JP2021100168A - Image forming apparatus and image forming method - Google Patents

Abstract

To provide a technique for receiving a plurality of jobs at the same time, while maintaining a balance between a hardware resource and power consumption.SOLUTION: An image forming apparatus 10 comprises: an image reading unit that performs DMA transfer of image data to a storage unit in a non-compressed state; a RIP processing unit that performs DMA transfer of dot data to the storage unit in a non-compressed state; an image forming unit that forms an image on an image formation medium; and a control unit that, when receiving other job during execution of one job in a plurality of types of jobs, and an amount of the dot data stored in a memory for the execution of one job is larger than a threshold set in advance, substitutes the dot data with compressed data generated through reversible compression of the dot data to increase an available area in the memory and receives other job. A memory control unit secures, in the memory, continuous areas for the DMA transfer with the image reading unit, the DMA transfer with the RIP processing unit, and the DMA transfer with the image forming unit.SELECTED DRAWING: Figure 2

Description

The present invention relates to an image forming apparatus and an image forming method, and relates to a technique for realizing efficient processing with a particularly small amount of hardware resources.

An image forming apparatus (for example, a printer, a multifunction printer, or a multifunction peripheral) may execute a long-time job such as a copying process using an automatic document feeder or a printing job with a large number of prints. When executing such a job, it is assumed that the image forming apparatus is constrained for a long time, while a large amount of memory is consumed and other jobs cannot be accepted. Such a problem of large amount of memory consumption. For example, as in Patent Documents 1 and 2, a technique of executing a reversible compression process in a memory and performing a swap process in the memory has also been proposed.

Japanese Unexamined Patent Publication No. 9-136456 Japanese Unexamined Patent Publication No. 11-157146

However, the inventor of the present application has focused on the potential problem of extra power consumption due to the processing of the processor in the technology that positively uses the lossless compression processing in the memory.

The present invention has been made in view of such a situation, and an object of the present invention is to provide a technique for accepting a plurality of jobs at the same time while maintaining a balance between hardware resources and power consumption.

The present invention provides an image forming apparatus capable of forming an image on an image forming medium and accepting a plurality of types of jobs. The image forming apparatus reads a memory, a storage unit having a memory control unit for controlling the memory, and a document image which is an image on a document, generates image data representing the document image, and generates the image data. The image reading unit is uncompressed and DMA-transferred to the storage unit, and halftone processing is performed on the image data to generate dot data representing the formation state of dots formed on the image forming medium. An RIP processing unit that DMA-transfers the dot data to the storage unit uncompressed, an image-forming unit that forms an image on an image-forming medium based on the dot data uncompressed and DMA-transferred from the storage unit, and the above. When one of a plurality of types of jobs is being executed and another job is received, the amount of dot data stored in the memory for executing the one job is preset. A control unit that increases the available area in the memory and receives the other job by replacing the dot data with the compressed data generated by reversibly compressing the dot data when the number exceeds the threshold value. The memory control unit has a continuous area for DMA transfer with the image reading unit, a continuous area for DMA transfer with the RIP processing unit, and a DMA between the image forming unit. A continuous area for transfer is secured in the memory, and when the dot data is reversibly compressed, the control unit expands the compressed data and transfers it to the image forming unit as dot data by DMA. To do.

The present invention provides an image forming method that forms an image on an image forming medium, can accept a plurality of types of jobs, and uses an image forming apparatus having a memory. The image forming method includes a memory control step for controlling the memory, reading a document image which is an image on a document, generating image data representing the document image, and uncompressing the image data to DMA in the memory. The image reading step to be transferred and the halftone processing are executed on the image data to generate dot data representing the formation state of dots formed on the image forming medium, and the dot data is uncompressed and the memory. A RIP processing step of DMA transfer to, an image formation step of forming an image on an image forming medium based on dot data uncompressed and DMA transferred from the memory, and one of the plurality of types of jobs. When another job is received during execution and the amount of dot data stored in the memory for executing the one job is larger than a preset threshold value, the dot data is input. The memory control step includes a control step of increasing the available area in the memory and receiving the other job by replacing the dot data with the compressed data generated by reversible compression, and the memory control step is the image reading step. A continuous area for DMA transfer between the two, a continuous area for DMA transfer between the RIP processing steps, and a continuous area for DMA transfer between the image forming steps are stored in the memory. When the dot data is reversibly compressed, the control step expands the compressed data and performs DMA transfer to the image forming step as dot data.

According to the present invention, it is possible to provide a technique for accepting a plurality of jobs at the same time while maintaining a balance between hardware resources and power consumption.

It is a schematic block diagram which shows the whole structure of the image forming apparatus 10 which concerns on one Embodiment of this invention. It is a block diagram which shows the functional structure of the image forming apparatus 10 which concerns on one Embodiment. It is a flowchart which shows the content of the copy process which concerns on 1st Embodiment. It is explanatory drawing which shows the memory area in the copy processing which concerns on 1st Embodiment. It is a flowchart which shows the content of the image formation process which concerns on 1st Embodiment. It is a flowchart which shows the content of the copy process which concerns on 2nd Embodiment.

Hereinafter, embodiments for carrying out the present invention (hereinafter, referred to as “embodiments”) will be described with reference to the drawings.

FIG. 1 is a schematic configuration diagram showing an overall configuration of an image forming apparatus 10 according to an embodiment of the present invention. FIG. 2 is a block diagram showing a functional configuration of the image forming apparatus 10 according to the embodiment. The image forming apparatus 10 includes an image reading unit 100, a control unit 210, an image forming unit 220 for forming a monochrome image, an operation display unit 230, a storage unit 240, a fax processing unit 250, and a single extension. It includes a circuit 260, a communication interface unit (also referred to as a communication I / F unit) 270, a RIP processing unit 280, a paper feeding unit 290, and a data bus 295 that connects them to each other.

The image reading unit 100 collects the first reflecting mirror 113, the first carriage 114, the second reflecting mirror 115, the third reflecting mirror 116, and the second carriage 117 between the document and the image sensor 121. It is equipped with an optical lens 118. The first reflecting mirror 113 reflects the diffuse reflected light L from the document in the direction of the second reflecting mirror 115. The second reflecting mirror 115 reflects the diffuse reflected light L in the direction of the third reflecting mirror 116. The third reflecting mirror 116 reflects the diffuse reflected light L in the direction of the condenser lens 118. The condenser lens 118 forms an image of diffuse reflected light L on each light receiving surface (not shown) of a plurality of light receiving elements included in the image sensor 121.

The image reading unit 100 has an automatic document feeder (also simply referred to as ADF) 160 and a platen (contact glass) 150, and reads an image (also referred to as an original image) from the original to obtain monochrome binary digital data. The image data ID is generated. The ADF 160 includes a paper feed roller 161 and a document reading slit 162. The paper feed roller 161 automatically feeds the original, and the original is read through the original reading slit 162. In this case, since the first carriage 114 is fixed at a preset sub-scanning position, the light source 112 mounted on the first carriage 114 is also fixed at a predetermined position.

The image sensor 121 is three CCD line sensors (not shown) that detect each of the three colors R, G, and B using a color filter (not shown) of each color component of R, G, and B. .. The image sensor 121 scans the document (secondary scan) with three CCD line sensors extending in the main scanning direction, and acquires an image on the document as a combination of voltage values corresponding to R, G, and B. In this way, the image sensor 121 can perform photoelectric conversion processing and output R, G, and B analog electric signals for each pixel in the main scanning direction. The image reading unit 100 can generate color scan data (RGB image data).

The first carriage 114 mounts the light source 112 and the first reflecting mirror 113, and reciprocates in the sub-scanning direction. The second carriage 117 mounts the second reflecting mirror 115 and the third reflecting mirror 116, and reciprocates in the sub-scanning direction. The first carriage 114 and the second carriage 117 are controlled by the control unit 210. As a result, the light source 112 can scan the document in the sub-scanning direction, so that the image sensor 121 can output an analog electric signal according to the two-dimensional image on the document. The image reading unit 100 executes binarization processing on the analog electric signal to generate image data FD for FAX, or executes color conversion processing to generate monochrome image data of 256 gradations.

The image forming unit 220 has a single exposure unit 221 for forming a monochrome image. The image forming unit 220 executes halftone processing on the monochrome image data of 256 gradations, and the image forming unit 220 forms dots on the print medium to generate dot data for reproducing the monochrome image. To do. The image forming unit 220 forms an image on the print medium based on the dot data. The print medium is also called an image forming medium.

The image reading unit 100, the image forming unit 220, the storage unit 240, the FAX processing unit 250, the extension circuit 260, and the communication I / F unit 270 have a Direct Memory Access (DMA) control function. The data bus 295 supports Quality of Service (QOS) values, for example based on the AXI protocol. In this example, the QoS value represents the priority of communication as 2-bit data having a value of 0 to 3. Specifically, for example, a QOS value of 0 indicates permission to use the dedicated band. A QOS value of 1 indicates a high priority, a QOS value of 2 indicates a medium priority, and a QOS value of 3 indicates a low priority.

At the time of facsimile transmission, the FAX processing unit 250 compresses the image data generated by reading by the image reading unit 100 and the image data to be transmitted by the facsimile acquired via the network LAN by the decompression circuit 260, and the communication I / It is transmitted via the F unit 270. At the time of receiving the facsimile, the FAX processing unit 250 can decompress and print the compressed image data which is the received data of the facsimile received via the telephone line by the decompression circuit 260. The communication I / F unit 270 can receive a print job via the network LAN, and the compressed image data included in the print job can be decompressed by the decompression circuit 260 to obtain image data for printing.

The decompression circuit 260 is dedicated hardware for compression processing and decompression processing (for example, Application Special Integrated Circuit (ASIC)). As described above, the processing of the FAX processing unit 250 and the processing of the print job can be handled by the processing of the single decompression circuit 260.

The control unit 210 includes processors such as an MPU (Micro Processing Unit) and a CPU (Central Processing Unit). In addition, the control unit 210 has controller functions related to interfaces such as various I / O, USB (universal serial bus), bus, and other hardware. The control unit 210 has a compression processing unit 211 and controls the entire image forming apparatus 10. The function of the compression processing unit 211 will be described later.

The storage unit 240 is a storage device including a hard disk drive, a flash memory, or the like, which are non-temporary storage media, and stores control programs and data for processing executed by the control unit 210, respectively. The storage unit 240 further includes a memory 241 and a memory control unit 242. The memory 241 is also called a main storage unit, and is a dynamic random access memory (DRAM). The memory control unit 242 controls reading and writing of data such as image data and control data to the memory 241.

FIG. 3 is a flowchart showing the contents of the copying process according to the first embodiment. In this example, the user assumes that the ADF160 is used to create a copy of a copy of a plurality of base papers as a typical copying application of the image forming apparatus 10. In step S10, the user sets a plurality of originals in the ADF 160 and leaves the number of copies as one (initial setting).

FIG. 4 is an explanatory diagram showing a memory area during the copying process according to the first embodiment. The memory 241 is composed of a text area 241T, a static area 241S, an image reading processing area 241PS, a RIP processing area 241PR, a printing processing area 241PP, an image data storage area 241D, a free area 241F, and a stack area 241V. ..

The text area 241T, also called a program area, is a fixed-size area in which a program translated into a machine language is stored. The static area 241S is a fixed size area in which static variables such as global variables are stored. A static variable is a variable that does not change at the time of operation of each process. The stack area 241V is a fixed size area in which automatic variables (local variables), function arguments, temporary variables such as return values, and the like are stored.

The image data storage area 241D is, for example, in C language, a physical memory reserved for storing image data by the malloc function, and is a dynamic area in which the physical memory can be released by the free function. The control unit 210 operates by allocating a physical memory for the storage area required for the operation by using the malloc function, and can release the physical memory by using the free function after the operation is completed. On the other hand, the image data storage area 241D is an area excluding the area secured by the heap area 241H. Therefore, the heap area 241H and the free area 241F are areas that fluctuate according to the operation of the image forming apparatus 10.

The image reading processing area 241PS is a memory area for executing image processing such as color conversion processing on color scan data (RGB image data). The RIP processing area 241PR executes halftone processing on 256-gradation monochrome image data, and the image forming unit 220 forms dots on the print medium to generate dot data for reproducing the monochrome image. A memory area for executing processing (RIP). The print processing area 241PP is a memory area for executing processing for controlling the exposure unit 221 using dot data.

