JPH0568151A - Image forming device - Google Patents

Abstract

PURPOSE:To read out image data from an original carried at an always stable speed by controlling an original feeder to feed an original to an original reading position only at the time of judging that a storage means has storage capacity necessary for image processing. CONSTITUTION:A PCU 81 controls the original feeding operation of an automatic document feeder(ADF), judges whether an original is set up in an original tray of the ADF or not, and when the original is set up, advances a program to the succeeding step. Then the data capacity DO of a main memory 82a which is necessary for image processing based upon respective set up and detected conditions such as a scale, paper size and original size is forecasted. The residual MS of the memory capacity of the memory 82a which is transmitted to an ICU 82 is compared with the capacity DO, and only when MS >DO is formed, the PCU 81 allows the ADF to execute original carrying operation. Consequently the image data of the original carried at an always stabilized speed can be read out at the original reading position.

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 having an automatic document feeder.

[0002]

2. Description of the Related Art Generally, a conventional image forming apparatus such as a digital copying machine equipped with an automatic document feeder for automatically feeding a document to a document reading position reads a document image with a scanner and reads image data of the document. Is temporarily stored in a readable / writable memory, image data is read out from the memory as necessary, various processing is performed on this image data in the image processing unit, and then stored again in the memory, and the processed image data is stored. It is configured to read out and form a visible image on a sheet by a laser printer.

Further, in the conventional image forming apparatus, when the memory capacity which can be used for storing the image data of the original document is exhausted, the operation of reading the original image by the scanner is stopped, or the original document is supplied by the automatic original feeder. It is configured to stop operation.

[0004]

Such a conventional image forming apparatus is configured to stop the reading operation of the original image when the memory capacity available for storing the image data of the original is exhausted. Therefore, when the memory capacity is exhausted and a stop instruction is issued while the image of one document is being read, the document is stopped at the document reading position until the memory capacity becomes available. It is necessary to wait in the state.

When the reading of the original image is started again in the state where the original is stopped at the original reading position, it takes time for the automatic document feeder to stabilize the original conveying speed. If the reading cycle is the same as before the stop, until the transport speed stabilizes,
There is a problem that the image data of the read original becomes, for example, stretched data.

Further, in order to control the reading operation of the original image by making the reading clock variable according to the feeding speed of the original, there is a problem that very complicated and highly accurate control is required. ..

Therefore, the present invention provides an image forming apparatus capable of reading the image data of a document which is always conveyed at a stable speed at the document reading position.

[0008]

A document feeding unit for feeding a document to a document reading position, a document reading unit for reading an image of the document supplied by the document feeding unit, and image data of the document read by the document reading unit. Storing means, an image forming means for forming an image on a sheet based on image data stored in the storing means, a storage capacity detecting means for detecting a usable storage capacity of the storing means, and an image forming means Storage capacity calculating means for obtaining the storage capacity of the storage means necessary for the image forming process by the image forming means, and the original supply means for the original when the storage capacity detected by the storage capacity detecting means is smaller than the storage capacity calculated by the storage capacity calculating means. And a control means for controlling so as not to supply.

[0009]

The image of the document supplied to the document reading position by the document supply unit is read by the document reading unit, and the image data of the read document is stored in the storage unit. The image forming unit forms an image on a sheet based on the image data stored in the storage unit. During such image formation, the storage capacity detecting means detects the usable storage capacity of the storage means, and the storage capacity calculating means obtains the storage capacity of the storage means necessary for the image forming processing by the image forming means. The control means controls so that the document supply means does not supply the document to the document reading position when the storage capacity detected by the storage capacity detection means is smaller than the storage capacity calculated by the storage capacity calculation means.

That is, the document feeding means is controlled by the control means.
Only when the storage means has a storage capacity necessary for image processing, the document is controlled to be supplied to the document reading position. Therefore, once the reading of the original image by the original reading means is started, the original is not stopped at the original reading position until the reading operation of the original image is completed, unless a trouble occurs. The reading operation of the original image is not started again from such a stopped state.

Therefore, it is possible to always read the image data of the original conveyed at a stable speed at the original reading position.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. Here, an example in which the image forming apparatus according to the present invention is applied to a digital copying machine is shown.

FIG. 2 is a sectional view showing the overall construction of a digital copying machine which is an embodiment of the image forming apparatus according to the present invention.

As shown in FIG. 1, the digital copying machine 10 of this embodiment is provided with a scanner section 11, a laser printer section 12, a multi-stage sheet feeding unit 13 and a sorter 14.

A double-sided automatic document feeder (ADF) 15 is installed on the upper part of the scanner section 11.
Is composed of a document placing table 16 made of transparent glass, a movable scanner unit 17, and a position control device for controlling the position of the scanner unit 17.

This position control device is a scanner unit
The position control device includes a scanner motor 18 for driving the motor 17, a pulley 19, and a wire 20 stretched between the scanner motor 18 and the pulley 19, and the position control device moves the scanner unit 17 along the longitudinal direction of the document table 16. It is configured so that it can be moved and stopped at a predetermined position.

