JPH08179439A - Original reader and image forming device - Google Patents

Abstract

PURPOSE: To obtain butting in a direction in scanning at the time of setting an original which requires butting in two directions in a conventional manner and to improve the operation of an original reader and an image forming device by providing an original position detecting means capable of moving. CONSTITUTION: The original reader and the image forming device are constituted to provide a butting part 2 against which the leading edge of the original D on an original platen glass 1 is butted, a detecting means 4 capable of scanning the original platen glass 1, for detecting the position of the original D in parallel with the butting part 2, an optical system having a lens for projecting an image on the original D on a recording medium and a control means capable of moving the lens of the optical system in a direction nearly perpendicular to an optical axis and controlling the moving amount of the lens, so as to place the position of the image projected on the image recording medium in a fixed position, based on the position information of the original obtained by the detecting means.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a document reading apparatus and an image forming apparatus used in a document reading section of, for example, an electrophotographic copying machine.

[0002]

2. Description of the Related Art In a conventional image forming apparatus of this type, FIG.
As shown in (a), an image of the original 201 placed on the original placing table 200 is image-exposed through a lens 202 onto a recording medium 203 such as a photosensitive drum to form an image 204, and a recording material is formed. An image is output to 205.

As a method of setting the original 201 on the original placing table 200, there are a one side reference method and a central reference method. In the one-sided reference method, as shown in the figure, two abutting portions 206 and 207 that are orthogonal to each other are provided on the original placing table 200, and two abutting portions 206 and 207 are provided on the leading edge and one side of the original 201 that are orthogonal to each other. Manuscript 2 by abutting against
The position of 01 is decided. In the central reference method, in the illustrated example, only the leading end of the original 201 is abutted 206, and the original is placed in the center according to an index (not shown) attached to the abutting portion 206.

Of these, the one-sided reference method requires only the document 201 to be abutted in two directions, so that the document 201 can be set very easily, but the center position of the projected image 204 on the recording medium 203 is also one side. It will be formed unevenly. In that case, the longitudinal center position of the conveying roller (not shown) that conveys the recording material 205 and the central position of the recording material 205 differ depending on the document size, and the conveyance of the recording material 205 becomes unstable due to, for example, diagonal feeding. There is.

On the other hand, in the center reference method, the projected image is always formed at the center of the recording medium regardless of the size, so that the conveyance is stable, but the work of aligning the index after the leading edge of the original is brought into contact with the abutting portion is required. It was necessary and the setting of the manuscript was very troublesome.

Therefore, conventionally, as shown in the figure, a one-sided reference system having good operability is adopted for setting the original 201, and the lens 202 is moved in the direction perpendicular to the optical axis according to the size of the original 201. The recording medium 20
It was adjusted so that the projection image 204 was located in the center of 3.

Further, in order to add functions such as automatic paper selection, automatic scaling, reduction layout, and enlargement layout, it is necessary to detect the size and position of the document.

In the illustrated example, assuming that the leading edge and one side position of the original 201 are determined, an original edge sensor 208 for detecting the original edge is provided as shown in FIG. 5B.
The position and size of the document 201 are detected by detecting the distance from the abutting portions 206, 207 to the document edge.

As shown in FIG. 6, several document edge sensors 208 are fixed below the document table glass 1, and when the document table cover 209 is closed, the open / close sensor 210 becomes 0N and the LED (light emitting diode) is turned on. Original 201
The phototransistor detects the intensity of the reflected light. Then, the original size is detected by comparing the intensities of the reflected light when the original table cover 209 is at a certain angle and when it is completely closed.

[0010]

However, in the case of the above-mentioned prior art, since it is premised that the original 201 is positioned by the abutting portions 206 and 207, the abutting of the original 201 is inaccurate. At some time, a deviation occurs between the original 201 and the formed image. Therefore, it was necessary to carefully perform the butting operation.

The present invention has been made to solve the above-mentioned problems of the prior art. Therefore, the purpose of the present invention is to provide movable document position detecting means.
Conventionally, it is possible to improve the operation of the document reading apparatus and the image forming apparatus by performing the scanning in one direction only when the document is set, which has conventionally required the collision in two directions.

There is also an effect of preventing image blur due to document misalignment.

[0013]

In order to achieve the above object, according to the present invention, an abutting portion for abutting one side of an original on a document placing table to position the original in one direction, Detecting means capable of scanning the document placing table to detect the position of the document in the direction parallel to the abutting portion, and a lens for projecting the image of the document on the recording medium are provided in the direction substantially perpendicular to the optical axis. An optical system that is movable, and a control unit that controls the amount of movement of the lens so that the position of the projected image on the image recording medium is located at a predetermined position based on the position information of the document obtained by the detection unit. It is characterized by comprising.

The home position of the scanning means is provided outside the document mounting area on the document mounting table, and the detection means is located between the document mounting area and the home position during detection standby, and only during detection. It is characterized by moving.

As the detection means, in addition to the scannable detection means, there is a fixed detection means for detecting the presence or absence of a document at a certain place, and based on the detection results of the scannable detection means and the fixed detection means. The feature is that the position and size of the document are calculated.

The detection means is a sensor capable of detecting the edge of the document.

The optical system is a variable power optical system, and the lens is movable in a direction parallel to the optical axis.

The image forming apparatus of the present invention is characterized in that the above-mentioned document reading device is used as a reading optical system.

[0019]

In the image forming apparatus of the present invention, one side of the original is abutted against the abutting portion and placed on the original table. The original is movable along the abutting portion, and is only positioned in the abutting direction.

The position of the original parallel to the abutting portion is
Detection is performed by scanning the detection means. Since the position of the original image and the position of the lens determine the position of the projected image on the recording medium, the control unit calculates the amount of movement of the lens and moves the lens by a prescribed amount so that the projected image position is formed at the prescribed position.

With this arrangement, the projected image can be formed at a substantially predetermined position on the recording medium regardless of the position of the document abutting the document, and the document is placed on the document table. Accurate positioning operation is not required when mounting. Therefore, it is not necessary to hit the document in two directions as in the conventional case, and the operability when the document is placed on the document table is improved.

The home position of the scanning means is provided outside the area where the original can be placed on the original placing table, and the detection means is located between the area where the original can be placed and the home position when waiting for detection, and only during the detection. By moving, the document can be effectively detected.

If, as the detection means, a fixed detection means for detecting the presence / absence of an original document at a certain place is provided in addition to the scannable detection means, the scannable detection means and the fixed detection means are provided. The position and size of the document can be calculated from the detection result.

[0024]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to illustrated embodiments.

FIG. 1 shows a main part of an image forming apparatus according to an embodiment of the present invention. That is, according to the present invention, the document table glass 1 as a document placing table and the document D provided on the document table glass 1 are abutted against each other so that the document D moves in one direction (Y in the figure).
Direction 2) butting portion 2 and the butting portion 2
A movable manuscript sensor 4 as a detecting means capable of scanning on the manuscript table glass 1 to detect the position of the manuscript D in the direction parallel to.
And

The movable manuscript sensor 4 is a manuscript end sensor composed of an LED (light emitting diode) and a phototransistor, is fixed to the belt 3 driven by the stepping motor 7, and is parallel to the abutting portion 2, that is, in the figure. Can be moved in the Y direction. The stepping motor 7 is drive-controlled by, for example, a DC controller board 8. Of course, as a driving method of the movable document sensor 4, various driving mechanisms capable of reciprocating movement can be adopted.

Reference numeral 6 denotes a home position detection plate of the movable document sensor 4, and the amount of movement from the home position detection plate can be detected from the number of pulses input to the stepping motor 7.

Reference numeral 5 denotes a fixed document sensor serving as a fixing detection means fixed at a fixed position, and like the movable document sensor 4, its structure is composed of an LED (light emitting diode) and a phototransistor. The movable and fixed document sensors 4 and 5 are the same as those shown in the conventional example, but a blue filter is attached to the phototransistor thereof. This is to prevent the document sensor from reacting to the document fixing pressure plate (not shown) painted in yellow.

FIG. 2 is a flow chart showing the scanning procedure of the movable document sensor.

First, when the original D is abutted against the abutting portion 2 at the left end of the original platen glass 1 and the pressure plate for fixing the original is closed, the sensor detects the closing of the pressure plate, and between the original mountable area and the home position. The movable document sensor 4 stopped at the standby position Y0 starts to move to the back side of the document glass 1 at a low speed for the home position search (S1 to 3). In FIG. 1, a dotted line indicates a low-speed moving process, and a solid line indicates a high-speed moving process.

When the home position 6 is detected by detecting the change in the intensity of the reflected light (S4), the switchback is performed and then the home position 6 starts moving at high speed to start the detection (S5).

Here, the reason why the moving speed is low first is to supplement the reaction speed of the movable document sensor 4. The home position plate 6 is located slightly outside the end surface of the document table on the back side. This is so that the home position can be detected even when the document is abutted on the back side.

When the movable document sensor 4 moving at high speed detects the document edge once (S6), it switches back after advancing a certain distance (S7, 8).

Then, at next low speed, the platen glass 1 starts moving toward the back side to obtain the accurate position of the document edge (S
9). The obtained document edge position is stored in the memory (S1
0). The movable manuscript sensor 4 moves toward the back side of the manuscript glass 1 when the home position is detected, because the backlash of the drive system of the movable manuscript sensor 4 is corrected, so that the accurate position of the manuscript edge is detected and the home position is detected. This is because it is necessary to make the moving direction of the sensor 4 the same when performing (in this embodiment, the direction toward the back side of the document table).

After obtaining one position of the document edge in this way, switch back is carried out to move at high speed (S5),
The other document edge position is obtained in the same procedure (S5 to S
10) Calculate the document width of the document D in the Y direction.

Then, the sensor 4 moves between the original mountable area and the home position (S12), and does not move except when detecting the original position and size.

On the other hand, the fixed original sensor 5 is an LED while the movable original sensor 4 detects the original position and the vertical width of the original D.
Is illuminated to illuminate the document surface, and it is determined whether the document D is at the position where the fixed document sensor 5 is located. And DC
The controller board 8 detects the document size as shown in Table 1 based on the information from the movable and fixed document sensors 4 and 5.

[0038]

[Table 1] After obtaining the size and position information of the document D in this way,
As shown in FIG. 5, the DC controller board 8 moves the lens 101 in the direction perpendicular to the optical axis so that the center of the projected image of the document on the photosensitive drum and the center of the recording material coincide with each other. However, a yellow filter is attached to the lens 101 so that the pressure plate painted yellow is not reflected on the copy paper.

FIG. 3 schematically shows the arrangement of the reading optical system and the image forming section of the electrophotographic copying machine to which the image forming apparatus of the present invention is applied.

That is, the document D placed on the document table glass 1 as the document placing table is optically scanned by the first scanning system 102 having the illumination lamp 103, the first mirror 104 and the like. The reflected light of the document D is cut into a predetermined width by a slit (not shown), and the second scanning system 108 that moves at a speed half that of the first mirror 104 and the first scanning system 102.
It is guided to the lens 101 via the second mirror 106 and the third mirror 107 above. Further, the fourth, fifth, and sixth mirrors 113, 112, 1 fixedly arranged on the lens base 109
An image is formed on a photosensitive drum 111 serving as a recording medium via 10 to form a latent image on the photosensitive drum 111.

The latent image on the photosensitive drum 111 is transferred onto a copy sheet as a recording material sent from the sheet feeding cassette 114a by the feeding roller 114b.

The lens 101 has a lens base 11 having a guide 116 parallel to the optical axis, as shown in FIG.
A two-dimensionally moving system is adopted by moving the lens base 117 in the direction perpendicular to the optical axis by means of a guide 118 which is arranged on the optical axis 7 and is perpendicular to the optical axis. As the drive mechanism of the lens base 117, various drive mechanisms such as a screw feed mechanism and a winding mechanism using a wire can be used as long as the feed amount can be controlled, and is controlled by the DC controller board 8. .

Further, the magnification is changed by moving the lens 101 in the direction parallel to the optical axis in accordance with the change of the focal length of the lens 101, and the enlargement / reduction copying of the document D becomes possible.

In the present embodiment, the position and size of the document D can be accurately detected by merely abutting the leading end of the document D against the leading end abutting portion 2 of the document table glass 1. Therefore, it is possible to reduce the time and effort required for setting the document D without causing a shift between the document D and the projected image due to the document shift.

[0045]

As described above, according to the present invention,
By combining the detection unit that detects the position of the document that abuts on the left edge of the platen with a movable lens, the document at an arbitrary position along the abutting part of the platen can be misaligned between the document and the image due to document misalignment. An image can be formed without causing it, and operability at the time of setting a document is significantly improved.

Further, the home position of the scanning means is provided outside the document mountable area on the document mounting table, and the detection means is located between the document mountable area and the home position in the standby state for detection. By moving only when
Documents can be detected effectively.

If, as the detecting means, a fixed detecting means for detecting the presence / absence of an original document at a certain fixed location is provided in addition to the scannable detecting means, the scanning capable detecting means and the fixed detecting means are provided. The position and size of the document can be calculated from the detection result.

[Brief description of drawings]

FIG. 1 is a plan view of a document detection mechanism according to an embodiment of the present invention.

FIG. 2 is a flowchart showing a document position detection procedure.

FIG. 3 is a schematic view of a general electrophotographic copying machine to which the document detecting mechanism of FIG. 1 is applied.

FIG. 4 is a diagram showing a moving lens mechanism.

FIG. 5 is a diagram showing a conventional document size detection mechanism.

FIG. 6 is an operation explanatory diagram of a conventional document detecting mechanism.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Manuscript table glass 2 Abutting part 3 Belt 4 Movable manuscript sensor (detection means) 5 Fixed manuscript sensor (detection means) 6 Home position detection plate 7 Stepping motor 8 DC controller board (control means) D manuscript 101 Lens 111 Photosensitive drum (recoding media)

Claims (6)

[Claims] Claim: What is claimed is: 1. An abutting section for positioning one side of an original on an original placing table against which the original is positioned, and scanning the original placing table to detect the position of the original in a direction parallel to the abutting section. Possible detecting means, an optical system provided with a lens for projecting an image of an original on a recording medium, the lens being movable in a direction substantially perpendicular to the optical axis, and the position of the original obtained by the detecting means An original reading apparatus comprising: a control unit that controls a movement amount of a lens so that a position of a projected image on an image recording medium is located at a predetermined position based on information. 2. A home position of a scanning means that can be scanned outside the document mounting area on the document mounting table, and the detection means is located between the document mounting area and the home position during detection standby. The document reading apparatus according to claim 1, wherein the document reading apparatus is moved only when the time. 3. As the detection means, in addition to the scannable detection means, there is provided fixed detection means for detecting the presence or absence of an original document at a certain place, and the scannable detection means and the fixed detection means are detected. 3. The document reading device according to claim 1, wherein the position and size of the document are calculated from the result. 4. The document reading device according to claim 1, wherein the detecting means is a sensor capable of detecting the end of the document. 5. The optical system is a variable power optical system, and the lens is movable in a direction parallel to the optical axis.
Or the document reading device described in 4. 6. An image forming apparatus using the document reading apparatus according to claim 1, 2, 3, 4 or 5 as a reading optical system.