JP3548190B2 - Digital image forming equipment - Google Patents

Description

[0001]
[Industrial applications]
The present invention relates to a digital image forming apparatus such as a digital copying machine and a printer.
[0002]
[Prior art]
For example, in a digital copying machine, image data obtained by reading an original image with an image sensor such as a CCD is temporarily stored in a page memory, and the image data is read out from the page memory to an image forming means to perform predetermined image formation. Is being done. When copying a plurality of copies, the image data for the previous document is read out from the page memory a plurality of times to form a predetermined number of images. When the image formation for the previous document is completed, the contents of the page memory are updated. Then, a predetermined number of images are formed for the next original, and thereafter, a predetermined number of images are formed for each original while sequentially rewriting the contents of the page memory.
[0003]
2. Description of the Related Art Conventionally, there has been proposed a digital copying machine in which a plurality of images are formed on a previous document and image data of the next document is read during the image forming period to improve the copying efficiency. For example, Japanese Patent Application Laid-Open No. 1-261966 has three page memories M1, M2, and M3. Image data for each document is sequentially and cyclically stored in each of the page memories M1, M2, and M3. The figure shows a configuration in which image data is read from corresponding page memories M1, M2, and M3 to form a predetermined number of images.
[0004]
FIG. 6 is a time chart showing the operation timing of reading image data and forming an image of a document in the conventional digital copying machine.
[0005]
As shown in the drawing, the first three originals are continuously scanned, and the image data D1, D2, and D3 for the first to third originals are stored in page memories M1, M2, and M3, respectively. It is stored in M3. When the storage of the image data D1 in the page memory M1 is completed, the image data D1 is read out from the page memory M1 to the image forming apparatus, and the formation of a predetermined number of images for the first document is started.
[0006]
The image forming operation based on the image data D1 read from the page memory M1 is repeated, and when a predetermined number of images have been formed on the first document, the image data D2 is read from the page memory M2 to the image forming apparatus. Then, the formation of a predetermined number of images for the second document is started. At the same time, scanning of the fourth document is started, and the contents of the page memory M1 are rewritten to image data D4 for the document.
[0007]
Thereafter, a predetermined number of images are sequentially formed on the K (≧ 2) th document, and at the same time, image data on the (K + 2) th document is read, and the image data D (K + 2) is replaced by (k). -1) The image data D (K-1) for the first document is cyclically stored in the page memory M (i) (i = 1, 2, 3) where a predetermined number of images are formed for each document. Is performed.
[0008]
[Problems to be solved by the invention]
In Japanese Patent Application Laid-Open No. Hei 1-261966, the image data of the (K + 3) th document cannot be read unless a predetermined number of images have been formed on the Kth document. Is expanded to three memories. Therefore, it is effective when the reading speed of the image data D (i) (i = 1, 2,... N) is relatively equal to the image forming speed, but is read out from the page memory M (i), for example. If the image forming speed based on the image data D (i) is lower than the reading speed of the image data, the image data D (i + 3) is read unless the image forming of the image data D (i) is completed. Therefore, it is difficult to improve the reading efficiency of image data.
[0009]
The above problem can be solved by increasing the page memory M (i) and increasing the reading capacity of the image data D (i) at the time of image formation. However, in this case, the memory capacity is increased, and the cost is reduced. Also disadvantageous.
[0010]
SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to provide a digital image device capable of improving copy efficiency with a small memory capacity.
[0011]
[Means for Solving the Problems]
The present invention relates to an image pickup unit that photoelectrically converts a document image and reads it as a digital image signal, a first storage unit that stores the digital image signal, a signal compression unit that compresses the digital image signal, A first transfer control means for transferring a digital image signal obtained by reading the first document to the first storage means, and transferring a digital image signal obtained by reading the second and subsequent originals to the signal compression means; Image forming means for reading a digital image signal from the first storage means to form an image, second storage means for storing the compressed signal compressed by the signal compression means, and reading from the second storage means Decoding means for decoding the compressed signal thus obtained, and when image formation based on the digital image signal stored in the first storage means is completed, the compressed signal for the next original is stored in the second storage means. The digital image signal decoded the reads are those with a second transfer control means for transferring to the first storage means (claim 1).
