JP2008026714A - Document size detector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To precisely detect a document size. <P>SOLUTION: The document size detector includes: a plurality of size detection sensors each disposed according to the corresponding sizes of documents to be placed on a light transmissive document table and composed of corresponding light emitting parts and light receiving parts; a detecting section that detects a document size when light traveling from the light emitting part of the size detection sensor to the light receiving part is shielded by a document placed on the document table; and a light shielding member with which light leaking from the end of the document placed on the document table is shielded relative to the light receiving part. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a document size detection device, and more particularly to a device for detecting the size of a document in an electrophotographic copying machine.

  Such a conventional document size detection device includes an openable / closable document cover for covering a document placed on a transparent document table provided at the top of the copier body, and a document document placed on the document table. A plurality of sensors composed of light-emitting and light-receiving elements arranged at the lower part of the document table according to the size, and a light emission with the document cover opened to a predetermined angle range provided on the surface of the document cover facing the document table surface Optical path setting means for establishing an optical path that guides light from the element through the document table and reflected to the light receiving element, driving means for driving each adjacent sensor by shifting the time, and driving by shifting the time In addition, there is known one provided with size determination means for determining the document size according to the presence or absence of light reception of the light receiving element of each sensor (see, for example, Patent Document 1).

Further, in the document size detecting apparatus including a plurality of light emitting elements and light receiving element pairs arranged in parallel at the lower part of the document table, and having a reflector that guides the light emitted from the plurality of light emitting elements to the light receiving elements with the document table interposed therebetween, The reflecting plate is a concave mirror having a single reflecting surface whose section is a condensing curve, and the rib-shaped light shielding plate that blocks the light path of each light emitting element and light receiving element pair from the light path of the other light emitting element and light receiving element pair is a concave mirror. What was provided in the inner surface of this is known (for example, refer patent document 2).
Japanese Patent Publication No. 5-14260 JP 62-234146 A

Conventionally, in order to detect the size of a document placed on a document table in this way, light from the light-emitting element is transmitted at a predetermined position on the document table using a light-emitting element and a light-receiving element, and transmitted / non-transmitted. Is used to detect the document size. The manufacturer of the electrophotographic copying machine has responded by changing the type of the document size detection unit according to the shipping country between the AB system, which is a document size in Japan, and the inch system, which is a foreign document size.
However, such a specification may be used for an office multifunction device, but in the case of a high-speed device used for light printing business, it is necessary to cope with various document sizes with one unit.
At this time, for example, the dimensional difference between an A4 size document and a letter size document is small, and the current document size detection unit cannot distinguish between the two.

For this reason, in such a document size detection unit for a high-speed machine, a plurality of light emitting elements are arranged at a fine pitch, and each light emitting element detects the edge of the corresponding document. However, light from the light-emitting element that should be shielded by the document leaks from the edge of the document due to variations in the position of the light-emitting element, variations in the light-emitting direction of the light-emitting element, or variations in the position of the light-receiving element. Is received, and the document size is not correctly detected.
The present invention has been made in consideration of such circumstances, and even if light from a light emitting element that should be shielded by the original leaks from the edge of the original, it is not received by the light receiving element. An original size detection device is provided.

  The present invention relates to a plurality of size detection sensors each of which is arranged in accordance with a plurality of sizes of a document placed on a translucent document table and includes a light emitting portion and a light receiving portion, and a light receiving portion to a light receiving portion of the size detection sensor. Can detect light from the edge of the document placed on the document table, and can detect light from the edge of the document placed on the document table. An original document size detection apparatus including a light shielding member is provided.

You may further provide the drive part which moves a light shielding member in order to put a light shielding member in a light-shielding state and a non-light-shielding state.
A document cover that is provided on the document table and can be manually opened and closed, and an open / close sensor that detects opening and closing of the document cover, and when the document cover is opened, the light shielding member is placed in a light shielding state to detect the document size, and the document cover There may be further provided a control unit for controlling the drive unit in order to place the light shielding member in a non-light-shielded state when is closed.
The light shielding member is a plate-like member. The light shielding state is a state in which the light shielding member is erected vertically below the document table, and the light shielding member is substantially parallel to the document table. It may be in a state of falling.

  When light from the light-emitting unit that should be shielded by the document placed on the document table leaks from the edge of the document, the light-shielding member shields the leaked light from the light-receiving unit, so that the document size is reliably detected. Is done.

FIG. 1 is an explanatory view of the configuration of an image forming apparatus (for example, an electrophotographic copying machine) to which the document size detecting apparatus of the present invention is applied.
The image forming apparatus 100 forms a monochrome image on a predetermined recording sheet (sheet) according to image data obtained by scanning a document placed on a document placing table 1 made of transparent glass. is there.
The image forming apparatus 100 includes a document placing table 1, a document cover 1a, an image reading unit 2, an optical writing unit 3, a developing device 4, a photosensitive member 5, a charger 6, a cleaner unit 7, a transfer unit 8, a fixing unit 9, The paper transport path 10, the paper feed trays 11 a to 11 d, and the paper discharge tray 12 are mainly configured.

  The image reading unit 2 mainly includes a light source holder 13, a mirror group 14, and a CCD 15. When the document is placed on the document table 1 and covered with the document cover 1a, the light from the light source of the light source holder 13 scans the document, and the light reflected from the document is converted into an optical path via the mirror group 14, and then the CCD 15 And converted into electronic image data.

The charger 6 is a charging means for uniformly charging the surface of the photoconductor 5 to a predetermined potential. Here, the charger type charger 6 is used, but a contact type roller type or brush type is used. A charger can also be used.
In this example, a laser scanning unit (LSU) including laser irradiation units 16a and 16b and mirror groups 17a and 17b is used as the optical writing unit 3, but an EL writing head in which light emitting elements are arranged in an array. Alternatively, an LED writing head can be used.

The optical writing unit 3 employs a two-beam system including two laser irradiation units 16a and 16b in order to cope with high-speed printing processing, and the burden associated with increasing the irradiation timing is reduced.
Then, laser light is irradiated from the laser irradiation units 16a and 16b in accordance with the input image data, and the photosensitive member 5 uniformly charged by the charger 6 is exposed through the mirror groups 17a and 17b, thereby exposing the photosensitive member. An electrostatic latent image corresponding to the image data is formed on the surface of the body 5.

The developing device 4 disposed in the vicinity of the photoconductor 5 visualizes the electrostatic latent image formed on the surface of the photoconductor 5 with black toner.
A cleaner unit 7 disposed around the photoconductor 5 removes and collects toner remaining on the surface of the photoconductor 5 after development and image transfer.

The image forming apparatus 100 includes a control unit (not shown) that performs integrated control of the entirety.
The control unit receives a signal from the CPU, a ROM that stores a control program executed by the CPU, a RAM that provides a work area for the CPU, a non-volatile memory that holds control data, and each unit detection unit of the image forming apparatus 100. The circuit includes an input circuit, an actuator that operates each unit drive mechanism of the image forming apparatus 100, a driver circuit that drives the motor, and an output circuit that drives the laser irradiation units 16a and 16b.

As described above, the electrostatic image visualized on the surface of the photoconductor 5 is applied by applying an electric field having a polarity opposite to that of the electrostatic image from the transfer unit 8 to the conveyed paper. Transferred onto recording paper.
For example, when the electrostatic image has a charge of (−) polarity, the polarity applied to the transfer unit 8 is (+) polarity.
The transfer belt 19 of the transfer unit 8 is stretched by a driving roller 20, a driven roller 21, and other rollers, and has a predetermined resistance value (for example, a range of 1 × 10 ⁹ to 1 × 10 ¹³ Ω · cm). ing.
An elastic conductive roller 22 that has conductivity and can apply a transfer electric field is disposed at a contact portion between the photosensitive member 5 and the transfer belt 19.

The electrostatic image (unfixed toner) transferred onto the recording paper by the transfer unit 8 is conveyed to the fixing unit 9 so that the unfixed toner is melted and fixed on the recording paper.
The fixing unit 9 includes a heating roller 23 and a pressure roller 24, and a heat source that makes the surface of the heating roller 23 a predetermined temperature (fixing temperature: approximately 160 to 200 ° C.) is built in the inner peripheral portion of the heating roller 23. Has been.
On the other hand, a pressure member (not shown) is arranged at both ends of the pressure roller 24 so as to come into pressure contact with the heating roller 23 with a predetermined pressure.
As a result, the unfixed toner on the conveyed recording paper is heated and melted by the heating roller 23 at the pressure contact portion (called a fixing nip portion) between the heating roller 23 and the pressure roller 24, and is thrown at the pressure contact portion. It is fixed on the recording paper by a repulsive action.

  The plurality of paper feed trays 11 a to 11 d are trays for storing recording sheets of various sizes used for image formation, and are provided below the image forming apparatus 100.

  2 is a top view showing a document size detection device provided in the image forming apparatus 100 shown in FIG. 1, FIG. 3 is a perspective view of the document size detection device shown in FIG. 2, and FIG. 4 is a diagram of the document size detection device shown in FIG. FIG. 12 is an enlarged view of a main part of FIG.

  As shown in FIG. 2, B5, A4, B4, and A3 originals and letter (LT) originals are aligned with the reference point P of the transparent glass original placing table 1, and the original One side is placed along the reference line R. As shown in FIGS. 2 to 4, the document placing table 1 includes an illumination substrate 44 and a light receiving substrate 45 for document size detection.

  As shown in FIG. 3, the light-emitting diode 44 and the photodiode 36 for detecting the A3 size, the light-emitting diode 32 and the photodiode 37 for detecting the B4 size, and the letter (LT ) A light emitting diode 33 and a photodiode 38 for size detection, a light emitting diode 34 and a photodiode 39 for A4 size detection, and a light emitting diode 35 and a photodiode 40 for B5 size detection are mounted, respectively.

  As shown in FIG. 4, the document cover 1a is pivotally supported by a support shaft 49. When the document cover 1a is opened in the direction of an arrow 48 by an operator, the illumination substrate 44 has a spring mechanism (not shown). As a result, it rises up to a predetermined angle in the direction of arrow 48 around the fulcrum 46. As shown in FIG. 12, the angle sensor 70 includes three photo interrupters 70a to 70c each including a light receiving portion and a light emitting portion, and is fixed to the main body. A light shielding piece 90 attached to the lower end of the document cover 1a is provided so as to be able to pass between the light receiving portions and the light emitting portions of the photo interrupters 70a to 70c. As will be described in detail later, when the light shielding piece 90 reaches the photo interrupter 70a, it is determined that the document cover 1a has been completely opened, and the light shielding members 53 and 54 are driven upright as shown in FIG. When the light shielding piece 90 passes through the photo interrupter 70b, it is detected that the document cover 1a is closed to a predetermined angle, and document size detection is started. That is, the light emitting diodes 31 to 35 are sequentially turned on, and the emitted light passes through the document table 1 and is received by the corresponding photodiodes 36 to 40, respectively. When the light shielding piece 90 is detected by the photo interrupter 70c, it is determined that the document cover 1a is completely closed.

  Therefore, as shown in FIG. 2, when an operator places a B5 size document on the document table 1 so that the corner thereof coincides with the reference point P and one side thereof coincides with the reference line R. The light emitted from the light emitting diode 35 is shielded by the original and is not received by the photodiode 40. Thereby, it is detected that the document is B5 size.

  Similarly, a document of A4 size, LT size, B4 size or A3 size is placed on the document placing table 1 so that the corner thereof coincides with the reference point P and one side thereof coincides with the reference line R. Even in this case, the light emitted from the light-emitting diodes 34, 33, 32, or 31 is shielded by those originals, and the respective light is not received by the corresponding photodiode. Thereby, each size of the document is detected.

  As shown in FIG. 4, the operator opens the document cover 1a in the direction of arrow 48, places the document in correspondence with the reference point P and the reference line R of the document table 1, and places the document cover 1a in the direction of arrow 47. When the image forming apparatus 100 is closed and the copy start button on the operation panel (not shown) is turned ON, the image forming apparatus 100 automatically detects the document size, selects a recording sheet corresponding to the size from the paper feed trays 11a to 11d, and performs image processing. Form.

  FIG. 5 is a control circuit diagram of the document size detecting device, and FIG. 6 is a signal waveform diagram. The operation of this embodiment will be described in more detail using these diagrams.

  In FIG. 5, the control part 50 is comprised from the microcomputer which consists of CPU, ROM, and RAM. The angle sensor 70 shown in FIG. 5 is output when the operator closes the document cover 1a to a predetermined angle as described above. The control unit 50 receives the output from the angle sensor 70, generates a clock signal CL shown in FIG. 6, and outputs it to the lighting signal generator 41.

  The lighting signal generator 41 generates the lighting signals A, B, C, and D shown in FIG. 6 based on the clock signal CL, and outputs them to the LED driver 42 and the selector 43. The LED driver 42 supplies current from the power source Vcc to the light emitting diodes 31 to 35 in order in synchronization with the lighting signals A, B, C, and D to emit light. The selector 43 selectively detects the light receiving / non-light receiving states of the photodiodes 36 to 40 connected to the power source Vcc in synchronization with the lighting signals A, B, C, and D, and outputs the signal S to the control unit 50. input. Based on the signal S, the control unit 50 recognizes a photodiode that does not receive light and detects the document size.

  In this manner, the light emitting diodes 31 to 35 periodically change the light emission timing, and the light reception signals from the corresponding photodiodes 36 to 40 are also selected in accordance with the light emission timing, and are sent to the control unit 50 as the signal S. Entered. Therefore, even if the photodiodes 36 to 40 receive light (crosstalk light) from a light emitting diode that does not correspond, the signal S is not affected. When the operator closes the document cover 1a, the angle sensor 70 detects this, and the control unit 50 stops the light emission of the light emitting diodes 31 to 35.

FIG. 11 is an explanatory diagram showing a situation in which a letter (LT) size document 51 and an A4 size document 52 placed on the document table 1 are detected.
Since the originals 51 and 52 have a small size difference, the light emitting diodes 33 and 34 and the photodiodes 38 and 39 detect the end portions of the corresponding originals in order to distinguish the sizes. That is, the irradiation light from the light emitting diode 33 is transmitted through the document placement table 1 and received by the photodiode 38, and the irradiation light from the light emitting diode 34 is transmitted through the document placement table 1 and received by the photodiode 39. It has become. Then, when the light placed on the photodiodes 38 and 39 is blocked by the document placed on the document table 1, the document is letter-sized, and only the light incident on the photodiode 39 is blocked. The document is recognized to be A4 size.

  By the way, the light emitting diodes 33 and 34 and the photodiodes 39 and 38 have inherent variations in their installation positions and light emitting directions. For example, as shown in FIG. 11, if the light emitting diodes 33 and 34 are shifted from their original positions to positions 33 a and 34 a, part of the irradiation light to be shielded by the originals 51 and 52 is the original 51 and 52. Since the light leaks from the end of 52 and is received by the photodiodes 38 and 39, the original size cannot be detected correctly.

Therefore, in the present invention, in order to block the light leaking from the end portion of the original and received by the photodiode, as shown in FIG. 11, plate-like light shielding members 53 and 54 are provided between the end portion of the original and the corresponding photodiode. Is installed.
7 and 8 are side views showing the light shielding member and its driving mechanism, and FIGS. 9 and 10 are plan views showing the light shielding member and its driving mechanism.

As shown in these drawings, the plate-shaped light shielding members 53 and 54 are installed perpendicularly to shafts 56 and 57 provided in parallel to the document reading unit 2, and the shafts 56 and 57 are respectively provided with bearings 58a and 58b and bearings. 59a and 59b are rotatably supported.
Pinions 60 and 61 are fixed to the shafts 56 and 57, respectively, and the pinions 60 and 61 mesh with the rack 62. The rack 62 is supported by the slide base 65 so as to be movable in the direction of the arrow 63 or 64. A linear actuator 66 with a built-in stepping motor is connected to one end of the rack 62, and the stepping motor of the linear actuator 66 is driven by a motor driver 55 in FIG.
Next, the operation of the drive mechanism for the light shielding members 53 and 54 configured as described above will be described.

As described above, when the operator starts closing the document cover 1a after placing the document on the document table 1, this is detected by the photo interrupters 70a and 70b (FIG. 12). Then, in the drive mechanism that holds the light shielding members 53 and 54 in the state of FIG. 8, the linear actuator 66 is driven and the rack 62 moves in the direction of the arrow 63. As a result, the pinions 61 and 60 rotate clockwise, respectively, and the light shielding members 53 and 54 stand up so as to be perpendicular to the document table 1 as shown in FIG. That is, the light shielding members 53 and 54 are arranged as shown in FIG.
Therefore, even if the placed document is A4 size or LT size, light from the light emitting diode 33 or 34 leaks from the end of the document 51 or 52 and is received by the photodiode 38 or 39. Since there is no, each size is detected correctly.

When the operator completely closes the document cover 1a as described above, this is detected by the photo interrupter 70c (FIG. 12), and the linear actuator 66 moves the rack 62 in the direction of the arrow 63. As a result, the pinions 60 and 61 rotate counterclockwise, and the light shielding members 53 and 54 are tilted as shown in FIG. 8 so as not to hinder the movement of the light source holder 13 and the mirror group 14 when reading a document. Yes.
In the case of a thick original such as a book original, copying is performed with the original cover open. In preparation for such a case, even if the document size is not detected, when the copy start button on the operation panel (not shown) is turned on by the operator, the light shielding members 53 and 54 are immediately driven to fall down, and a predetermined copy is made. Operation is performed without any problems.

1 is a configuration explanatory diagram of an image forming apparatus according to the present invention. FIG. 1 is a top view illustrating a document size detection device according to an embodiment of the present invention. 1 is a perspective view illustrating a document size detection device according to an embodiment of the present invention. 1 is a side view showing a document size detection device according to an embodiment of the present invention. It is a control circuit diagram of an embodiment of the present invention. It is a signal waveform diagram of the control circuit of the embodiment of the present invention. It is a principal part front view of embodiment of this invention. It is a principal part front view of embodiment of this invention. It is a principal part top view of embodiment of this invention. It is a principal part top view of embodiment of this invention. It is operation | movement explanatory drawing of embodiment of this invention. It is a principal part enlarged view of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Document stand 1a Document cover 2 Image reading part 3 Optical writing unit 4 Developer 5 Photoconductor 6 Charger 7 Cleaner unit 8 Transfer unit 9 Fixing unit 10 Paper conveyance path 11a, 11b, 11c, 11d Paper feed tray 12 Ejection Paper tray 13 Light source holder 14, 17a, 17b Mirror group 15 CCD
16a, 16b Laser irradiation unit 19 Transfer belt 20 Drive roller 21 Driven roller 22 Elastic conductive roller 23 Heating roller 24 Pressure roller 31-35 Light emitting diode 36-40 Photo diode 41 Lighting signal generator 42 LED driver 43 Selector 44 For illumination Substrate 45 Light receiving substrate 46 Support point 47 Arrow 48 Arrow 49 Support shaft 50 Control unit 51 A4 size document 52 Letter size document 53 Light shielding member 54 Light shielding member 55 Motor driver 56 Shaft 57 Shaft 58a Bearing 58b Bearing 59a Bearing 59a Bearing 60 Pinion 61 Pinion 62 Rack 63 Arrow 64 Arrow 65 Slide base 66 Linear actuator 70 Angle sensor 90 Light-shielding piece 100 Image forming apparatus P Reference point R Reference line

Claims (4)

  A plurality of size detection sensors each having a light emitting portion and a light receiving portion, which are arranged according to a plurality of sizes of a document placed on a translucent document table, and light from the light emitting portion to the light receiving portion of the size detection sensor. A detection unit that detects a document size by being shielded from light by a document placed on a document table, and a light shielding member that can shield light leaking from an edge of the document placed on the document table to a light receiving unit. Document size detection device.   2. The document size detection apparatus according to claim 1, further comprising a drive unit that moves the light shielding member to place the light shielding member in a light shielding state and a non-light shielding state.   A document cover that is provided on the document table and can be manually opened and closed, and an open / close sensor that detects opening and closing of the document cover, and when the document cover is opened, the light shielding member is placed in a light shielding state to detect the document size, and the document cover The document size detection apparatus according to claim 2, further comprising a control unit that controls the drive unit to place the light shielding member in a non-light-shielded state when the shutter is closed.   The light shielding member is a plate-like member. The light shielding state is a state in which the light shielding member is erected vertically below the document table, and the light shielding member is substantially parallel to the document table. The document size detection device according to claim 2, wherein the document size detection device is in a state of falling down.

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