JP2003032442A - Image reading device and image forming device - Google Patents

Abstract

(57) [Problem] To control an image forming apparatus so that an image forming position on an image sensor becomes constant even when the thickness of a document sheet changes. SOLUTION: Light is applied to an image surface of a document sheet S conveyed while the back surface is in contact with a conveyance support roller 16, and reflected light from the image surface is photoelectrically converted by an image sensor 17 via a lens (not shown). And read the image. Original sheet S
The position of the transport support roller 16 is controlled so that the position of the image formed on the image sensor 17 by the lens becomes constant in accordance with the detected thickness.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image reading apparatus for controlling a focus position of a read image by changing a thickness of a document and an image forming apparatus equipped with the image reading apparatus.

[0002]

2. Description of the Related Art Conventionally, in a document-conveying-type digital copying machine (image forming apparatus), a document (sheet) is conveyed with its back surface in contact with a backup roller, and at this time, light is transmitted from above the document surface to the document surface. The light reflected by the image on the original surface is irradiated above the contact portion of the backup roller C
A document reading device for reading a document by photoelectrically converting it by a photoelectric conversion element such as a CD is well known. In this case, there are various originals (sheets) having various thicknesses, but the shift of the focus position due to the shift of the read image position due to the thickness change is not adjusted. .
In particular, even when a lens such as a SELFOC lens having a strict focus position is used, the focus position is not adjusted.

[0003]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object thereof is to provide an image side of an original sheet conveyed with the back surface of the original sheet in contact with a backup roller. In a device that reads light by irradiating light and photoelectrically converting the reflected light from the image through an image sensor through a lens, controls so that the image formation position on the image sensor remains constant even if the thickness of the original sheet changes It is to be.

[0004]

According to a first aspect of the present invention, the back surface of the original sheet is brought into contact with the conveyance assisting roller so that the image surface of the original sheet is irradiated with light, and the reflected light from the image surface is passed through the lens. In an image reading device that performs photoelectric conversion by an image sensor, a means for detecting the thickness of a document sheet, and a conveyance assisting roller so that the image forming position of the image on the image sensor by the lens becomes constant corresponding to the detected thickness. An image reading apparatus having means for controlling the position of.

According to a second aspect of the present invention, in the image reading apparatus according to the first aspect, the means for detecting the thickness of the original sheet is a reference position display member provided at the axial center of a roller rotating in contact with the original sheet. The image reading device comprises a position detection device that detects a displacement of the reference position display member.

According to a third aspect of the present invention, there is provided an image forming apparatus including the image reading apparatus according to the first or second aspect.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS First, a digital copying machine (image forming apparatus) to which the present invention is applied will be described. FIG. 1 is a schematic configuration diagram of the digital copying machine. The sheet feeding unit 82, the image forming unit 81, and the original document conveying device (sheet conveying device) 11 mounted on the upper portion of the main body are mainly configured. Document feeder (AD
F) 11 conveys the document (sheet) S to the reading position, and after reading according to the operation mode (rear sheet discharging mode / front sheet discharging mode / winding mode) preset according to the thickness of the document S. Document S is conveyed in the direction a and discharged to the first document discharge tray 26 at the rear (rear side) of the apparatus. The document S after reading and reversing is guided in the direction c, and is fed to the front (front side) of the apparatus. The sheet is discharged to the two original discharge tray 12, or is guided to the first original discharge tray 26 at the rear of the apparatus after reading and is wound in the b direction by the winding storage guide 27. Further, when the user rotationally moves the take-up storage guide 27 to the upper side of the apparatus, the rear end of the original after winding is separated from the apparatus housing, and the original S is from the upper side or the side of the storage guide 27 at the user operation position. Taken out. Here, the front side of the apparatus (front side) is the direction of the display screen of the operation section 51, and the rear side of the apparatus (rear side) is the side opposite to the direction of the display screen of the operation section 51, that is, in the rear discharge mode. This is the side of the first document discharge tray 26 for discharging the document S.

The upper unit of the ADF 11 is connected to the lower unit in a vertically openable and closable manner by a connecting member such as a hinge (not shown). An operation unit 51 and a second document discharge tray 12 are mounted on the upper part of the upper unit so as to face the front of the apparatus, and a take-up storage guide 27 swings between the upper surface and the rear surface of the unit at the rear end of the upper part of the unit. Supported as possible.

The winding / accommodating guide 27 is connected to the upper unit by a connecting means including a supporting member for supporting the support shaft 29, and is rotatable about the support shaft 29.
By the user's operation, the winding position on the rear side of the apparatus (the setting position of the winding and storing guide 27 shown in FIG. 1) and the front side of the apparatus (front side)
It is configured to be movable to the take-out position of.