[0012]
A third storage unit for storing the digital image signal in the digital image forming apparatus;
Signal reading means for reading the image data stored in the third storage means to the signal compression means,
After the digital image signal obtained by reading the second and subsequent originals is once transferred to the third storage means by the first transfer control means, the signal compression means reads out the signal from the third storage means by the signal readout means. Image data is read by the means, and the compressed signal compressed by the signal compression means is stored in the second storage means;
Upon completion of image formation based on the digital image signal stored in the first storage means, the second transfer control means reads a compressed signal for the next original from the second storage means and decodes the compressed signal. Transferring a digital image signal to the first storage means;(Claim 2).
[0013]
Further, in the digital image forming apparatus, a determination unit that determines whether the compressed signal can be stored in the second storage unit, and a determination unit that determines whether the compressed signal cannot be stored in the second storage unit. The image forming apparatus further comprises image forming control means for directly reading a digital image signal from the storage area of No. 3 to form an image.
[0014]
[Action]
According to the first aspect of the invention, the digital image signal obtained by reading the first document image is stored in the first storage means, and the digital image signal is read from the first storage means. Image formation is started. When image formation for the first document is started, reading of digital image signals is started for the second and subsequent documents. The digital image signal for each document is sequentially stored in the second storage unit after being compressed by the signal compression unit.
[0015]
The reading of the digital image signal for the second and subsequent originals is performed until the image formation for the first original is completed. When the image formation for the first original is completed, the second storage means is used. The compressed signal for the second document stored in the first document is read out, decoded and transferred to the first storage means, and the image formation for the second document is started.
[0016]
Thereafter, each time image formation for the previous document is completed, a compressed signal for the next document is read from the second storage means, decoded, transferred to the first storage means, and transferred to the first storage means. The formation takes place. In addition, during the image formation period for the second and subsequent originals, digital image signals are sequentially read for the remaining originals each time a storage area is generated in accordance with the readout of image data from the second storage means, The data is compressed and stored in the second storage means.
[0017]
According to the second aspect of the present invention, the digital image signals for the second and subsequent originals are temporarily stored in the third storage means, and are read out from the third storage means to the signal compression means for compression. Is done. Then, this compressed signal is stored in the second storage means.
[0018]
According to the third aspect of the present invention, the compressed signal is recorded in the second storage means.YouOtherwise, the digital image signal is read out directly from the third storage area to the image forming means, and the image is formed.
[0019]
【Example】
FIG. 1 is a schematic configuration diagram of an embodiment of a digital copying machine (image forming apparatus) according to the present invention.
[0020]
The digital copying machine 1 has a contact glass 2 and an automatic document feeder 3 on its upper surface, and has an optical mechanism L, a control mechanism C, an image forming means P, and a transfer paper transfer mechanism F inside.
[0021]
When the copying and the operation are started, the automatic conveyance device 3 conveys the originals G placed on the original tray 3a one by one to a predetermined position of the contact glass 2, and discharges the image data when reading of the image data is completed. It is discharged to the tray 3b.
[0022]
The optical mechanism L includes a light source unit 4 including a halogen lamp 41 and a reflecting plate 42, an image forming unit 5 including reflecting mirrors 51, 52, 53 and a lens unit 54, a solid-state imaging device 61 such as a CCD, and a CCD 61. The imaging unit 6 includes a driver 62.
[0023]
When the copying operation is started, the optical mechanism L causes the halogen lamp 41 to emit light, and scans the original G placed on the contact glass 2 in the main scanning direction (the direction A in the drawing). The image data of the original G is read. The light emitted from the halogen lamp 41 is applied to the reflection plate 42 onto the document G, and the light reflected from the document G is guided to the imaging unit 6 by the reflecting mirrors 51 to 53 of the image forming unit 5, and is reflected by the lens unit 54. The light image of the original G is formed on the imaging surface of the CCD 61. Then, the light image of the document G is photoelectrically converted by the CCD 61 and read as an electric signal (hereinafter, referred to as an image signal). After being converted into a digital signal, the image signal is temporarily stored in a page memory A (or B) in the control mechanism C. The details of the control mechanism C will be described later.
[0024]
The image forming means P includes an image data output section 7 for outputting image data from the control mechanism C, and an image forming section 8 for forming an image based on the image data. The unit 71 includes a polygon mirror 72 and a reflecting mirror 73. The image forming unit 8 includes a photosensitive drum 81, a charging device 82, a blank lamp 83, a developing device 84, a transfer device 85, a separating device 86, and a cleaning device 87. The transfer paper transport mechanism F includes a paper feed unit 9 and a paper discharge unit 10, and is provided below the image forming unit P. The paper supply unit 9 includes a paper supply cassette 91, a paper supply roller 92, a guide plate 93, and a registration roller pair 94 in order from the upstream side, and the paper discharge unit 10 includes a transport belt 101, a discharge roller pair 102, and a A paper output tray 103 is provided. Note that a fixing device 11 is provided between the transport belt 101 and the discharge roller pair 102 of the paper discharge unit 10 so that the transferred image is fixed when the transfer paper is discharged.
[0025]
The laser emitting section 71 emits a laser beam modulated by the image data read from the control mechanism C toward the polygon mirror 72. This laser light is applied to the photosensitive drum 81 via the polygon mirror 72 and the reflection mirror 73. At this time, the polygon mirror 72 rotates the reflecting surface in synchronization with the light emission timing of the laser light emitting unit 71, and scans the laser beam irradiated on the photosensitive drum 81 in the sub-scanning direction (the direction parallel to the drum axis). The rotation of the photosensitive drum 81 causes the laser beam to relatively scan the peripheral surface of the drum, thereby forming a latent image of the document G on the peripheral surface of the photosensitive drum 81.
[0026]
The peripheral surface of the photosensitive drum 81 to which the laser light is irradiated is charged to a predetermined potential in advance by the charging device 82, and the latent image of the document G is formed by displacing the surface potential of the portion irradiated with the laser light. Is done. Unnecessary portions of the latent image are removed by the blank lamp 83, and the latent image on the original G is visualized by attaching charged toner by the developing device 84. Transfer paper is fed from the paper feed unit 9 at a predetermined timing in synchronization with the rotation operation of the photosensitive drum 81. This transfer paper is pressed against the peripheral surface of the transfer device 85 on which the development of the document G is formed, whereby the development of the document G is transferred to the transfer paper to form an image.
[0027]
Then, the transferred transfer paper is separated from the photosensitive drum 81 by the separation device 86, conveyed to the fixing device 11 by the conveyance belt 101, and the transferred image is fixed, and then, by the discharge roller pair 102. The paper is discharged to the paper discharge tray 103. The toner remaining on the peripheral surface of the photosensitive drum 81 after the transfer is removed by the cleaning device 87 before the next image formation is started.
[0028]
The control mechanism C is provided at an appropriate position in the main body of the copying machine, and includes three memories 12, 1314, a compression / decompression circuit 15, an address controller 16, and a control unit 17.
[0029]
The memories 12 and 13 are, for example, page memories capable of storing image data for one page of A3 size, and the memory 12 (hereinafter, page memory A) is a memory for storing image data for image formation. A page memory B (hereinafter referred to as a page memory B) is a memory for temporarily storing image data of a document G read by the CCD 61 while image data is being read from the page memory A and image formation is being performed. The memory 14 (hereinafter, referred to as a memory C) is a memory that compresses and stores image data of a plurality of originals G.
[0030]
If image data of a plurality of originals G can be read while image data is being read from the page memory A and image formation is being performed, the image data of each original G is temporarily stored in the page memory B. At the same time, the data is read out and compressed by the compression / decompression circuit 15, and then stored in the memory C.
[0031]
The compression / decompression circuit 15 compresses the image data at a predetermined ratio and decompresses and decodes the compressed image data (hereinafter referred to as compressed data). The compressed image data is compressed, and when the compressed data of the next original G is transferred from the memory C to the page memory A, the compressed data is decoded.
[0032]
The address controller 16 manages addresses of compressed data stored in the memory C. The compressed data is cyclically stored in a storage area of the memory C as described later, and the address controller 16 stores the read start address and the compressed data when reading the compressed data in the memory C. And the write start address at the time of writing.
[0033]
2A and 2B are diagrams showing a storage method of the compressed data in the memory C. FIG. 2A shows a state where the compressed data is stored in order from the head of the storage area, and FIG. FIG. 7C is a diagram illustrating a state where compressed data is separated and cyclically stored in the generated empty region, and FIG. 7C is a diagram illustrating a state where the empty region of the memory C is smaller than the compressed data and cannot be stored.
[0034]
In the figure, S indicates the start address of the entire stored compressed data, and E indicates the end address of the entire stored compressed data. The start address S corresponds to the read start address of the compressed data, and the end address E is the address immediately before the start address of the empty area, and substantially corresponds to the write start address.
[0035]
In the initial state, the start address S and the end address E are initially reset to the start (address 0) of the address allocated to the storage area of the memory C, as shown in FIG. , DA (k) are stored in order from the beginning of the storage area of the memory C, and the end address E is stored every time the compressed data DA1, DA2, ..., DA (k) is stored. , A (k) are updated to the end addresses A1, A2,..., A (k) of the compressed data DA1, DA2,. On the other hand, the start address S is held at the start address (address 0) of the memory C unless the compressed data DA (i) (i = 1, 2,..., K) is read during this time. Each time DA2,..., DA (k) is read, the end addresses A1, A2,..., A (k) of the compressed data DA1, DA2,. 2 (b)).
[0036]
Then, as shown in FIG. 2B, when the storage area remaining in the memory C becomes smaller than the next compressed data DA (r + 1), if there is an empty area at the end of the memory C, the compression is performed. The data DA (r + 1) is separated and stored cyclically in the free space at the rear end of the memory C and in the free space at the front end of the memory C. The end address E is It is changed to the end address A0 of the compressed data DA (r + 1) stored in the empty area at the front end.
[0037]
In this case, as shown in FIG. 2C, the compressed data D1 is stored at the leading end of the memory C, and when there is no empty area, the trailing end of the compressed data DA (r + 1) partially overlaps with the compressed data DA1. Therefore, the compressed data DA (r + 1) is not stored in the memory C. Even if there is an empty area at the leading end of the memory C, if the trailing end of the compressed data DA (r + 1) is stored at the leading end of the memory C, for example, if it partially overlaps with the compressed data DA3, the compressed data DA (R + 1) is not stored in the memory C. That is, when there is no area in which the compressed data DA (r + 1) can be continuously recorded cyclically, it is determined that there is no storable area, and the transfer of the image data D (r + 1) from the page memory B to the memory C is performed. And waits until a storable area is created in the memory C.
[0038]
In the above case, the end address E is changed beyond the head address. Therefore, the presence or absence of a storable area in the memory C is determined by determining whether the end address E exceeds the head address.
[0039]
The address controller 16 updates the start address S and the end address E according to the writing / reading of the compressed data, and sends this information to the control unit 17.
[0040]
The control unit 17 controls reading and image formation of image data of the document G, and centrally controls driving of the page memories A and B, the memory C, the compression / decompression circuit 15 and the address controller 16. The control unit 17 determines the presence or absence of a storable area in the memory C based on the update information of the start address S and the end address E, and controls writing and reading of the compressed data to and from the memory C based on the determination result. I do.
[0041]
FIG. 3 is a time chart showing an example of operation timings of reading image data and image formation (reading) of the document G of the digital copying machine according to the present invention.
[0042]
In the figure, D1 to D6 indicate image data obtained by reading six originals G, and DA2 to DA6 indicate compressed data obtained by compressing the image data D1 to D6. The image data D1 of the first document G is stored in the page memory A, and the image data D2 to D6 of the second and subsequent documents G are stored in the page memory B. The output period of the image data D1 to D4 in the page memory A is a period during which a plurality of images are formed on each of the first to fourth originals G.
[0043]
The output of the compressed data DA2 to DA6 in the page memory B corresponds to the input of the compressed data DA2 to DA6 in the memory C, and the image data D2 to D6 of the page memory B is compressed and transferred to the memory C. The output of the image data D2 to D5 in the memory C corresponds to the input of the image data D2 to D5 in the page memory A, and the compressed data DA2 to DA5 in the memory C is decoded and transferred to the page memory A. It is shown that.
[0044]
As shown in the figure, the image data of the first document G is stored in the page memory A, read out immediately, and a predetermined number of images are formed. During this image forming period (output period of the image data D1 of the page memory A), the image data D2, D3, and D4 of the second to fourth originals G are read, and the image data D2 and D3 are stored in the page memory A. Once stored in B, it is immediately read out, compressed and stored in memory C. When the reading of the image data D4 of the fourth original G into the page memory B is completed, the image formation on the first original G is already completed, and the compression of the second original G from the memory C is completed. Since the data DA2 has been transferred to the page memory A, the data DA2 is transferred to the memory C when the transfer of the compressed data DA2 ends.
[0045]
.. Are decoded from the memory C and transferred to the page memory A, and a predetermined number of images are formed on each of the originals G. The image data D5, D6,... Of the remaining originals G are read into the page memory B during the image forming period of the originals G, sequentially compressed, and stored in the memory C.
[0046]
Next, the reading of image data and the image forming operation of the digital copying machine according to the present invention will be described with reference to the flowcharts of FIGS.
[0047]
First, when the copy key is turned on (YES in step S0), the optical mechanism L is scanned to start reading image data of the document G (step S2). The image data of the first document G read by the CCD 61 is stored in the page memory A (step S4), and the image data is read from the page memory A to start image formation (step S6). When the reading of the image data is completed, it is determined whether or not the reading of the predetermined number of image data, that is, the reading of the image data for the number of copies to be made set by the operator is completed (step S8). When reading of the predetermined number of image data is completed (YES in step S8), image formation on the first document G is completed (step S10).
[0048]
If reading of the predetermined number of image data has not been completed (NO in step S8), the flow shifts to step S32 (see FIG. 5) to determine whether or not the standby flag is set to "1". The standby flag is a flag for controlling reading of the image data of the next document G. If the flag is reset to “0”, it indicates a readable state, and if it is set to “1”, it indicates an unreadable state. Show. The standby flag is set to “1” when the storage area of the compressed data is exhausted in the memory C as described later, and is reset to “0” when the storage area is generated by reading the compressed data.
[0049]
If the standby flag is reset to "0" in step S32 (NO in step S32), it is determined whether image data remains in the page memory B (step S34). If image data remains in the page memory B (YES in step S34), the process proceeds to step S42, and the image data of the next original G is not read (steps S36 to S40 are skipped). Transfer of the stored image data to the memory C is started.
[0050]
On the other hand, if no image data remains in the page memory B (NO in step S34), it is determined whether or not there is a next original G (step S36). If there is no next original G (NO in step S36), the process returns to step S8 to form an image based on the image data stored in page memory A, and if there is the next original G (YES in step S36), The image data of the original G is read, the image data is stored in the page memory B (step S40), and the transfer of the compressed data obtained by compressing the image data to the memory C is started (step S42).
[0051]
Subsequently, it is determined whether or not there is a storage area in the memory C (step S44). This determination is made based on whether the start address S exceeds the end address E, as described above. If the start address S exceeds the end address E, it is determined that there is no storage area in the memory C. If there is a storage area in the memory C (YES in step S44), the image data stored in the page memory B is compressed by the compression / decompression circuit 15, and then stored in a predetermined storage area of the memory C, and the end address E is stored. After changing to the end address of the compressed data (step S46), the process returns to step S8. On the other hand, if there is no storage area in the memory C (NO in step S44), the transfer of the image data stored in the page memory B to the memory C is stopped (step S48), and the standby flag is set to “1”. (Step S50), returning to step S8.
[0052]
If the standby flag is set to "1" in step S32 (YES in step S32), it is determined whether or not there is unprocessed data in which no image is formed in the memory C (step S52). If there is unprocessed data in the memory C (YES in step S52), the process returns to step S8 to form an image based on the image data stored in the page memory A, and if there is no unprocessed data in the memory C (step S52). (NO), after a predetermined number of images are formed based on the image data in the page memory A (YES in step S54), the image data in the page memory B is read out, and the image formation is started (step S56). Then, after forming a predetermined number of images based on the image data in the page memory B (YES in step S58), the start address S and the end address E of the memory C are reset to "0" (step S60). Return to step 2.
[0053]
When reading of the predetermined number of image data is completed (YES in step S8), image formation on the first document G is completed (step S10), and then reading of image data of all documents G is completed. It is determined whether or not image data has been read from all the originals G (step S12: YES). It is determined whether or not it is (step S14).
[0054]
If the reading of the image data of all the originals G has not been completed (NO in step S12), or if there is unprocessed data in the memory C (YES in step S14), the next original G stored in the memory C Is read out, decoded by the compression / decompression circuit 15, and then transferred to the page memory A (step S20). Subsequently, the start address S of the memory C is changed to the end address of the read image data (step S22), the standby flag is reset to “0” (step S24), and the process returns to step S6 to return to the page memory A. , A predetermined number of images are formed on the next original G based on the image data transferred to.
[0055]
On the other hand, if there is no unprocessed data in the memory C (NO in step S14), it is determined whether the standby flag is set to "1" (step S16), and the standby flag is reset to "0". If (NO in step S16), it is determined that a predetermined number of images have been formed for all the originals G, and the start address S and the end address E of the memory C are reset to "0" (step S18), and image formation is performed. End the operation.
[0056]
If the standby flag is set to "1" (YES in step S16), since the image data remains in the page memory B, the image data is read directly from the page memory B to the image forming means P and the image is read. The formation is started (Step S26). After forming a predetermined number of images based on the image data (YES in step S28), the start address S and the end address E of the memory C are reset to "0" (step S30), and image formation is performed. End the operation.
[0057]
When the image forming time of the previous document G is substantially equal to the reading time of the image data of the next document G, it is not necessary to compress and store the image data of the next document G. It is preferable that the image data of the document G is alternately stored in the page memory A and the page memory B, respectively, and the image data is read directly from the page memories A and B to form a predetermined image. Even when the number of originals G is two, image data of both originals G is stored in page memories A and B, and image data of the first original G is read from page memory A to form a predetermined number of images. The image data of the second document G may be read from the page memory B to form a predetermined number of images. This makes it possible to maintain good copy efficiency regardless of the number of documents and the number of image forming copies.
[0058]
As described above, the image forming apparatus includes the page memory A for forming an image, the page memory B for reading image data of the document G, and the memory C for storing compressed data obtained by compressing image data. During the image formation, the image data of the next original G is read, and the compressed data obtained by compressing the image data is sequentially stored in the memory C. Can be continuously read regardless of the image forming operation.
[0059]
In the above embodiment, the image data for the second and subsequent documents G is temporarily stored in the page memory B, the image data is read from the page memory B, compressed, and then stored in the memory C. Compresses the image data output from the CCD 61 by the compression / decompression circuit 15.ShitsuMay be stored in the memory C. By doing so, the configuration of the control mechanism C can be simplified, and the reading speed of the image data of the document G can be further increased.
[0060]
In the above embodiment, the digital copying machine has been described. However, the present invention can be applied to a digital image forming apparatus including a document reading apparatus such as a facsimile and an image forming apparatus. Also, the present invention can be applied to a case where a system of a digital image forming apparatus is configured by combining a single document reading apparatus and an image forming apparatus.
[0061]
【The invention's effect】
As described above, according to the present invention, the first storage means for storing a digital image signal obtained by reading a document, the signal compression means for compressing the digital image signal, and the second storage means for storing the compressed signal A digital image signal for the first original is stored in the first storage, and the digital image signal is read out from the first storage to form an image on the first original. The digital image signal for the original after the first sheet is compressed and stored in the second storage means. Each time the image formation for the previous original is completed, the compressed signal for the next original is sent from the second storage means. Since reading, decoding, and transfer to the first storage means for image formation of the next original, digital image signals of many originals can be read at high speed with a small storage capacity. Can.
[0062]
In addition, regardless of the image forming operation for the previous document, if the storage area of the compressed signal is provided in the second storage means, the digital image signal of the unprocessed document can be read, so that the image forming efficiency is improved.
[0063]
Further, the image data of the second and subsequent originals is temporarily stored in the third storage means, and the image data is read out from the third storage means and compressed, so that the image data is independent of the compression speed of the image data. Image data can be read.
[0064]
When the compressed data cannot be stored in the second storage means, the digital image signal is read directly from the second storage means and the image is formed based on the digital image signal. Even when the obtained digital image signal has a large capacity, an image can be formed without lowering the image forming efficiency.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram of an embodiment of a digital copying machine (image forming apparatus) according to the present invention.
2A and 2B are diagrams showing a storage method of compressed data in a memory C, wherein FIG. 2A shows a state where compressed data is stored, and FIG. And (c) is a diagram showing a state where compressed data cannot be stored.
FIG. 3 is a time chart showing an example of operation timings of reading image data and forming an image (reading) of a document of the digital copying machine according to the present invention.
FIG. 4 is a flowchart showing image data reading and image forming operations of the digital copying machine according to the present invention.
FIG. 5 is a flowchart showing image data reading and image forming operations of the digital copying machine according to the present invention.
FIG. 6 is a time chart showing operation timings of reading image data and forming an image of a document of a conventional digital copying machine.
[Explanation of symbols]
1 Digital copier (digital image forming device)
2 Contact glass
3. Automatic document transport device
L Optical mechanism
4 Light source
41 Halogen lamp
5 Imaging unit
6 Imaging unit
61 CCD (Solid-state imaging device)
62 Driver
P image forming means
7 Image data output section
71 Laser emitting unit
72 polygon mirror
8 Image forming unit
81 Photoconductor drum
82 Charging device
84 Developing device
85 Transfer device
F transport mechanism
9 Paper feed section
91 Paper cassette
10 Paper output unit
103 Output tray
11 Fixing device
C control mechanism
12, 13 page memory
14 memory
15. Compression / expansion circuit
16 Address controller
17 Control part

Claims (3)

Imaging means for photoelectrically converting a document image to read as a digital image signal; first storage means for storing the digital image signal; signal compression means for compressing the digital image signal; First transfer control means for transferring the digital image signal to the first storage means, and transferring the digital image signal obtained by reading the second and subsequent originals to the signal compression means; and the first storage means. Image forming means for reading a digital image signal from the means to form an image, second storage means for storing a compressed signal compressed by the signal compression means, and a compressed signal read from the second storage means When image formation based on the digital image signal stored in the first storage means is completed, a compressed signal for the next original is read from the second storage means. Digital imaging apparatus, wherein a decoded digital image signal and a second transfer control means for transferring to the first storage means. The digital image forming apparatus according to claim 1,
Third storage means for storing the digital image signal,
Signal reading means for reading the image data stored in the third storage means to the signal compression means,
After the digital image signal obtained by reading the second and subsequent originals is once transferred to the third storage means by the first transfer control means, the signal compression means reads out the signal from the third storage means by the signal readout means. Image data is read by the means, and the compressed signal compressed by the signal compression means is stored in the second storage means;
Upon completion of image formation based on the digital image signal stored in the first storage means, the second transfer control means reads a compressed signal for the next original from the second storage means and decodes the compressed signal. A digital image forming apparatus for transferring a digital image signal to the first storage means. 3. A digital image forming apparatus according to claim 2, wherein said judging means judges whether or not said compressed signal can be stored in said second storage means, and when said compressed signal cannot be stored in said second storage means, A digital image forming apparatus, comprising: image forming control means for reading a digital image signal directly from the third storage area to form an image.

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