The image reading processing area 241PS, the RIP processing area 241PR, and the printing processing area 241PP are all memory areas (continuous areas) that are continuous in advance when the image forming apparatus 10 is started in order to improve the efficiency of the control function for DMA transfer. It is also called.).

In step S20, the user presses a start switch (not shown) to cause the image reading unit 100 to start reading an image. As a result, the image reading unit 100 uses the image reading processing area 241PS to generate color scan data (RGB image data) each time one document is read by the ADF 160. In step S30, the image forming apparatus 10 starts an image output process as a copy process.

FIG. 5 is a flowchart showing the contents of the image forming process (step S30) according to the first embodiment. In step S31, the image reading unit 100 executes the color conversion process using the image reading processing area 241PS. As a result, the image reading unit 100 generates 256-gradation monochrome image data, performs DMA transfer without compression, and stores it in the image data storage area 241D of the memory 241.

In step S32, the image reading unit 100 executes the background color removing process using the image reading processing area 241PS. The background color removal process is a process of forming white pixels having a gradation value of 255 when the gradation value of 256-gradation monochrome image data is close to white pixels (for example, 240 gradation values or more). As a result, the image forming unit 220 can remove the background color to make the characters easier to read, and can acquire image data having a high lossless compression rate as described later.

In step S33, the RIP processing unit 280 uses the RIP processing area 241PR to execute halftone processing on the 256-gradation monochrome image data to which the background color removal processing has been performed. As a result, the RIP processing unit 280 generates dot data representing the dot formation state on the print medium by the image forming unit 220. The background color removing treatment is not an essential configuration for the present invention.

In step S34, the RIP processing unit 280 executes the dot data update process. In the dot data update process, the RIP processing unit 280 discards the dot data of the page on which the image has been formed, transfers the dot data by DMA without compression, and stores the dot data in the image data storage area 241D of the memory 241.

In step S35, the image forming unit 220 executes the image output process. In the image output process, the image forming unit 220 forms an image on the print medium based on the dot data for image forming on the next page, and outputs the printed matter from the image forming apparatus 10. As described above, since the image forming process is executed uncompressed in principle, the power consumption associated with the compression process can be eliminated.

In step S40, the control unit 210 determines whether or not another job such as a fax job or a print job has been received. If there is no reception, the control unit 210 advances the process to step S80, and if there is a reception, the control unit 210 advances the process to step S50.

In step S50, the control unit 210 determines whether or not the accumulated amount of dot data A (see FIG. 4) in the image data storage area 241D is larger than the preset threshold value. The accumulated amount A corresponds to, for example, the accumulated amount of dot data for three pages when the image forming process of the second page is completed when the reading of the fifth page is completed in the image reading process. To do. When the accumulated amount A is larger than the threshold value, the control unit 210 advances the process to step S60, and when the accumulated amount A is equal to or less than the threshold value, the control unit 210 advances the process to step S80.

In step S60, the compression processing unit 211 of the control unit 210 executes the memory area allocation process. In the memory area securing process, the compression processing unit 211 is a process of losslessly compressing the stored dot data to increase the available area in the image data storage area 241D. For the lossless compression process, for example, run length compression (RLE) and delta row compression (DRC) can be used. Run-length compression compresses continuous data of the same value by expressing it in a length continuous with that data. Delta row compression can thin out pixel data with zero line-to-row differences.

The run-length compression and the delta row compression can increase the compression rate when pixels having the same pixel value are consecutive. In the present embodiment, since the image forming unit 220 adjusts the image data in which the white pixels having the gradation value 255 are widely continuous by the background color removing process (step S32), the dot data also covers the area of the pixels having the same value. Will have a wide range.

Thereby, the present embodiment can compress the dot data with a high compression rate. In this way, the compression processing unit 211 can effectively increase the available area in the memory 241 by replacing the uncompressed dot data with the compressed data generated by losslessly compressing the dot data.

If the free area 241F is sufficient, the swap area can be secured in the free area 241F by the malloc function, and the compressed data can be stored in the swap area. The control unit 210 can also "increase the available area in the memory 241 by replacing the dot data with the compressed data generated by losslessly compressing the dot data" by such a method.

In step S70, the fax processing unit 250 executes the fax data storage process. In the FAX data storage process, the FAX processing unit 250 stores the compressed image data (PEG data), which is the received data of the facsimile received via the telephone line, in the image data storage area 241D at the time of receiving the facsimile. At this time, the control unit 210 sets a predetermined flag.

The image forming apparatus 10 executes such processing (steps S20 to S70) up to the final page of the document set in the ADF 160. When the flag is set, the RIP processing unit 280 losslessly compresses the newly generated dot data in the dot data update process (step S34) and then stores the newly generated dot data in the image data storage area 241D. On the other hand, the control unit 210 expands the compressed data and performs DMA transfer to the image forming unit 220 as dot data.

As described above, the image forming apparatus 10 according to the first embodiment suppresses power consumption by avoiding the compression process in the normal job processing while realizing the efficient DMA control function, and a plurality of jobs. Hardware resources such as a large amount of memory can be suppressed by using lossless compression processing for relatively infrequent cases in which processing is required in parallel. As a result, the image forming apparatus 10 is realized as an apparatus in which hardware resources and electric charge consumption are well-balanced.

FIG. 6 is a flowchart showing the contents of the copying process according to the second embodiment. The image forming process according to the second embodiment is different from the image forming process according to the first embodiment in that the processes in steps S40 to S70 are replaced with the processes in steps S40a and S42. The image forming process according to the second embodiment is a process corresponding to the case where a priority job (also referred to as an interrupt job) is received.

In step S40a, the control unit 210 determines whether or not the priority job has been received. The priority job means a job having a higher priority than the running job, and is a process for requesting that the running job be stopped and interrupt processing is performed. If the priority job is not received, the control unit 210 advances the process to step S80, and if the priority job is received, the control unit 210 advances the process to step S41.

In step S41, the compression processing unit 211 of the control unit 210 executes the ZSWAP processing. In the ZSWAP process, the compression processing unit 211 is a process of losslessly compressing the dot data accumulated in the dot data update process and saving it in a predetermined area in the image data storage area 241D or the above-mentioned swap area.

In step S42, the image forming apparatus 10 executes the priority job execution process. In this example, the preferred job is assumed to be an urgent print job. An urgent print job is a print job that is set to be urgent on a personal computer (not shown). In the priority job execution process, the image forming apparatus 10 stops the copying process being executed, that is, stops the ADF 160 and executes an urgent print job. On the other hand, the operation display unit 230 displays that the interruption by the emergency print job has occurred, and restarts the copying process when the emergency print job is completed.

As described above, the image forming apparatus 10 according to the second embodiment can not only receive other jobs during the copying process but also realize the interrupt processing. As a result, the image forming apparatus 10 is realized as an apparatus that realizes interrupt processing in which hardware resources and electric charge consumption are balanced.

The present invention can be implemented not only in the above embodiments but also in the following modifications.

Modification 1: In the above embodiment, the image forming apparatus assumes reception of one job, that is, another job during the monochrome copying process using the ADF 160, but for example, a plurality of job stands 150 are used. It can also be applied when executing a color copying process for a number of copies or when executing a print job for a plurality of copies. As described above, the present invention can be widely applied to an image forming apparatus capable of accepting a plurality of types of jobs.

Modification 2: In the above-described embodiment and modification, parallel processing of a plurality of types of jobs such as FAX reception and print job reception during copying processing is assumed, but an urgent print job is received during execution of the print job. It can also be applied to parallel processing of similar jobs such as.

Modification 3: In the above-described embodiment and modification, the usable area in the memory is increased by lossless compression, but the dot data may be deleted. Specifically, for example, when one job is received by the image forming apparatus and is a print job described in the page description language, the control unit 210 analyzes the print job to generate dot data, and the print job is generated. It is assumed that the print job is stored in the memory 241 even after the print job is analyzed, and the other jobs are priority jobs that are received during the processing of the print job and should be interrupted and processed in the middle of the print job.

In this case, the control unit 210 losslessly compresses the dot data to the memory when the amount of dot data stored in the memory 241 for executing one job is larger than a preset threshold value. When a priority job is received after increasing the available area in the memory and it is determined that the area in the memory is insufficient during the processing of the priority job, the compressed data can be deleted to increase the available area. After the priority job is completed, the control unit 210 can analyze the print job and generate dot data again.

10 Image forming apparatus 100 Image reader 160 Document stand cover 150 Document stand (contact glass)
210 Control unit 211 Compression processing unit 220 Image forming unit 221 Exposure unit 230 Operation display unit 240 Storage unit 250 FAX processing unit 260 Expansion circuit 270 Communication interface unit 280 RIP processing unit 290 Paper feeding unit 295 Data bus

Claims (5)

An image forming apparatus capable of forming an image on an image forming medium and accepting a plurality of types of jobs.
A storage unit having a memory and a memory control unit that controls the memory,
An image reading unit that reads a manuscript image that is an image on a manuscript, generates image data representing the manuscript image, and DMA-transfers the image data to the storage unit without compression.
RIP processing in which halftone processing is executed on the image data to generate dot data representing the formation state of dots formed on the image forming medium, and the dot data is DMA-transferred to the storage unit without compression. Department and
An image forming unit that forms an image on an image forming medium based on dot data uncompressed and DMA-transferred from the storage unit, and an image forming unit.
When another job is received while executing one of the plurality of types of jobs, the amount of dot data stored in the memory for executing the one job is preset. A control unit that increases the available area in the memory and receives the other job by replacing the dot data with the compressed data generated by losslessly compressing the dot data when the number exceeds the threshold value.
With
The memory control unit has a continuous area for DMA transfer with the image reading unit, a continuous area for DMA transfer with the RIP processing unit, and a DMA transfer between the image forming unit. A continuous area for the memory is secured in the memory.
When the dot data is losslessly compressed, the control unit is an image forming apparatus that expands the compressed data and performs DMA transfer to the image forming unit as dot data. The image forming apparatus according to claim 1.
The image reading unit has an automatic document feeder and has an automatic document feeder.
The one job is a copying process of copying only one copy of a plurality of originals by using the automatic document feeder.
The other job is the reception of a facsimile during the copying process.
The control unit is an image forming apparatus that losslessly compresses the received data of the received facsimile and stores it in the memory. The image forming apparatus according to claim 1 or 2.
The one job is a print job received by the image forming apparatus and described in a page description language.
The control unit analyzes the print job to generate dot data, and even after the analysis of the print job, stores the print job in the memory.
The other job is a priority job that is received during the processing of the print job and should be interrupted and processed in the middle of the print job.
When the amount of dot data stored in the memory for executing the one job is larger than a preset threshold value, the control unit losslessly compresses the dot data into the memory. An image forming apparatus that receives the priority job after increasing the available area and deletes the compressed data when it is determined that the area in the memory is insufficient during the processing of the priority job. The image forming apparatus according to any one of claims 1 to 3.
The image reading unit executes a background color removing process on the image data, and then performs a background color removing process.
The RIP processing unit executes halftone processing on the image data on which the background color removal processing has been executed to generate the dot data, and the dot data is transferred to the storage unit by DMA without compression. apparatus. An image forming method that forms an image on an image forming medium, can accept a plurality of types of jobs, and uses an image forming apparatus having a memory.
A memory control process for controlling the memory and
An image reading step of reading a manuscript image, which is an image on a manuscript, generating image data representing the manuscript image, and DMA-transferring the image data to the memory without compression.
A RIP processing step of executing halftone processing on the image data to generate dot data representing the formation state of dots formed on the image forming medium, and DMA-transferring the dot data to the memory without compression. When,
An image forming step of forming an image on an image forming medium based on dot data uncompressed and DMA-transferred from the memory, and an image forming step.
When another job is received while executing one of the plurality of types of jobs, the amount of dot data stored in the memory for executing the one job is preset. A control step of increasing the available area in the memory and receiving the other job by replacing the dot data with the compressed data generated by losslessly compressing the dot data when the number exceeds the threshold value.
With
The memory control step is a continuous area for DMA transfer between the image reading step, a continuous area for DMA transfer between the RIP processing step, and a DMA transfer between the image forming step. A continuous area for is secured in the memory,
The control step is an image forming method in which, when the dot data is losslessly compressed, the compressed data is expanded and transferred as dot data to the image forming step by DMA.

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