JPH09185227A - Erase device for copier - Google Patents

Abstract

(57) [Abstract] [Problem] Shadow due to document thickness, document edge detection error,
The latent image is erased in consideration of the erase control error, the alignment error between the transfer sheet and the photoconductor image, and the like to obtain a good copy image without the original shadow. An eraser for a copying machine that erases a latent image in an unnecessary area outside a document. The eraser 9 is provided with an LED array for erasing a latent image in an unnecessary area on the photoconductor 1, and is positioned between the document image writing device (mirror 8) and the developing unit 10 across the photoconductor 1 in the direction perpendicular to the rotation direction. Let Make the reflection density of the original platen darker than the background reflection density of the original and lighter than the reflection density inside other machines. Document contour detection sensor 21
Then, the position and contour of the document set on the document table are detected by comparing with the reflection density of the document pressure plate. Original contour detection sensor 2
Based on the document contour detection result of No. 1, the blinking of the LED of the eraser 9 is controlled corresponding to the latent image on the photoconductor 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an erase device of a copying machine for erasing a latent image in an unnecessary area.

[0002]

2. Description of the Related Art Some image forming apparatuses using an electrostatic latent image, such as a copying machine, are equipped with an erasing device (or an eraser) for erasing a latent image in an unnecessary area formed on a photoconductor. There are three types of latent image erasing by front and rear edge erasing, side erasing, and special mode erasing.

In the leading edge erase, the eraser is fully turned on by turning on the start key of the main body of the apparatus, and is turned on up to a position (8 + 2 mm or 8-1 mm in the standard) slightly over the leading edge of the document, and the P sensor pattern is changed every time. It prevents development and also prevents clamp marks and shadows on the leading edge of documents. During image density control (during P sensor pattern development), all erasing of the eraser is turned off before the pattern image, resulting in P sensor erasing. Then, after the pattern image has passed, the leading edge of the paper is erased again by fully lighting. In addition, the width can be adjusted for both the front end erase (blank) and the rear end erase. In the side erase, the eraser is turned on for each size in order to erase the charges on both ends of the photosensitive drum depending on the paper size and the magnification. This is because the load is not applied to cleaning. Further, in order to prevent the back side of the copy from being smeared, side erase is performed inside the width of the document. The lighting condition of the eraser changes depending on the combination of the paper feed cassette data and the magnification data. In the special mode erase, it changes from the cassette data when erasing the frame, and changes depending on the input data when editing (outer / inner erase, circle / inner color). For example, 128 LEDs are used at a pitch of 2.5 mm. Then, the erase is controlled.

By the way, for example, Japanese Patent Laid-Open No. 21788/1990.
In Japanese Patent Laid-Open No. 3-137671, a technique for controlling the LED group according to the document size reduction ratio is disclosed in
JP-A-2-25863 discloses a technique of arranging an LED group and trimming which is a copy outside a document or only a selected part of the document surface and erasing a latent image in an unnecessary area during composite copying.
Techniques for detecting the leading edge position and the tilt of a document during prescan and correcting the tilt with a document moving motor are disclosed.

[0005]

Among these prior arts, the above-mentioned JP-A-2-217883 and JP-A3-1 are mentioned.
Erase in the technology of No. 37671 is targeted at (1) erasing unnecessary latent images outside the original size, including during zooming, and (2) erasing unnecessary latent images other than the desired composite copy or trimming copy. . However, the original referred to in (1) above has a standard size, and since the latent image erasing area is mechanically determined by multiplying it by the scaling factor, it cannot correspond to an irregular-shaped original.
There was a problem that the erasure could be excessive or insufficient. Further, in the above (1) and (2), there is a problem that the erasure becomes excessive and deficient similarly when there is a misalignment in the automatic document feeder and the handset.

According to the present invention, by directly detecting the contour of a document set automatically or manually on the document table and erasing the latent image in an unnecessary area outside the document, the problem of erasing excess or deficiency is improved. It is an object of the present invention to provide an erasing device for a copying machine that can be used.

In addition to the above-mentioned object, the present invention incorporates external input conditions such as variable magnification / vertical movement of the image / trimming copy / white area for preventing transfer paper wrapping around a fixing roller. An object of the present invention is to provide an erasing device for a copying machine capable of erasing a latent image in a region.

Further, the present invention does not require a prescan as in the technique of Japanese Patent Laid-Open No. 25863/1990 and enables high speed copying.
An object of the present invention is to provide an erasing device for a copying machine which can achieve cost reduction without requiring a dedicated detection sensor.

