JP2004348501A - Image output device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a controller capable of extracting the performance of a tandem type color laser printer. <P>SOLUTION: An image output device comprises a storage means for storing printing data, an engine interface means for supplying printing data to a printer engine in accordance with an image synchronizing signal, a 1st transfer means for transferring the stored printing data to the engine interface means in parallel in each color, and a 2nd transfer means for transferring data other than the printing data transferred by the 1st transfer means. The priority order of the 1st and 2nd transfer means is specified on the basis of the image synchronizing signal. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

【００３１】
【表２】

【００３２】
【表３】

【００３３】
【表４】

【００３４】
【発明の効果】
以上説明したように、本発明の実施形態によれば、タンデム方式のカラープリンタの連続印刷処理において、プリンタエンジンの発生する同期信号タイミングから予測した並行転送される印刷データのオーバーラップのレベルに基づいてバス競合制御を行なうことにより印刷動作の遅延を抑制する効果を奏する。
【図面の簡単な説明】
【図１】本発明の一実施例による画像出力装置の構成を示すブロック図である。
【図２】一般的なプリンタの構成を説明する図である。
【図３】タンデムカラーレーザープリンタに供給する画像タイミングの例を示すものである。
【図４】本発明の実施例による処理フローを説明する図である。
【図５】本発明の実施例による割り込み処理を説明するフローチャートである。
【符号の説明】
１ ＣＰＵ
２ ＲＯＭ
３ 外部ｉ／ｆ
４ ページメモリ
５ ＤＭＡＣ
６ 画像出力部
７ バス調停部
８ プリンタエンジン
６１ａ〜ｄデコーダ
６２ａ〜ｄ バッファメモリ
６３ エンジンｉ／ｆ部[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an image output device such as a printer controller that supplies image data to a color printer engine.
[0002]
[Prior art]
As shown in FIG. 2, a page printer as an image printing apparatus is connected to a host computer having a printer driver via a network, a USB interface, and the like, and intermediate output data generated from printing source data by a device such as the host computer. And an engine unit that acquires output image data output from the controller unit and outputs the image to a medium such as paper. Intermediate output data suitable for the controller is generated by software generally called a printer driver. Further, the controller unit converts the intermediate output data into output image data suitable for the engine unit, and outputs it as a video signal to the engine unit in synchronization with an image transfer permission signal from the engine unit. The engine controls and drives the electrophotographic process, and reproduces the input video signal as an image on a medium such as paper.
[0003]
In an electrophotographic process type color printer, a high-speed printing method by parallel processing called a tandem method as disclosed in JP-A-9-192542 has been proposed and put to practical use. In the tandem system, photosensitive drums for four colors are arranged in a line, and printing processes for the respective colors are overlapped to reduce the printing time.
[0004]
[Problems to be solved by the invention]
FIG. 3 shows the print data output timing of the tandem system, in which a indicates the page synchronization signal, and b to e indicate the transfer timing of the print data. As shown in the figure, in the tandem-type electrophotographic printer, transfer of print data from the first color is started after a predetermined time (t1) when the page synchronization signal a is given. Further, a time difference (t2, t3, t4) of the output timing corresponding to the time for the printing paper to move between the drum intervals is given, and the printing data of each color starts to be sequentially transferred. The lower part of FIG. 3 shows the timing when printing is performed continuously on the second page and the third page following the processing of the first page. In the figure, the time from the completion of the data transfer of the first page to the start of the data transfer of the second page is different from the time from the completion of the data transfer of the second page to the start of the data transfer of the third page. As shown in the figure, the transfer of the first color of the second page can be started before the transfer of the fourth color of the first page is completed. Thus, the overlap between the pages can be reduced by the tandem type electrophotographic printer. It is a feature.
[0005]
Here, the reason why the interval between pages fluctuates as described above will be described.
[0006]
In the data transfer for the second and subsequent pages in the continuous printing operation, similarly to the first page, the transfer start is requested at the timing when the data necessary for output is stored in the page memory. Naturally, the shorter the page interval, the shorter the print processing time, but this page interval varies for the following reasons. As described above, the printer driver running on the host computer generates the intermediate output data, but the processing time varies depending on the print source data. In addition, there is an effect of the processing that is passed from the host computer via the external i / f of the controller, is processed, and is stored in the page memory after being processed. The problem here is the data transfer performed on the CPU bus. In the processing of the first page, all the intermediate output data is converted into printable data, stored in the page memory, and then transferred to the image output unit, so that data transfer from the host computer to the page memory and page memory Data transfer from the CPU to the image output unit does not compete on the CPU bus. However, in the second and subsequent pages, the transfer of the intermediate output data of the next page is immediately started from the host computer as soon as the transfer from the page memory to the image output unit is started. And a conflict will occur. The increase in the waiting time for the data transfer from the host computer due to the competition on the CPU bus in this way also delays the start of printing the next page, and consequently hinders the performance of the printer. Of course, the problem of the delay due to the bus contention can be avoided by sufficiently widening the bandwidth of the CPU bus, but an expensive high-speed DMA / high-speed memory system / high-speed bus system is required for that purpose.
[0007]
The present invention has been made in view of the above problems, and has as its object to provide an inexpensive image output apparatus that can suppress a delay in a printing operation due to parallel processing during continuous printing.
[0008]
[Means for Solving the Problems]