The second original discharge tray 12 is made of a comb-shaped metal wire, is arranged on the upper part of the upper unit in a slanted manner from the rear of the unit to the front, and is inverted and discharged. Is stored so that it can be taken out at a user operation position in front of the device.

As will be described later with reference to FIG. 2, the operation unit 51 is provided with a key group 30 such as a start key, a numeric keypad, a clear / stop key, an initial setting key, a mode key, and a liquid crystal touch panel 57, and each is operated by the user. The operation mode can be set and operation start / stop instructions can be given. The liquid crystal touch panel 57 also has an input operation unit including function keys that appear appropriately for each screen, and a display unit that displays a message such as the number of copies or the device status. For the setting contents such as the operation mode by the user operation, the operation unit 5
1 to the main controller 61.

The reading unit 17 is a scanner unit including a light source (not shown), an imaging lens (selfoc lens), a shading plate, a photoelectric conversion element (CIS contact image sensor), a scanner motor, etc., and is inserted from the front of the apparatus. The conveyed original is irradiated with light from above the conveying path, the reflected light is imaged on the light receiving surface of the CIS image sensor through the imaging lens, and the image surface is sequentially converted into an image signal (image data). .

Near the downstream side of the carrying roller 14 (the carrying roller 1
4 and the first document discharge tray 26 and in the vicinity of the transport roller 14), a branching claw (not shown) is provided, and a solenoid mechanism (not shown) attracts / disengages according to a preset operation mode. It is driven by the release operation. By the branch claw,
In the front paper ejection mode, the read original is branched to the second original paper ejection tray 12 side, and in the rear paper ejection mode and the winding mode, the read original is the first original paper ejection tray 2
Branch to 6 side.

On the other hand, an original table 20 is arranged on the front upper surface of the lower unit, and a first table is arranged on the rear rear surface of the unit.
The document discharge tray 26 is attached so as to project.
On the original table 20, the original S is placed with its image surface facing upward,
The document S inserted from the front of the apparatus is guided to the nip portion of the transport roller 13.

The registration sensor 18 is an optical reflection type sensor arranged near the upstream side of the reading unit 17, detects that the leading edge of the document reaches the reading unit 17, and is turned on to pass the trailing edge of the document. It will be turned off later. Registration sensor 18
Based on the trailing edge detection timing, the branch pawl return processing and the conveyance motor 43 stop processing in the rear paper discharge mode are performed.

The first document discharge tray 26 is made of a metal wire formed in a comb-teeth shape so as to be inclined toward the downstream side in the conveying direction, and extends from the discharge port downstream of the conveying roller 14 toward the rear of the apparatus. The original discharged in this state is stored as it is. When the take-up storage guide 27 is at the take-up position, the comb-teeth-shaped wire of the first document delivery tray 26 and the comb-teeth-shaped wire of the take-up storage guide 27 intersect, and the first document delivery tray 26 Part of this is also used as a receiving port (guide means) for the winding and storing guide 27.

The transport drive rollers 13 to 15 and the backup roller 16 are stepping motors, which are supplied with a power supply voltage from the main body of the apparatus and are rotated in the forward and reverse directions by the drive of the transport motor 43.

On the other hand, the image forming unit 81 has a drum-shaped photosensitive member 33 as a center, and around the photosensitive member 33, a charging charger 31, a writing unit and a developing unit 32, and a transfer unit are arranged in the order of steps of the electrophotographic process. A charger 36, a separation charger 37, etc. are arranged. The writing unit constitutes a laser writing optical system including a laser output unit (including a laser diode and a polygon mirror), an imaging lens, and a mirror.

Further, in the lower part of the image forming unit 81, first to third roll transfer papers 78 to 80 are mounted so as to be freely drawn out, and a common vertical transport unit (paper feed roller 71).
~ 75, including the cutters 76, 77)
The transfer paper cut according to the length of the original is fed and conveyed to the transfer position side of. Further, on the downstream side of the transfer position of the photoconductor 33 in the transport direction, a transport belt, a fixing unit (fixing roller 35, pressure roller 34, etc.), paper discharge rollers 38, 3
A paper discharge unit including 9 and paper discharge trays 40 and 41 are sequentially provided.

As a result, the first to third roll transfer papers 7
8 to 80, depending on the document length detected on the ADF 11 side,
Selected and cut, and the photoconductor 33 is selected by the vertical transport unit.
Will be transported to the transfer position. On the other hand, on the side of the photoconductor 33 that is rotationally driven in the sub-scanning direction, an electrostatic latent image is formed by the optical writing in the main scanning direction by the writing unit, and a toner image is formed by being developed by the developing unit 32. It
The cut transfer sheet transported by the vertical transport unit is synchronized with the leading edge of the toner image while the photoconductor 33
Is conveyed by the conveyor belt driven at the same speed as
Receive the transfer of the toner image. The transfer sheet after the transfer is subjected to the fixing process by the fixing unit, and then, depending on the size of the transfer sheet, it is discharged via the discharge rollers 38 and 39 to the discharge trays 40 and 4.
1 discharged on top.

Next, the hardware configuration of the electrical equipment control system shown in FIG. 2 will be described. In addition to the operation unit 51 and the ADF 11, an image processing unit (not shown) that is a distributed control device is connected to the main controller 61 that controls the entire digital copying machine. The decentralized control device and the main controller 61 exchange machine statuses, operation commands, and the like as necessary. Further, the transport motor 43 and various clutches required for transporting the document S include an input / output unit (I / O).
It is connected to the main controller 61 via 63. Further, the registration sensor 18 for detecting document position information necessary for driving the transport motor 43 and various clutches is connected to the main controller 61 via an input / output unit (I / O) 63. Further, the document insertion portion of the ADF 11 is provided with an optical reflection type document thickness sensor 64 for detecting the thickness of the document to be inserted and conveyed.

The main controller 61 includes detection signals from the registration sensor 18 and the document thickness sensor 64, and the conveyance motor 4
Based on the status signal of 3 and the setting signal of the operation unit 51,
Drive control of the carry motor 43 (including speed control), display control of the liquid crystal touch panel 57 in the operation unit 51, and the like are performed. In addition, the memory of the main controller 61 (RAM /
The ROM) stores the operation mode (including the front paper discharge mode / rear paper discharge mode / rewinding mode, correction mode) input / set from the operation unit 51, and is stored each time the operation mode is changed. It is configured to update the content.

In the digital copying machine having such a structure, when the SELFOC lens is used as the reading lens of the reading unit 17, the SELFOC lens has a strict focus position, and the change in the thickness of the original or the glass plate of the original table is used. The out-of-focus position causes the image to blur.

Therefore, in order to avoid this, the present invention is characterized by detecting the thickness of the document and automatically controlling so that the focus position becomes constant. Hereinafter, embodiments of the present invention will be described. FIG. 3 is a schematic configuration diagram of the document thickness detection mechanism according to the embodiment of the present invention, in which the transport drive roller 1 is used.
3, a black-and-white pattern member 100 attached to the tip of the upper shaft 13a, and a position detection device 200 provided so as to face the black-and-white pattern member 100.

FIG. 4 is a diagram showing a mode of thickness detection by the position detecting device 200. Light emitted from the light emitting portion 200a through the lens is reflected by the black-and-white pattern member 100 and received through the lens. The light is received by the unit 200b. The light receiving unit 200b is composed of a PSD sensor,
The sensor is further connected to an amplifier circuit 300 as shown in FIG. 5, amplifies the photoelectrically received light reception signal to a processing level, and then sends it to the control unit 400. The received light receiving signal is recognized as the moving position data of the transport driving roller 13, that is, the document thickness data based on the preset content.
That is, when the document S is inserted into the transport driving roller 13 (FIG. 3), the upper shaft 13a of the transport driving roller 13 is pushed upward, and therefore the black-and-white pattern member 100 is also pushed upward, so that the output of the PSD sensor is output. Is output as the position of the incident light (the position of the center of gravity), and the document thickness data can be obtained.

The detection output of the document thickness by the PSD sensor will be further described. FIG. 6 is a cross-sectional configuration diagram of the PSD sensor. In the figure, the PSD sensor has a P layer on the front surface of the flat silicon, an N layer on the back surface, and It is composed of the I layer in the middle. In principle, when a light spot is incident on the PSD sensor, a charge proportional to the light energy is generated at the incident position, and the generated charge passes as a photocurrent through the P layer, which is a resistance layer. The mold is divided and output from the electrodes attached to the ends of the P layer and the N layer. At this time, since the resistance layer is configured to have a uniform resistance value on the entire surface,
The photocurrent is divided and output in inverse proportion to the distance (resistance value) to the electrode. Here, when the distance between the P layer electrodes is L, the current output from each electrode is I1, I2, and the center of the PSD sensor is the origin, if a light spot is irradiated from the origin to a distance X, then (I2 Since −I1) / (I1 + I2) = 2X / L, the position (center of gravity position) X of the incident light can be obtained. When the incident light is the reflected light from the black-and-white pattern 100, when a document (sheet) having a standard thickness is used, it is possible to set the light so that the black pattern and the white pattern are equally irradiated. The output of the PSD sensor due to the reflected light indicates the origin. If the black-and-white pattern 100 changes depending on the thickness of the original (sheet), the change in the reflected light, that is, the incident light of the PSD sensor reflects the position of the incident light (position of the center of gravity). The thickness of (sheet) can be obtained.

Next, the focus position control of the original when the original is conveyed will be described with reference to FIG. A close-up image sensor (CI) having a backup (conveyance support) roller 16 near the document entrance of the digital copying machine, and a reading unit 17 on the opposite side of the contact point between the roller 16 and the document.
S) 17a is provided. A stepping motor (not shown) is provided on a bearing portion (not shown) of the backup roller 16, and the backup roller 16 is driven by this motor.
Up and down to raise or lower the image surface of the original to adjust the focus position. In FIG. 8A, a document having a thickness S1 is conveyed,
Assuming that the distance from the CIS 17a is t and the document is being read, the thickness S2 (S
When the document of 2 <S1) is conveyed, the backup roller 16 is raised to maintain the distance t from the CIS 17a.

In this operation, the detection output of the document thickness detecting device 200 connected to the ADF 11 (FIG. 2) is transmitted to the main controller 61, and the CPU (not shown) of the main controller 61 causes the bearing portion (not shown) of the backup roller 16 to be received. The backup roller 16 is moved up and down by a stepping motor (not shown) provided to control the focus position. FIG. 8 is a flow chart of this focus position adjustment. The flow of focus position control will be described based on FIG. 8. This process is started by the operation of the digital copying machine, and an entrance sensor installed at the entrance of the platen glass is used. It is checked whether a document has been inserted (S1). When the document is inserted (S1, YES), the pre-feed of the document starts (S2), and the document passes through the conveyance roller 13 and reaches the registration sensor 18. At this time, the pre-feed is stopped (S3), and the upper shaft 13b of the conveyance roller 13 is
The thickness of the document is measured by moving (S4). Then, based on this measurement result, the backup roller 16 is moved so that the distance between the image surface of the document and the CIS 17a is t (S5), the document feed is started (S6), and this process is terminated. When the document is not inserted (S1, NO), the process returns to the check again whether or not the document is inserted.

According to the present embodiment, the back surface of the original sheet is brought into contact with the backup roller 16 to irradiate light from the front surface side of the original document, and the reflected light from the original image is applied through the lens to the contact-type photoelectric sensor. In an image reading device that photoelectrically converts an image by a conversion element to read an image, an upper shaft 13 of a conveyance roller is used.
The thickness of the original is measured by the position detection device 200 including the black-and-white pattern 100 attached to a, the light emitting portion 200a, and the PSD sensor 200b, and the backup roller 16 is moved up and down based on the result. Even if it changes, it can be controlled with a simple configuration so that a constant imaging position can be easily obtained. High-performance reading can be performed when a SELFOC lens having a strict focus position is used as the lens.

[0030]

According to the first aspect of the invention, even if the thickness of the original sheet changes, the image forming position of the image sensor can be controlled to be constant without depending on the thickness. Therefore, it is possible to always read a uniform image. Effect corresponding to claim 2: Since the thickness of the original sheet can be detected with a simple structure, it is possible to easily control the image forming position of the image sensor to be constant. Effect corresponding to claim 3: In an image forming apparatus provided with an image reading device having the effect corresponding to claims 1 and 2, since the effects of the inventions of claims 1 and 2 are exhibited, high-quality image formation It can be performed.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a digital copying machine to which the present invention is applied.

FIG. 2 is a hardware configuration diagram of an electrical equipment control system of a digital copying machine to which the present invention is applied.

FIG. 3 is a schematic configuration diagram of a document thickness detection mechanism according to the embodiment of the present invention.

FIG. 4 is a diagram showing an aspect of thickness detection according to the embodiment of the present invention.

FIG. 5 is an output circuit diagram of a PSD sensor to which the present invention is applied.

FIG. 6 is a cross-sectional configuration diagram of a PSD sensor to which the present invention is applied.

FIG. 7 is a mechanism diagram of focus position control according to the embodiment of the present invention.

FIG. 8 is a flowchart of focus position control according to the embodiment of the present invention.

[Explanation of symbols]

11 ... ADF, 13 ... conveying rollers, 16 ... backup rollers, 17 ... reading section, 18 ... registration sensor, 20 ...
Document table, 70 ... Registration roller, 71 ... Paper feed roller, 100 ... Black and white pattern, 200 ...

Claims (3)

[Claims] 1. An image reading apparatus for irradiating light to an image surface of a document sheet, the back surface of which is in contact with a conveyance assisting roller, and photoelectrically converting reflected light from the image surface through an image sensor through a lens, It has a means for detecting the thickness of the original sheet, and a means for controlling the position of the conveyance assisting roller so that the image forming position of the image on the image sensor by the lens becomes constant according to the detected thickness. Image reading device. 2. The image reading apparatus according to claim 1,
The means for detecting the thickness of the original sheet comprises a reference position display member provided on the axis of a roller that rotates in contact with the original sheet, and a position detection device for detecting a displacement of the reference position display member. Image reading device. 3. An image forming apparatus comprising the image reading device according to claim 1.