The scanner unit 17 includes a lamp reflector assembly 21 for exposing a document, a CCD (photoelectric conversion element) linear image sensor 22, and a plurality of reflecting mirrors 2 for guiding a reflected light image from the document to the CCD linear image sensor 22.
3 and a lens 24 for forming a reflected light image from the original on the CCD linear image sensor 22.

When scanning a document placed on the document table 16, the scanner section 11 reads the document image while the scanner unit 17 moves along the lower surface of the document table 16 and uses the ADF 15. If you want to do this, A with the scanner unit 17 stopped at a predetermined position below the ADF 15.
It is configured to read an image of a document conveyed by the DF15.

The image data obtained by reading the original image with the scanner unit 17 is subjected to various processing by an image processing control unit, which will be described later, included in the digital copying machine 10. The image is temporarily stored in a memory provided therein, and image data in the memory is given to the laser printer section 12 in accordance with an output instruction to form an image on a sheet.

The multi-stage paper feeding unit 13 includes a first cassette 28,
It has a second cassette 29, a third cassette 30, and a fourth cassette 31 that can be added by selection. In the multi-stage paper feeding unit 13, the papers are sent out one by one from the papers stored in these cassettes, and are conveyed toward the laser printer unit 12.

The laser printer unit 12 is a manual document tray 2
5. A laser writing unit 26 and an electrophotographic process unit 27 for forming an image are provided.

The laser writing unit 26 is a semiconductor laser which emits a laser beam according to the image data from the above-mentioned memory, a polygon mirror which deflects the laser beam at an equal angular velocity,
And the laser beam deflected at a constant angular velocity is used in the electrostatic photography process section.
It has an f-θ lens and the like for correcting so that the light is deflected at a constant speed on the photosensitive drum 27a of 27.

The electrophotographic process unit 27 comprises a charging device, a developing device, a transfer device, a peeling device, a cleaning device, a discharging device and a fixing device 32 around the photosensitive drum 27a according to a well-known mode. ..

A transport path 33 is provided downstream of the fixing device 32 in the transport direction of the sheet on which an image is to be formed.
33 is a transport path 34 leading to the sorter 14 and a multi-stage paper feeding unit
It branches off to a conveyance path 35 leading to 13.

The transport path 35 is branched in the multi-stage paper feeding unit 13, and a reversal transport path 36 and a double-sided / composite transport path 37 are provided as the transport paths after branching.

The reverse conveyance path 36 is a conveyance path for reversing the front and back of the paper with respect to the image forming position of the photosensitive drum 27a in the double-sided copy mode for copying both sides of the original. The duplex / composite transport path 37 transports paper from the reverse transport path 36 to the image forming position on the photoconductor drum 27a in the duplex copying mode, or forms an image of different originals or images of different colors on one side of the paper. Photosensitive drum 27a without reversing the paper in single-sided composite copy mode for composite copy
Is a transport path for transporting to the image forming position.

The multi-stage paper feeding unit 13 includes a common conveyance path 38, and the common conveyance path 38 transfers the papers from the first cassette 28, the second cassette 29 and the third cassette 30 to the electrophotographic process section 27. It is configured to be carried out toward.

The common transport path 38 joins the transport path 39 from the fourth cassette 31 on the way to the electrophotographic process section 27 and communicates with the transport path 40.

The conveyance path 40 merges with the double-sided / composite conveyance path 37 and the conveyance path 41 from the manual document tray 25 at a confluence point 42 to form an image between the photoconductor drum 27a of the electrostatographic process section 27 and the transfer device. It is configured to reach the formation position.
The confluence point 42 of the two conveyance paths is provided at a position close to the image forming position.

Therefore, in the laser writing unit 26 and the electrophotographic process unit 27, the image data read out from the above-mentioned memory is scanned by the laser writing unit 26 with a laser beam so that the photosensitive drum 27a is scanned.
The toner image formed as an electrostatic latent image on the surface of the sheet is visualized by the toner, and is electrostatically transferred and fixed on the surface of the sheet conveyed from the multi-stage sheet feeding unit 13.

The sheet on which the image is thus formed is sent from the fixing device 32 to the sorter 14 via the conveying paths 33 and 34, or is conveyed to the reverse conveying path 36 via the conveying paths 33 and 35.

Next, the structure and operation of the ADF 15 will be described.

FIG. 3 is a sectional view of the ADF 15 attached to the scanner section 11 of the digital copying machine 10 of FIG.

The ADF 15 sets the set originals to 1
It is configured so that it is automatically fed sheet by sheet to the scanner unit 11 and one or both sides of the document can be read by the scanner unit 17 of FIG. 2 according to the operator's selection.

As shown in FIG. 3, the ADF 15 includes a document tray 50 on which a document 51 is set, a document pickup roller 52 driven via an electromagnetic clutch (not shown), a pair of transport rollers 53, and a transport path of the document 51. Solenoid-driven change lever 54 that can switch between the two, and a document support drum (platen roller) that can rotate in two directions (the direction of the arrow shown in the figure)
55, left and right supply rollers 56L and 56R for feeding the original 51 in cooperation with the platen roller 55, a transparent original support glass 57,
Left and right document guides 58L and 58R, left and right document ejection rollers
59L and 59R, solenoid driven left and right movable guides 60L and 60 which cooperate with the document discharge rollers 59L and 59R, respectively.
R, solenoid-driven movable document discharge guide 61, document discharge conveyance path 62, discharge roller pair 63, discharge tray 64, solenoid-driven rotatable document reverse guide 65, document reverse guide 65
Is provided with a reversing conveyance path 66 formed on one side thereof, a reversing conveyance roller pair 67 driven via an electromagnetic clutch, and a rotating shaft 68.