In the present invention, in order to solve the above problem, in an image output device connected to a printer engine for printing image data and supplying color image data to the printer engine, storage means for holding print data, Engine interface means for supplying print data to the printer engine in accordance with a synchronization signal, first transfer means for transferring the held print data to the engine interface means in parallel for each color, and transfer by the first transfer means And second transfer means for transferring data other than the print data to be transmitted, and the first and second transfer means are characterized in that a priority is specified based on an image synchronization signal.
[0009]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
[0010]
<Explanation of device configuration>
FIG. 1 is a block diagram showing a configuration of a controller of a tandem type color laser beam printer according to an embodiment of the present invention.
[0011]
As shown in FIG. 1, the system of the present embodiment has a configuration in which a CPU 1, a ROM 2, an external interface 3, an image memory 4, a DMAC 5, and an image output unit 6 are connected to a system bus. And execute data transfer via the system bus. The CPU 1 controls the entire apparatus and generates print data that can be output to the printer engine 8 from print data received from the external i / f3. The ROM 2 stores processing procedures (programs) processed by the CPU 1, font data, and the like. The external i / f3 is a LAN interface such as Ethernet (registered trademark) or an i / o interface such as USB, IEEE1284, or IEEE1394, and receives print data from a higher-level device (host computer). The image memory 4 temporarily stores one page of print data generated by the CPU 1. At this time, in order to save the memory capacity, the CPU 1 performs a print data compression process and stores the print data in a compressed data format. The DMAC 5 transfers the compressed print data from the image memory 4 to the image output unit 6 for each color. The image output unit 6 extends the print data and outputs the print data to the printer engine 8 in accordance with the print timing of the printer engine 8. The printer engine 8 is a tandem-type laser beam printer and needs to simultaneously transfer print data of a plurality of colors.
[0012]
Next, the internal configuration of the image output unit 6 will be described. Decoders 61a-d decompress print data transferred for each color. Reference numerals 62a to 62d denote FIFO (first-in / first-out) memories for each color, which temporarily store print data output from the decoders 61a to 61d for each color, and store the print data in the engine i / f 63 at a predetermined timing. Is output. The FIFOs 62a to 62d adjust the speed of data transfer by the DMAC 5 and the speed of data transfer to the printer engine. Reference numeral 63 denotes an engine i / f, which performs command / response communication processing with the printer engine 8 and synchronizes with a horizontal synchronization signal / vertical synchronization signal from the printer engine 8 at the time of printing to provide a FIFO 62a for each color. , And print data is output to the printer engine 8.
[0013]
A feature of the present invention resides in a method for controlling the right to use the system bus in the arbitration unit 7, and dynamically sets the transfer priority based on the data transfer timing for each color detected from the synchronization signal generated by the printer engine 8. It is in. Normally, the right to use the bus is evenly allocated to a request by a round robin method or the like. In this method, the right to use the system bus is controlled based on the print data output timing of the tandem method.
[0014]
Hereinafter, this method will be described with reference to the timing chart of FIG. 3 again.
[0015]
As described above, the time difference (t2, t3, t4) is given to the transfer of the print data of each color. At the operation timing in the upper part of FIG. 3, printing of each color performed in parallel on the system bus is performed as follows. Data transfer is increased or decreased stepwise at predetermined time intervals.
[0016]
1 color (C) → 2 colors (C, M) → 3 colors (C, M, Y) → 4 colors (C, M, Y, K) → 3 colors (M, Y, K) → 2 colors (Y , K) → 1 color (K)
In the continuous printing operation, the data overlaps with the data transfer of the other color of the previous page due to the page interval. For the first to second pages in the lower part of FIG.
[0017]
1 color (C1) → 2 colors (C1, M1) → 3 colors (C1, M1, Y1) → 4 colors (C1, M1, Y1, K1) → 3 colors (M1, Y1, K1) → 4 colors (C2 , M1, Y1, K1) → 3 colors (C2, Y1, K1) → 4 colors (C2, M2, Y1, K1) → 3 colors (C2, M2, K1) → 4 colors (C2, M2, Y2, K1) ) → 3 colors (C2, M2, Y2) → 4 colors (C2, M2, Y2, K2) → 3 colors (M2, Y2, K2) → 2 colors (Y2, K2) → 1 color (K2)
(C1 indicates the first color of the first page, and C2 indicates the first color of the second page.)
Further, no overlap time occurs between the second and third pages. The presence or absence of the overlap at the time of transfer of the print data can be determined from the interval (Tp) of the page synchronization signal a as follows.
[0018]
(1) No overlap occurs.
[0019]
t2 + t3 + t4 + t5 ≦ Tp (level 1)
(2) Overlap occurs in the first color.
[0020]
t2 + t3 + t5 ≦ Tp <t2 + t3 + t4 + t5 (level 2)
(3) Overlap occurs between the first color and the second color.
[0021]
t2 + t5 ≦ Tp <t2 + t3 + t5 (level 3)
(4) The first color, the second color, and the third color overlap.
[0022]
Tp <t2 + t5 (level 4)
That is, since t2 to t5 are predetermined values, it is possible to determine the presence or absence of the overlap of the subsequently output pages when the interval (Tp) of the page synchronization signal a is detected. Further, the relationship between the elapsed time (Tx) based on the page synchronization signal a obtained based on the above determination and the number of colors (the number of simultaneous occurrences) competing with each other is shown in Tables 1-1 to 1-1 for each of the overlap levels. It is shown in FIG. As described above, it is possible to predict the contention of the system bus accompanying the transfer of the print data of each color at each elapsed time, and to secure a necessary and sufficient band. Also, for data transfer (hereinafter referred to as host data transfer) from the host computer to the page memory, which occurs simultaneously, priority is given to a band other than the band secured for the print data transfer of each color. It is possible to suppress the waiting time caused by the contention of the system bus.
[0023]
Next, an example of bandwidth control of the system bus allocated according to the above conditions will be described.
[0024]
In the system bus according to the present embodiment, band control is performed based on the allocation ratio at the time of access contention set for the bus arbitration unit 7 for each of the elapsed times. The allocation ratio is determined as follows based on the number of simultaneous occurrences N (1 to 4) in Tables 1-1 to 1-4 described above. First, when the band of the entire bus is set to M (4 ≦ M), the allocation of each color to print data transfer is set to 1 / M. When four colors are simultaneously transferred in the print data transfer, that is, when the number of simultaneous occurrences is 4, the ratio of (M−4) / M is set in the host data transfer. Further, a ratio of (M−N) / M is given to the host data transfer according to the increase / decrease of the simultaneous occurrence number N. In other words, for each elapsed time, an assignment for a color for which no transfer occurs is assigned to host data transfer.
[0025]
Next, an example of a specific arbitration control method when M = 5 will be described.
[0026]
The arbitration control is performed by comparing the priority levels given to each bus request, and the highest priority level assigned to each simultaneously generated request is permitted. Further, when there are a plurality of requests of the highest priority level, permission is equally given among them by the round robin method. The same priority level is assigned to the print data transfer of each color, and 2 × N−1 (N = 1, 2, 3, 4) is given as the priority level according to the number of simultaneous occurrences N. For host data transfer, a priority level is assigned as follows for each bus cycle, with M bus cycles as a cycle. When M = 5, 2 × M−2 (M = 1, 2, 3, 4, 5) is assigned to each bus cycle as a priority level. For example, when N = 1, the priority level of the print data transfer of each color is “1”, whereas the priority level of the host data transfer is “0” “2” “4” “6” “ 8 ", and the bandwidth is allocated at a rate of 4/5 of the whole. Also, when N = 4, similarly, the priority level of the print data transfer of each color is “7”, and the allocation of the band to the host data transfer is １ ／. As described above, the bus arbitration method of the present embodiment can be realized with a relatively simple configuration of counting the bus cycle and comparing the priority level value.
[0027]
<Operation description>
In the above configuration, the operation of the CPU 1 will be described according to the flowchart shown in FIG. The CPU 1 receives the data sent from the host computer via the external interface 3 (step S501), and generates print data that can be output to the printer engine 8 (step S502). Further, compression processing is performed on the generated print data, and the print data is temporarily stored in the image memory 4 (step S503). When print data of a predetermined total amount (pages or blocks of a predetermined size) is generated, the CPU 1 issues a print start instruction as a command to the printer engine 8 via the engine i / f circuit (step S504). . Upon starting the printing operation, the printer engine 8 having received the print start instruction outputs a vertical / horizontal synchronization signal indicating the transfer timing of the print data. The CPU 1 detects the vertical synchronizing (page synchronizing) signal from the printer engine 8 by the engine i / f circuit 63 (step S505), and calculates the interval from the previous page from the count value of the horizontal synchronizing signal (step S506). Further, the above-described overlap level (level 1 to level 4) is determined from the page interval (step S507), and the contention level of the print data set for each elapsed time based on Tables 1-1 to 1-4. Is held (step S508). However, in the case of the first page, since the overlap with the previous page does not occur, the overlap level is handled as level 1. Subsequently, the transfer start timing of the first color is detected (step S509). The data start timing is defined by the elapsed time from the synchronization signal generated by the printer engine 8, and is calculated from the transport speed of the printing paper and the distance to each photosensitive drum. If the data start timing is detected, the DMAC 5 is controlled to start the transfer of the print data (step S510). Further, a timer for detecting a period in which the priority set first is applied is started (step S511), and interrupt processing is enabled (step S512). The processes of steps S501 to S512 are repeatedly executed until the last page (step S513), and the printing process is completed when the transfer of all data of the last page is completed (step S514).
[0028]
FIG. 5 is a flowchart of the interrupt processing enabled in FIG.
[0029]
When the elapsed time measurement timer reaches the set time, an interrupt to the CPU 1 occurs, and the priority of the next period is set to the bus arbitration unit 7 by referring to the table held in step S508 (step S601). At the same time (step S602), the time corresponding to the next period is set again in the elapsed time measuring timer (step S603). If the interrupt occurrence timing matches the data transfer start timing of each color (step S604), the transfer start permission is set to the DMAC 5 to start the transfer of the print data of the corresponding color (step S604). In this way, when the start of the DMA transfer is instructed for each color, the print data (compressed data) stored in the image memory 4 is transferred to the decoders 61a to 61d for each color. The decoders 61a to 61d expand the compressed print data, and accumulate the print data in FIFOs 62a to 62d for respective colors. The print data stored in the FIFOs 62a to 62d is sequentially read out by the engine i / f circuit 63 in accordance with the operation timing of the printer engine 8, and is converted into a serial signal by a parallel-to-serial conversion (not shown). Will be forwarded to
[0030]
[Table 1]

[0031]
[Table 2]

[0032]
[Table 3]

[0033]
[Table 4]

[0034]
【The invention's effect】
As described above, according to the embodiment of the present invention, in the continuous printing process of the tandem type color printer, based on the overlap level of the print data transferred in parallel predicted from the synchronization signal timing generated by the printer engine. By performing the bus contention control in this way, an effect of suppressing a delay in the printing operation can be obtained.
[Brief description of the drawings]
FIG. 1 is a block diagram illustrating a configuration of an image output device according to an embodiment of the present invention.
FIG. 2 is a diagram illustrating a configuration of a general printer.
FIG. 3 illustrates an example of image timing supplied to a tandem color laser printer.
FIG. 4 is a diagram illustrating a processing flow according to an embodiment of the present invention.
FIG. 5 is a flowchart illustrating an interrupt process according to an embodiment of the present invention.
[Explanation of symbols]
1 CPU
2 ROM
3 External i / f
4 page memory 5 DMAC
6 image output unit 7 bus arbitration unit 8 printer engines 61a-d decoders 62a-d buffer memory 63 engine i / f unit

Claims (2)

In an image output device connected to a printer engine for printing image data and supplying color image data to the printer engine,
Storage means for holding print data;
Engine interface means for supplying print data to the printer engine according to the image synchronization signal;
First transfer means for transferring the held print data to the engine interface means in parallel for each color;
A second transfer unit for transferring data other than the print data transferred by the first transfer unit,
An image output device, wherein the first and second transfer means are assigned priorities based on an image synchronization signal. The image output device according to claim 1, wherein the first and second transfer units share a data bus.

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