JPH0572854A - Original discrimination device for both side copying device and its method of utilization - Google Patents

Abstract

PURPOSE:To efficiently carry out appropriate process according to the type of document carried by an automatic document feeder device. CONSTITUTION:The both side copying device is provided with the circulatory automatic document feeding device 2 sequentially carrying document 32 loaded on a document tray 31 to a document exposure part 6 for exposure is also provided with a reversal path 40 reversing the front and back of the document, and the front and the back of the document 32 is selectively reversed and carried to the document exposure part 6 for exposure. A pair of image sensors 69a and 69b are provided in this device to detect the existence of image information on a front side and a back side of the carried document 32 inside the automatic document feeder device 2, a front side only document, a back side only document, and the both side document are discriminated, and processes appropriate for each document 32 are carried out.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a document identifying device in a double-sided copying machine having an automatic document feeder and a method of using the same.

[0002]

2. Description of the Related Art In recent years, copying machines and the like have become multifunctional, and there are copying machines having a double-sided copying function, for example.
In order to make effective use of the document, a circular automatic document feeder (RDF) that can automatically convey originals on the contact glass and has a reversing function is provided so that not only single-sided originals but also double-sided originals can be handled. There is something I did.

Therefore, the copy modes are a single-sided / one-sided mode for obtaining a single-sided copy from a single-sided original, a single-sided / double-sided mode for obtaining a double-sided copy from a single-sided original, and a double-sided / single-sided mode for obtaining a single-sided copy from a double-sided original. It is possible to select from four types of two-sided-two-sided mode for obtaining a two-sided copy from an original.

[0004]

However, in such a processing mode, the original stacked on the RDF is either a single-sided original or a double-sided original, and it seems that the single-sided original and the double-sided original are mixed. The case is not assumed,
If they are mixed, one of the originals is uniformly considered according to the setting mode of the user.

For example, in the duplex-single-sided mode setting, if a single-sided original is mixed in the double-sided original, this single-sided original is also regarded as a double-sided original.
(Blank paper) is also used for single-sided copying, and blank sheets are mixed in the resulting single-sided copying, resulting in waste of processing time and transfer paper.

Also, when the duplex / duplex mode is set,
When a single-sided original is mixed in the double-sided original, the double-sided copy operation is also performed on the single-sided original, resulting in a waste of unnecessary processing time.

Similarly, when a single-sided original is mixed with a double-sided original in the processing mode, the back side information of the double-sided original is not copied.

Therefore, the operator needs to be aware of whether the originals are single-sided originals or double-sided originals when setting the originals in the RDF, and when the originals are mixed, the originals are removed. Therefore, it is troublesome because it is necessary to form a different set or to remake the originals as a double-sided original or a single-sided original so as to correspond to other types of originals.

For this reason, an image sensor for detecting the presence or absence of backside image information is provided for an original conveyed by RDF to determine whether the original to be copied is a single-sided original or a double-sided original. The applicant of the present invention has proposed automatic identification and different copy processing according to the identification result. According to this, the operator does not need to be aware of whether the originals to be stacked and set on the RDF are single-sided, double-sided, or mixed, and what form the resulting copy should have is determined. The operability can be improved by pointing. However, even in such a proposal example, for example, a back-side one-sided original is regarded as a two-sided original, and there is room for improvement in terms of lack of proper processing and cost.

[0010]

According to the first aspect of the present invention, the originals stacked on the original tray are sequentially conveyed to the original exposure section for exposure, and a reverse path for reversing the front and back of the original is provided. In a double-sided copying machine equipped with a circulation type automatic document feeder for selectively exposing the original by reversing the original and feeding it to the original exposing section, the original being conveyed in the automatic document feeder A pair of image sensors for detecting the presence / absence of image information on the front surface and the back surface are provided.

According to the second aspect of the present invention, the pair of image sensors detect the presence or absence of image information for a predetermined width of a part of the document being conveyed. The width can be freely set.

Further, in the invention according to claim 4, the pair of image sensors detect the presence or absence of image information for a predetermined length of a part of the document being conveyed, and in the invention according to claim 5, The predetermined length can be set to an arbitrary length, and in the sixth aspect of the invention, the predetermined length is set according to the document size.

According to the seventh aspect of the invention, the density level for detecting the presence or absence of image information can be set freely.

According to the eighth aspect of the invention, the detection level for determining that there is image information can be freely set with respect to the amount of image information detected by the image sensor.

According to the ninth aspect of the invention, the predetermined width, predetermined length, predetermined density level, and predetermined detection level can be set independently on the front side of the document and the back side of the document.

Further, in the invention according to claim 10, at least one of the pair of image sensors is arranged at a position where at least one end surface of the document being conveyed crosses, and the size of the document is also detected.

Further, in the invention described in claim 11, these claims 1, 2, 3, 4, 5, 6, 7, 8, 9 or 1
A control means for controlling switching of the reversal path based on the detection result of the presence or absence of backside image information by the image sensor described in 0 is provided,
A mode 1 is used to form an image in the same manner as the original according to the type of one side / both sides of the original, a mode 2 is used to form an image regardless of the type of one side / both sides of the original, and the front / back sides of the original are printed. Regardless of the mode 3, the image information of the surface having the image information is sequentially left-justified, and the mode 3 in which double-sided image formation is performed is set to be selectable.

[0018]

Whether the original conveyed by the automatic original conveying device to the original exposing section is a front single-sided original, a back single-sided original, or a double-sided original by detecting presence / absence of front-side image information and rear-side image information by a pair of image sensors. Since it is automatically identified, it is possible to save the processing time and the paper by eliminating the wasteful image forming process for the blank surface that does not have the image information. It is sufficient to select only the image form to be obtained as a result without considering whether it is a manuscript or a two-sided manuscript, and the operability is good. In particular, as in the mode 3, only the surface having the image information is front-justified to form the double-sided image, so that the processing time is not wasted and the paper can be saved. At this time, since the detection target by the pair of image sensors is limited to a region having a predetermined width of a part of the document or a predetermined length in the conveyance direction, the image sensor to be used becomes small and inexpensive, The signal processing time is also shortened. In particular, the predetermined length in the sub-scanning direction can be freely set to an arbitrary length, and for example, by corresponding to the document size, it is possible to accurately detect the double-sided document corresponding to various sizes. Further, since the density level for detecting the presence or absence of the image information can be set freely, or the detection level with the image information with respect to the detected image information amount can be set freely, for example, a document stain, a scribble, etc. can be set as the image information. It is also possible to increase the detection accuracy without making a mistake. Further, by changing the setting conditions on the front side of the document and the back side of the document, flexibility is enhanced. Further, since the image sensor is disposed at a position where at least one end face of the document being conveyed is crossed and the size of the document is also detected, the cost can be reduced.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described with reference to FIGS. First, an example of a double-sided copying system to which the present invention is applied will be described with reference to FIG. This copying system is roughly a copying machine main body 1 which is a copying apparatus main body.
A circulating type automatic document feeder 2 placed on the main body 1 of the copying machine, and a reversing unit 3 on the discharge side of the main body 1 of the copying machine.
And a post-processing device, for example, a sorter unit 4, which are arranged side by side.

The basic structure and operation of the copying machine body 1 will be described with reference to FIG. First, a document (described later) on the contact glass 6 is exposed by the flash lamp 5 with a power source, and the reflected light is imaged on the belt-shaped photoreceptor 10 through the first mirror 7, the through lens 8 and the second mirror 9. Let Here, the photoconductor 10 has already been charged by the charging charger 11, and a latent image is formed by imaging exposure. This latent image is developed by the developing device 12 and becomes a visible image. The visible image is, for example, a three-stage paper feed tray 13, 14, 1.
It is transferred by the action of the transfer charger 17 to the transfer paper 16 that is selectively fed from any one of No. 5 and No. 5. The surface of the photoconductor 10 after the transfer is cleaned by the cleaning device 18. On the other hand, the transfer paper 16 after transfer passes through the fixing device 19 and undergoes a fixing process, and heads toward the paper discharge side.

The behavior of the transfer paper 16 after the fixing process differs depending on the copy mode. First, in the case of simple paper discharge mode,
The switching claw 20 is switched to the one different from that shown in the drawing,
At the same time, the switching claw 21 is switched to the state shown in FIG.
6 is discharged onto the main body tray 22 by turns. That is, the copied surface faces downward and is discharged onto the main body tray 22 in the copy order (page order). Further, in the case of the sorter mode, the switching claw 21 is switched to a direction different from that shown in the drawing, the transfer paper 16 is discharged to the outside of the copying machine main body 1, and passes through the reversing unit 3 and, if necessary, the reversing path. It is reversed at 23, and when it is unnecessary, it goes to the sorter unit 4 as it is. Transfer sheets 1 that are sequentially conveyed in the sorter unit 4
6 is controlled to be switched by the deflecting claws 24 and discharged into a predetermined bin 25 for sorting and stacking. By the way, the reversing unit 3 is provided on the upstream side of the sorter unit 4 in the case of executing double-sided copying, as described later, the front side (= the youngest in the page order) is copied first, and then the back side is copied. When the sheet is ejected from the copying machine main body 1 side as it is, the surface (the younger one in the page order) of the transfer sheet 16 ejected to the bin 25 faces upward, and the page order is not. Therefore, in this case, This is because the reversing unit 3 reverses the front and back and then performs the sorter processing. Therefore, in the case of single-sided copying, inversion processing is unnecessary.

On the other hand, after the front side copy in the double-sided copy mode, the switching claw 20 is in the illustrated state and the transfer paper 1
6 is discharged onto the double-sided tray 26 with the copy side facing up. The pages are arranged in order from the bottom. The transfer paper 16 once stacked on the double-sided tray 26 is fed from the lowest transfer paper by the double-sided paper feeding belt 27,
It is sent to the transfer section through the same path as when the paper is fed from 3, 14, and 15, and the back side copy is made by the image on the photoconductor 10 and is discharged to the main body tray 22 or the sorter unit 4 side.

The copy processing by the copying machine body 1 is performed in cooperation with the document processing on the RDF 2 side. Next, the basic configuration and operation of the RDF2 side will be described with reference to FIG. The RDF 2 basically has an ADF mode and an RDF mode. In the ADF mode, a preset number of copies is made for one original, and this is repeated for all originals. Then, one copy is obtained by making one copy of each original and making one copy, and this is repeated for a preset number of copies.

First, the operation when a one-sided original is assumed will be described as a basic. A document 32 stacked and set with the document surface facing down on the document tray 31 is fed by a paper feed belt 33.
Is fed by turn from the lowest document side, and the intermediate conveyance path 3
4 and further through the turn conveyance path 35, the document surface is directed downward and toward the contact glass 6 side. After passing through the turn conveyance path 35, it is conveyed by the conveyance belt 36 and stopped at a predetermined position on the contact glass 6. Therefore, after being subjected to the above-described exposure and subjected to a necessary copy operation, the sheet is discharged from the contact glass 6 by the transport belt 36 which is driven again. At this time, the original 32 is picked up from the surface of the contact glass 6 by the branch claw 37, and advances to the guide space 40 along the turn conveying path 38 and the branch claw 39. In this operation, when the rear end of the original 32 passes through the guide claw 41 on the left end of the contact glass 6, the transport drive source that has been used so far begins to reverse, and the original 32 is fed backward with the rear end as the front end and turned. It is fed into the conveyance path 42, and is discharged to the uppermost position of the original 32 on the original tray 31 by the discharge roller 44 provided in the paper discharge port 43. That is, the document surface is re-stacked with the document surface facing downward as in the setting. This serves as a circulation path for exerting the RDF function. In this operation, the pre-exposure original document and the post-exposure original document are selectively separated from each other by a partition 45.
Since it is clearly partitioned by, it is possible to know whether or not a round of exposure has been completed.

Next, the operation for a double-sided original will be described separately for the ADF mode and the RDF mode. First, when a double-sided original is processed in the ADF mode, the originals 32 stacked on the original tray 31 are fed in order from the lowest one by the paper feeding belt 33 as described above, and the intermediate conveyance path 34 and the turn conveyance path are provided. It is sent to the contact glass 6 via 35. At this time, the front side of the double-sided document faces downward, and is ready for copying. When the required number of copies have been exposed, they are discharged from the contact glass 6 by the conveyor belt 36, and proceed to the guide space 40 through the turn conveyor path 38 and the branching claws 39 as in the above case. The trailing edge of the document 32 is the guide claw 41.
After passing through, the original transport drive source starts to reverse, and the original 32 is fed backward with the trailing edge side as the leading edge. At this time,
Due to the action of the branching claw 46, the original 32 is again conveyed to the intermediate conveyance path 34.
Sent in. Therefore, the front side and the back side of the original are reversed from those in the previous conveyance, and the guide space 40
Etc. constitute an inversion path. The original 32 sent to the intermediate carrying path 34 is sent to the contact glass 6 via the turn carrying path 35. At this time, the back side of the double-sided document faces downward, and is exposed and used for copying.
When the exposure for a predetermined number of copies is completed, the original 32 is discharged from the contact glass 6 by the driving of the conveyor belt 36.
Branching claw 37, turn conveyance path 38, switched branching claw 3
9, the sheet is discharged to the uppermost position of the original 32 on the original tray 31 by the discharge roller 44 via the discharge path 40. As a result, the sheets are stacked on the document tray 31 in the same state as the initial set state with the front side facing downward.

On the other hand, when a double-sided original is processed in the RDF mode, the original 3 stacked and set on the original tray 31 is set.
The sheets 2 are fed in order from the lowest one by the sheet feeding belt 33, and are fed onto the contact glass 6 through the intermediate conveyance path 34 and the turn conveyance path 35. At this time, the front side of the double-sided document faces downward, and is ready for copying. When the exposure for one time is completed, it is discharged from the contact glass 6 by the conveyor belt 36, and as in the case described above, the turn conveyor path 3
8. Go to the guide space 40 according to the branch claw 39. Manuscript 32
When the trailing edge passes through the guide claw 41, the transport drive source that has been used up to now starts to reverse, and the original 32 is fed backward with the trailing edge side as the leading edge. At this time, the original 32
Is again fed into the intermediate conveyance path 34. Therefore, the previous conveyance is a state in which the front and back sides of the document are reversed, and the guide space 40 and the like constitute the reversal path. The original 32 sent to the intermediate carrying path 34 is sent to the contact glass 6 via the turn carrying path 35.
At this time, the back side of the double-sided document faces downward, and is exposed and used for copying. When the exposure for one time is completed, the original 32 is transferred to the contact glass 6 by driving the conveyor belt 36.
It is ejected from above, and is ejected to the uppermost position of the original 32 on the original tray 31 by the ejection roller 44 via the ejection path 40 according to the branching claw 37, the turn conveying path 38, and the switched branching claw 39. As a result, the sheets are stacked on the document tray 31 in the same state as the initial set state with the front side facing downward. As a result, in the case of double-sided / double-sided copying, one copy of double-sided copying is formed by circulating the document twice. Such an operation is repeated for each document.

Considering the ADF mode and the RDF mode as described above, as the post-processing apparatus, the ADF mode is suitable for a system including the sorter unit 4 as in the present embodiment, and the RDF mode is partially provided. It can be said that it is suitable for a system including a staple unit that performs a binding process.

The control system in the main body 1 of the copying machine and the control system in the RDF 2 for performing such operations are shown in FIGS. 3 and 4, respectively.
Shown in. First, the main body of the copying machine 1 is basically controlled mainly by a micro CPU 51 which executes a control program, and a ROM 53, a RAM 54, an NVR via an address, control and data bus 52.
An AM (nonvolatile RAM) 55, an input / output port 56, and a serial communication control unit 57 are connected. An output load such as a motor, a solenoid, a clutch, etc., and an input element such as a sensor in the copying machine body 1 are connected to the micro CPU 51 via an input / output port 56. Further, although only one serial communication control unit 57 is shown in the figure, in order to exchange signals with the sorter unit 4, the paper feed control system, the operation panel unit, etc. in addition to the RDF 2 which will be described later, only the necessary amount is prepared. There is.

The same applies to the RDF2 side,
As shown in FIG. 4, it is controlled mainly by the CPU 61 which executes the control program of the RDF 2, and the ROM 6 via the address, control and data bus 62.
3, RAM 64, NVRAM (nonvolatile RAM) 65,
The output load such as a motor, solenoid, and clutch in the RDF 2 to which the input / output port 66 and the serial communication control unit 67 are connected, and input elements such as a sensor are connected to the CPU 61 via the input / output port 66. The serial communication control unit 67 is for transmitting and receiving signals to and from the micro CPU 51 on the copying machine main body 1 side.

In the present embodiment, however, whether the original 32 is a single-sided original (a front-sided single-sided original or a rear-sided single-sided original) or a double-sided original in the RDF 2 is automatically determined by the presence or absence of the front-side image information and the back-side image information. An image detection circuit 68 for identifying is provided. The image detection circuit 68 is a circuit that counts image data (multi-valued data) detected by an image sensor (described later), and adopts a method of counting multi-valued data to improve detection accuracy. Binary data may be used to convert the data.

First, a pair of CCDs (with an illumination light source) 69a and 69b serving as image sensors are RDFs as shown in FIG.
The turn transport path 3 upstream of the exposure position in 2
5 is arranged so as to face both sides of the original conveyed.
That is, when the front and back sides of the original set on the contact glass 6 are used as the reference, the CCD 69a functions for detecting the back side image and the CCD 69b functions for detecting the front side image. For this reason, the guides are arranged inside and outside of the turn conveying path 35, and a part of the guide of the turn conveying path 35 is an opening or a light transmitting portion corresponding to these CCDs 69a and 69b. The analog image signal output from the CCD 69 is amplified by the signal processing circuit 70, and the A / D converter 71
Is converted into a digital multilevel signal by. This signal is subjected to correction processing by the shading correction circuit 72, output to the multi-value processing circuit 73, input data is judged by a threshold value set in advance for each document, and output to the multi-value data counting circuit 74. Therefore, two sets of the image detection circuit 68 shown in FIG. 5 are prepared, one for the CCD 69a and one for the CCD 69b.

FIG. 6 shows an example of the structure of the multi-valued data counting circuit 74. First, the GATE signal output as the document reading effective area set by the CPU 61 and the CCD 6
Clock signal CLK used for reading 9a, 69b
The multi-valued data is latched by the flip-flop 75 and input to the adder 76 by and. In the adder 76, the value before being fed back from the flip-flop 78 of the subsequent flip-flops 77 and 78 is added. Here, the multi-valued data is output as the signal A by the flip-flop 75 at the rising edge of the clock signal CLK and enters the adder 76. At the same time, flip-flop 7
A feedback signal is input to the adder 76 as the signal C from 8. Until the image data is first input, the signal A from the flip-flop 75 and the flip-flop 7 are input.
The signals B and C from 7, 78 are both 0. In the adder 75, when carry is generated as a result of addition of the signal A and the signal C, the carry is input to the counter 79. This counter 79
, 1, 2, ..., N are prepared so that the number of pixels in the maximum image area, that is, the same number as the number of dots can be counted. These counters 79 are adders 76
The carry output from is counted to detect the image data. The count value of the counter 79 of 1 to n is GAT
At the end of E, the data is latched by the flip-flop 80, read by the CPU 61 and transmitted to the micro CPU 51 of the copying machine body 1 side, and whether or not there is image information on the front surface and the back surface of the original 32, that is, in the case of a double-sided original. Determine if there is.

As described above, in the RDF 2, whether or not the original 32 conveyed on the contact glass 6 is a double-sided original is automatically identified. Therefore, the conveyance processing is performed by the switching control according to the type of the original 32. RDF2
The originals stacked and set on may be a mixture of single-sided originals and double-sided originals, and copy processing in the mode shown in FIG. 7 is possible.

Mode 1 is a mode for obtaining a copy in exactly the same manner as an original. That is, when the image information surfaces are represented as A to F, as shown in the drawing, for four originals 32 which are a double-sided original, a single-sided original, a double-sided original, and a single-sided original, a double-sided original is copied, and a single-sided original is copied. It is a mode to let. For such mixed originals, double-sided copy processing is not performed in the case of a single-sided original, so the processing time can be shortened.
Also, a double-sided original is not treated as a single-sided original and single-sided copying is not performed, and there is no missing copy. Furthermore, as shown in the process of the second sheet, the back side single-sided original is copied only on the back side,
As shown in the process of the fourth sheet, the front side single-sided original is in a state in which only the front side is single-sided copied.

Mode 2 is a mode for obtaining only one-sided copy regardless of whether the original 32 is a single-sided original or a double-sided original. That is, for a single-sided original, only one-sided copying is performed as it is, and for a double-sided original, single-sided copying of front and back images is continuously performed.
Six single-sided copies can be obtained from a mixed original document. That is,
A single-sided original is copied as a single-sided original on one side, and the wasteful copy processing on the back side of a blank sheet regarded as a double-sided original is not performed.

Mode 3 is a mode for making a double-sided copy, but especially under a situation where a single-sided original / double-sided original is mixed, regardless of the front and back of the original (related to single-sided original / double-sided original) Instead, only the surface actually having the image information is focused on, and these image information are provided in order of double-sided copying in order of forward alignment. In the illustrated example, the front side image information D of the next double-sided original is copied on the back side of the transfer paper 16 on which the back side image information C is front-side copied, and the back side image information E of this double-sided original is transferred to the next transfer sheet 16. The surface is copied, and so on. According to this mode, it is possible to reduce the processing time without wasteful copy processing for the side having no image information, and the copy to be obtained is front-justified double-sided copy, and there is no blank back page in the middle, so the paper is It also saves money.

Therefore, the operator does not need to be particularly aware of the original 32 set in the RDF 2, and as shown in the above three modes, it is sufficient to set the mode to obtain what kind of copy result. is there. Figure 8
Indicates a full dot display type display unit 81 provided in a part of an operation panel unit (not shown) for performing such mode setting. The display unit 81 uses a display element such as a liquid crystal display or a fluorescent display tube, and a substantially transparent sheet-shaped matrix touch switch 82 is laid on the surface of the display unit 81, and various types of copying such as a paper feed table, image density, and magnification change are made. It is configured so that modes and the like can be selectively designated and displayed. In the figure,
A portion schematically shown by a double frame represents the selected portion. Focusing on the processing mode that is the gist of the present embodiment, in the double-sided selection unit 83, the portion indicated by the single and double keys 84 is for setting mode 1, the portion indicated by the single key 85 is for setting mode 2, and both keys 8
The part indicated by 6 is for mode 3 setting. That is, the display of these keys 84 to 86 indicates what type of copy result product is to be obtained, regardless of the mode of the original.

Next, how these mode processes are actually controlled and executed will be described. First, the processing of mode 1 will be described with reference to the flowchart of FIG.
In the RDF 2, the originals 32 stacked on the original tray 31 are fed and conveyed onto the contact glass 6 in order from the lowest side. In the middle of the process, the presence or absence of the surface image information of the original 32 is detected by the CCD 69b. If the front side image information is present, the front side of the original 32 is copied and then the CCD 6
Based on the detection signal of 9a, it is detected whether there is backside image information. If there is backside image information (= double-sided original),
The transfer paper 16 having the front surface copied is discharged to the double-sided tray 26, and the double-sided original 32 is turned upside down on the RDF 2 side to be conveyed and set again on the contact glass 6 (back side facing downward). Therefore, a copy operation is performed, the back side of the transfer paper 16 fed from the double-sided tray 6 is copied, double-sided copying is performed, and the sheet is discharged to the main body tray 22 or the sorter unit 4 side (these are referred to as discharged outside the machine). ). The original 32 is inverted and re-stacked on the original tray 31. That is, the normal double-sided mode processing in the RDF mode is performed. Even if there is the next original 32, the presence or absence of the front side image information and the rear side image information is detected after the document is similarly fed,
For a double-sided original, double-sided copying is performed in the same manner. In the case of a single-sided original with a white back side and no back side image information, after making a front side copy (single sided copy) of the front side image of the original,
The transfer paper 16 is discharged to the outside of the machine, while the original 32 is not inverted and is stacked on the original tray 31. That is, the normal single-sided / single-sided mode processing is performed. On the other hand, even for a single-sided original, if the front side is a blank single-sided original,
After the document 32 is reversed and conveyed in the RDF 2, the document 3
The back side of 2 will be copied on one side. That is, the normal single-sided copy is performed after performing the reversing process of the original 32 without performing the copy operation on the blank surface. In addition,
In the case of a double-sided blank original, the original is simply discharged in the normal direction. Such processing is performed until the original 32 is exhausted.
It is performed depending on whether the original is a one-sided original or a two-sided original.

Next, the processing of mode 2 will be described with reference to the flowchart of FIG. Basically, it is the same as the processing in the mode 1, but in the processing in the case where it is determined as the double-sided original based on the CCDs 69a and 69b, the transfer paper 16 on which the front surface copy of the front surface image is made is ejected to the outside of the machine as it is. The difference is that the back side image of the original is also processed as a front side copy on the next transfer paper 16 as a paper.

The processing of mode 3 will be described in accordance with the example illustrated in FIG. 7 while referring to the flowchart in FIG. First, a flag n for indicating the front side / back side of a document is prepared, and initially the flag n is set to 0 for processing from the front side.
Reset to. Next, as described above, the first original 32 is fed and set on the contact glass 6, and the presence / absence of front and back image information is detected by the CCDs 69a and 69b in the middle thereof. First, the presence / absence of front surface image information is detected, and if there is a front surface image, the value of the flag n is evaluated. Since n = 0 now, the front surface image is copied and discharged onto the double-sided tray 27. Therefore, the original 32
It is determined whether there is a back side image on the basis of the detection signal of the CCD 69a. If there is a double sided original, the original 32 is RDF2.
Then, the image is reversed and conveyed again on the contact glass 6, and the back side image of the original 32 is copied on the back side of the transfer paper 16 fed from the double-sided tray 27 to form a double-sided copy and ejected outside the machine. The original 32 is reversed and re-stacked. If the next original 32 is present, it is set on the contact glass 6 and the presence or absence of front and back image information is checked. In this case, for example, if there is no front side image and only the back side image, the value of the flag n is evaluated. Since n = 0 now, the flag n is set to 1, and the document 32 is inverted by the RDF 2 and the back side is set on the contact glass 6, and the front side copy of the back side image is performed. 16 is discharged to the double-sided tray 27. Then, the original 32 is reversed and discharged. The presence or absence of front-side image information and back-side image information is also checked for the next original, here the third original 32. Here, for example, a double-sided original, but since n = 1 in the flag check, the front side image of the double-sided original is copied on the transfer paper 16 fed from the double-sided tray 27 to make a double-sided copy. Discharge to the outside. On the other hand, since the original 32 is a double-sided original, the reverse processing is performed in the RDF 2, the front side copy of the back side image is performed, the transfer paper 16 is discharged to the double sided tray 27, and the original 32 is reversed and discharged. When the process shifts to the next original 32 process, the copy process is performed on the front side image because it is the front side single sided original here, but since n = 1 here,
The back side copy is performed on the transfer sheet 16 fed from the double-sided tray 27. After the copy, the transfer sheet 16 is ejected to the outside of the machine and has no back side image. Therefore, the flag n is reset to 0, and the original 32 is set to the original. It is transferred and discharged. In this way
Only the side with the image is double-sided with justification.

Next, the second embodiment of the present invention is shown in FIG.
14 to FIG. In this embodiment, the CCD 69
The object of detection by a and 69b is devised. Basically, as shown in FIG. 12, the detection target by the CCD 69 is not the entire area of the original 32, but only a part indicated by the area E. That is, the area E has a predetermined width in the main scanning direction and a predetermined length in the sub scanning direction. When the original 32 is conveyed with the center as a reference, it is not necessary to use, for example, the CCD 69 having the maximum original width, and the CCD 69 need only have the width of the area E, which is inexpensive. Further, also in the sub-scanning direction, it is not necessary to detect for the maximum document length, and it is only necessary to detect the length of the area E, and the detection time (processing time) can be shortened. Even if the detection target area is limited to a part of the whole area such as the area E as described above, a normal image is considered to be in the area E unless the original is very special, so that the detection accuracy is lowered so much. There is no such thing.

The area E is not fixed but can be set freely here. FIG. 13 shows a state in which the display unit 81 is in the image information setting mode. The switching from the display state (normally copied) shown in FIG. 8 to the image information setting mode may be performed, for example, by inputting a preset personal identification number with a ten-key pad for the number of copies or the like. It may be a method. Various setting switches are displayed on this mode screen. First, a document pattern 87 and a detection area mark 88 are displayed on the display section 81, and four switches 89, 90, 91 and 92 are provided around the document pattern 87 and the detection area mark 88. The switch 89 relatively moves the detection area on the document in the main scanning direction (left and right direction in the drawing). The switch 90 relatively moves the detection area on the document in the sub-scanning direction (vertical direction in the drawing). These switches 89 or 90
When is pressed, the detection area mark 88 moves horizontally or vertically. The switch 91 increases or decreases the width of the detection area in the main scanning direction. When the switch 91 is pressed, the width of the detection area mark 88 is increased or decreased. The switch 92 increases or decreases the length of the detection area in the sub-scanning direction. When the switch 92 is pressed, the length of the detection area mark 88 is increased or decreased. Further, a switch 94 for increasing / decreasing the determination density level of the image information is provided adjacent to the display of the density level pattern 93. When the switch 94 is pressed, the black portion in the density level pattern 93 changes. If the determination density level is increased by the switch 94, the probability that a stain on the original 32 is mistaken for image information is reduced. The switch 95 is for varying the detection level for recognizing whether or not the amount determined as having image information based on such density level setting is actually regarded as having image information in the detected document. is there. If the detection level is set low by the switch 95, it is easy to determine that there is information even in a small amount of black image, and if it is set high, the opposite is done. The switches 96 and 97 are switches for setting the detection area, density level, and detection level by the switches 89 to 92, 94, and 95 independently for the front surface and the back surface, respectively. The setting mode is the one that was pressed. The setting by these switches is performed when the machine is installed or when the user's usage conditions, environment, etc. change.

Here, the setting data processing by the switches 89 to 92 selectively fetches the data output from the shading correction circuit 72 in the image detection circuit 68 into the multilevel halftoning processing circuit 73, resulting in The detection area E is limited to. The density setting by the switch 94 corresponds to setting the threshold value of the multi-value quantization processing circuit 73. The detection level setting by the switch 95 sets a level for determining whether the value counted by the counting circuit 74 is image information when the CPU 61 reads it.

The effective read area is limited by the GATE signal given to the circuit shown in FIG. 6 by the setting of the CPU 61. Such a GATE signal is generated by the circuit shown in FIG. That is, this circuit is CCD6
This is a circuit for designating an arbitrary area E of the image read by 9a and 69b. The main scanning counter 100 counts the reading start position in the main scanning direction, and the main scanning counter 101 counts the reading end position in the main scanning direction. The sub-scanning counter 102 counts the reading start position in the sub-scanning direction, and the sub-scanning counter 103 counts the reading end position in the sub-scanning direction. The main scanning counters 100 and 101 generate LSYNC once for each main scanning.
This counter 100, 101 and CP which are cleared by a signal and count up by a read clock CLK
The count values latched in the latches 104 and 105 by U61 are compared by the comparators 106 and 107, respectively. At the reading start position, the L level changes to the H level, and at the reading end position, the H level changes to the L level. Similarly, the sub-scanning counters 102 and 103 are cleared by the document valid period signal FGATE, and LSYNC
The counters 102 and 10 are incremented by
3 and the count values latched in the latches 108 and 109 by the CPU 61 are respectively comparators 110 and 111.
Compared by At the reading start position, the L level changes to the H level, and at the reading end position, the H level changes to the L level. These comparators 106, 10
By inputting the outputs of 7, 110 and 111 to the AND gate 112, the GATE signal can be obtained.
The relationship between each signal and the detection area E is as shown in FIG.

Further, a third embodiment of the present invention will be described with reference to FIGS. In this embodiment, for example, the image sensor 69a is used not only for detecting the presence or absence of an image but also for detecting a document size. Therefore, the image sensor 69a is arranged at a position where at least one end face of the document 32 being conveyed crosses. FIG. 15 shows the arrangement positions for the originals 32 of various sizes (B5 to A3) when the conveyance is based on the center. For example, at least one end surface of these originals 32, that is, between CDs, between EFs, between GHs, IJs.
The image sensor 69a is arranged at a position where all the spaces cross each other, for example, across the space AB.

According to such arrangement of the image sensor 69a, the hatched portion is the detection area of the image sensor 69a. First, the leading edge of the original 32 is the image sensor 6
Until reaching 9a, the black image is detected over the detection width AB (the image sensor reading optical system is provided with means such as irregular reflection so that the area without a document becomes a black image).
Then, the leading edge of the original 32 reaches the image sensor 69a,
Until the trailing edge passes, for example, in the case of A4 size, black is detected for the image information portion and white is detected for the non-image information portion between AA ′ on the original 32, and the original 32 is detected.
Black is detected between the outside A'B. At this time, most of the peripheral portion of the document 32 is a blank space portion, which is a non-image information portion, so that there is a boundary between black detection and white detection inside and outside in the vicinity of A ′. The rear end of the original 32 is the image sensor 69a.
After that, black is detected again across AB.

Therefore, first, when a white image appears for the first time within the entire detection width AB, it is set as the leading edge of the document. If the entire detection width AB is detected as black and continues for a certain period or more, it is set as the trailing edge of the document. The position where the position of the white image appears at the rightmost position in FIG. 15 between the front end and the rear end of the original is the end surface of the original 32. Based on the detection results of these document leading edge, document trailing edge, and document edge surface,
The document size can be detected by recognizing the document area, and the presence or absence of image information is determined by the frequency of appearance of a black image in the document area.

FIG. 16 is a flow chart showing the processing based on the detection signal of the image sensor 69a. The black image is detected over the entire detection width AB until the leading edge of the original 32 reaches the position of the image sensor 69a. At this time, when the power is turned on, the flag is reset to 0, and the above operation is repeated until the document appears. When the leading edge of the original 32 reaches the image sensor 69a, a white image portion begins to appear on the image sensor 69a, and after the timer is cleared, the flag is 0 here, so the flag is set to 1. And
The detected image leading edge detection timing is stored in the memory MA. After that, since the flag is 1, the maximum value of the white image (that is, the position of A ′ shown in FIG. 15) is compared with the value stored in the memory MC, and the maximum value of the white image is larger. In that case, the value is stored in this memory MC,
If it is small, leave it as it is. Here, the memory MC is reset to 0 at the time when this processing is passed the first time, and the maximum value of the white image is always stored in the memory MC here. Further, the peripheral portion of the original 32 is a blank portion which is usually a non-image portion, and it is almost unlikely that the contents of the memory MC are changed as a result of the above-mentioned size determination thereafter.

When a black image is detected over the entire detection width AB while the document is passing, it is checked whether the timer has timed out. This is to avoid mistaken detection of the trailing edge of the document and detection of a black image in the middle of the document.
When the time is over, the trailing edge of the original is detected, the flag is reset to prepare for the next operation, and the timing of detecting the trailing edge of the original is stored in the memory MB. As a result, the data necessary for size certification is available.
The main scanning width and the sub-scanning length are determined by MB-MA to specify the document size.

Incidentally, the presence / absence of document image information is detected as a process while the document 32 is passing over the image sensor 69a, the white image is counted, and the rear end of the document 32 passes through the image sensor 69a and the document is detected. It will be certified after the size is determined. In short, if this white image count number ≈ MC × MA × dot density per unit area,
It can be determined that there is no image information.

In order to perform such processing, an image area designating circuit 113 is added to the multilevel halftoning processing circuit 73 in the image detecting circuit 68 of this embodiment as shown in FIG. A schematic block diagram of the image area designating circuit 113 is shown in FIG. The counter 114 is driven by LGATE given as a document reading timing signal from the CPU 61 and the clock CLK used for reading the CD 69a.
Counts unconditionally, and the content of the counter 114 is stored in the flip-flop 116 according to the condition of the input data (through the AND gate 115). As a result, the maximum value of the white image is stored in the flip-flop 116. A flip-flop 116 is provided every time the main scanning line is completed.
Is read by the CPU 61, the counter 114,
The flip-flop 116 is cleared to prepare for the operation of the next main scanning line.

Incidentally, the counter circuit 74 in the case of the present embodiment.
May be configured as shown in FIG. Basically, it is the same as that shown in FIG. 6, but one counter 79 is provided.

[0053]

Since the present invention is configured as described above, the original conveyed by the automatic original conveying device to the original exposing unit detects the presence or absence of the front side image information and the back side image information by the pair of image sensors, and the front side single sided side original. It is automatically identified whether it is a single-sided original, a single-sided original, or a double-sided original.
By eliminating the wasteful image forming process on the blank surface having no image information, the processing time and the paper can be saved. As the operator, the original loaded on the automatic document feeder is a single-sided original or a double-sided original. You don't have to be conscious of that and select only the desired image form.
The operability will be good. Particularly, as in the mode 3 of the invention described in claim 11, only the surface having the image information is front-justified to form the double-sided image, so that the waste of the processing time can be eliminated and the paper can be saved. At this time, the image to be used is limited by limiting the detection target by the pair of image sensors to an area having a predetermined width of a part of the document or a predetermined length in the transport direction as in the invention of claim 2 or 4. The sensor becomes smaller and cheaper, and the signal processing time for detection can be shortened. In particular, the predetermined length in the sub-scanning direction can be set to an arbitrary length as in the invention according to claim 5, and further, as in the invention in claim 6, for example, by corresponding to the document size, Accurate double-sided original detection is possible for various sizes. Further, the density level for detecting the presence or absence of image information can be set freely as in the invention according to claim 7, or the detection level with image information with respect to the amount of image information detected according to the invention in claim 8. If the setting is freely set, it is possible to improve the detection accuracy so that, for example, a document stain, a doodle, etc. are not mistaken for image information. Further, as in the invention according to the ninth aspect, by changing the setting conditions independently on the front side of the document and the back side of the document, the flexibility is enhanced. In addition, claim 1
According to the invention described in No. 0, the image sensor is arranged at a position where at least one end face of the document being conveyed crosses, and the size of the document is also detected, so that the cost can be reduced.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of an RDF showing a first embodiment of the present invention.

FIG. 2 is a schematic configuration diagram showing the entire copying system.

FIG. 3 is a block diagram showing a control system on the copying machine main body side.

FIG. 4 is a block diagram showing a control system on the RDF side.

FIG. 5 is a block diagram showing an image detection circuit configuration.

FIG. 6 is a block diagram showing a count circuit configuration.

FIG. 7 is an explanatory diagram showing an example of copy processing.

FIG. 8 is a plan view showing a display unit.

FIG. 9 is a flowchart showing a mode 1 process.

FIG. 10 is a flowchart showing a mode 2 process.

FIG. 11 is a flowchart showing a mode 3 process.

FIG. 12 is an illustration of a detection area showing a second embodiment of the present invention.

FIG. 13 is a plan view of the display unit showing an image information setting mode.

FIG. 14 is a circuit diagram for generating a GATE signal.

FIG. 15 is an explanatory diagram of a detection area showing a third embodiment of the present invention.

FIG. 16 is a flowchart showing processing such as document size detection.

FIG. 17 is a block diagram showing an image information circuit.

FIG. 18 is a block diagram showing an image area specifying circuit.

FIG. 19 is a block diagram showing a counter circuit.

[Explanation of symbols]

 2 automatic document feeder 6 original exposure section 31 original tray 32 original 40 reversing path 69a, 69b image sensor

Continuation of front page (51) Int.Cl. ⁵ Identification number Office reference number FI Technical display location G03G 15/04 119 H04N 1/00 108 H 4226-5C 1/04 106 A 7251-5C 1/12 Z 7037- 5C (72) Inventor Daisuke Abe 1-3-6 Nakamagome, Ota-ku, Tokyo Within Ricoh Co., Ltd.

Claims (11)

[Claims] 1. An original document stacked on an original tray is sequentially conveyed to an original document exposure section for exposure, and an original document is selectively inverted to have an inversion path for inverting the original document. In a double-sided copying machine equipped with a circulation type automatic document feeder for conveying to an exposure section and exposing it, the presence / absence of image information on the front and back sides of a document being conveyed in the automatic document feeder is detected. A document identifying apparatus in a double-sided copying apparatus, which is provided with a pair of image sensors. 2. The document identification in a double-sided copying apparatus according to claim 1, wherein the pair of image sensors detect the presence or absence of image information for a predetermined width of a part of the document being conveyed. apparatus. 3. The document identifying apparatus in a double-sided copying apparatus according to claim 2, wherein the predetermined width is set to an arbitrary length. 4. The double-sided copying apparatus according to claim 1, wherein the pair of image sensors detect the presence or absence of image information for a predetermined length of a part of a document being conveyed. Document identification device in. 5. The document identifying apparatus in a double-sided copying apparatus according to claim 4, wherein the predetermined length can be freely set to an arbitrary length. 6. The document identifying device in a double-sided copying machine according to claim 5, wherein the predetermined length is set according to the document size. 7. The document identifying apparatus in a double-sided copying apparatus according to claim 1, wherein a density level for detecting the presence / absence of image information can be freely set. 8. The document identifying apparatus in a double-sided copying apparatus according to claim 1, wherein a detection level for determining that there is image information can be freely set with respect to the amount of image information detected by the image sensor. 9. The front side of the original and the back side of the original can be set independently of each other.
A document identifying device in the double-sided copying device according to item 7 or 8. 10. A double-sided copying apparatus according to claim 1, wherein at least one of the pair of image sensors is arranged at a position where at least one end face of a document being conveyed crosses, and the size of the document is also detected. Document identification device. 11. Claims 1, 2, 3, 4, 5, 6, 7,
A control means for controlling switching of the reversal path based on the detection result of the presence / absence of back side image information by the image sensor described in 8, 9, or 10 is provided, and image formation in the same mode as the original is performed according to the type of one side / both sides of the original. Mode 1 and one side of the original
Mode 2 for single-sided image formation regardless of the type of both sides
And a mode 3 in which image information of a side having image information is sequentially left-justified regardless of the front side / back side of the original to perform double-sided image formation. How to use the device.