequentially stored for each band of the first intermediate buffer 63.

Next, when one page of print data is stored in the first intermediate buffer 63 (S14: Yes), the extended buffer setting process control (see FIG. 7) is executed (S1).
Five). When this control is started, first, an initial value “1” is set as the count value I of the band counter provided in the control memory 61 of the RAM 60, and the extension band of the extension band number memory in the control memory 61 is set. An initial value "0" is set as the number N (S20).

Next, the load LI of the data processing stored in the I-th band of the first intermediate buffer 63 indicated by the band count value I is calculated (S21). Here, when a character code or control code for document data is stored in the I-th band, the number of codes is calculated as a load LI. When image data is stored, the number of codes is calculated for each dot line. The number of rasters in the sub-scanning direction perpendicular to the printing direction (main scanning direction) for printing
Is calculated as

Next, when the load LI is equal to or smaller than the threshold value K stored in the ROM 52, that is, when it is not necessary to provide the extended print image buffer 68 (S22: No),
The process moves to S26. On the other hand, when the load LI is larger than the threshold value K and equal to or less than twice the threshold value K (S22: Yes)
, S23: No), the number N of extension bands is incremented by one (S25), and the routine goes to S26. However, if the load LI is 2
When it is larger than the double threshold value K (S22 / S23: Ye
s), and the number N of extension bands is incremented by two (S2
4), proceed to S26.

Next, the band count value I becomes the final "7
If it has not reached "0" (S26: No), the band count value I is incremented by one (S27), and the process returns to S21. Then, S21 to S27 are repeatedly executed, and when the band count value I reaches the final “70” (S2
6: Yes), the extended print image buffer 68 corresponding to the number N of extended bands is set by the memory management program (S28), this control ends, and the process returns to S16 of print control. For example, when the number N of extension bands is "5", as shown in FIG.
, A buffer capacity of 50 KB corresponding to the five extension bands is set, and “X0000” is set as the head address of the extension print image buffer 68.

Next, print processing control is executed (S16), and
It returns to S11. This print processing control is the same as that of a normal laser printer.
3 and sequentially decodes (decodes) the print data for each band from the first band, and based on the data in the load font memory 66 and the created font memory 67, converts the dot image data corresponding to each character code. It is created and sequentially stored in the print image buffer 69 and the extended print image buffer 68. On the other hand, the dot image data stored in the image buffers 68 and 69 are sequentially read from the head data, and printed on the printing paper P by scanning with the laser beam LB.

Here, since the print data having a large data processing load LI is stored in the band of the first intermediate buffer 63, the processing time is required for the decoding processing.
Even if the dot image data creation process is delayed, the dot image data for the printing process is added to the extended print image buffer 6 in addition to the print image buffer 69.
8, so that the occurrence of a so-called print overrun error in which dot image data for print processing does not exist in the print image buffers 68 and 69 can be prevented as much as possible.

As described above, the first intermediate buffer 6
3, the load LI of the data processing for decoding the compressed print data stored in 3 is larger than the threshold value K for the document data or the number of bands determined to be larger than the threshold value K for the image data. Extended print image buffer 69
Buffer capacity is expanded, so that even if the load of data processing such as decoding slows down the dot image data creation processing, the dot image for printing processing in the print image buffers 68 and 69 can be used. There is no data loss and the print image buffer 68
The buffer capacity of 69 can be set to an optimum capacity according to the load LI of data processing of print data, and print overrun can be suppressed as much as possible.

Here, the correspondence between the means described in the claims and the configuration in the above embodiment will be described. The load calculating means corresponds to the extension buffer setting processing control, especially S20 to S21. , And S27, which correspond to the determination means, in particular, in S22 to
Step S23 is equivalent to the buffer expansion means, in particular, step S28 of the expansion buffer setting process control.

It should be noted that the threshold value K for document data and the threshold value K for image data used in the embodiment are merely examples, and may vary depending on the buffer capacity of each band of the intermediate buffers 63 to 65. It can be set appropriately. still,
In S25 and S26 of the extended buffer setting process control, the extended print image buffer 68 may be set to have a capacity proportional to the number of bands determined to be larger than the threshold value K or the double threshold value 2K. . It should be noted that various changes may be made to the devices and means of the above-described embodiment based on existing technology or technology obvious to those skilled in the art within the scope of the technical idea of the present invention.

[0039]

As described above, according to the printer of the first aspect, a printer including a reception data buffer, an intermediate buffer, a print image buffer, and a printing unit is provided with a load calculation unit, a determination unit, and a buffer expansion unit. Means and
Since the configuration is such that the buffer capacity of the print image buffer is extended by a capacity proportional to the number of bands determined to have a load of data processing for decoding the compressed print data stored in the intermediate buffer larger than the threshold value, Even if the process of creating dot image data is delayed due to a large load, the print image buffer does not run out of dot image data for print processing, and the buffer capacity of the print image buffer is reduced. An optimal capacity can be set according to the load, and print overrun can be prevented as much as possible.

According to the second aspect of the present invention, when the print data is document data, the load calculating means includes:
Since the load is calculated based on the number of codes such as character codes and control codes, the load of data processing such as decoding of print data of a document received from an external device can be grasped with high accuracy.

Further, according to the printer of the third aspect, when the print data is image data, the load calculating means includes:
Since the load is calculated based on the number of rasters in the direction orthogonal to the printing direction for printing for each dot line, the load of data processing such as decoding of image data received from an external device can be grasped with high accuracy. it can.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of a laser printer.

FIG. 2 is a block diagram of a control system of the laser printer.

FIG. 3 is a diagram illustrating a memory map of a RAM.

FIG. 4 is a diagram illustrating a memory structure of a first intermediate buffer.

FIG. 5 is a diagram illustrating a memory structure of a print image buffer and an extended print image buffer.

FIG. 6 is a schematic flowchart of a print control routine.

FIG. 7 is a schematic flowchart of an extended buffer setting process control routine;

[Explanation of symbols]

 1 Laser Printer 50 Video Controller 52 ROM 60 RAM 62 Receive Data Buffer 63 First Intermediate Buffer 68 Extended Print Image Buffer 69 Print Image Buffer 80 Data Transmission Equipment PM Printing Mechanism

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-4-49079 (JP, A) JP-A-6-44014 (JP, A) JP-A-3-114856 (JP, A) JP-A-2- 29353 (JP, A) JP-A-5-324220 (JP, A) JP-A-6-1011 (JP, A) JP-A-6-171160 (JP, A) (58) Fields investigated (Int. ⁷ , DB name) B41J 5/30 G06F 3/12

Claims (3)

(57) [Claims] 1. A reception data buffer for storing print data received from an external device, an intermediate buffer for storing print data received from the reception data buffer, and dot image data obtained by decoding the print data of the intermediate buffer into a dot image. And a printing means for receiving dot image data from the print image buffer and printing the print data on a print medium, the compressed print data stored in each of the plurality of bands of the intermediate buffer. Load calculating means for calculating the load of the data processing to be decoded; determining means for receiving an output from the load calculating means and determining, for each band of the intermediate buffer, whether the load is greater than a predetermined threshold value Receiving the result of the judgment by the judgment means, and setting the load of the data processing to a predetermined value. A buffer expansion means for expanding the buffer capacity of the print image buffer by a capacity proportional to the number of bands determined to be larger than the threshold value. 2. When the print data is document data, the load calculating means is configured to calculate the load based on the number of codes such as character codes and control codes. 2. The printer according to 1. 3. When the print data is image data, the load calculating means is configured to calculate the load based on the number of rasters in a direction orthogonal to a printing direction for printing for each dot line. Claim 1 characterized by the following:
Printer according to.