JPH1011239A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming device capable of forming an image with little deterioration of the image while reducing the memory capacity for storing image data at the time of receiving image information in parallel to convert it into data in parallel. SOLUTION: The image forming device parallelly receives image information from plural host devices 4 to 6 by reception buffers 10 to 12 provided corresponding to plural host interfaces 7 to 9, parallelly converts image information received by the plural reception buffers into image data by plural converting means, stores image data in a storage device and then forms an image based on stored image data. The image forming device stores image data converted by a part of the converting means among image data converted by the plural converting means as it is, and stores image data coverted by the other converting means by compressing.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus such as a printer, a copying machine, a facsimile, and the like.

[0002]

2. Description of the Related Art Conventionally, there has been known an apparatus which is connected to a host apparatus and forms an image on a recording medium based on image information from the host apparatus. This device converts image information sent as code data from a host device into an intermediate code called a display list by an emulation program corresponding to the host device, and converts the display list into a bitmap format on a storage device by a system program. After expanding as image data of
An image is formed based on the image data. In particular, in recent years, a plurality of host devices can be connected to the image forming apparatus, and a plurality of reception buffers for storing image information from the host device are provided.
2. Description of the Related Art There has been known an image forming apparatus capable of receiving image information from a plurality of host devices in parallel in time (for example, Japanese Patent Application Laid-Open No. Hei 6-149497).

[0003] However, in the conventional image forming apparatus as described in JP-A-6-149497, although it is possible to receive image information from a plurality of host devices in parallel, a subsequent emulation program or the like is required. Since the development into the image data and the image formation based on the developed image data were performed as a series of operations, after all, until the image formation of the image information of one host device is completed, the other host device is used. Processing such as development of image information received from the device into image data by an emulation program or the like has not been performed. Therefore, after the image forming apparatus receives image information from a plurality of host devices in parallel, it has been difficult to reduce the entire processing time required until image formation based on the image information is completed.

[0004] In order to solve such a drawback, the present applicant divides the processing necessary until image formation is completed after receiving image information into a plurality of tasks, and divides the tasks into a plurality of tasks received from a plurality of host devices. An image forming apparatus that processes the above image information in parallel by allocating the image information in a time-division manner has been proposed (Japanese Patent Application No. 9-1996).
No. 2488). According to the image forming apparatus according to the above proposal, it is possible to develop image information from a plurality of host devices into image data at high speed and form an image.

[0005]

However, in an image forming apparatus such as a laser printer, for example, the image forming operation is performed in units of one page, so that one page of image data is stored in a storage device. Need to be kept. Accordingly, when the invention according to the above proposal is applied to an image forming apparatus such as a laser printer, and image information from a plurality of host devices is to be processed in parallel and developed into image data, The capacity of a storage device for storing image data increases in proportion to the number of host devices connected to the image forming apparatus. Therefore, there is a problem that the image forming apparatus can be speeded up, but the cost of the image forming apparatus increases. In order to solve such a problem of cost increase, image data after expansion by a plurality of emulation programs or the like is uniformly compressed and stored in a storage device, and the stored image data is expanded to form an image. It is also possible to do. However, when the compression becomes irreversible, the original image data cannot be restored, and the image may be degraded.

The present invention has been made in view of the above problems, and has as its object to receive image information from a plurality of host devices in parallel and convert the image information into image data in parallel. Conversion, storing the image data in a storage device, and storing the image data in comparison with a device that stores all image data without compression when forming an image based on the stored image data. An object of the present invention is to provide an image forming apparatus capable of forming an image with less image deterioration compared to an apparatus that compresses and stores all image data while reducing the memory capacity.

[0007]

According to a first aspect of the present invention, there is provided an image forming apparatus which is connected to a plurality of host devices by a plurality of host interfaces and is compatible with the plurality of host interfaces. With the provided receiving buffer, receives the image information from the plurality of host devices in parallel, converts the image information received in the plurality of receiving buffers into image data in parallel by a plurality of conversion means, After storing the image data in a storage device, in an image forming apparatus that performs image formation based on the stored image data,
In the image data converted by the plurality of conversion means, the image data converted by some conversion means is stored as it is, and the image data converted by other conversion means is compressed and stored. Is what you do.

In the image forming apparatus of the present invention, the image information received by the plurality of receiving buffers is converted into image data in parallel by the plurality of converting means, and a part of the converted image data is stored as it is. And the other part,
Compress and store. Thus, even if the storage capacity of the storage device for storing the image data is limited, all the image data can be stored, and some of the image data are stored without being compressed. Therefore, it is possible to eliminate image degradation based on at least the part of the image data.

According to a second aspect of the present invention, in the image forming apparatus according to the first aspect, priorities are assigned to the plurality of conversion means, respectively, and the image data converted by the high priority conversion means is not compressed. Is stored.

In the image forming apparatus of the present invention, the image data converted by the conversion means having the higher priority is stored without being compressed.

According to a third aspect of the present invention, in the image forming apparatus according to the second aspect of the present invention, the image data is allocated to each of the conversion units based on the storage capacity of the storage device for storing the image data and the priority of the conversion units. The storage area is determined.

In the image forming apparatus according to the third aspect, based on the storage capacity of the storage device for storing the image data and the priority of the converting means, the converting means sequentially compresses the data in descending order of priority. When the storage device has no storage area capable of storing the image data before compression of the remaining conversion means, the compressed image can be stored for the remaining conversion means. Allocate storage space for

According to a fourth aspect of the present invention, in the image forming apparatus of the second or third aspect, the priorities are determined in accordance with characteristics of the converting means.

According to the image forming apparatus of the present invention, the priority of the conversion means is determined according to the characteristics of the conversion means. As a result, it is possible to give a high priority to the conversion means for converting into image data which causes inconveniences such as image degradation and prolonged processing time when compressed.

Here, the size of the image data converted by the conversion means before compression is determined by the paper size (for example, A4 paper or A3 paper) and the resolution (for example, 200 DPI or 400 DPI) selected by the conversion means. ) Will be different. Therefore, the storage capacity required to store the image data converted by the conversion unit changes depending on the paper size and resolution.

Therefore, an image forming apparatus according to claim 5 is the image forming apparatus according to claim 2 or 3, wherein the priority is set based on the paper size and / or resolution selected by the conversion means, or any one of them. It is characterized in that the order is determined.

In the image forming apparatus according to the fifth aspect, the priority is determined based on one of the paper size and the resolution selected by the converting means. For example, among the conversion units, the priority of the conversion unit having the selected paper size or resolution that is large is lowered.

According to a sixth aspect of the present invention, in the image forming apparatus,
In the image forming apparatus according to the third or fourth aspect, a setting unit for setting the priority order is provided.

According to the image forming apparatus of the present invention, the setting means for setting the priority order allows the user of the image forming apparatus to set the priority order of the conversion means.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is applied to a laser printer as an image forming apparatus will be described below. FIG. 1 is a laser printer according to the present embodiment (hereinafter referred to as a laser printer)
Simply called "printer". FIG.

The printer 1 is a printer engine (hereinafter, referred to as an "engine") 3 for forming an image on a recording medium such as recording paper, and the control of the engine 3 and the engine are required to form an image. A printer controller (hereinafter, referred to as “controller”) 2 for outputting image data. The controller 2 includes a CPU (Central Processing Unit) 13 for performing various controls such as image processing, and a CP.
A program ROM (read only memory) 14, which stores a program required for control by U13,
It is composed of a RAM (random access memory) 15 as a storage device for storing image data and used as a working area of the CPU 13. The engine 3 is a part for forming an image on a recording medium by a well-known electrophotographic method, and is an optical writing device for forming a latent image on a uniformly charged photoconductor, A developing device for visualizing the image, a transfer device for transferring the toner image formed on the photoreceptor by the developing device onto a recording medium such as a recording paper, and a toner image after the transfer on the recording paper And a fixing device for fixing the image on the sheet.

The printer 1 according to the present embodiment can be connected to three host devices, a first host 4, a second host 5, and a third host 6. To this end, the controller 2 includes three host interfaces, a first host interface 7, a second host interface 8, and a third host interface 9, and a first reception buffer 1 corresponding to each host interface.
0, second receiving buffer 11, and third receiving buffer 12
It has.

An emulation program corresponding to each of the plurality of host devices is stored in the program ROM 14. In the present embodiment,
First to third emulation programs are stored to correspond to the command systems of the three types of host devices. This emulation program is a program for converting image information sent as code data from the host device into an intermediate code called a display list. The process of converting image information into a display list by an emulation program is called emulation.

The processing operations performed by the controller 2 including the above-mentioned "emulation" will be described below by taking as an example a case where image information is sent from the first host 4. Image information from the first host 4 is stored in the first reception buffer 10 via the first host interface 7. When the image information is stored in the first reception buffer 10, a CPU interrupt occurs, and the CPU 13 is notified that the image information has been sent. The CPU 13 that has received the notification by the CPU interrupt stores the program ROM
14 corresponding to the first host 4 stored in
Call the emulation program. Then, by executing the first emulation program, the CPU 13 analyzes the image information in the first reception buffer 10 and converts the image information into a display list.
The display list is converted into image data by the CPU 13 executing a system program stored in the program ROM 14, and is stored in the RAM 1.
5 is drawn in an image buffer formed in a part of the storage area No. 5.

The image data drawn in the image buffer is sent to the optical writing device of the engine 3 via the engine interface 20. The optical writing device is provided with a light emitting element that generates a light beam, and the light emitting element blinks based on the image data to form a latent image on the photoconductor as described above.

Here, in the present embodiment, the image information sent from the first host 4, the second host 5, and the third host 6 are received in parallel in time, and stored in the respective reception buffers. It is possible to Then, so-called multi-emulation, in which image information stored in the respective reception buffers is processed in parallel by time division, is possible.

In order to execute the multi-emulation, in the present embodiment, the processing executed by the controller 2 is divided into a plurality of tasks. FIG. 2 shows the divided tasks. As shown, the tasks are:
Three emulation tasks corresponding to the above-described first to third emulation programs, three drawing tasks corresponding to the three emulation tasks,
It is divided into eight tasks, one print control task and one engine control task. Of these tasks, the other tasks except the emulation task are formed as a part of the above-described system program.

Here, the emulation task converts the image information stored in the reception buffer into a display list as described above, and the drawing task converts the converted display list into the image buffer as image data. It is to draw. Therefore,
In the present embodiment, the emulation task and the drawing task constitute a conversion unit that converts image information into image data. The print control task manages the assignment of the drawing task to the CPU 13 and performs control for image formation in the printer 1. Further, the engine control task controls the image forming, paper discharge processing, error processing, and the like in the engine 3. These tasks are managed by a “scheduler” which is a part of the above-described system program. The above-mentioned scheduler achieves multi-emulation by allocating the CPU 13 to each task in a time-sharing manner.

In the printer 1 that executes such multi-emulation, the system program including the scheduler determines the emulation task to which the CPU 13 is assigned, that is, which emulation program is permitted to use the CPU 13. Use and manage. This management table is
It is stored in AM15.

FIG. 3 shows an example of the management table. FIG. 3 is an explanatory diagram illustrating a configuration example of the management table. In the illustrated example, each emulation program is assigned a priority order 31 in order, and the priority order 31 is used as a parameter to set the ID3 of the emulation program of each priority order.
Data such as 0, actual image size 32 that can be calculated from the name, resolution, and paper size, and compressed image size 33 that is the image size after compression are managed. Here, assigning priorities to the emulation programs is equivalent to assigning priorities to the conversion means for converting the image information formed by the emulation task and the drawing task into image data. The data in the management table is written by the operation of the system program during an initialization process immediately after the power of the printer 1 is turned on.

In this embodiment, based on the actual image size 32 and the compressed image size 33 written in the management table as described above, the image data converted by the emulation program up to any priority is compressed. Without memorizing it as a real image,
The calculation unit to be described later determines which of the priorities the image data converted by the emulation program should be stored as a compressed image. (Hereinafter, margin)

When the calculating means determines that the image data to be stored as the real image is, for example, the image data converted by the emulation program having the priority X, the priority 0 in the management table is determined.
For emulation programs from X to X, R
An area required for storing the real image in the AM 15 (this area is referred to as “real image buffer”) is allocated. On the other hand, an area necessary for storing the compressed image in the RAM 15 (this area is referred to as a “compressed image buffer”) is allocated to the emulation programs having the priority orders from X + 1 to n.

Here, the calculation operation of the calculation means will be described with reference to FIG. FIG. 4 is a flowchart for explaining the calculation operation in the calculation means. In the present embodiment, the calculating means is the program RO
The calculation program stored in M14 functions by obtaining the right to use the CPU. That is, the CPU 13
Functions as a calculating means in combination with the above calculation program.

First, the calculating means initializes a variable i representing the total size of the remaining image buffer with the total capacity Ia usable as an image buffer in the RAM 15 (4).
02). Thereafter, the priority determination means is called to determine the priority of each emulation program (40).
3). When the priority of each emulation program is determined, the priority variable X is initialized to 0 (404).
Then, the actual image size T [X]. Subtract Rx and update i. When the remaining image buffer total size i is updated, it is determined whether or not the size of the updated i can secure the compressed image sizes of all the remaining emulation programs with lower priority (405).

If the result of this determination is "Yes", up to the emulation program of the priority set in the current priority variable X can be stored as a real image. Therefore, the priority variable X is incremented by one, and the process returns to step 405. The steps 405, 406, and 408 are performed until the result of the determination in step 406 becomes “No”.
Is repeated. If the result of the determination in step 406 is "No", it is determined that the real image buffer is to be allocated to the emulation programs of the priorities 0 to X-1 and the emulations of the priorities X to n are determined. Determines to allocate a compressed image buffer to the program (40
7).

Next, regarding the method of determining the priority of each emulation program, (1) the priority is determined based on the characteristics of the emulation program, and (2) the priority is determined based on the size of the actual image size. This will be described separately for each case.

(1) When the priority is determined based on the characteristics of the emulation program Each of the emulation programs provided for a plurality of host devices has its own characteristics. That is, there are emulation programs having various characteristics, such as those mainly based on bitmap images, those mainly based on vector graphics, and those mainly based on text data, according to the image information sent from the host device. I do.

Here, for example, in the case of mainly using a bitmap image, a high compression ratio cannot be expected even if compression is performed. On the other hand, if you try to compress to the desired compression ratio,
The result of the compression is lossy compression, and it is impossible to reproduce the original image data even if it is expanded. Therefore, when an image is formed based on the decompressed image data, problems such as deterioration of the image occur.

In the case of vector graphics, printing bands are fluctuated up and down, so that compression and decompression frequently occur, which may cause a problem that processing takes time. Therefore, priorities of emulation programs not suitable for compression as described above are set high in advance, and a real image buffer is assigned to the emulation programs. Thereby, it is possible to prevent a problem due to compression.

The priorities according to the characteristics of each emulation program determined as described above are stored in the ROM 14 or the nonvolatile RAM 22 in the controller 2 as a priority table. Then, at the time of initialization immediately after turning on the power of the image forming apparatus, the management table described above is created with reference to this priority order table.

(2) When Priority is Determined Based on Actual Image Size Each emulation program may differ in the selected resolution and paper size. The actual image size required by each emulation program differs depending on the resolution and paper size. For example, 20
The actual image size is larger at 400 DPI than at 0 DPI (dot / inch), and the actual image size is smaller at A3 size than at A4 size.

By storing an image having a large real image size as a compressed image with a low priority,
It is possible to increase the number of emulation programs to which the real image buffer is allocated. As a result, it is possible to reduce the probability of occurrence of image degradation due to compression.

In this embodiment, when the power of the image forming apparatus is turned on, the emulation program determines what resolution and paper size are selected.
The system program detects by checking the corresponding flag of the emulation program. Then, when the actual image size is detected based on the detected flag, the actual image size is stored in the management table. This is performed at the time of initialization immediately after the power of the image forming apparatus is turned on. Therefore, when the priority order is determined, the actual image size is already stored in the management table.

In the printer according to the present embodiment,
On the operation panel 19, setting means for setting the priority order is provided. By this setting means, the nonvolatile RAM 2
The setting of the contents of the priority order table stored in No. 2 can be changed. When the contents of the priority table are changed by the setting means, the real image buffer and the compressed image buffer are allocated according to the changed priority of each emulation program. As a result, the priority of the emulation program can be changed in accordance with the desire of the user who uses the printer 1, for example, the desire to set a high priority of the emulation program that is frequently used.

In this embodiment, multi-emulation is performed by connecting three host devices, but any number of host devices may be used. When the configuration of the image forming apparatus that performs the multi-emulation is generalized, a block diagram as shown in FIG. 5 is obtained. In FIG. 5, n host devices (symbol A) can be connected, and host interfaces (symbol B), reception buffers (symbol C), and emulation programs (symbol D) are provided by n each in accordance with the connection. An example is shown.

[0046]

According to the image forming apparatus of the present invention, all image data can be stored even if the storage capacity of the storage device for storing image data is limited. Since part of the image data is stored without being compressed, image degradation based on at least the part of the image data can be eliminated. Therefore, while reducing the storage capacity of the storage device for storing the image data as compared with the device that compresses and stores all the image data, the image is compared with the device that compresses and stores all the image data. It has an excellent effect that deterioration can be reduced.

In particular, according to the image forming apparatus of the second aspect,
Since the image data converted by the high-priority conversion means is stored without compression, it is possible to prevent at least deterioration of an image based on the image data converted by the high-priority conversion means. Has an effect.

According to the image forming apparatus of the third aspect, based on the storage capacity of the storage device for storing image data and the priority of the conversion means, the conversion is performed in the order of higher priority. The area for storing the image data before compression is sequentially allocated to the means, and when the storage device has no storage area for storing the image data before compression of the remaining conversion means, the remaining conversion means is compressed. Since a storage area enough to store an image is allocated, there is an excellent effect that a situation in which image data must be compressed and stored can be reduced as much as possible.

Further, according to the image forming apparatus of the present invention, it is possible to give a high priority to the conversion means for converting into image data which, when compressed, causes inconvenience such as image deterioration and prolonged processing time. So you can
There is an excellent effect that image data by the conversion means can be stored without compression.

According to the image forming apparatus of the present invention, the priority order of the conversion means is determined based on the sheet size and / or the resolution which affect the size of the image data. This has an excellent effect that the priority of each conversion means can be determined according to the size of the image data by each conversion means. Further, for example, among the conversion units, the priority of the conversion unit having a large selected paper size or resolution is lowered, and
If the image data converted by the conversion means is compressed and stored, there is an excellent effect that more converted image data can be stored without being compressed.

In particular, according to the image forming apparatus of the present invention, the user of the image forming apparatus can set the priority order of the conversion means. There is an excellent effect that the priority of the conversion means can be changed in accordance with a desire to set a high priority of the means.

[Brief description of the drawings]

FIG. 1 is a configuration block diagram of a laser printer according to an embodiment.

FIG. 2 is an explanatory diagram illustrating division of a multi-emulation task.

FIG. 3 is an explanatory diagram illustrating a management table.

FIG. 4 is a flowchart for explaining a calculation operation in a calculation unit.

FIG. 5 is a block diagram generalizing the configuration of an image forming apparatus that performs multi-emulation.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Printer 2 Printer controller 3 Printer engine 4 1st host device 5 2nd host device 6 3rd host device 7 1st host interface 8 2nd host interface 9 3rd host interface 10 1st receiving buffer 11 2nd receiving buffer 12th 3 reception buffer 13 CPU 14 program ROM 15 RAM 16 font ROM 17 option RAM 18 panel interface 19 operation panel 20 engine interface 21 CPU bus 22 non-volatile RAM 23 first emulation task 24 second emulation task 25 third emulation task 26 drawing task 27 print control task 28 engine control task 30 emulation ID 31 priority 32 actual image size 33 Shrink the image size

Claims (6)

[Claims] 1. A plurality of host devices are connected to a plurality of host devices, and image data from the plurality of host devices is received in parallel by a reception buffer provided corresponding to the plurality of host interfaces. Converting the image information received by the plurality of reception buffers into image data in parallel by a plurality of conversion units; storing the image data in a storage device; and forming an image based on the stored image data. In the image forming apparatus, the image data converted by some of the conversion means among the image data converted by the plurality of conversion means is stored as it is, and the image data converted by another conversion means is compressed. An image forming apparatus characterized by storing information. 2. The image forming apparatus according to claim 1, wherein a priority order is set for each of said plurality of conversion means, and image data converted by the conversion means having a higher priority is stored without compression. Image forming device. 3. The image forming apparatus according to claim 2, wherein each of the conversion units is based on a storage capacity of a storage device for storing image data and a priority of the conversion unit. An image forming apparatus for determining a storage area to be allocated to a printer. 4. An image forming apparatus according to claim 2, wherein said priorities are determined according to characteristics of said converting means. 5. The image forming apparatus according to claim 2, wherein the priority is determined based on a paper size and / or a resolution selected by said conversion means. Image forming device. 6. The image forming apparatus according to claim 2, further comprising a setting unit for setting the priority.