JP2003143373A - Image read optical system unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image read optical system unit that can easily detect a position of a light source without the need for using a particular member such as an expensive optical sensor and easily return the light source to its home position after the end of scanning drive. SOLUTION: In the image read optical system unit where a light source capable of being driven for scanning is placed under contact glass and a CCD element receives a reflected light in the original placed on the contact glass receiving a light from the light source while applying scanning drive to the light source to read information of the original image, a reference reflection sheet with a mark for detecting the position of the light source is placed to an area of the contact glass to which the light from the light source is emitted but on which no original is placed, and it is characterized in that the CCD element receives a reflected light in the detection mark to detect the position of the light source when the light source is subjected to scanning drive and the light source is stopped at the home position on the basis of the detection signal.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is used in an image forming apparatus or the like, and a CCD device receives reflected light from a document placed on a contact glass while scanning and driving a light source, and thereby information of a document image is obtained. The present invention relates to an image reading optical system unit for reading the image.

[0002]

2. Description of the Related Art In an image forming apparatus using electrophotography, the surface of a photosensitive drum is uniformly charged, and the charged surface of the photosensitive drum is irradiated with light (image exposure) based on certain image information. To form an electrostatic latent image (charge image),
The electrostatic latent image is developed using a developer containing toner charged to a predetermined polarity, the obtained toner image is transferred to the surface of a transfer sheet such as paper or OHP film, and the transferred toner image is heated by a heat roller ( An image is formed by heat fixing with a fixing roller). In such an image forming process, the above image information is obtained by an image reading optical system unit, and based on the image information, the image information is written, for example, the surface of the charged photosensitive drum is irradiated with laser light. To form an electrostatic latent image. Further, the image reading optical system unit is also used as a scanner which is an external device of an information processing apparatus such as a computer. In this case, the image information obtained by the optical system unit is used by a computer or the like. The image data is transmitted to the information processing apparatus, and based on the image information, image processing and printing by a printer or the like connected to the computer are performed.

In such an image reading optical system unit, a contact glass (original plate) is arranged on the upper surface, and below this, a light source such as a halogen lamp, a reflection mirror, an optical lens and a CCD element are provided. By scanning and driving the light source to irradiate the entire surface of the original placed on the contact glass with light, and the reflected light from the original is received by the CCD element via a reflection mirror or an optical lens, predetermined image information is obtained. (Document information) is read. That is, the image information read here is output and its output value (CC
Based on the D output value), the above-described image writing, image processing by a computer or the like is performed.

[0004]

By the way, in the above-mentioned optical system unit, since the light is emitted to the original while the light source is driven to scan, the timing for reading the image information is accurately set. , After the scanning drive is completed,
The light source (or the carriage on which it is mounted) must be returned to its home position. Conventionally, an optical sensor such as a PI (photo interrupter) sensor is used to return the light source to the home position. That is, a light emitting element and a light receiving element are provided at a predetermined position (near the home position), and the light source (or a carriage to which the light source is attached) cuts off a light beam from the light emitting element to the light receiving element. The position is detected, and the motor driving the light source (or the carriage to which the light source is attached) is stopped based on the detection signal, so that the light source is stopped at the predetermined home position after the scanning drive. However, in order to stop the light source at the home position by such a method, it is necessary to use an expensive optical sensor, which has a disadvantage of increasing the cost of the device.

Therefore, an object of the present invention is to detect the position of the light source easily without using a special member such as an expensive optical sensor, and to easily return the light source to the home position after scanning driving is completed. It is to provide a reading optical system unit.

[0006]

According to the present invention, a light source provided so as to be scan-driving is provided below a contact glass, and a document placed on the contact glass is scanned while the light source is driven to scan. The reflected light of the original from the light source is C
In an image reading optical system unit that receives information from a document image by receiving light from a CD element, the contact glass is irradiated with light from the light source, but a position detection mark of the light source is provided in a region where the document is not placed. Is provided, the CCD element detects the position of the light source by receiving the reflected light from the detection mark when the light source is scanned and driven, and based on the detection signal. , An image reading optical system unit characterized in that the light source is stopped at the home position.

The image information of the original is read by receiving the reflected light of the original from the light source by the CCD element. In the present invention, this CCD element is used as the position sensor of the light source at the same time when the image information is read. To use. That is, a reference reflection sheet having a mark for detecting the position of the light source is provided in a region of the contact glass on which the document is placed, on which the document is not placed, and the reference reflection sheet from the detection mark formed on the reference reflection sheet is provided. The position of the light source is detected by the CCD element receiving the reflected light, and the light source can be positioned at the home position by stopping the movement of the light source at a certain timing from that point. Therefore, in the present invention, the light source is positioned at the home position without using a special optical sensor, which is extremely advantageous in terms of cost. Further, since the CCD element also serves as a sensor, the number of parts of the device is small, which is also advantageous in simplifying the structure of the device.

In the present invention, it is preferable that the reference reflection sheet having the mark for detecting the position of the light source is provided in a region near the home position of the light source. Further, it is preferable that the reference reflection sheet is a white sheet and the position detection mark of the light source is a black mark. That is, the white sheet has the highest reflectance and is most suitable as the reference sheet, the black mark has the lowest reflectance, and the black mark provided on the white sheet can be surely detected. Optimal. Further, the reference reflection sheet, so as to traverse the moving direction of the light source,
It is preferable that it extends over the entire edge of the contact glass.
The amplification factor can be adjusted and the output of the CCD element can be adjusted. For example, in a copying machine, the image density can be adjusted. In this case, it is preferable that the detection mark is provided on one end of the reference reflection sheet. Furthermore, in the present invention, it is preferable that a plurality of the detection marks are provided in parallel at intervals along the moving direction of the light source. Accordingly, when the contact glass is dirty, it is possible to reliably prevent the inconvenience such as erroneously detecting the dirt as a detection mark.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described below with reference to specific examples of an image reading optical system unit shown in the accompanying drawings. 1 is a side sectional view of an image reading optical system unit of the present invention, FIG. 2 is a diagram showing an example of a schematic arrangement structure inside a carriage provided in the optical system unit of FIG. 1, and FIG. FIG. 4 is a side cross-sectional view showing an enlarged main part of the optical system unit of FIG. 1, and FIG. 4 is a partially enlarged plan view showing an arrangement example of position detection marks of a light source on the reference sheet shown in FIG. is there.

In FIG. 1, the image reading optical system unit is provided with a box-shaped frame body 1, and a large area contact glass 2a is attached to the upper surface of the frame body 1. A narrow contact glass 2b is attached in parallel with the large-area contact glass 2a. That is, a document cover (not shown) is provided so as to be openable and closable so as to cover the upper surface of the frame body 1. Image information is read by irradiation. Therefore, the document size display plate 3 is provided at one end of the large-area contact glass 2a, and the display plate 3 can be used to accurately place the document at a predetermined position according to the size. . On the other hand, in most commercially available copying machines, the document cover is provided with an automatic document feeder, and the document conveyed by this automatic feeder passes over the above-mentioned narrow contact glass 2b. Image information is read by irradiating light from a light source with respect to a document passing on the contact glass 2b. Therefore,
In this case, since the document is moving, the scanning of the light source is not performed at the time of reading the image information, and the light source is stopped below the contact glass 2b (that is, the lower side of the contact glass 2b is , Generally set to the home position of the light source, which will be described later). Of course, in the optical system unit of the type in which the automatic document feeder is not provided on the document cover, the narrow contact glass 2b as described above is not provided.

A carriage 5 is provided inside the frame body 1. The carriage 5 has a light source 10 and reflection mirrors 11a, 11b, 11 as shown in FIG.
c, a lens 12 and a CCD element 13 are provided.
That is, the reflected light of the document from the light source 10 indicated by the arrow X in FIG. 2 is received by the CCD element 13 via the reflection mirrors 11a, 11b, 11c and the lens 12, and this reflected light is reflected by the CCD element. By receiving light at 13, the image information is read.

In FIG. 2, three reflecting mirrors 1 are provided.
Although 1a, 11b, and 11c are provided, the number and position of them are not limited to the example of FIG.
The number and the position thereof are arbitrary as long as they can be reliably received by the CCD element 13 via the lens 12. In addition, regardless of the position of the carriage 5, as long as the reflected light X can be reliably received by the CCD element 13 via the lens 12, the lens 1
It is possible to dispose the 2 and the CCD element 13 inside the frame 1 and outside the carriage 5, or in this case, a part of the reflection mirrors can be arranged outside the carriage 5.

As described above, when the image information of the original placed on the contact glass 2a having a large area is read, it is necessary to scan and drive the light source 10.
To this end, as shown in FIGS. 1 and 2, the frame 1
A drive pulley 20 and a driven pulley 22 are provided inside the, and a wire (or belt) 24 is stretched around these pulleys 20 and 22, and the drive pulley 20 is
It is provided so as to be driven and rotated by a drive motor 28 via the drive transmission member 26. Also, the carriage 5
An engaging plate 3 that engages with the wire 24 is provided on one side surface.
0 is provided. That is, the drive motor 28 drives the wire 24 via the drive pulley 20, and the drive of the wire 24 causes the scanning drive of the carriage 5, and thus the light source 10 provided inside the carriage 5.
The scanning drive of is also performed.

When the light source 10 is scanned and driven as described above to read image information of a document placed on the contact glass 2a, the light source 10 is located near the end of the large-area contact glass 2a, for example. It stops at the home position below the narrow contact glass 2b, slides from this home position, and illuminates the entire surface of a document of a predetermined size placed on the contact glass 2a,
After the reflected light is received by the CCD element 13, it slides in the opposite direction and stops at the original home position. In the present invention, in order to stop the light source 10 that is scan-driven as described above at a predetermined home position, as shown in FIG. On the lower side of the display plate 3, the reference reflection sheet 40
Is provided. This reference reflection sheet 40 is usually
It is made of a high reflectance white sheet, extends over the entire edge of the contact glass 2a so as to cross the moving direction of the light source 10, and is further shown in FIG. 4 (a) or 4 (b). As described above, the mark 42 for detecting the position of the light source 10 is formed on at least the lower surface of the end portion of the reference reflection sheet 40.

That is, the reference reflection sheet 40 is the light source 1
Light from 0 is emitted, but the original is located in an area where the original is not placed, and the reference reflection sheet 4 does not interfere with reading of image information of the original placed on the contact glass 2a.
The reflected light from 0 can be received by the CCD element. Therefore, the reflected light from the detection mark 42 formed on the reference reflection sheet 40 is reflected by the CCD element 1.
By receiving light, the position of the light source 10 is detected,
With this detection signal, the light source 10 can be stopped at the home position by stopping the drive motor 28 at a constant timing.

In order to detect the detection mark 42 with high accuracy, the reference reflection sheet 40 is preferably a white sheet having high reflectance, and the detection mark 42 is a black mark having low reflectance. Is good. Further, it is preferable that the detection mark 42 is a solid mark having a certain size in order to prevent erroneous detection of dirt or the like on the contact glass 2a. Further, the detection mark 42 may be one, as shown in FIG. 4A, for example.
As shown in FIG. 4 (b), 2 are arranged in parallel at small intervals.
Individuals or more can be received.

That is, in the example of FIG. 4A, the reference sheet 4 is first fed by the light source 10 which returns after the scanning drive is completed.
Since the CCD element 13 receives the reflected light from 0, the output value of the CCD element 13 is high, and then the reflected light from the detection mark 42 is received by the CCD element 13 and the CCD
The output value of the element 13 decreases. Therefore, when such a decrease in the output of the CCD element 13 continues for a certain period of time, the drive motor 28 stops at a certain timing. On the other hand, FIG.
In the example of (b), the light source 1 that returns after the scanning drive is completed.
In 0, the detection mark 42 is first irradiated, then the surface of the reference reflection sheet 40 having a small width is irradiated, and then the detection mark 42 is irradiated again. Therefore, the CCD element 13
The output value of 1 decreases first for a certain period of time, then increases momentarily, and then decreases again for a certain period of time. The position of the light source 10 is detected by this process, and the drive motor 28 stops at a fixed timing. In this way, the light source 10 can be stopped at the home position. In the present invention, it is most preferable to provide two detection marks (particularly black marks) in parallel, as shown in FIG. 4B, in order to reliably prevent malfunction due to dirt on the contact glass 2a. It is suitable.

Further, according to the present invention, the CCD output value can be adjusted by using the above-mentioned reference reflection sheet 40, especially the white sheet. That is, the CCD element 13 when the reflected light from the reference reflection sheet 40 is received.
By adjusting the output value of by changing the amplification factor,
For example, the image density can be easily adjusted.
Further, in the above example, the reference reflection sheet 40 is provided on the upper surface of the contact glass 2a, but it may be provided on the lower surface of the contact glass 2a. However, it is preferable to provide the reference reflection sheet 40 on the upper surface of the contact glass 2a in terms of reattachment of the reference reflection sheet 40 and the like. Furthermore,
Although the example shown in FIG. 1 shows an example in which the contact glass 2b having a small width is provided, it goes without saying that the present invention can be applied to an optical system unit in which such a contact glass 2b is not provided. Needless to say.

[0019]

According to the present invention, the reference reflection sheet having the position detecting mark of the light source is provided in the area of the contact glass on which the original is not placed, and the reference reflection sheet is formed. CC reflected light from the detection mark
When the D element receives the light, the position of the light source can be detected, and thus the light source can be positioned at the home position. Therefore, the light source is positioned at the home position without using a special optical sensor, which is extremely advantageous in terms of cost. Also, C
Since the CD element also serves as a sensor, the number of parts of the device is small, which is advantageous in terms of simplifying the structure of the device.

[Brief description of drawings]

FIG. 1 is a side sectional view of an image reading optical system unit of the present invention.

FIG. 2 is a view showing an example of a schematic arrangement structure inside a carriage provided in the optical system unit of FIG.

FIG. 3 is a side sectional view showing an enlarged main part of the optical system unit of FIG.

FIG. 4 is a partially enlarged plan view showing an arrangement example of position detection marks of a light source on the reference sheet shown in FIG.

[Explanation of symbols]

1: frame 2a: large area contact glass for document placement 2b: narrow contact glass 5: Carriage 10: Light source 11a-11c: Reflecting mirror 12: Lens 13: CCD element 28: Drive motor 40: Reference reflection sheet 42: Light source position detection mark

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Atsushi Ishizaki             Kyocera 1-22-28 Tamatsukuri, Chuo-ku, Osaka-shi             Within Mita Co., Ltd. (72) Inventor Yasuyuki Horiguchi             Kyocera 1-22-28 Tamatsukuri, Chuo-ku, Osaka-shi             Within Mita Co., Ltd. F-term (reference) 5C072 AA01 BA02 CA02 EA05 LA02                       LA14 LA15 MB06 RA07 RA16                       VA07

Claims (6)

[Claims] 1. A light source provided so as to be scan-driving below a contact glass, and an original document placed on the contact glass is scanned and driven by the CCD element while reflecting light from the light source while driving the light source. In an image reading optical system unit which receives light and reads information of an original image, the contact glass is provided with a position detection mark of a light source in a region where the light from the light source is irradiated but the original is not placed. A reference reflection sheet is provided, and when the light source is driven to scan, the CCD element detects the position of the light source by receiving the reflected light from the detection mark, and the light source is detected based on the detection signal. An image reading optical system unit that stops at the home position. 2. The optical system unit according to claim 1, wherein the reference reflection sheet is provided in a region near a home position of the light source. 3. The optical system unit according to claim 1, wherein the reference reflection sheet is a white sheet, and the position detection mark of the light source is a black mark. 4. The optical system unit according to claim 1, wherein the reference reflection sheet extends over the entire end portion of the contact glass so as to traverse the moving direction of the light source. 5. The optical system unit according to claim 4, wherein the detection mark is provided at one end of the reference reflection sheet. 6. The optical system unit according to claim 5, wherein a plurality of the detection marks are provided in parallel at intervals along the moving direction of the light source.