JPH05134329A - Image forming device - Google Patents

Abstract

PURPOSE:To easily detect the size of an original without imprinting the image of a rear surface when the image of the both-side original is formed. CONSTITUTION:The imprinting is eliminated by forming the surface of an original cover 11B which is provided on an original platen 11 and which interposes the original G by the material of a black color or a color which is hardly reflected and controlling the output of a laser after the reflectivity of the image of the rear surface of the original G is reduced. Besides, the size of the original is detected by distinct time difference until the white-color surface of the original G is detected from the black-color surface of the cover 11B or the integration of the number of pulses.

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 such as an electrophotographic copying machine using an electrostatic recording method.

[0002]

2. Description of the Related Art When an image is copied by an electrophotographic copying machine, an original document is exposed and scanned on the image surface while being covered with a document cover and pressed onto a transparent glass plate.

The original cover is a highly flexible material because it presses the entire area of the original image with a uniform pressure distribution, and at the same time, a white background having a high reflectance is generally used for the purpose of enhancing the contrast of the original image. Has been done.

[0004]

However, in the case of copying a so-called double-sided original having an image on the front and back sides, the white background original cover is liable to stain the rear surface image and the original cover, especially when the original is thin paper. However, there is a possibility of imprinting, and thus clear images may not be obtained.

Further, in the apparatus having the function of detecting the size of the original, if the original is completely covered with the original cover, the contour of the original cannot be detected, and therefore the original cover has a special identification plate. Etc. must be provided.

Regarding the document size detecting means, JP-A-62-62
-222237, Japanese Utility Model Laid-Open No. 62-58450, and Japanese Laid-Open Patent Publication No. 59-11091, all of which require a special detection device, resulting in a complicated structure and high cost. Will be invited.

As a result of solving and improving this point, the present invention provides
With an extremely simple configuration, clear images can be recorded even when copying double-sided originals. Furthermore, the original size can be easily detected without the need for a marking plate for identification, and regardless of the original size. An object of the present invention is to provide an image forming apparatus in which a black portion does not occur around the image.

[0008]

The above objects can be achieved by the following three inventions.

According to a first aspect of the present invention, in an image forming apparatus including an original table for performing image exposure by sandwiching and supporting an original between a pressing member and a glass plate, the sandwiching surface of the pressing member is black or hard to reflect. An image forming apparatus comprising a color material is provided, and a second aspect of the present invention is a document table for performing image exposure by sandwiching and supporting a document between a pressing member and a glass plate. In the image forming apparatus, the sandwiching surface of the pressing member is made of a black or hardly reflective color material, and the document size is detected by detecting the black or hardly reflective color material surface around the document. According to a third aspect of the present invention, there is provided an image forming apparatus including a document table that performs image exposure by sandwiching and supporting a document between a pressing member and a glass plate. The black side Or constructed with a flame reflected color of the material, there is provided an image forming apparatus and inhibits the scanning exposure of the document around by sensing the black or hardly reflected color material surface of the original ambient.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of the present invention is shown in FIGS.
FIG. 1 shows the main configuration of a multicolor image forming apparatus. A is an image reading system, B is a laser writing system unit, C is an image forming unit, and D is a paper feeding unit. A color image is formed.

In the reading system A, 11 is a document table, and the document stored in the document table 11 is illuminated by a halogen lamp 13 attached to a carriage 12 that slides in the horizontal direction. The movable mirror unit 15 is provided with mirrors 16 and 17, and similarly slides in the horizontal direction, and in combination with the mirror 14 attached to the carriage 12, the optical image of the original is led to the lens reading unit 20. To do.

The carriage 12 and the movable mirror unit 15 are driven via wires (neither shown) connected to a stepping motor, and V and 1/2 V, respectively.
It is slid in the same direction at the speed of.

The lens reading unit 20 includes a lens 21, a prism 22, a first reading substrate 24, a red channel (hereinafter R-c).
It is composed of a CCD 25 (referred to as h), a second reading substrate 26, and a cyan channel (hereinafter referred to as C-ch) CCD 27.

The light image of the original document transmitted by the mirrors 14, 16 and 17 is focused by the lens 21 to form a prism.
An R-ch image and a C-ch image are separated by a dichroic mirror provided in 22. An R-ch CCD 25 provided on the first reading substrate 24 and a C-ch CCD 27 provided on the second reading substrate 26. An image is formed on each of the light receiving surfaces of.

The image signals output from the R-ch CCD 25 and the C-ch CCD 27 are processed by a signal processing section. In the signal processing unit, color signals that have been color-separated according to the color of the toner are output and input to the laser writing system unit B that is the exposure unit.

In the laser writing system unit B, a laser beam generated by a semiconductor laser (not shown) is rotationally scanned by a polygon mirror 32 rotated by a driving motor 31, and an optical path is bent by a mirror 34 via an Fθ lens 33. Then, a bright line is formed by being projected on the peripheral surface of the image carrier 30 to which electric charges have been applied by the charger 35 which is a charging means in advance.

On the other hand, when the scanning is started, the beam is detected by the index sensor, the modulation of the beam by the first color signal is started, and the modulated beam scans the peripheral surface of the image carrier 30. Therefore, the main scanning by the laser beam and the sub-scanning by the rotation of the image carrier 30 are performed by the image carrier.
A latent image corresponding to the first color is formed on the circumferential surface of 30. This latent image is developed by the developing device 36 in which red toner (latent image medium) is loaded in the developing means to form a toner image on the drum surface. The toner image thus obtained is held on the drum surface and passes under the cleaning device 39, which is a cleaning means separated from the peripheral surface of the image carrier 30, and enters the next copy cycle.

That is, the image carrier 30 has the charger 35.
Then, the second color signal output from the signal processing unit is input to the writing system unit B, and writing is performed on the drum surface in the same manner as in the case of the first color signal described above. An image is formed. The latent image is developed by a developing device 37 loaded with a second color toner, for example, blue toner.

The blue toner image is formed in the presence of the previously formed red toner image.

A developing device 38 having a black toner forms a black toner image on the surface of the drum based on a control signal generated by the signal processing section. AC and DC biases are applied to the sleeves of the developing units 36, 37, and 38, respectively.
The jumping development by the component developer is performed, and the development is performed without contacting the grounded image carrier 30.

In this way, the color image formed on the peripheral surface of the image carrier 30 is transferred from the paper feed cassette 41 of the paper feed section D to the paper feed roller 41 in the transfer device 40 provided as a transfer means.
A. It is transferred onto the recording paper which is the recording medium sent by the paper feed roller 42. The recording paper on which the toner image is transferred is separated
It is separated from the drum surface by 43 and is carried into a fixing device 45 via a conveyor belt 44 to fix the image, and then discharged to a paper discharge tray 46.

Further, the blade 39A of the cleaning device 39 is attached to the image carrier 30 in which the recording paper is separated from the drum peripheral surface.
And 39B come into contact with each other to remove the residual toner, and after the completion of the removal, the toner is separated from the peripheral surface again to start a new color image forming process.

On the other hand, manual feeding of recording paper is performed by a manual feeding device 50 provided above the paper feeding cassette 41.

The manual paper feeding device 50 is provided on the upper surface of the paper feeding cassette 41 with the guide plate 51, the photosensor PS, and 2
It is composed of a pair of conveying rollers 52 and 53.

When the recording paper is manually inserted between the guide plate 51 and the upper surface of the paper feed cassette 41, the photo sensor PS detects the front end of the recording paper and sends a signal to the control section of the apparatus to convey each of the above-mentioned conveyances. The roller is set to be rotatable and manually fed, while the operation of the sheet feeding roller 41A is kept stopped.

FIG. 2 shows the structure of the original table 11. The original G has a transparent glass plate 11A with the image surface facing downward.
Is pressed and supported by a flexible original cover 11B as a pressing member in a state of being in contact with, and an image is exposed and scanned by an optical system incorporated in the main body of the image forming apparatus.

The original cover 11B uses a matte black material on the sandwiching surface, that is, the inner surface, and when a double-sided original is sandwiched, the image on the rear surface, that is, the side facing the original cover 11B is the original. It is prevented from being reflected by the cover 11B.

As the color of the material of the inner surface of the original cover 11B, in addition to black, a non-reflective color, for example, a color in the wavelength range in which the photoreceptor is hard to sense may be used. In that case, the reflected light of the back side image cannot be avoided to some extent as shown in FIG. 3, but the density of the back side image can be eliminated or ignored by raising the reference of the laser exposure output to the level shown by the broken line. It is possible to lower it. Further, in an analog type copying machine having an EE function, it is processed as a document image having a background color and the back side image is not recorded.

This concept is based on the automatic document feeder (ADF)
It can also be applied to the document transport belt used for
The same effect can be obtained as in the case of the manuscript cover.

Further, the size of the document G can be easily detected by using the document cover 11B.

As shown in FIG. 4, a sensor such as a CCD covers the entire inner surface of the manuscript cover 11B in which the manuscript G is sandwiched prior to image exposure, and a sensor such as a CCD is used to move the manuscript G from the end surface of the manuscript cover 11B toward the manuscript G from AA to Z-. Scan to Z.

The read output of the sensor is low and flat as shown in FIG. 5A in the range (A-A, BB) where the document G does not exist, but the range where the document G exists (C- C, DD, Z-Z) shows a high level and a height difference according to the image pattern as shown in FIG. 6A, the time T until the output difference or the pattern difference is detected or the scanning is performed. The standardized size of the document G can be determined by accumulating the number of pulses.

Further, since the size of the original G can be detected while the original cover 11B is pressed, a so-called static original size detecting method in which the size of the original G is detected by a reflection type sensor fixed at a fixed position in the copying machine is used. It is useful as a cover for manuscripts.

Further, when the original G is recorded on a transfer paper larger than that, it is possible to record the above-mentioned range where the original G does not exist as a margin.

In this case, the exposure scanning by the image reading system A of the document G is performed by the exposure scanning shown in FIGS. 5 (a) and 6 (a).
After the sensor output shown in FIG. 5 is obtained, the document cover portion is discriminated based on the program in which the information is read in advance, and the laser output to the image carrier 30 by the laser writing system B is controlled, respectively. As shown in FIGS. 6B and 6B, the exposure action on the surface of the document cover 11B around the document G is stopped.

Therefore, regardless of the size of the document G, the entire margin of the image can be used as a margin.

[0037]

As described above, according to the present invention, it is possible to form an image having a high image quality even with a double-sided original, and it is possible to detect the original size with a simple device, and a black portion does not occur around the image regardless of the original size. Thus, an extremely useful image forming apparatus has been provided.

[Brief description of drawings]

FIG. 1 is a cross-sectional configuration diagram of an image forming apparatus of the present invention.

FIG. 2 is a perspective view of a document table of the apparatus.

FIG. 3 is a pattern diagram of reflected light of a document image on the document table.

FIG. 4 is an explanatory diagram showing a relationship between a document and a document cover.

FIG. 5 is a pattern diagram showing a relationship between a sensor output for detecting a document cover surface and a laser output to a photoconductor.

FIG. 6 is a pattern diagram showing a relationship between a sensor output for detecting a document cover surface and a laser output to a photoconductor.

[Explanation of symbols]

 11 Original plate 11A Glass plate 11B Original cover A Image reading system B Laser writing system C Image forming part D Paper feeding part 30 Image carrier 35 Charging device 36, 37, 38 Developing device 39 Cleaning device 40 Transfer device 41 Paper feeding cassette G Manuscript

Claims (3)

[Claims] 1. An image forming apparatus comprising an original table for performing image exposure by sandwiching and supporting an original between a pressing member and a glass plate, wherein the pressing surface of the pressing member is made of a black or non-reflective color material. An image forming apparatus characterized by being configured. 2. An image forming apparatus including an original table for performing image exposure by sandwiching and supporting an original between a pressing member and a glass plate, wherein the pressing surface of the pressing member is made of a black or non-reflective color material. An image forming apparatus configured to detect a document size by detecting the black or hardly reflective color material surface around the document. 3. An image forming apparatus comprising an original table for performing image exposure by sandwiching and supporting an original between a pressing member and a glass plate, wherein the pressing surface of the pressing member is made of a black or non-reflective color material. An image forming apparatus configured to prohibit scanning exposure around a document by detecting the black or hardly reflective color material surface around the document.