JP2003152959A - Image scanner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image scanner in which damage on an original image and sticking of toner to an original tray are prevented in continuous reading operation. SOLUTION: At least one of the irradiating time period, the number of irradiating times of the irradiating light emitted from an original-lighting lamp 204, and the temperature of the original tray is measured. When one of the measured value is not less than a specified value, a CPU 101 decreases an adjustment value D for an adjustment part 102 for the amount of light, and the amount of irradiated light emitted from the original-lighting lamp 204 is decreased. Based on this, a read-out image data value is increased. The amount of light at sheet through mode is made less than that at book mode.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image reading device for reading images such as characters and photographs.

[0002]

2. Description of the Related Art Conventionally, an image reading device receives the reflected light of an optical system that irradiates a document and converts it into an electric signal to read an image. A halogen lamp, a fluorescent lamp, or the like is used as the document irradiating means, and all of them have high heat generation.

In the reading mode, a book mode in which an optical system is moved below the platen glass for reading an original placed on the platen glass, and a document in which the optical system is fixed are read. There is a sheet-through mode in which the sheet is moved and read on the platen glass.

[0004]

However, in the conventional technique, when a large number of originals are continuously read, the time for emitting the irradiation light becomes long, and the temperature of the original glass plate rises.
There is a possibility that the toner of the original image formed by heat fixing such as toner is melted and the original glass is contaminated. In particular, in the read mode in the sheet through mode, the optical system is fixed at one place, so the rate of temperature rise is higher than in the book mode, and the above possibility is further enhanced.

The present invention has been made in view of the above problems, and provides an image reading apparatus capable of preventing the damage of the original image and the adhesion of toner to the glass of the original plate even in the continuous reading operation. The purpose is to do.

[0006]

SUMMARY OF THE INVENTION An image reading apparatus according to the present invention is an optical system having a transparent original plate member for placing an original document and an original document irradiation unit for irradiating an original document placed on the original plate member. At least one of reading means for reading the image of the original document irradiated by the original document irradiation means in the main scanning direction, irradiation time of the irradiation light emitted by the original document irradiation means, the number of irradiations, and the temperature of the original table member. And a light quantity control means for reducing the light quantity of the irradiation light emitted by the document irradiation means when any of the measured values measured by the measurement means exceeds a predetermined value. It is characterized by

[0007] The light amount control means is for irradiation time of irradiation light,
When the measured value of at least one of the number of irradiations and the temperature of the platen member exceeds a predetermined value, the light amount of the irradiation light is reduced to damage the original image due to the temperature rise of the platen member or the original document. The harmful effects such as adhesion of toner to the base member glass are prevented in advance.

An optical system driving means for moving the optical system in a sub-scanning direction substantially orthogonal to the main scanning direction is provided, and a reading mode of the reading means is applied to an original placed on the original table member. When a book mode for reading while moving the optical system and a sheet through mode for reading a document on the platen member with the optical system fixed are provided, the light amount control by the light amount control means is at least the above-mentioned. It may be executed in the seat through mode.

When the light amount control means performs the light amount control in both the book mode and the sheet through mode, the light amount control means reduces the light amount in the sheet through mode as compared with the light amount in the book mode. This corresponds to the document irradiating means moving in the book mode, whereas the document irradiating means is fixed at one place in the sheet through mode.

It is preferable to further include image processing means for processing the image data read by the reading means in accordance with the change of the light quantity by the light quantity control means. This image processing includes, for example, changing the gamma value. As a result, it is possible to prevent an adverse effect caused by changing the light amount.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a side sectional view showing a schematic structure of an image reading apparatus including an automatic document feeder 300 (Auto Document Feeder, hereinafter referred to as ADF) and an image reading unit (reading means) 200 used in a copying machine or the like. . ADF300 is
It is attached to the upper surface of the image reading unit 200 so that it can be opened upward with one side on the back side as a spindle.

When reading in the book mode, the ADF 300
The original is placed on the original table glass (original table member), the ADF 300 is lowered again to press the original to bring it into close contact with the original table glass 201, and the optical system drive motor 202 drives the optical system 203 to move the optical system 203. While moving from the leading end reading position P1 of the document to the trailing reading position P2 of the document, the document illumination lamp (document irradiating means) 204 is turned on to scan the image of the document.

ADF3 is used for reading in the sheet through mode.
The document is fed by setting 00. That is, the originals set in the original feed tray 301 are fed one by one by the pickup roller 302, and the registration rollers 304
Lead to. The registration roller 304 guides the conveyed original document to a paper ejection roller 306 after passing the original document reading position P3 below the platen roller 305 on the original platen glass 201, and then the original document is ejected by the paper ejection roller 306. It is discharged onto the tray 307. At this time, the optical system 203 is driven by the optical system drive motor 202 in advance to read the reading position P3.
After a lapse of a predetermined time after the passage of the leading edge of the document is detected by the registration sensor 303, the document illumination lamp 204 is turned on to start the reading operation.

The reflected light from the original of the light emitted from the original illumination lamp 204 is reflected by the first mirror 205 in the direction parallel to the original table glass 201, and the second, third
The light is incident on the condenser lens 208 by the mirrors 206 and 207 and forms an image on the sensor surface of the CCD sensor 209. At this time, the second and third mirrors 206 and 207 are connected to the optical system 203.
Since it moves in the same direction as at half the speed, the optical path length from the reflecting surface of the document to the condenser lens 208 is kept constant, and the image formation position by the condenser lens 208 is always the sensor surface of the CCD sensor 209. Maintained at.

The CCD sensor 209 converts the incident reflected light into an electric signal and outputs it to the image signal processing section 210.
The image signal processing unit 210 converts this electric signal into a digital signal, further performs necessary processing for improving the image quality, and then stores it in the image data area in the RAM 104. This image data is used for print output by a printer unit (not shown) or transmission processing by a facsimile transmission unit (not shown).

Next, the configuration of the control hardware of the image reading apparatus of this embodiment will be described with reference to the block diagram of FIG. The entire device is controlled by executing a control program by the CPU 101. The control program is stored in a nonvolatile storage device such as a ROM (not shown). C
The PU 101 includes a light amount adjusting unit 102 and a pressure plate opening / closing sensor 1.
03, RAM 104, ROM 105, timer 106, image reading unit 200, ADF 300, etc. are connected. C
The PU 101 and the light amount adjusting unit 102 constitute a light amount control means.

The image reading section 200 mainly has an optical motor 202, an optical system 203, a CCD 209, and an image signal processing section 210. The optical motor 202 includes an optical system 203.
Is a motor for driving. The optical system 203 includes a document illumination lamp 204 and a thermistor 211. The thermistor 211 detects the temperature in the vicinity of the platen glass 201 irradiated with the light from the document illumination lamp 204. The original illumination lamp 204 is controlled by the CPU 101 to control the light quantity adjusting unit 10.
2 and the amount of light is adjusted. The image signal processing unit 210 refers to the gamma conversion table data in the ROM 105 and performs a predetermined process on the image signal.

The ADF 300 mainly has a document presence / absence sensor 308, an ADF motor 309, and a registration sensor 303. The ADF motor 309 is the ADF 300.
Drives paper feeding, etc.

The RAM 104 stores a temperature measurement value P, a lighting time measurement value Q, a lighting frequency measurement value R, an extinction time measurement value S, a temperature comparison value p (here, 100 ° C.), and a lighting time comparison value q.
(Here, 40 seconds), comparison value r of lighting times (here, 60
Times), a storage area for various parameters such as the turn-off time comparison value s, and an image data area for storing image data.
Although these various parameters are accessed by the CPU 101, the image signal processing unit 210 can directly access the image data area.

The operation of the image reading apparatus of the present embodiment having the above structure will be described below with reference to the flow chart of FIG.

At the start of the reading operation, the CPU 101 first determines whether it is the book mode reading or the sheet through mode reading (S11). This can be determined based on the states of the input signal from the pressure plate opening / closing detection sensor 103 and the input signal from the document presence / absence sensor 308 of the ADF 300. That is, when the signal from the pressure plate opening / closing sensor 103 detects the open state of the pressure plate, or when the signal from the document presence / absence sensor 308 detects the absence of a document, it is determined to be the book mode reading, and the signal from the pressure plate opening / closing sensor 103 is detected. When the closed state of the pressure plate is detected and the signal from the document presence / absence sensor 308 detects the presence of the document, it is determined that the sheet through mode is read.

When the reading mode is determined in this way, the CPU 101 outputs the value d1 or d2 corresponding to the reading mode determined as the light amount adjustment value D to the light amount adjusting section 102 (S12, S13). In the present embodiment, the light amount adjustment value D is set by the light amount adjusting unit 102 by the document illumination lamp 204.
It corresponds to the time ratio of outputting the ON signal to the ON / OFF signal output to. For example, when the light amount adjustment value D sent from the CPU 101 to the light amount adjusting unit 102 is “30”,
The ratio of the ON signal sent from the light quantity adjusting unit 102 to the document illumination lamp 204 per unit time is 30%. In the present embodiment, the value d1 is set to “100” in the book mode reading.
(S12), and the value d in the case of sheet through mode reading
2 is set to "70" (S13).

After that, the CPU 101 outputs a light amount control start signal to the light amount adjusting unit 102 at a timing necessary for reading an image, and the light amount adjusting unit 102 which has received the signal outputs the C signal in advance.
Lighting control of the original illumination lamp 204 is started at a rate according to the light amount adjustment value D sent from the PU 101 (S1).
4).

When the reading operation is started (S15), CP
U101 is the thermistor 2 attached to the optical system 204
11, monitoring of the temperature value and lighting time (light-off time),
The measurement / monitoring of the number of times of lighting is started (S16). After that, this measurement is continuously performed while the power source of the device is turned on. The RAM 10 is used to monitor these three values (P, Q, R).
Each comparison value stored in 4 (p, q, r)
And these three values are periodically compared. As shown in the RAM 104 of FIG. 2, in the present embodiment, the temperature comparison value p is 100 ° C., the lighting time q is 40 seconds,
A value corresponding to 60 times is stored in the number of times of lighting r. The temperature value indicated by the thermistor 105 (temperature measuring means) is sequentially stored in the temperature measured value P. A timer 106 (time measuring means) is used to measure the lighting time. Timer 1
06 is controlled by the CPU 101 according to the light amount control start signal output from the CPU 101 to the light amount adjusting unit 102, and the lighting time per one time is obtained by measuring the time from ON output to OFF output of the light amount control signal. Desired. The timer value measured by this is stored in the RAM 104.
It is added to the lighting time value Q stored therein. The number of times of lighting is incremented by 1 for reading one original document with respect to the number of times of lighting R stored in the RAM 104. The values P, Q, R measured in this way are compared with the corresponding comparison values p, q, r (S17, S18, S1).
9) If any of the measured values matches or exceeds the corresponding comparison value, the CPU 101 reduces the adjustment value D by a predetermined ratio and reduces the adjustment value D after updating to reduce the current light amount. It is output to the adjusting unit 102 (S20). In the present embodiment, this reduction rate is 80% of the current light amount. That is, in the book mode reading, if the adjustment value D is "100", it is reduced to "80". In the case of sheet through mode reading, if the adjustment value D is "70", it is reduced to "56".

The reflected light of the document illuminated by the document illumination lamp 204 is reflected by the first, second and third mirrors 205, 20.
An image is formed by the CCD sensor 209 via 6, 207 and the condenser lens 208, and the CCD sensor 209 converts the incident reflected light into an electric signal, and the electric signal is converted into an electric signal.
Output to 0. The image signal processing unit 210 converts this electric signal into a digital value, and based on the conversion result, the CPU 101
Increase / decrease processing is performed according to the offset value O sent from (S21). The offset value O is changed according to the output adjustment value D when the CPU 101 outputs the adjustment value D to the light amount adjusting unit 102. Specifically, when the adjustment value D is decreased, the offset value O is increased. The characteristics of the gamma conversion table are shown in the graph of FIG. In this graph, the horizontal axis shows the input value of the image data after A / D conversion, and the vertical axis shows the output value of the image data after gamma conversion. A /
A value obtained by increasing or decreasing the value of the image data after D conversion with the offset value O is referred to, and the output value of the corresponding image data after gamma conversion is obtained by referring to the gamma conversion table stored in the ROM 105. .

Further, the lighting time and the number of times of lighting are such that when the original illumination lamp 204 remains off for a certain period of time (S22,
Yes), the value is cleared (S23). As for the continuous turn-off time of the document illumination lamp 204, the time from the OFF output to the ON output of the light amount adjustment start signal is measured by the timer 106. This measurement value is compared with the extinction time comparison value s stored in the RAM 104, and when the extinction time measurement value S is equal to or more than the extinction time comparison value s, the lighting time measurement value Q and the number of times of lighting measurement value R are determined. Clear to 0.

After that, when the next original is read (S24, Y
es), and returns to the first step S11.

Although the preferred embodiment of the present invention has been described above, various modifications and changes can be made. For example, the specific numerical values such as the specific temperature, time, number of times, and reduction rate described above are merely examples, and the present invention is not limited to these numerical values. Further, the parameters used to determine the reduction of the adjustment value D are the temperature, the lighting time, and the number of times of lighting, but it is not always necessary to use all of them, and only a part of them may be used. Good. Although the present invention is applied to both the book mode and the sheet through mode, it may be applied only to the sheet through mode.

[0030]

According to the present invention, even if irradiation is performed for a long time by the document irradiating means by continuous reading operation, the light quantity of the irradiating light is reduced based on at least the temperature near the document irradiating means, the irradiation time or the number of times of irradiation. As a result, there is no risk of the original table being soiled or the original being damaged due to dissolution of the original toner due to excessive temperature rise of the original table. Further, by correcting the image data value such as gamma conversion by the amount of the irradiation light amount dropped, it is possible to perform a good reading operation that does not depend on the change of the irradiation light amount.

[Brief description of drawings]

FIG. 1 is a side sectional view showing a schematic configuration of an image reading device including an automatic document feeder (ADF) and an image reading unit according to the present invention.

FIG. 2 illustrates a configuration of control hardware of the image reading apparatus according to the embodiment of the present invention.

FIG. 3 is a flowchart showing an operation of the image reading apparatus according to the embodiment of the present invention.

FIG. 4 is a graph showing gamma conversion characteristics of a gamma conversion table at various light amounts.

[Explanation of symbols] 101 ... CPU 102 ... Light intensity adjustment unit 103 ... Pressure plate opening / closing sensor 104 ... RAM 105 ... ROM 106 ... Timer 200 ... Image reading unit 201 ... Platen glass 202 ... Optical system drive motor 203 ... Optical system 204 ... Original illumination lamp 205, 206, 207 ... First, second and third mirrors 208 ... Condensing lens 209 ... CCD sensor 210 ... Image signal processing unit 211 ... Thermistor 300 ... Automatic Document Feeder (ADF) 301 ... Original document feeding tray 302 ... Pickup roller 303 ... Registration sensor 304 ... Registration roller 305 ... Platen roller 306 ... Paper ejection roller 307 ... Original document output tray 308 ... Document presence sensor

Continued front page    F-term (reference) 2H108 AA19 CA03 CA10 JA00 JA04                 2H109 AB01 AB22 AB25 CA01 CA17                 5B047 AA01 AA05 BC11 CA17 CA19                       CB03                 5C072 AA01 BA20 CA02 CA14 LA02                       LA18 UA13 VA06

Claims (7)

[Claims] 1. A transparent manuscript table member for mounting a manuscript, an optical system having a manuscript irradiation means for irradiating a manuscript placed on the manuscript table member, and a manuscript irradiated by the manuscript irradiation means. A reading unit for reading an image in the main scanning direction, an irradiation time of irradiation light emitted by the document irradiation unit,
Measuring means for measuring at least one of the number of irradiations and the temperature of the original plate member, and when any of the measured values measured by the measuring means exceeds a predetermined value, it is emitted by the original document irradiation means. An image reading apparatus comprising: a light amount control unit that reduces a light amount of irradiation light. 2. An original mounted on the original plate member as an reading system of the reading means, comprising an optical system driving means for moving the optical system in a sub-scanning direction substantially orthogonal to the main scanning direction. A book mode for reading while moving the optical system and a sheet-through mode for reading an original by moving the original on the original plate member while the optical system is fixed, and the light amount control by the light amount control means is at least 2. The process is executed in the sheet through mode.
The image reading device described. 3. The light amount control means performs the light amount control in both the book mode and the sheet through mode,
The image reading apparatus according to claim 2, wherein the light amount in the sheet through mode is lower than the light amount in the book mode. 4. The image processing means according to claim 1, further comprising image processing means for processing the image data read by said reading means in response to a change of the light quantity by said light quantity control means. Image reading device. 5. The image reading apparatus according to claim 4, wherein the image processing means increases or decreases the image data value according to the change of the light amount as the processing of the read image data. 6. A document feeding means for feeding a document placed on a document feeding tray, and a document fed by the document feeding means is conveyed to a predetermined reading position on the document table member. 4. The image reading apparatus according to claim 2, further comprising a document conveying unit. 7. The light amount control means resets the irradiation time and the number of times of irradiation to initial values when the continuous light-off time of the document irradiation means exceeds a predetermined time. Image reading device.