The distance between the platen roller 55 and the document supporting glass 57 is preferably set larger than the thickness of the document 51.

The document detecting sensor S1 ...
The signals from the document detection sensors S1 to S5, which are respectively output when the document 51 is detected, are sent to a central control unit (PCU) (not shown) which will be described later.

In this PCU, by operating various electromagnetic clutches and solenoids at a predetermined timing, the document 51 passes through a document reading position (exposure position) P as described later.
Is configured to be controlled to be transported.

Next, the operation of the ADF 15 will be described.

When copying only one side of the original 51, a plurality of originals 51 are set on the original tray 50 and the input keys of the operation panel (described later) provided in the digital copying machine 10 of FIG. 2 are used. Input the copy mode (scanning of one side of original, number of copies, copy density, etc.).

When the print switch on the operation panel of the digital copying machine 10 is pressed, the main motor (not shown) of the ADF 15 starts rotating.

Next, the clutch of the document pickup roller 52 is turned on, and the rotating document pickup roller 52 is rotated.
Feeds only the uppermost original of the plurality of originals 51 set on the original tray 50. At this time, the conveyance roller pair
The clutch of 53 also turns on at the same time, and the 53
Is also driven to rotate.

When the leading edge of the fed document 51 reaches the first document detection sensor S1, the solenoid of the change lever 54 is excited, and the change lever 54 moves from the position shown by the alternate long and short dash line in FIG. 3 to the position shown by the solid line. Is switched to. Further manuscript 51
As the feeding of the document is continued, the leading edge of the document 51 is guided along the side surface of the change lever 54 and guided toward the fourth document detection sensor S4.

After the leading edge of the original 51 is detected by the fourth original detection sensor S4, the original 51 is temporarily stopped from being conveyed at the timing when the original 51 is supported by the platen roller 55 and the right supply roller 56R. To do.

Next, at a predetermined timing, the clutch of the right transport roller 56R is turned on, and the document supporting glass 57R is turned on.
Then, the feeding of the original 51 to the exposure position P is started again.

The platen roller 55 rotates the exposure position P in the clockwise direction while the document 51 is pressed against the surface of the platen roller 55 by the document guide 58R on the right side. Pass from right to left. At this time, at the exposure position P, the image data of the document 51 is shown in FIG.
It is read by the scanner unit 17 of.

The document 51 that has passed the exposure position P passes under the document guide 58L on the left side and the document discharge roller 59L on the left side.
Will be transported to. The edge of the original 51 is the original discharge roller 59L
Left movable guide 60L
When the document 51 is sandwiched, the movable guide 60L is pressed against the document discharge roller 59L.

As a result, the document discharge roller 59 is attached to the document 51.
The conveyance force is given by the frictional force of L, and the document 51 is guided along the upper surface of the document discharge movable guide 61,
After passing through 62, the sheet is discharged onto a sheet discharge tray 64 by a pair of sheet discharge rollers 63.

A fifth document detecting sensor S5 provided in the document discharge / conveyance path 62 detects the rear end of the document 51 and detects the document 51.
Is for determining that the paper has been discharged onto the paper discharge tray 64.

When a plurality of originals 51 are set on the original tray 50, the next original is fed at the timing when the trailing edge of the previous original passes the exposure position P.

The original tray 50 is provided with an original detection sensor (not shown) for detecting whether or not the original 51 is set, and the above operation is repeated until the last original 51 is exhausted.

Next, when copying both sides of the original 51,
When the print switch on the operation panel of the digital copying machine 10 is pressed, the document pickup roller 52 feeds only the top document of the plurality of documents 51 set on the document tray 50.

When the leading edge of the fed document 51 reaches the first document detection sensor S1, the clutch of the transport roller pair 53 is turned on, and the transport roller pair 53 is also rotationally driven. At this time, the solenoid of the change lever 54 is in the non-excited state, the change lever 54 is at the position shown by the alternate long and short dash line in FIG. 3, and the leading edge of the document 51 is guided toward the second document detection sensor S2. To be done.

The document 51 that has passed through the second document detection sensor S2
With the leading edge of the left side being sandwiched between the platen roller 55 and the left side supply roller 56L, the clutch of the left side conveyance roller 56L is turned off, and the conveyance of the document 51 is once stopped.

Next, at a predetermined timing, the transport roller 56L
Then, the clutch is turned on again, and the feeding of the document 51 to the exposure position P of the document supporting glass 57 is started again.

The platen roller 55 rotates the exposure position P in the counterclockwise direction in a state where the original 51 is pressed against the surface of the platen roller 55 by the left original guide 58L.
The original document 51 passes through the exposure position P from left to right in FIG.
In this way, the exposure scanning of one side of the document 51 is started.

The original 51 that has passed the exposure position P passes under the right original guide 58R and the right original discharge roller 59R.
Sent to. The solenoid of the movable guide 60R on the right side is excited at the timing when the leading edge of the document 51 reaches the document discharge roller 59R, and the movable guide 60R is pressed against the document discharge roller 59R while the document 51 is sandwiched.

The document 51 conveyed by being sandwiched by the movable guide 60R and the document discharge roller 59R is guided to the reversing conveyance path 66, and conveyed by the reversing conveyance roller pair 67 toward the third document detection sensor S3. It

When the leading edge of the document 51 reaches the third document detection sensor S3, the solenoid of the document reversing guide 65 is excited, and the document reversing guide 65 is drawn from the position shown by the solid line with the pivot shaft 68 as the center. It is rotated along the arrow shown in the figure to the position shown by, and the reversal conveyance path 66 is opened. At the same time, the solenoid of the change lever 54 is excited and the change lever 54
Is switched from the position indicated by the alternate long and short dash line to the position indicated by the solid line.

The leading edge of the original 51 is further provided with a pair of reverse conveying rollers 67.
It is guided to the conveying roller pair 53 by the guide roller 53 and guided toward the fourth document detection sensor S4 along the side surface of the change lever 54 which is switched to the position shown by the solid line. Then, when the leading edge of the document 51 is sandwiched between the platen roller 55 and the right supply roller 56R, the conveyance of the document 51 is temporarily stopped.

In this state, the reverse conveyance path length (from the contact point between the platen roller 55 and the supply roller 56R, the fourth document detection sensor S4, the change lever 54, the conveyance roller pair 53, the third document detection sensor S3, If the length of the original is longer than the length of the original that passes through the pair of conveying rollers 67 and the reverse conveying path 66 and reaches the contact point between the movable guide 60R and the original discharge roller 59R, the original reverse guide 65 is rotated. Since the reverse conveyance path 66 is open, even if the leading edge of the document is stopped, the portion of the document after the reverse conveyance roller pair 67 is moved from the position sandwiched by the reverse conveyance roller pair 67 to the movable guide 60R. A natural flexure is formed between the position sandwiched between the document discharge roller 59R and the document discharge roller 59R.

Reversing conveyance path by rotation of the document reversing guide 65
The degree of opening of 66 is, for example, the size of the document detected by a document size detection device (not shown) which will be described later that can detect the size of the document, or the size of the document input by the operator through the input keys of the operation panel. The opening degree may be set in advance so that the reverse conveyance path 66 is opened according to the size.

Next, after the trailing edge of the document 51 has passed the exposure position P, the document is fed again to the exposure position P of the document supporting glass 57 at the timing with the scanner unit 17.

The platen roller 55 guides the original 51 to the original.
While being pressed against the surface of the platen roller 55 by the 58R, the exposure position P is rotated in the clockwise direction so that the original 51
Passes through the exposure position P from right to left in FIG. At this time, at the exposure position P, the image data of the document 51 is read by the scanner unit 17.

The document 51 that has passed the exposure position P passes under the document guide 58L on the left side and the document discharge roller 59L on the left side.
Will be transported to. The edge of the original 51 is the original discharge roller 59L
Left movable guide 60L
The solenoid of is excited and the movable guide 60L is pressed against the document discharge roller 59L with the document 51 being sandwiched,
To transport.

When the reading of the image on the second side of the original 51 is completed, the solenoid of the original reversing guide 65 is de-energized, the original reversing guide 65 returns to the position shown by the solid line, and the leading edge of the next original 51 is returned. Is waited for to be guided to the reverse conveyance roller pair 67.

The document 51 conveyed by being sandwiched by the movable guide 60L and the document discharge roller 59L is guided along the upper surface of the document discharge movable guide 61, passes through the document discharge / conveyance path 62, and passes through a pair of discharge rollers. The sheet is discharged onto the sheet discharge tray 64 by 63.

When a plurality of originals 51 are set on the original tray 50, when the rear side of the original passes the exposure position P at the time of scanning exposure of the second side of the previous original, the following Will be sent.

The above-mentioned operation is repeated until the last original 51 is left on the original tray 50.

Next, the operation panel provided on the upper portion of the digital copying machine 10 shown in FIG. 2 will be described.

FIG. 4 is an external view of the operation panel of the digital copying machine 10 of FIG. 2, and FIG. 5 is an enlarged view of the basic screen of the display section of the operation panel of FIG.

As shown in FIG. 4, the operation panel 70 is provided with a display section 70a which also serves as an input section at substantially the center thereof, and a print switch 70b and a clear key 70c at the right end. The display unit 70a may be configured by a transparent touch panel on the display surface of the dot matrix liquid crystal display unit, for example.

FIG. 5 shows a state in which the basic screen at power-on is enlarged and displayed on the display unit 70a of FIG.
At the upper part of the display unit 70a, a magnification selection area 71 where the copy magnification can be selected, a paper size selection area 72 where the paper size can be selected, a copy density selection area 73 where the copy density can be selected, and a copy number where the copy number can be selected. In the number selection area 74 and the lower left part of the display unit 70a, a sorter selection area 75 in which the sorter type can be selected and the lower right part of the display unit 70a are
There is provided a plus function selection area 76 capable of selecting a copy mode such as double-sided copy from a single-sided original.

When the operation panel 70 touches the magnification selection area 71 of the display section 70a, a magnification setting screen (not shown) is displayed. When the paper size selection area 72 is touched, a copy size selection area is displayed on the paper size setting screen (not shown). When the user touches 73, the copy density setting screen (not shown) is switched to, and when the copy number selection area 74 is touched, the copy number setting screen (not shown) is switched.

Further, the operation panel 70 is provided with a sorter selection area 75.
When you touch, the display switches in the order of “Non-sort”, “Sort”, “Group”, “Staple sort” and “Saddle stitch setting screen”. Touch the plus function selection area 76 and copy mode not shown It is configured to switch to the setting screen.

Next, the control system of the digital copying machine 10 shown in FIG. 2 will be described.

FIG. 6 is a block diagram showing the configuration of the control system of the digital copying machine 10 shown in FIG. In the figure, thick arrows between blocks indicate image data flows, solid arrows indicate control signal flows, and broken bidirectional arrows indicate communication control lines.

As shown in the figure, the digital copying machine 10 includes a control system for controlling the operation of the entire copying machine. This control system includes a central control unit (PCU) 81 and an image processing unit (ICU). 82, operation board unit (OP
U) 83, sorter control unit (FCU) 84, input data preprocessing unit (CCU) 85, and laser control unit 86.

The PCU 81 has a central processing unit (CPU) and controls each part of the digital copying machine 10 in a centralized manner, that is, by communicating the ICU 82, OPU 83 and FCU 84 (broken line arrow shown in the figure). Is configured to control.

The OPU 83 controls the operation panel 70 shown in FIG. 4, and the FCU 84 controls the sorter 14 shown in FIG.

A load 87 such as a motor and solenoid related to the scanner section 11 in FIG. 2, a load 88 such as a motor, solenoid and high voltage unit related to the laser printer section 12, AD
Loads such as motors, clutches and switches related to F15
The PCU 81 is configured to directly control the sequence control of the load 90 such as the motor, the clutch, and the sorter associated with the multi-stage paper feeding unit 13, that is, the desk 89.

The processing of image data described later is directly performed by the CPU included in the ICU 82. Figure 6
2, the ICU 82 preprocesses the image data from the CCD linear image sensor 22 of FIG. 2 and stores it in the main memory 82a included in the ICU 82.
And a laser control unit 86 for outputting the image data stored in the main memory 82a to the laser printer section 12 can be controlled in parallel.

The CCU85, ICU82 and laser control unit 86 are independent control units. Unless the control target image data is the same, the CCU85, ICU82 and laser control unit 86 control units are parallel. It is possible to independently perform processing, and it is possible to operate without being affected by the processing status of other control units. However,
The CPU included in the PCU 81 is configured to control the processing of image data by the ICU 82 by communication.

Next, the processing from the input of image data to the output will be described.

FIG. 7 is a block diagram of an image processing control unit included in the digital copying machine 10 shown in FIG. 2 for performing processing from input to output of image data.

As shown in the figure, the image processing control section includes an image data input section 91, an image data processing section 92, an image data output section 93, and a memory 94 including a RAM (random access memory). ..

Image data input unit 91, image data processing unit 92
The image data output unit 93 is the CCU85, ICU82 of FIG.
And the laser control unit 86, respectively. Therefore, the image data processing unit 92 is connected to the PCU 81 through the ICU 82 as shown in FIG. 6, and the PCU 81 is configured to control the operation of the image processing control unit together with the CPU of the ICU 82. Also, memory
Reference numeral 94 is a memory corresponding to the main memory 82a of the ICU 82.

The image data input section 91 includes a CCD section 91a, a histogram processing section 91b and an error diffusion processing section 91c.

The image data input unit 91 binarizes and converts the image data of the original read from the CCD linear image sensor 22 of FIG. 2 to obtain a histogram as a binary digital amount, and the image data by the error diffusion method. Are processed and stored once in the memory 94.

That is, in the CCD unit 91a, after the analog electric signal corresponding to each pixel density of the image data is A / D (analog / digital) converted, MTF correction, black and white correction or gamma correction is performed, and the 256th floor It is output to the histogram processing unit 91b as a key (8-bit) digital signal.

In the histogram processing section 91b, the CCD section 91
The digital signal output from a is added for each pixel density of 256 gradations to obtain density information (histogram data), and if necessary, the obtained histogram data is sent to the CPU of the ICU82, or The data is sent to the error diffusion processing unit 91c.

The error diffusion processing section 91c performs an error diffusion processing which is a kind of pseudo halftone processing. That is, in the error diffusion processing unit 91c, the 8-bit / pixel digital signal output from the CCD unit 91a becomes 1 bit (binary) by the method of reflecting the binarization error in the binarization judgment of the adjacent pixel. The redistributed calculation is performed in order to faithfully reproduce the density of the local area in the original that has been converted.

The operation of the image data input unit 91 is started by the PCU.
The instruction is given by the PC 81, and the PCU 81 starts the sequence control of the load 87 related to the scanner unit 11 in FIG. 2 under the condition that the print switch 70b of the operation panel 70 shown in FIG. The ICU 82 is instructed at the command level in accordance with the tip synchronizing signal. P
The CU81 also uses the main memory 82a of the ICU82,
That is, the memory capacity is constantly monitored by communication.

The image data processing unit 92 includes multi-valued processing units 92a and 92b, a synthesis processing unit 92c, a density conversion processing unit 92d, a scaling processing unit 92e, an image processing unit 92f, an error diffusion processing unit 92g, and a compression processing unit 92h. Is included.

The image data processing unit 92 is a processing unit for finally converting the input image data into image data desired by the operator, and stores it in the memory 94 as output image data obtained by finally converting the image data. Until this is done, processing is performed in this processing unit.

Each processing unit included in the image data processing unit 92 functions as necessary, and the function may not be executed in some cases.

In the multilevel halftoning processing units 92a and 92b, the data binarized by the error diffusion processing unit 91c is converted again into 256 gradations.

In the synthesizing section 92c, a logical operation for each pixel,
That is, the operation of logical sum, logical product, or exclusive logical sum is selectively performed. The data to be calculated is the pixel data stored in the memory 94 and the bit data from the pattern generator (PG).

The density conversion processing section 92d arbitrarily sets the relationship between the input density and the output density for the digital signal of 256 gradations based on a predetermined gradation conversion table.

In the scaling processing section 92e, the pixel data (density value) for the scaled target pixel is obtained by performing interpolation processing with the known data that is input according to the instructed scaling ratio. After the scanning is scaled, the main scanning is scaled.

In the image processing unit 92f, various image processings may be performed on the input pixel data to collect information on the data string such as feature extraction.

The error diffusion processing unit 92g performs the same processing as the error diffusion processing unit 91c of the image data input unit 91.

In the compression processing section 92h, binary data is compressed by the encoding called run length. Regarding the compression of the image data, the compression functions in the final processing loop when the final output image data is completed.

The operation of the image data processing unit 92 is based on the function set by the operator using the operation panel 70 shown in FIG. 4, and the data to be processed in the operation of the image data input unit 91 is stored in the memory 94. , And P
It is started by the CU 81 sending an image processing command to the ICU 82.

The image data output unit 93 includes a restoration unit 93a, a multi-value quantization processing unit 93b, an error diffusion processing unit 93c, and a laser output unit 93d.
Is included.

The image data processing unit 93 is a memory in a compressed state.
The image data stored in 94 is restored, the original 256 gradations are converted again, and the error diffusion of the 4-valued data that is a smoother halftone expression than the binary data is performed, and the image is output to the laser output section 93d. It is configured to transfer data.

That is, the decompression unit 93a decompresses the image data compressed by the compression processing unit 92h.

In the multi-valued processing unit 93b, the image data processing unit
Processing similar to that of the multi-value quantization processing units 92a and 92b of 92 is performed.

The error diffusion processing unit 93c performs the same processing as the error diffusion processing unit 91c of the image data input unit 91.

In the laser output section 93d, the digital pixel data is converted into an ON (ON) / OFF (OFF) signal for driving the laser on the basis of the control signal from the PCU 81, and the laser is turned ON / OFF. ..

The data handled by the image data input section 91 and the image data output section 93 are basically stored in the memory 94 in the form of binary data in order to reduce the capacity of the memory 94. It is also possible to process in the form of four-valued data in consideration of deterioration of image data.

The conditions for starting the operation of the image data output unit 93 are as follows:
That is, the image data in which the processing desired by the operator (processing corresponding to the function set by the operation panel 70 shown in FIG. 4) is completed is present in the memory 94. Whether or not the image data stored in the memory 94 has been completely processed is managed by the PCU 81.

Next, the structure and operation of the document size detecting device provided on the document tray of the ADF 15 will be described.

FIG. 8 is a plan view of a main part of the document tray included in the ADF 15 shown in FIGS. 2 and 3, and FIG. 9 is a document size detection provided on the document tray of the ADF 15 shown in FIGS. FIG. 10 is a circuit configuration diagram showing the configuration of the detection circuit included in the apparatus, FIG. 10 is a graph showing the relationship of the input voltage to the analog port with respect to the position where the detector is in the ON state, and FIG. 11 is the document size and document tray setting. It is explanatory drawing which shows the ON / OFF (OFF) state of the detector with respect to a direction.

As shown in FIG. 8, the document tray 15a provided in the ADF 15 corresponds to the document tray 50 shown in FIG. The document size detection device of this embodiment is
Multiple detectors DWS on the document tray 15a
1, DWS2, DWS3, DWS4, DLS1 and DLS2.

Multiple detectors DWS1, DWS2, DWS3, DWS
4, DLS1 and DLS2 are arranged at predetermined positions where the size of the original placed on the original tray 15a can be detected, and are turned on when the presence of the original is detected. It is configured.

As shown in FIG. 9, in the detection circuit included in the document size detection device of FIG. 8, the detectors DWS1 and DW are used.
The S2, DWS3 and DWS4 and the detectors DLS1 and DLS2 are connected to the CPU 81a included in the PCU 81 shown in FIG. 6 through analog ports 81b and 81c, respectively.

This detection circuit converts the size of the detected document into an analog voltage according to the ON / OFF state of each detector shown in FIG. 11 and the relationship shown in FIG. 10, and outputs the signals DWS and DLS corresponding to the size to the CPU 81a. Send to.

The detected original size is displayed together with the paper size in the paper size display area that can be displayed on the display section 70a of the operation panel 70 shown in FIG.

Next, the control of the operation of the ADF 15 shown in FIGS. 2 and 3 will be described.

FIG. 12 is a block diagram showing the configuration of the control system related to the control of the operation of the ADF 15 shown in FIGS. 2 and 3, among the configurations of the control system shown in FIG. In the figure, solid arrows show the flow of control signals, and broken two-way arrows show communication control lines.

As shown in the figure, A shown in FIGS.
The control system related to the control of the operation of the DF15 is the PCU81,
Equipped with ICU82 and OPU83, PCU81, ICU
The configurations and operations of the 82 and the OPU 83 are the same as the configurations and operations described with reference to FIG. However, PCU81 is AD
8 and 9 included in the F-related load 89 are directly connected to the document size detecting device 89a shown in FIGS. 8 and 9 through a line for sending the size of the document placed on the document tray 15a of the ADF 15 by an analog signal.

The communication control line indicated by the broken double-headed arrow in the drawing connecting the PCU 81 and the ICU 82 enables the IC
Commands and data for recognizing the available memory capacity of the main memory 82a of U82 are communicated.

The instruction to receive and store the image data of the original read by the scanner unit 17 of FIG.
Issued from PCU81 to ICU82.

Therefore, unless the instruction reaches the ICU 82 at the command level via the above-mentioned communication control line, I
The main memory 82a of the CU 82 does not store image data. Regarding the operation of ADF15 (conveyance of original),
The CU 81 manages everything and directly controls the sequence.

The scanner section 11 shown in FIG. 2 is an embodiment of the document reading means of the present invention. The laser printer unit 12 of FIG. 2 is an embodiment of the image forming means of the present invention. 2 and 3
The ADF 15 is an embodiment of the document feeding means of the present invention.
The PCU 81 shown in FIGS. 6 and 12 is an embodiment of the control means of the present invention. The ICU 82 of FIGS. 6 and 12 is an embodiment of the storage capacity calculating means of the present invention. The main memory 82a shown in FIGS. 6 and 12 or the memory 94 shown in FIG. 7 is an embodiment of the storage means of the present invention. Multiple detectors of FIGS. 8 and 9
DWS1, DWS2, DWS3, DWS4, DLS1 and DLS2 are examples of the storage capacity detecting means of the present invention.

Next, the control operation when the PCU 81 controls the document feeding operation of the ADF 15 will be described.

FIG. 1 is a flow chart showing an example of the control operation of the ADF 15 by the PCU 81.

As shown in the figure, first in step ST1, it is determined whether or not a document is set on the document tray 50 of the ADF 15 shown in FIGS. If it is determined that the originals are set in the original tray, step
When the process proceeds to ST2 and it is determined that the original is not set, the operation ends.

Next, in step ST2, the size of the set original document is set in the ADF 15 as shown in FIGS.
It is detected by the document size detecting device shown in.

Then, in step ST3, setting conditions such as the magnification set through the magnification setting screen which is switched by touching the magnification selection area 71 of the operation panel shown in FIG. 5 and the original detected by the original size detecting device. Main memory required for image processing from the size and the paper size set via the paper size setting screen that is switched by touching the paper size area 72 on the operation panel.
Predict the data capacity DO of 82a.

Then, in step ST4, the main memory
Obtain and confirm the remaining capacity MS of the memory capacity of 82a. For this confirmation, the PCU 81 instructs the ICU 82 to transmit the memory remaining amount data (pixel unit; pixel) by a command.

Then, in step ST5, the main memory
The remaining capacity MS of the memory capacity of 82a is compared with the estimated data capacity DO of the main memory 82a necessary for image processing,
It is determined whether MS is greater than DO. MS is DO
If it is larger than MS, the process proceeds to step ST6. If MS is not larger than DO, the process returns to step ST4.

For example, if the size of the document on the document tray of the ADF 15 is A4, the copy magnification setting condition is 1 ×, and the paper size is A4, the prediction of the main memory 82a necessary for image processing is performed in step ST3. The data capacity DO is
It is expected to be about 16 × 10 ⁶ pixels. Next, in step ST4, 20 × 10 ⁶ pixels are equal to the remaining memory capacity MS.
It is assumed that the data is transmitted from the ICU 82 to the PCU 81. In this case, in step ST5, the MS is DO
It is determined that the difference is larger, and the process proceeds to step ST6.

At step ST6, the PCU 81 instructs the ADF 15 to carry out the document conveying operation.

If the automatic magnification is set so that, for example, an A4 size original is enlarged and copied onto an A3 size sheet, in step ST3, the data capacity DO of the main memory 82a required for image processing is increased. Is expected to be approximately 31 × 10 ⁶ pixels. Next, in step ST4, it is assumed that 20 × 10 ⁶ pixels are transmitted from the ICU 82 to the PCU 81 as data of the remaining memory capacity MS. In this case, it is determined in step ST5 that MS is not larger than DO. That is, an A4 size original can be stored in the main memory 82a, but the ICU 82 cannot perform enlargement processing to an A3 size sheet. Therefore, the process returns to step ST4, until the memory remaining amount MS becomes equal to or larger than the A3 size paper (about 31 × 10 ⁶ pixels), that is, until the memory remaining amount MS becomes larger than the predicted data capacity DO,
Instruct the ADF 15 to put the document on the document tray.

According to this embodiment, the ADF 15 does not carry the original document until the data capacity required for the image processing can be stored in the main memory 82a, and the original document is put on the original tray and sent from the ICU 82. The remaining memory capacity MS of the memory 82a is monitored and the subsequent processing is judged (step ST5).

As for the data of the remaining memory capacity MS,
Even if there is no instruction from the PCU81, basically, the ICU82 is connected to the PC before and after the ICU82 performs some data processing.
You may send it to U81.

Further, the control operation of the ADF 15 by the PCU 81 described above is programmed in advance and, for example, an RO (not shown) connected to the PCU 81 shown in FIG.
The program may be stored in M (read only memory) and the CPU of the PCU 81 may read the program from the ROM and execute the program. The program may be executed during the operation of the copying machine.

According to the above embodiment, the ADF 15 is a PCU.
By 81, control is performed so that the document is supplied to the document reading position only when main memory 82a has a memory capacity necessary for image processing. Therefore, once the reading of the document image is started, the document is not stopped at the document reading position until the operation of reading the one document image is completed, unless trouble occurs. The reading operation of the original image is not started again from the stopped state.

Therefore, at the document reading position, it is possible to always read the image data of the document conveyed at a stable speed. As a result, a stable copy image can always be obtained.

[0142]

As described above, according to the present invention, the document feeding means for feeding the document to the document reading position, the document reading means for reading the image of the document fed by the document feeding means, and the reading by the document reading means. Storage means for storing the image data of the recorded original, image forming means for forming an image on a sheet based on the image data stored in the storage means, and storage capacity detection for detecting the usable storage capacity of the storage means Means, a storage capacity calculating means for obtaining the storage capacity of the storage means necessary for the image forming processing by the image forming means, and the storage capacity detected by the storage capacity detecting means is smaller than the storage capacity calculated by the storage capacity calculating means. And a control unit for controlling the document supply unit so as not to supply the document. Therefore, at the document reading position, it is possible to always read the image data of the document conveyed at a stable speed.

[Brief description of drawings]

FIG. 1 is a flowchart showing an example of an ADF control operation by a PCU.

FIG. 2 is a cross-sectional view showing the overall configuration of a digital copying machine that is an embodiment of the image forming apparatus according to the present invention.

3 is a cross-sectional view of an ADF attached to a scanner unit of the digital copying machine of FIG.

4 is an external view of an operation panel of the digital copying machine of FIG.

5 is an enlarged view of a basic screen of a display unit of the operation panel of FIG.

FIG. 6 is a block diagram showing a configuration of a control system of the digital copying machine of FIG.

7 is a block configuration diagram of an image processing control unit included in the digital copying machine of FIG. 2 for performing processing from input to output of image data.

FIG. 8 is a plan view of relevant parts showing a document tray included in the ADF shown in FIGS. 2 and 3;

9 is a circuit configuration diagram showing a configuration of a detection circuit included in a document size detection device provided in the document tray of the ADF shown in FIGS. 2 and 3. FIG.

FIG. 10 is a graph showing the relationship of the input voltage to the analog port with respect to the position where the detector is in the ON state.

FIG. 11 is an explanatory diagram showing an on / off state of a detector with respect to a document size and a document tray setting direction.

12 is a block diagram showing a configuration of a control system related to the control of the operation of the ADF shown in FIGS. 2 and 3 among the configurations of the control system shown in FIG.

[Explanation of symbols]

 10 Digital copier 11 Scanner section 12 Laser printer section 15 ADF 81 PCU 82 ICU 82a Main memory 94 Memory DWS1, DWS2, DWS3, DWS4, DLS1, DLS2 detector

Claims (1)

[Claims] 1. A document feeding unit for feeding a document to a document reading position, a document reading unit for reading an image of the document supplied by the document feeding unit, and image data of the document read by the document reading unit are stored. Storage means, an image forming means for forming an image on a sheet based on the image data stored in the storage means, a storage capacity detecting means for detecting a usable storage capacity of the storage means, and the image forming Storage capacity calculating means for obtaining a storage capacity of the storage means necessary for image forming processing by means, and when the storage capacity detected by the storage capacity detecting means is smaller than the storage capacity calculated by the storage capacity calculating means, An image forming apparatus comprising: a control unit that controls a document supply unit so as not to supply a document.