Furthermore, in the techniques disclosed in Japanese Patent Laid-Open Nos. 2-217883 and 3-137671, unnecessary areas are erased on the assumption that the set original has a fixed size and that the set state has no inclination or delay. Therefore, although the erasure may be excessive or insufficient, the present invention also has an object to provide an erasing device of a copying machine capable of improving these problems.

In the present invention, the document is thick, so that it is likely to be a shadow of the illumination system, and the document contour detection error, the erase control error, and the alignment error between the transfer sheet and the photoconductor image are taken into consideration. That is, the representative of the unnecessary latent image is a shadow due to the paper thickness of the document edge, and in order to surely erase this shadow, if a variation in the reading and writing positions is included, it is embedded in the document for several mm from the detected document contour and erased. It is necessary to eliminate the latent image by taking into account these areas because the necessary area is erased depending on the original document if it is excessively embedded in the original document. It is also an object of the present invention to provide an erasing device for a copying machine that can obtain the above.

[0011]

In order to achieve the above object, the erasing device of a copying machine according to the present invention is to erase a latent image in an unnecessary area outside a document in a copying machine. An apparatus including an original back member having a reflection density higher than a background original reflection density and lighter than a reflection density inside another machine, and a position of an original set on an original table as compared with a reflection density of the original back member. Equipped with a document contour detection sensor for detecting contours and a plurality of light emitting elements for erasing latent images in unnecessary areas on the photoconductor, the photoconductor is traversed in a direction perpendicular to the rotation direction of the photoconductor between the document image writing device and the document image developing device. And an eraser blinking control device for controlling blinking of each light emitting element of the eraser corresponding to a latent image on the photoreceptor based on the document contour detection result of the document contour detection sensor. To do.

In order to achieve the above object, the erase device of the copying machine according to the second aspect is such that the erase blinking control device corrects the image detected by the document contour detecting sensor by image information separately input from the input device. It is characterized by adding terms.

In order to achieve the above object, in the erase apparatus of the copying machine according to the third aspect, the document image reading device also serves as the document contour detecting sensor, and the reading information of the sensor of the document image reading device is read. Of these, the inner edge of a continuous area that substantially matches the standard reflection density of the document backside member registered in advance is determined as the document contour line set on the document table,
The black-and-white information inside the line area determined to be the original contour line is determined to be the original image and transferred to the writing device, and the other areas are regarded as unnecessary areas and transferred to the erase blinking control device. Is characterized by.

In order to achieve the above object, the erase apparatus of the copying machine according to the fourth aspect of the present invention is designed so that the unnecessary range to be erased is a line which is further dented from the contour line of the detected document with a certain width toward the center of the document. Set the outside width as 0m
It is characterized in that a plurality of setting widths including m can be selected.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1A is a conceptual diagram of an image forming process portion of a copying machine in which an eraser is located between a document image writing device and a developing unit. Registration rollers, 3 transfer separation chargers, 4 separation claws, 5 cleaning blades, 6 static elimination lamps, 7 charging chargers, 8 mirrors of the document image writing device, 9
Is an eraser, and 10 is a developing unit. Further, 11 is a transfer paper. FIG. 1B shows the photoconductor 1 and the eraser (LED).
The arrangement relationship with the (array) 9 is shown. The eraser (LED array) 9 is connected to the LED array blinking control device 12.

FIG. 1C is a sectional view showing the structure of the scanner portion of the copying machine, in which 13 is a contact glass and 1 is a glass.
4 is the first scanner, 15 is the second scanner, 16 is the scanner home position detection sensor, 17 is CC
D and 18 are lenses, 19 and 20 are APS sensors, 21
Is a document contour detection sensor, and 22 is a document irradiation lamp.

FIG. 2 is a diagram showing the positional relationship (A) between the original contour detection sensor 21 and the original irradiation lamp 22 with respect to the original 23 placed on the contact glass 13 and the relationship between the scanning direction and the reflected light amount (B). . In the figure, reference numeral 24 is an original scale, and scanning is performed from a position on the original scale 24 side where the original scale 24 is removed to a position where the end of the contact glass 13 is removed, and the amount of reflected light at that time is (B).
Changes as shown in FIG. R1 is a position outside the original scale 24, R6 is a position outside the contact glass 13,
The amount of reflected light inside the machine, which is the smallest. Further, R2 is the amount of light reflected by the back surface of the original scale 24, R3 and R5 are the amounts of reflected light by the pressure plate or the ADF belt surface (if the leading edge of the original 23 is in close contact with the original scale 24, this portion does not exist), and R4 is the original surface. And the amount of reflected light of R4 is the largest. It should be noted that the left end side of R4 in the drawing is the front end area of the document, and the portion where the amount of reflected light gradually decreases thereafter is the portion where the characters, figures, etc. of the document are described.

FIG. 3 is a control block diagram at the time of forming an image in the copying machine as described above. In addition to the above configuration, the control device 30, the input interface 31, the output interface 32, the memory 33, the document leading edge reference position detection sensor 34, the moving position detection sensor 35 of the document contour detection sensor 21, the separate input device 36, and the latent image writing. Laser emission control device 37, display device 3 for warning message of no document
8 is provided. The memory 33 includes (1) the standard reflection density of the lower surface of the original scale, (2) the original pressure plate (or the standard reflection density of the ADF original conveying belt), (3) the blinking timing chart of the erase LED of the unnecessary latent image, and (4) external input. Standard value, (5) Correction data for detection error, original high pressure shadow, etc.,
(6) The standard document size (A4, A5 ...) And the like are stored. The document leading edge reference position detection sensor 34 is unnecessary because the document leading edge reference position can be calculated if the start timing and the moving speed of the scanner are controlled. Further, a document contour detection sensor 21 for detecting the document surface reflection density
The moving position detection sensor 35 can be eliminated by processing the read data of the scanners 14 and 15 which are document image reading sensors. Separate input device 36
Is, for example, an operation unit provided in the apparatus main body, and (1) image scaling ratio, (2) image position movement designation value (forward / backward / left / right shift),
(3) White spot on the tip (prevention of wrapping around the fixing roller transfer paper)
Is for entering. The LED array blinking control device 12 of the eraser 9 for erasing the unnecessary latent image is
Controls the blinking timing and blinking coordinate position.

A copy job of the apparatus of this embodiment will be described with reference to the flow chart of FIG. When the copy start switch on the operation panel is turned on, a copy job is started (step 1), and the first and second scanners 14 and 1 for scanning the original document are started.
The scan operation 5 starts (step 2). Then, a document presence / absence detection sensor (not shown) compares it with the standard reflection density data of the pressure plate (or ADF document transport belt) in the memory 33 to determine the presence / absence of a document (step 3).

If there is no document, the process proceeds to step 16 to display a warning message on the display device 38 of the operation panel to end the copy job (step 17). If there is a document,
The feeding of the transfer paper 11 from a paper feed tray (not shown) is started, the contour reading of the original 23 on the contact glass 13 is started, and the reading of the original image is also started at the same time (step 4).

Next, the contour and position of the document 23 are detected and specified (step 5). That is, the document contour detection sensor 21 scans the contact glass 13 to measure the reflection density, and the document pressure plate (or A
The reflection density data of the DF document conveyance belt) or the back surface of the document scale 24 is compared with the absolute value of the detected reflection density data, and as a result, the detection position is the region of the document pressure plate (or ADF document conveyance belt) (R2 in FIG. 2). If it is), it is confirmed that the measurement result is within the concentration range registered in the memory 33, and if it is out of the range, it means that a detection error has occurred, so abnormal processing is executed. If it is within the range, the manuscript 23 is inside it,
The original background surface of the same density (R4 in FIG. 2) can be detected, and its contour can be specified as a closed rectangular shape (step 6). When the accuracy of the document contour detection sensor 21 is unsatisfactory or when the number of sensors is small, the standard document size may be registered in the memory 33, and may be compared and estimated with the detection data to be specified. Also, as a precaution, it is preferable to compare with the reflection density of a general-purpose original document registered in the memory 33 to confirm that there is no erroneous detection. In order to facilitate detection of the contour area of the document, the back surface of the document may be colored with a slightly high density. For example, the document pressure plate (or the ADF document conveyance belt) is colored yellow, or the back surface of the document scale 24 and the document pressure plate are finished with a metallic luster.

Then, the automatic transfer paper selection function is executed from the specified original size to identify the image in the original (step 7). Then, the correction process is performed in consideration of the copying conditions desired by the operator (step 8). As correction data, alignment error, document thickness shadow, etc.
There are image top-bottom adjustment (image shift), trimming, etc. (external input 1), or a bite-in and erase value (external input 3) within the original outline. If there is a data correction item, after correcting the data, the data is transferred to the original image writing device and the eraser 9 (step 9), and the latent image in the unnecessary area is erased (step 1).
0), execute the copying process (image formation) (step 1
1), transfer / separation process (step 12), fixing process (step 13), discharge process of copied transfer paper (step 14)
Then, the copying job is completed by returning the scanners 14 and 15 to their home positions (step 15). In addition, in the case of copying a large number of sheets, the above steps are repeated.

[0023]

The erase device of the copying machine according to the first aspect of the present invention directly reads the contour of the set document and erases the unnecessary portion latent image based on the data. There is an effect that it is possible to perform accurate erasing even for irregular position and irregular-sized originals.

The erasing device of the copying machine according to claim 2 is
Since the input data from the input device can be added separately, in addition to the common effects described above, there is an effect that an editing function desired by the operator, such as scaling and trimming, can be performed.

The erasing device of the copying machine according to claim 3 is
Since the document image reading sensor also functions as the document contour reading sensor, in addition to the common effects described above, data can be acquired at the same time as the scanning operation of the document image reading sensor. There is an effect that it becomes possible.

The erase device of the copying machine according to claim 4 is
In addition to the common effects described above, the setting of the necessary biting width has the effect of enabling optimum erase corresponding to various originals.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram (A) of an image forming process portion of a copying machine in which an eraser is located between a document image writing device and a developing unit, and a diagram showing a positional relationship between a photoconductor 1 and an eraser (LED array). B) is a sectional view showing the structure of the scanner portion of the copying machine.

FIG. 2 is a positional relationship between a document contour detection sensor and a document irradiation lamp for a document placed on a contact glass (A).
FIG. 6 is a diagram showing a relationship (B) between the scan direction and the amount of reflected light.

FIG. 3 is a control block diagram during image formation in the copying machine according to the embodiment of the present invention.

FIG. 4 is a flow chart of an operation in the copying machine according to the embodiment of the present invention.

[Explanation of symbols]

 1 Photoreceptor 2 Registration Roller 3 Transfer Separation Charger 4 Separation Claw 5 Cleaning Blade 6 Eliminating Lamp 7 Charging Charger 8 Mirror of Original Image Writing Device 9 Eraser 10 Developing Unit 11 Transfer Paper 12 LED Array Flashing Control Device 13 Contact Glass 14 First Scanner 15 Second Scanner 16 Scanner Home Position Detection Sensor 17 CCD 18 Lens 19, 20 APS Sensor 21 Original Contour Detection Sensor 22 Original Irradiation Lamp 24 Original Scale 30 Controller 31 Input Interface 32 Output Interface 33 Memory 34 Original Tip Reference Position Detection Sensor 35 Moving position detection sensor of original contour detection sensor 36 Separate input device 37 Latent image writing laser emission control device 38 Display device R1 Position beyond original scale R2 document reflected by the rear surface of the scale amount R3, R5 position disengaged the reflected light R6 contact glass by the reflected light amount R4 document surface by a pressure plate or ADF belt surface

Claims (4)

[Claims] 1. An erase device of a copying machine for erasing a latent image in an unnecessary area outside a document, the document rear member having a reflection density higher than a background reflection density of the document and lighter than a reflection density inside another machine; A document image that includes a document contour detection sensor that detects the position and contour of the document set on the document table in comparison with the reflection density of the document backing member, and a plurality of light-emitting elements that erase latent images in unnecessary areas on the photoconductor An eraser located between the writing device and the document image developing device in a direction perpendicular to the rotation direction of the photoconductor, and the eraser corresponding to the latent image on the photoconductor based on the result of document contour detection by the document contour detection sensor. And an erase blinking control device for controlling blinking of each of the light emitting elements. 2. The copying machine according to claim 1, wherein the erase blinking control device adds an image correction term based on input information from an input device to the detection result of the document contour detection sensor. Erase device. 3. The document image reading device also serves as the document contour detection sensor, and the read information of the sensor of the document image reading device is substantially continuous with a standard reflection density of a document back surface member registered in advance. The inside edge of the area is judged to be the contour line of the document set on the platen, and the black and white information inside the line area judged to be the contour line of the document is judged to be the document image and transferred to the writing device. 3. The erase apparatus of the copying machine according to claim 1, wherein the erase processing is performed as if it is an unnecessary area and is transferred to the erase blinking control apparatus. 4. The unnecessary range to be erased is an area outside a line which is further dented by a fixed width in the original center direction from the detected original contour line, and the fixed width can be selected from a plurality of set widths including 0 mm. The erasing device for a copying machine according to any one of claims 1 to 3, wherein: