JPH0846756A - Original reader - Google Patents

Abstract

PURPOSE:To accurately discriminate original size without being affected by thickness of the original in the original reader in which the original on a platen glass is subject to exposure scanning to read an image of the original. CONSTITUTION:A detection slit window 12 is provided aside a platen glass 11 of a main body section 10 in the main scanning direction and an original retainer 30 is provided with an angle sensing light source 32 emitting a nearly linear ray to a lamp carriage 15 in standby at a lower position of a sensing window 12 through the sensing window 12. When a CCD image sensor 19 sensing an image light senses the ray from the angle sensing light source 32, a CPU 21 activates a photo sensor 20 under the platen glass 11 based on the output and discriminates the size of the original based on data from the photo sensor 20.

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 used in a copying machine, an image scanner or the like for reading a document by exposing and scanning a document on a platen glass, and more particularly, using a photo sensor below the platen glass. The present invention relates to a document reading device that determines a document size.

[0002]

2. Description of the Related Art Conventionally, an original reading device provided in a copying machine, an image scanner, etc., for exposing and scanning an original on a platen glass, the original size being controlled by photosensors provided at a plurality of locations below the platen glass. A device having a function of automatically discriminating is well known. The discriminating document size is output to an external image forming apparatus as data for setting an exposure scanning range or together with the information of the read document, and is used as a sheet to be used when forming an image based on the document information. It is used as data for automatic selection and supply.

In such a document reading device,
It is necessary to distinguish from the document pressing plate that covers the document from above and presses it against the platen glass, and let the photosensor detect only the document. As a method of distinguishing the original from the original pressing plate, a method of coloring the original contact surface of the original pressing plate,
There is a method of detecting the document size immediately before closing the document pressing plate while keeping the document pressing plate white. But,
If the original contact surface of the original pressing plate is colored, the color may be read as image information.
A method of widely detecting a document immediately before closing the document pressing plate is widely used.

In a document reading device that detects the size of a document just before the document pressing plate is completely closed, in order to detect the timing of detecting the size of the document, Japanese Patent Laid-Open No. 63-1460.
The techniques described in Japanese Patent No. 27 and Japanese Patent Laid-Open No. 4-163437 are used. That is, JP-A-63-1460
The document reading device described in Japanese Patent Publication No. 27 has an actuator protruding from one of the document pressing plate and the main body of the device, and the other having a sensor for detecting the state of light at a position corresponding to the actuator. The actuator cuts off the optical path immediately before the document pressing plate is closed, and the sensor detects this.

Further, in the technique disclosed in Japanese Patent Laid-Open No. 4-163437, an actuator is projected on one of the document pressing plate and the main body of the apparatus, and on the other side, a photo sensor is provided at a position corresponding to the actuator. With a micro switch for activating, the actuator presses the micro switch while the document pressing plate is closing, and the photo sensor is activated.

[0006]

However, the document reading apparatus as described above has a drawback that the production cost is increased due to the relatively complicated structure using the actuator and the micro switch. Also, when a thick original is placed on the platen glass, the original pressing plate will not close sufficiently,
Since the optical path is not sufficiently blocked, the sensor may not detect this or the actuator may not be able to press the microswitch. Further, since it is detected only when the document pressing plate is in a predetermined open / closed state, it is not possible to easily change the open / closed state of the document pressing plate for determining the document size or its timing.

The present invention has been proposed in order to solve the above-mentioned drawbacks, and an object thereof is to make it possible to accurately detect the size of a document regardless of the thickness of the document with a simple structure.
Another object of the present invention is to provide a document reading device that can easily select and change the open / closed state of the document pressing plate at the timing of detecting the document size.

[0008]

In order to solve the above problems, a document reading apparatus according to the present invention is equipped with a light source for simultaneously exposing the entire area of a document placed on a platen glass in the main scanning direction. A carriage that moves in the sub-scanning direction to expose and scan the document surface, and is emitted from the light source,
An image sensor that detects light (image light) reflected on the document surface and changes it into an electric signal for each pixel in the main scanning direction; and an image sensor that is supported so as to be rotatable about an axis parallel to the sub scanning direction. A document reading device having a document pressing plate capable of covering an upper surface of a platen glass, and a photo sensor provided at a plurality of positions below the platen glass and for detecting the presence or absence of a document located immediately above the platen glass. An angle detection light source that irradiates a linear light beam to the carriage that is stationary at a standby position, and is irradiated from the angle detection light source and guided from the carriage to the image sensor Control means for controlling the timing of the document size detection by the photosensor based on the position of the light beam detected by the sensor in the main scanning direction; It has a discriminating means for discriminating the document size based on the output of the photo sensor.

The angle detecting light source emits a light beam from the side of the platen glass of the document pressing plate toward the carriage stationary at the standby position. After this light beam is applied to the carriage, it is guided to the image sensor through the same optical path as the image light. Further, it is desirable that the light rays are emitted substantially in parallel and do not diffuse as much as possible. When the light beam irradiates a predetermined position in the main scanning direction of the carriage, the control means detects this by an electric signal from the image sensor and detects the data of the photo sensor at this time.

[0010]

In the document reading apparatus of the present invention, when a document is placed on the platen glass and the document pressing plate is closed so as to cover the platen glass, the light beam from the angle detecting light source stands still at the standby position. It is irradiated to the top. This light beam is guided to the image sensor, converted into an electric signal for each pixel, and output to the control means. With the operation of closing the document pressing plate, the position irradiated by the light beam moves in the main scanning direction, and when the document pressing plate is closed to a predetermined position, the position irradiated by the light beam from the angle detection light source is changed. Based on the output from the detected image sensor, the control means detects that the document pressing plate has reached a position at a predetermined angle,
The data of each photosensor at this time is output to the determination means. The discriminating means discriminates the document size based on this data.

Therefore, the timing for detecting the document size can be easily changed by changing the setting in the control means. That is, the timing for detecting the output of the photosensor is determined by setting the position in the main scanning direction irradiated by the light beam from the light source for angle detection. Therefore, the timing can be easily changed by changing the setting position. It becomes possible.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a document reading apparatus according to the present invention will be specifically described below with reference to the drawings. FIG. 1 is a schematic front view showing a document reading apparatus of the present invention.

The document reading apparatus according to the present embodiment has a main body 10 having a platen glass 11 on which a document is placed on an upper surface thereof.
When viewed from the operator of the main body 10, the hinge 33 is provided on the rear side.
And a document pressing plate 30 that covers the platen glass 11 from above by rotating around the hinge 33. The upper surface of the main body 10 includes the platen glass 11 as well as the platen glass 11 described above. A detection window 12 is provided on the side of 11 and has a slit-like opening in the main scanning direction (direction perpendicular to the paper surface in FIG. 1). In addition, as shown in FIG. 2, the exposure lamp 13 and the first mirror 14 are mounted inside the main body 10 and travel along the platen glass 11 in the sub-scanning direction (the direction of the arrow shown in the figure). While exposure lamp 1
A lamp carriage 15 for irradiating the original with light from 3 and reflecting the reflected light on the first mirror 14, and a second mirror 16
And the third mirror 17 are mounted, and the image light reflected by the first mirror 14 is reflected by the second mirror 16 and the third mirror 17 while traveling in the sub-scanning direction (the arrow direction shown in the drawing). A mirror carriage 18, a CCD image sensor 19 for detecting the image light reflected by the third mirror 17, a photo sensor 20 arranged at several places below the platen glass 11 for detecting the presence or absence of the document directly above, and a lamp. A CPU 21 for controlling each part of the apparatus such as a motor M for running the carriage 15 and the blinking of the exposure lamp 13 and a storage device 22 for storing and rewriting set values are provided.

The CPU 21 functions as a control means for controlling the operation of the photosensor 20 based on the output from the CCD image sensor 19, and as a discrimination means for discriminating the document size based on the data from the photosensor 20. It also has the function of. The above-mentioned lamp carriage 15 is configured to turn on the exposure lamp 13 to irradiate the document surface with light when reading the draft, and turn off the exposure lamp 13 when the reading is completed. Further, it is set to return to the lower side of the detection window 12 and wait after the reading is completed.

Further, the mirror carriage 18 is driven at a speed half that of the lamp carriage 15, and always guides the image light to the CCD image sensor 19 with a constant optical path length. As shown in FIG. 3, the document pressing plate 30 has
An elastic member 31 having a white surface for pressing the original against the platen glass 11 when the original pressing plate 30 is closed, and a lamp carriage 15 that is on the side of the elastic member 31 and faces the detection window 12 and is on standby through the detection window 12. An angle detection light source 32 for irradiating a substantially linear light beam is provided.

In the document reading apparatus of this embodiment having the above structure, when the document is placed on the platen glass 11 and the document pressing plate 30 is closed, the light source 32 for angle detection passes through the detection window 12 and the main body. The lamp carriage 15 standing by inside 10 is irradiated with light rays. This light beam is sequentially reflected by the first mirror 14, the second mirror 16 and the third mirror 17, and is incident on the CCD image sensor 19.
The CCD image sensor 19 converts this light beam into an electric signal for each pixel and outputs it to the CPU 21. Light source 3 for angle detection
As shown in FIG. 4, the irradiation position of the light beam from No. 2 is from the operator side of the detection window 12 (right side in FIG. 4) to the operator's back side (left side in FIG. 4) as the document pressing plate 30 is closed. ) Is irradiated.

When the original pressing plate 30 rotates and the light beam of the angle detecting light source 32 irradiates a predetermined position of the lamp carriage 15, and the CCD image sensor 19 outputs a signal to detect this, the CPU 21 Operates the photo sensor 20 based on this. Then, each photosensor 20 irradiates light directly above, detects whether there is an original document directly above from the obtained amount of received light, and outputs this data to the CPU 21. The CPU 21 determines the platen glass 1 from the correspondence between the position of each photo sensor 20 and the data.
The size of the original placed on the sheet 1 is determined, and a corresponding signal is output to an external device.

When the original pressing plate 30 completely covers the platen glass 11, the elastic member 31 covers the original with the platen glass 1.
Press to 1. After this, when a start button (not shown) is pressed, the lamp carriage 15 moves in the direction of the arrow shown in FIG. 1, the exposure lamp 13 lights up, and the document surface is exposed and scanned. The light (image light) reflected on the document surface is the first mirror 1
4, the light is sequentially reflected by the second mirror 16 and the third mirror 17, and is incident on the CCD image sensor 19. CCD
The image sensor 19 converts this image light into an electric signal for each pixel and outputs it to the CPU 21. The CPU 21 outputs the input data to the image forming unit, or the transmitting unit in a facsimile or the like. When the reading of the original is completed, the exposure lamp 13 is turned off, the lamp carriage 15 and the mirror carriage 18 return to the standby position, and the next original is read.

As described above, according to the document reading apparatus of this embodiment, the angle detecting light source 32 is provided on the lower surface of the document pressing plate 30, and the document is detected based on the position of the light beam emitted from the angle detecting light source 32. The state where the pressing plate 30 is closed to a predetermined position is detected. Therefore, the open / closed state of the document pressing plate 30 can be detected without being affected by the thickness of the document.
Even for thick originals, the photo sensor 2
It is possible to control 0 to determine the document size.

Further, since the state of the document pressing plate 30 can be detected by utilizing the CCD image sensor 19, the cost can be kept low without the need for an actuator or a micro switch. Furthermore, CCD
Since the image sensor 19 can detect various open / closed states of the document pressing plate 30 in a wide range, the state of the document pressing plate 30 can be changed by changing the setting of the condition for operating the photo sensor 20 by the control means. Select whether to detect the document size in the state,
It can be changed easily.

The control means is set so that the photo sensor 20 operates even when the start button (not shown) is pressed, and when the document is read while the document pressing plate 30 is open and when the document is closed and read. In either case, the document size may be automatically determined.

[0022]

As described above, in the document reading apparatus of the present invention, the document pressing plate is provided with the light source for angle detection, and the light beam from the light source for angle detection is irradiated based on the position in the main scanning direction. The condition that the document pressing plate is closed to a predetermined position is detected. Therefore, the state of the document pressing plate can be detected without being affected by the thickness of the document, and even for a thick document or the like, the photosensor can be controlled at accurate timing to determine the document size. Moreover, since the state of the document pressing plate is detected using the image sensor and the photo sensor is operated by the control means,
Costs can be kept low without the need for actuators or microswitches.

Further, since the image sensor can detect various open / closed states of the document pressing plate in a wide range, the state of the document pressing plate can be changed by changing the setting of the condition for operating the photo sensor by the control means. It is easy to arbitrarily select and change the state in which the document size is detected.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing an embodiment of a document reading apparatus according to the present invention.

FIG. 2 is a plan view showing a main body of the document reading apparatus of FIG.

FIG. 3 is a side view showing the document reading apparatus of FIG.

FIG. 4 is an explanatory diagram showing a relationship between an opening / closing angle of a document pressing plate and a state of light incident from a detection window into a main body unit in the document reading apparatus of FIG.

[Explanation of symbols]

 11 Platen Glass 12 Detection Window 13 Exposure Lamp 15 Lamp Carriage 18 Mirror Carriage 19 CCD Image Sensor 20 Photo Sensor 21 CPU 30 Original Press Plate 32 Light Source for Angle Detection

Claims (1)

[Claims] 1. A document placed on a platen glass,
A carriage that simultaneously exposes the entire area in the main scanning direction is mounted, and a carriage that moves in the sub-scanning direction to expose and scan the document surface, and light emitted from the light source and reflected by the document surface (image light) are detected, An image sensor that changes into an electric signal for each pixel in the main scanning direction, an original pressing plate that is rotatably supported about an axis parallel to the sub scanning direction, and that can cover the upper surface of the platen glass, In a document reading device having a plurality of positions below the platen glass and a photo sensor for detecting the presence or absence of a document at an immediately upper position, a document beam is fixedly supported on a lower surface of the document pressing plate, and a linear light beam stands by. A light source for angle detection that irradiates the carriage that is stationary at a position, and a light source that is emitted from the light source for angle detection and guided from the carriage to the image sensor. A control means for controlling the timing of the document size detection by the photosensor based on the position of the light beam detected in the main scanning direction, and a determination means for determining the document size based on the output of the photosensor. A document reading device characterized by: