JPH0832763A - Document reader - Google Patents

Abstract

PURPOSE:To reduce the power consumption of the device and prolong the life of a distance sensor by performing a processing for stopping the measuring operation of the distance sensor when a document cover is closed below a prescribed quantity. CONSTITUTION:A CPU 1 generates document size codes according to a decided document size and transfers them to a CPU 2 for main body control. The CPU 2 latches the document size codes DATA0-DATA3 transferred from the CPU 1 once detecting the document cover reaching a prescribed angle with the document cover prescribed angle signal from an angle detecting mechanism, and decides the document size. When the document cover is closed below the prescribed angle while sensor data are read in from the distance sensor unit, an error position code showing a deficiency in range finding time is transferred following an sensor error code and when the power source is turned OFF during an initial mode, the error position code is transferred.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a document reading device used in a copying machine or the like, and more particularly to a document reading device having a function of automatically detecting the size of a document.

[0002]

2. Description of the Related Art Conventionally, many document reading devices used in copying machines and the like have been developed which have a function of automatically detecting a document size. As a method of detecting the document size, a plurality of reflective photosensors are provided below the platen, the presence or absence of the document at the detection position of each sensor is detected with the document cover open, and the combination of the detection results is used to detect the document. Methods for detecting size are known.

For example, in the copying machine described in Japanese Patent Laid-Open No. 4-66968, a plurality of photosensors each consisting of a light emitting element and a light receiving element are provided below the document table, and each photosensor responds to the amount of light received. Generated electrical signal
It is input to the input port of the main body control CPU that controls the operation of the main body of the copying machine. Then, the main body control CPU detects the state of each input port in a series of operation control, determines the document size from the detection result, and controls the copying operation.

[0004]

However, in the above-mentioned conventional apparatus, since the size of the original is determined by the control program of the CPU for controlling the main body, the original size is detected in order to change or increase or decrease the detected size. It is necessary not only to add a sensor for the control, but also to change the control program itself of the device body. Then, it is practically impossible to change the detection size or add a detection sensor to the device once put on the market.

Further, in recent years, a distance sensor including a light emitting element such as an LED and a position detecting element (hereinafter referred to as PSD) has been developed, and its application is widely expected. If a high-precision sensor such as a distance sensor is used as the document size detection sensor,
The amount of data to be processed increases, the processing speed is reduced, and the operation control of the apparatus main body is adversely affected to some extent.

In order to solve such a problem, the inventors of the present invention have disclosed in Japanese Patent Application No. 5-241841 a plurality of distance sensors arranged at a plurality of positions on a platen and output signals (distance information) of the distance sensors. ) To determine the original size, output the original size data, and read the original size data transferred from the size detection control circuit to determine the original size and execute the operation control of the apparatus main body. An original reading device provided with a main body control circuit was proposed. By using this document reading device, even when the detection size is changed or a document size detection sensor is added, it is possible to easily cope with the adverse effect on the control of the document reading operation. Further, even when compared with a conventional type device that determines the document size by detecting the amount of received light, it is possible to significantly increase the specifications in terms of the detection life of the sensor and the floating of the document.

The present invention is an original reading apparatus of the type in which the size of an original is determined by using a plurality of distance sensors as described above, and further reduces the power consumption of the apparatus and extends the life of the distance sensor. The purpose is to provide a device.

[0008]

In order to achieve the above object, a document reading apparatus according to the present invention includes a document table on which a document is placed, a document cover which is openable and closable with respect to the document table, and a document table. A plurality of distance sensors arranged facing each other at a plurality of predetermined positions on the platen corresponding to the size of the document placed on the table and measuring distances in each predetermined position direction, and distances measured by the plurality of distance sensors Based on the information of the document, a document presence / absence determining means for determining the presence / absence of a document at each predetermined position on the document table, and a document for determining the size of the document placed on the document table based on the determination result of the document presence / absence determining means A document size detection circuit including a size determination unit and a document size data output unit for outputting data of the document size determined by the document size determination unit, and a document cover opening / closing amount for detecting the opening / closing amount of the document cover. When the output means and the document cover open / closed amount detection means detect that the document cover is opened to a predetermined amount or more, the document size data output by the document size data output means is fetched to read the document. A reading operation control circuit and a distance measuring stopping means for stopping the distance measuring operation of the distance sensor when the document cover opening / closing amount detecting means detects that the document cover is closed more than a predetermined amount. It is characterized by having.

[0009]

According to the above construction, the plurality of distance sensors measure the distances in the respective predetermined position directions on the document table, and the document presence / absence determining means, based on the information about the distances measured by the plurality of distance sensors, The presence / absence of a document at each predetermined position on the document table is determined, and the document size determination means determines the size of the document placed on the document table based on the determination result of the document presence / absence determination means. The output unit outputs the document size data determined by the document size determination unit. The cover opening / closing amount detecting means detects the opening / closing amount of the document cover.

The reading operation control circuit fetches the original size data output by the original size data output means when the original cover opening / closing amount detecting means detects that the original cover is opened more than a predetermined amount. , Control the reading operation of the document. The distance measuring stop means stops the measuring operation by the distance sensor when the document cover opening / closing amount detecting means detects that the document cover is closed by a predetermined amount or more.

As described above, the process of discriminating the document size from the output result of each distance sensor is performed by the document size detection circuit provided separately from the reading operation control circuit. It controls the reading operation of the original by fetching data. Further, since the distance measuring operation of the distance sensor is stopped when the document cover is closed by a predetermined amount or more, the power consumption is reduced accordingly, and the life of the distance sensor can be extended. Since the distance measuring operation of the distance sensor is stopped when the document cover is closed by a predetermined amount or more, the stop of the distance measuring operation does not hinder the reading operation control by the reading operation control circuit.

[0012]

【Example】

[Explanation of the overall configuration of the document reading unit of the copying machine main body] FIG.
FIG. 2 is a perspective view showing a document reading unit provided on an upper portion of a copying machine main body according to an embodiment of the present invention, and FIG. 2 is a side sectional view seen from the arrow X direction. As shown in FIG. 2, the copying machine main body 1 has an upper surface serving as a document reading unit, and below the document reading unit, an image forming unit including a photosensitive drum PC and a paper feeding unit ( (Not shown).

The document reading section includes a document glass 7 for placing a document provided on the upper surface of the copying machine body 1, a document cover 2 for holding the document on the document glass 7, and a front end of the upper surface of the copying machine body 1. Operation panel 4 provided in the section and the original glass 7
An optical system that exposes the upper original surface and forms an image of the reflected light on the surface of the photosensitive drum PC, and distance sensor units FD1, FD2, FD3, CD for detecting the original size.
1 and CD2.

Although not shown in the drawing, well-known devices necessary for constructing an image forming unit such as a developing device, a transfer charger, a cleaner, an eraser, and a charger are provided around the photosensitive drum PC. The electrostatic latent image formed on the photoconductor drum PC by the optical system is visualized as a toner image by the developing device, and the toner image is formed on the paper supplied from the paper supply unit by the transfer charger. After being transferred, it is fixed and discharged to the outside of the copying machine main body 1. In addition, the copying machine main body 1 is provided with a control unit (not shown) that performs overall control of the copying machine main body 1 including control of document reading and document size detection.

The optical system is provided below the original glass 7, and has a first slider 10 holding an exposure lamp and a reflection mirror, and a second slider 11 holding the reflection mirror.
And reflecting mirrors 12, 13, and 14. The first slider 10 is capable of moving the lower side of the original glass 7 in the horizontal direction (the horizontal direction indicated by the double-headed arrow Y in FIG. 2) so that the entire surface of the original glass 7 can be illuminated from below. The slider 11 is the first slider 10
The movement of the first slider 10 is about half (left half in FIG. 2) of the movement range of the first slider 10.

The optical system thus constructed exposes the original with the exposure lamp of the first slider 10, and the reflected light from the original is exposed to the first slider 10 and the second slider 11.
Of the photoconductor drum P provided below the reflection mirror 14 via the reflection mirror and the reflection mirrors 12, 13, and 14.
It is guided so as to form an image on the surface of C. The manuscript cover 2 shown in FIG. 1 can cover the entire surface of the manuscript glass 7, and is rotatably attached to the upper surface of the copying machine main body 1 with its rear part as an axis. The surface of the original glass 7 can be opened and closed. A white document pressing surface 6 is attached to the lower surface of the document cover 2,
When the document cover 2 is closed, the document holding surface 6 holds the document on the document glass 7. Also,
A magnet 3a is attached to a part of the lower surface of the document cover 2, and a reed switch 3b is attached to a position corresponding to the magnet 3a on the upper surface of the copying machine body 1.
When the manuscript cover 2 is closed, the magnet 3a comes into contact with the reed switch 3b and is detected, and a manuscript cover closing signal notifying that the manuscript cover 2 is closed is sent to the control section.

An angle detection mechanism is provided between the rear portion of the document cover 2 and the main body 1 of the copying machine to detect whether or not the original cover 2 is below a specified angle with respect to the upper surface of the main body 1 of the copying machine. 5 are provided. The angle detection mechanism 5 outputs a document cover prescribed angle signal when the angle of the document cover 2 with respect to the copying machine body 1 is equal to or less than a prescribed angle. For example, an actuator is provided on the original document cover 2 side and the copying machine body 1 is provided. In addition to the one configured by providing the photo interrupter on the side, various configurations can be used.

[Explanation of Distance Sensor Unit] As shown in FIG. 2, the distance sensor units FD1, FD2,
The FD3, CD1 and CD2 are provided at predetermined positions below the original glass 7, and the distance sensor units FD1 and F2 are provided.
D2 and FD3 are arranged at respective fixed positions for detecting the moving direction of the first slider 10 with respect to the original placed on the original glass 7, and the distance sensor units CD1 and CD2 are the first. The sliders 10 are arranged at respective fixed positions in order to perform detection in the horizontal direction perpendicular to the moving direction of the slider 10. However, among these distance sensor units, the unit F shown by the broken line in the figure
D3 and CD2 are optional. Further, the distance sensor units FD1 to FD3 are installed below the moving path of the first slider 10, and the distance sensor units CD1 to CD2 are installed below the moving path of the second slider 11.

FIG. 3 is a diagram showing the structure of each distance sensor unit shown in FIG. 1 and the manner of light emission and light reception.
3B is a view seen from a side surface, and FIG. Each distance sensor unit has two light emitting elements (LED1, 2),
Built-in one light receiving element (PSD), LED1
The reflected light from the position illuminated by the LED and the reflected light from the position illuminated by the LED 2 are received by one PSD, and the distance to each position can be detected.

FIG. 4 is a diagram showing a configuration of a sensor control circuit incorporated in each distance sensor unit shown in FIG. As shown in the figure, this sensor control circuit 40 is
An LED drive circuit 41 for driving the D1 and D2 and a signal processing circuit 42 for converting a PSD analog detection signal into a digital signal are provided.
L depending on the state of the LED signal input to the drive circuit 41
Control is performed so that either one of ED1 and ED2 emits light.
Then, the light emitted from the LED 1 or the LED 2 is reflected by the object to be measured, enters the PSD, and is detected. Further, the distance from the detection position where the incident light is detected on the PSD to the object to be measured can be detected.

The PSD outputs an analog detection signal corresponding to the detection position, and this analog detection signal is converted into a digital signal by the signal processing circuit 42 and then the clock signal C
It is output as a sensor output signal (sensor data) in synchronization with LK. With the distance sensor units FD1 to FD3 and CD1 to CD2 having the above-described configuration, the LEDs 1 and 2 of the distance sensor units respectively emit light toward a predetermined position of the document placed on the document glass 7, and The reflected light is received by the PSD and sensor data corresponding to the light receiving position of the PSD is output. Then, as will be described in detail later, the control unit compares the sensor output value with a preset threshold value of the sensor output value to determine whether or not there is a document at a predetermined position on the document glass 7. It is designed to judge.

FIG. 5 is a diagram for explaining the installation state of the distance sensor unit. Each of the distance sensor units has a LED1, LED1 so that the PSD receives the light diffusely reflected by the document surface.
It is installed so that the light emitted from 2 is obliquely applied to the document surface. Also, each distance sensor unit
The beam is installed so as to be inclined and emitted so that the beam reaching distance to the document cover 2 becomes long. For example, in the distance sensor units FD2 and FD3, as shown in FIG.
As shown in (a), the distance sensor units FD2, FD
It is installed so as to incline toward the front (rightward in the figure) from right above so that the beam reaching distance from 3 to the document cover 2 becomes long. This is because the distance from the distance sensor units FD2, FD3 to the document glass 7 and the document cover 2 are determined when the presence or absence of the document at the predetermined position P1 on the document glass 7 is determined with the document cover 2 opened at the specified angle. This is to make a large difference from the distance. The larger the difference between the distances, the lower the threshold for determining the presence / absence of a document based on the sensor data of PSD can be set.
Although the threshold value will be described in detail later, when the threshold value is set low, the allowable range for the floating of the document from the document glass 7 and the reduction of the output due to the sensor life becomes wide.

The LED of each distance sensor unit is
Irradiation is performed on a predetermined position (P1 in FIG. 5A and P2 in FIG. 5B) on the original glass 7 which is determined according to the original size.
As for D1 and CD2, as shown in FIG. 5 (b), the beam having the longer beam reach to the document cover 2 (in FIG. 5 (b), the beam emitted from LED1)
Only the other beam is not used.

Next, the arrangement of the distance sensor units and the mechanism by which the control unit of the copying machine body 1 detects the document size will be described. 6A to 8A are diagrams showing the relationship between the arrangement of the distance sensor unit and the document size. FIGS. 6 to 8B are tables showing the correspondence between the result of determination of the presence or absence of a document based on the sensor data corresponding to each LED of each distance sensor unit and the document size. keeping. Note that FIG. 6 shows an apparatus for domestic use, and FIGS. 7 and 8 show an apparatus for Europe.

As shown in each of FIGS. 6 to 8 (a),
The distance sensor units FD1 to 3 and CD1 and CD2 are arranged at positions corresponding to respective document sizes, and the LEDs 1 and 2 of the respective distance sensor units irradiate positions to corresponding to the corresponding document size. It is possible to detect the presence or absence of the originals at the positions. or,
In the table of each figure (b), “◯” indicates that the document is detected to exist in the positions 1 to 4 shown in (a).
“×” indicates that it is detected that there is no document.

In the control unit, the distance sensor units FD1 to FD1
3, the document size is detected by referring to the detection results of the presence or absence of the document at the positions 1 to 3 detected based on the sensor data from the CDs 1 and 2, and the table shown in the figure. For domestic use, it is basically possible to detect centimeter type document sizes, but since foreign-affiliated companies are required to be able to detect inch type document sizes as well, the sensors FD1 and FD2 provided as standard equipment are required. In addition to being able to detect centimeter type originals by using CD1 and CD1, inch type originals can also be detected by additionally providing distance sensor units FD3 and CD2.

In many cases for Europe, it is sufficient if the A4 size and the 8.5 * 13 size can be distinguished. In this case, the sensor arrangement shown in FIG. 7A is sufficient. Also, depending on the region, letter, A4, 8.5 * 1
3 and legal (8.5 * 14) sizes may be required to be distinguished. In this case, the sensor arrangement shown in FIG. 8A is used. In the arrangement of FIG. 8A, not only the distance sensor units FD3 and CD2 are added to the arrangement of FIG. 7A, but also the position of the distance sensor unit FD2 is changed.

Further, the distance sensor unit cannot be installed below the area of the original glass 7 on which the A5T original is placed, because the second slider 11 passes therethrough. Therefore, the distance sensor unit FD1 for detecting the A5T original is
The A5T document is arranged at a position deviating to the downstream side (the right side in FIGS. 6 to 8) of the second slider 11 with respect to the position right below the right end position, and is tilted in the upstream direction (left direction in FIGS. 6 to 8). (See FIG. 2).

Although the distance sensor unit has been described above, the distance sensor is not easily affected by the amount of light. Therefore, when the distance sensor is used for detecting the document size, the measurement accuracy can be maintained for a long period of time. For example, the document density O.S. is over a machine life of 5 years, that is, 24 hours * 365 days * 5 years = 43800 hours (about 50,000 hours). D (-
The log10 (reflectance of the document) value of 0.80 or more and the floating of the document from the document glass 7 of 5 mm or more can satisfy the required performance.

This means that when the conventional light amount detecting type sensor has a service life of 12000 hours, the document density O. D value 0.2
5. The specifications are greatly improved with respect to the document having a floating standard of 3 mm. Moreover, a circuit for turning on / off the sensor in synchronization with the main switch, which is necessary when using the light amount detection type sensor, is unnecessary.

[Explanation of Operation Panel and Control Unit] FIG.
2 is a top view showing an operation panel 4 of the copying machine main body 1 shown in FIG. 1. FIG. As shown in the figure, the operation panel 4 has a ten-key for the operator to input numerical values and the like to the copying machine main body 1, a start key for instructing the copying process, and a clear for clearing the input contents. A key, a cursor movement key, a liquid crystal display LCD for performing various displays, and the like are provided.

In this embodiment, when resetting the threshold value (initial processing), the operator operates the operation panel 4
The initial mode is set by simultaneously pressing the "#" key and the start key. In addition, the liquid crystal display section L
When the cursor movement key is pressed while the display shown in (1) of FIG. 25 is displayed on the CD, "←" on the display is displayed at the right position of "without option" and the right position of "with option". It is possible to move between them, and it is possible to select whether or not to use the optional distance sensor units FD3 and CD2.

FIG. 10 is a block diagram of the control unit of the copying machine main body 1 shown in FIG. As shown in the figure, this control unit includes a one-chip CPU 1 for detecting a document size and an EEPRO.
It is composed of a document size detection board 101 having M and a main body control board 102 having a one-chip CPU 2 for main body control. The CPU 1 outputs the above-mentioned LED signal and clock signal CLK to each of the distance sensor units FD1 to FD3, CD1 and CD2. Each distance sensor unit irradiates each of the LEDs 1 and 2 in synchronization with this LED signal, and in synchronization with the clock signal CLK, sensor data OUTF1, OUTF2, OUTF3, O for the CPU 1 is output.
It outputs UTC1 and OUTC2. In addition, EEPROM
Stored therein are the above-described threshold value for the CPU 1 to determine the presence or absence of a document, the above-described document size table for the CPU 1 to determine the document size, and the like.

FIG. 11 is a time chart showing the timing of fetching the clock signal CLK issued by the CPU 1 shown in FIG. 10, the LED signal and the sensor data from each distance sensor unit. As shown in the figure, the LED signal is switched ON / OFF at a cycle several times as long as the clock signal CLK. Then, the LEDs 1 and 2 of each distance sensor unit are alternately turned on in accordance with this LED signal. Therefore, the sensor data OUTF1-3, OUTC1
2 to 2, a signal indicating the presence / absence of a document at the position illuminated by the LED 1 of each distance sensor unit and a signal indicating the presence / absence of the document at the position illuminated by the LED 2 are turned on.
It will be alternately output in conjunction with the switching of / OFF. (However, distance sensor unit FD1 and CD2
As for the sensor data OUTF1 and OUTC2, only one LED is used.
Only the signal from is output. FIG. 12 is a diagram showing a correspondence relationship between a document size code issued by the CPU 1 shown in FIG. 10 and a document size (paper out, including a sensor error code).

The CPU 1 determines the 4-bit original size code (DATA in FIG. 10) according to the determined original size.
0 to 3) are generated and transferred to the main body control CPU 2. As shown in the figure, the document size can be determined from the document size codes DATA0 to DATA3. The CPU 2 reads the document size codes DATA0 to DATA3 transferred from the CPU 1 at the timing when it detects that the document cover 2 has reached the specified angle from the document cover specified angle signal from the angle detection mechanism 5 (see FIG. 1). Latch to determine the document size.

FIG. 13 shows original size codes DATA0 to DATA0.
3 is a time chart showing the transfer timing of No. 3;
As shown in (a), the document size codes DATA0 to DATA3 from the CPU1 to the CPU2 are transferred in synchronization with the BUSY signal pulse. When there is an abnormality in the distance sensor unit, as shown in FIG. 13B, instead of the document size code, a sensor error code indicating the sensor abnormality (see the bottom row of FIG. 12) and which sensor The error position code, which indicates whether or not a failure has occurred, are alternately transferred as codes DATA0 to DATA3.

FIG. 14 shows the fault sensor No. It is a figure which shows the correspondence of an error position code and.
The error position code shown in (a) represents an abnormality in the distance sensor units FD1 to FD3, and the error position code shown in (b) represents an abnormality in the distance sensor units CD1 and CD2. That is, in the figure, the failure sensor No. 1 to 3 are distance sensor units FD1 to FD3, respectively.
The failure sensor No. Reference numerals 4 to 5 correspond to the distance sensor units CD1 and CD2, respectively. Moreover, DATA0 of the error position code indicates which of the error code tables in FIGS. 14A and 14B is based.

If the document cover 2 is closed below the specified angle while reading the sensor data from the distance sensor unit, the sensor error code follows,
When the error position code of insufficient distance measuring time shown in (b) is transferred and the power is turned off in the initial mode, etc., following the sensor error code, the initial error A or ( The error position code of the initial error B shown at the bottom of b) is transferred.

As described above, the document size code DATA
0 to 3 or the sensor error code, the error position code, and the initial errors A and B are transferred from the CPU 1 to the CPU 2, so that the CPU 2 can obtain the information of the document size or the error information (the error information in the case of the sensor error). It is possible to obtain the number of the distance sensor unit that is awake.

On the other hand, as shown in FIG. 10, the CPU 2 instructs the CPU 1 to perform the internal processing on the CPU 1 by a "distance measuring signal" which tells the CPU 1 whether or not the original cover 2 is opened beyond the specified angle. The "initial signal", the "SIM signal" for setting the initial mode, etc. are transferred. [Description of Initial Processing] Next, the purpose of the initial processing will be described. FIG. 15 shows the initial and 500
It is a characteristic view of the output value (sensor output value) of the sensor data output from the distance sensor unit after 00 hours. In the figure, a distance A indicates the distance between the sensor and the original when the original is placed in a regular installation position in close contact with the original glass 7, and a distance B indicates the original cover 2 for latching data.
Shows the distance between the sensor and the document cover at the position.

In the figure, the document density O. Considering that the D value of 0.80 and the float of the original from the original glass 7 of 5 mm are within the allowable range, the original density O. The initial document detection curve using a white document with a D value of 0.05 and the document density O.D. The original detection curve after 50,000 hours using a gray original with a D value of 0.80 is displayed.

Assuming that the sensor output value does not change with time in a white original, if the threshold value S is set by the sensor output value between the distance A and the distance B in the initial characteristic diagram, the original will be output when data is latched. The sensor output value (point E) of the existing portion is equal to or higher than the threshold value S, and the sensor output value (point X) of the portion without the document is equal to or lower than the threshold value S. Therefore, by comparing the sensor output value of each distance sensor unit with the threshold value S, the presence or absence of the document can be determined.

Looking at the case where the original is floated 5 mm above the original glass 7, the initial sensor output value is point C.
The sensor output value after 50,000 hours is indicated by the point Y. Therefore, for example, if the lifespan of 50,000 hours and the floating of the original document of 5 mm are regarded as the allowable range, the sensor output value of the floating 5 mm after 50,000 hours (point Y) and the sensor output value in the initial absence of the original document (point X). It is sufficient to set the threshold value S between and. With the above,
Even if the initial process is never performed after the threshold value S is initialized, the document density O. With a gray original having a D value of 0.80, it is possible to allow the original to float up to 5 mm over a life of 50,000 hours.

Further, for example, the sensor output value (point Z) when the original is floated 10 mm after 50,000 hours
If a threshold value is set in advance between the sensor output value (point X) when there is no document in the initial stage, the document density O. D
A gray original with a value of 0.80 floats 10m after 50,000 hours.
Although it is possible to set m as the allowable range, as can be seen from the figure, the sensor output value (point Z) and the sensor output value (point X)
There is almost no margin between and. Therefore, the original density O. If a gray original having a D value of 0.80 has an allowable range of 10 mm, a malfunction may occur, for example, when an error occurs in detecting a specified angle for data latch due to the deformation of the original cover 2 with time.

On the other hand, if the initial process is performed several times during 50,000 hours, the threshold value can be set with a sufficient margin even when the floating of the document is within the allowable range of 10 mm. The reason for this will be described below. As shown in FIG. D value 0.
05 and original density O. When a document with a D value of 0.80 is at the same distance from the sensor, the sensor output value will be about 4 to
Since there is only a difference of about 5 (DEC), the difference between the sensor output values of the white original document and the gray original document will be ignored here, and the description will be given with reference to FIG.

For example, if the initial processing is performed again when the detection curve is in the state shown by the alternate long and short dash line in the figure after the initial setting of the threshold value, the initial threshold value is the sensor output value (point W) and the sensor output value (point X). ), And the threshold value to be set again may be set between the sensor output value (point Z) and the sensor output value (point V). In this case, it is possible to set with a large margin as compared with the case where the initial process is not performed again for 50,000 hours, that is, the case where it is set between the sensor output value (point Z) and the sensor output value (point X). You can see from the figure. Although not shown, it can be inferred that a larger margin can be set by increasing the number of re-initialization.

The above is a description of the purpose of the initial processing. In this embodiment, however, the initial processing is performed with the original cover 2 closed without placing the original on the original glass 7 for the following reason. I shall.
FIG. 16 shows the document density O. White original with D value of 0.05 and original density O.D. FIG. 9 is a characteristic diagram of sensor output values for a gray original having a D value of 0.80. For example, in the case shown in FIG. 16, if the regular threshold value is defined as (sensor output value when a white original is detected at the distance A) -30, the regular threshold value S1 is 120-30 = 90DEC. . It can be seen from the figure that the presence / absence of a document can be determined with a sufficient margin at this threshold value S1 (90 DEC).

However, the original density O. If a threshold value is set with a document having a D value of 0.80 placed, the threshold value S2
Becomes 115-90 = 85 DEC. With this shifted threshold value S2 (85 DEC), the margin with respect to the sensor output value U (79 DEC) at the distance B to the document cover 2 at the time of data latch is small. Further, the original density O. D value 1.
If a threshold value is set in a state in which 70 gray originals are placed on the original glass 7, the threshold value S3 is 100-30 = 70.
It becomes DEC. Thus, the threshold value S3 (70DE
When C) is set, the document cover 2 at the time of data latch
Since the sensor output value U at the distance B up to is about 79 DEC, the sensor output value exceeds the threshold value S3 (70 DEC) even if no document is placed, indicating that there is a document. Therefore, when setting the threshold value, it is necessary not to place a document having a high density on the document glass 7, but to set the threshold value S by placing a white document equivalent to the document glass 7 on the document glass 7.

Further, if a threshold value that nothing is placed on the original glass 7 is set, the set threshold value will be a completely shifted value, and the original size detection will malfunction. From the above reason, in the present embodiment, attention is paid to the fact that the document pressing surface 6 is white, and the threshold value is set with the document cover 2 closed without the document placed on the document glass 7. Therefore, an accurate threshold value is set (the same applies to an automatic document feeder such as an ADF).

[Description of Operation of Copy Machine Main Body 1] Next, the operation of the copy machine main body 1 will be described based on a flowchart. FIG. 17 is a flowchart showing the main routine of the control of the document size detecting CPU 1. By the control of the CPU 1 according to this flowchart, the document reading unit executes an initial process (initial mode surrounded by a dotted line in the figure) and a document size detection process (document size detection mode surrounded by a dotted line in the diagram).

When the SIM signal is sent from the CPU 2, the destination is checked first. When it is necessary to confirm whether the current destination is centimeter type or inch type in the destination check and reset the document size table,
The setting is performed (S1). Although the destination is checked every time here, the destination may be checked, for example, at the time of initial processing and written in the EEPROM instead of performing it every time.

Here, the data transfer timing in the initial mode is shown in FIG. 18, but as shown in FIG.
Initial signal from CPU2 is active (Low)
If the signal is longer than the prescribed time T, it is determined that the initial signal is ON (there is an instruction for initial processing), and the processing in the initial mode is executed (S2, S).
3). The specified time T is provided to remove noise, and if the specified time T is set to about 0.5 sec, the noise can be sufficiently removed without affecting the processing speed. When the initial process starts, the CPU
The BUSY signal to 2 is set to Low level (Low level during the initial processing), and the initial flag indicating that the initial processing is being performed is set to ON (S4).

Then, the sensor data is read from each distance sensor unit (S5), and when the sensor output value is larger than the maximum value MAX of the specified output (for example, 250DEC) (S5).
6) or the minimum value MIN of the specified output (for example, 10DEC)
When it is smaller (S7), it is determined that the sensor is damaged or the harness is not properly connected, and a sensor error is generated (S1).
0).

The sensor output value is the maximum value MAX of the specified output.
And the minimum value MIN, the threshold value S is calculated for the LEDs 1 and 2 of each distance sensor unit from the read sensor data and written in the EEPROM (S
8). Here, the sensor data itself is EEPRO.
The threshold value may be calculated when the presence or absence of the original is written in M, but in order to determine the presence or absence of the original at a higher speed, it is desirable to write the threshold value after the operation in the EEPROM. .

Then, the initial flag is reset to OFF and the initial processing is completed (S9). When the initial processing is completed, the BUSY signal is issued to the CPU 2 again. On the other hand, in step S2, if the initial signal from the CPU 2 is inactive (Hi), it is determined that there is no instruction for initial processing, and the processing for detecting the document size is executed. Also, in steps S2 and S3,
Initial signal from CPU2 is active (Low)
That is, even if the signal is ON, if the signal is shorter than the specified time T, it is determined that the signal is an error, it is determined that there is no instruction of the initial processing, and the processing of the document size detection is executed.

In the document size detection mode, first, C
The distance measurement signal from PU2 is checked (S11). If the distance measurement signal is ON, it is determined that the document cover 2 is open at a specified angle or more. Then, the initial flag is checked (S12). If the initial flag is set to ON, it is determined that there is an error in the initial processing (S22), and an error code is output (S19).

When the initial flag is set to ON, the initial signal becomes inactive when the power is turned off or the original cover 2 is opened during the initial processing of S5 to S10, and the EEPR is set.
It is conceivable that the threshold value in the OM has been overwritten halfway and is not a normal threshold value. Here,
By setting the default value of the initial flag to the ON (set) state and resetting the initial flag to OFF only when the initial process is normally completed, it is possible to check whether or not the initial mode process is completed. .

If the initial flag is OFF in step S12, it is determined that the initial processing has been completed normally, and sensor data is read from each distance sensor unit (S13 to S15). While reading the sensor data, it is constantly checked whether the distance measurement signal is OFF (S14). If the distance measurement signal is OFF, the sensor data reading from each distance sensor unit is completed. Before the operation, it is determined that the document cover 2 is closed at a specified angle or less (that is, a distance measuring error has occurred) (S20), and an error code indicating that the distance measuring time is insufficient (see FIG.
(See (b)) is output (S19).

In step S14, the distance measurement signal is turned off.
If the reading of the sensor data is completed without
It is checked whether or not the sensor output value of the read sensor data exceeds the specified maximum value MAX (for example, 250DEC) (S16). Then, when it is larger than the specified maximum value MAX, it is determined that a sensor error has occurred (S21), and an error code is output (S19).

Next, the sensor output value of the read sensor data is compared with the threshold value S to judge the presence / absence of a document at each position (S17). Then, the document size is determined with reference to this determination result and the document size table, the document size is coded (S18), and transferred to the CPU 2 (S19). On the other hand, when the distance measurement signal is OFF in step S11, it is determined that the document cover 2 is closed at the specified angle or less, and the sleep mode process is performed (S25). Here, the sensor output value is the specified minimum value M
When it is smaller than IN, it is judged as a sensor error and an error code is output (S23, S24).

As described above, by checking whether or not the sensor output value is smaller than the specified minimum value MIN when the distance measurement signal is OFF, it is possible to accurately determine whether or not there is a sensor error. . That is, if it is determined whether or not there is a sensor error based on whether or not the sensor output value is smaller than the specified minimum value MIN, even when the document cover 2 is opened to a state close to a vertical state, the distance sensor unit is used as the distance sensor unit. An object (ceiling etc.) farther away is detected as an object to be measured, and the sensor output value approaches 0 as much as possible, so it is erroneously determined to be a sensor error. However, by making a check when the distance measurement signal is OFF, such an erroneous determination can be avoided.

The sleep mode processing includes processing for stopping the supply of power to each distance sensor unit and CP.
The processing of lowering the clock signal CLK issued by U1 or stopping the document size detection operation of the CPU 1 is performed. In the sleep mode, when the document size detection operation of the CPU 1 is stopped, the transfer of the document size code to the CPU 2 is also stopped, but when the document size detection operation of the CPU 1 is not stopped, the document size detection CPU 1
Alternatively, the document size code may be latched on the side and the latched document size code may be continuously sent to the main body control CPU 2.

As described above, in the document size detection mode, when the document cover 2 is closed below the specified angle, the process of the sleep mode is started, so that the power consumption of the apparatus is suppressed and the light emission intensity of the LED is reduced. The decrease can be suppressed. FIG. 19 is a flowchart showing a main routine of control of the main body control CPU 2. The operation of the copying machine body 1 will be described with reference to this flowchart.

First, after performing various initial settings and starting the internal timer, it is determined whether or not the operator has instructed the initial mode (pressing the "#" key and the start key) (S101 to S103). If the initial mode is instructed, the initial signal is activated (Low level), and the initial mode subroutine is executed (S108).

If the operator has not instructed the initial mode, a copy process etc. is carried out after a normal document size reading subroutine (S104 to S10).
6). FIG. 20 is a flowchart of the document size reading subroutine of step S104 shown in FIG. The main body control CPU 2 latches the document size code sent from the document size detection CPU 1 as follows according to this flowchart.

When the reading of the original size is started, the detection mechanism 5
It is determined whether or not the original cover 2 is below the specified angle by checking the original cover specified angle signal from (S201). If the document cover specified angle signal is ON, it is considered that the document cover 2 is below the specified angle, and the latch flag is checked (S202).
If the latch flag is OFF, the latch flag is set to ON (S203), the document size code is latched (S204), the distance measurement signal is turned OFF, and the CPU 1 is notified that the document cover 2 is at the specified angle or less. Notify (S205).

The latch flag is provided to latch the document size code only once after the document cover 2 is closed to the specified angle. If the latch flag is set to ON in step S202, It is determined that the document size code is already latched after the document cover 2 is closed to the specified angle, and step S20 is performed.
The processes of 3 to S205 are not performed.

In step S201, the document cover 2
Is opened above the specified angle, the latch flag is reset to OFF so that the original size data can be latched when the original cover 2 becomes below the specified angle (S206), and the distance measurement signal is turned on. Original cover 2
Informs the CPU 1 that is opened over the specified angle (S207).

21 to 24 are flowcharts of the initial mode subroutine of step S108 shown in FIG. 19, and FIG. 25 is a view showing the display on the liquid crystal display unit LCD in the initial mode. The operation of the initial process will be described with reference to this flowchart and the drawings. First, the state counter S is reset to "1" (S301), the liquid crystal display LCD displays as shown in FIG. 25 (1), and the operator operates the cursor movement key to select the presence or absence of the option sensor. (S30
2, 303). The operator operates the cursor movement key and then presses the start key to instruct whether the optional sensor is present or absent.

Then, from the value of the state counter S, it is determined from which step to start processing (S304). When the state counter S = 1 in step S304, the presence or absence of the optional sensor is determined according to the instruction content from the operator described above (S311). When it is determined that the optional sensor is present, the original size table for the optional sensor is set (see FIGS. 6B and 8B), and when it is determined that the optional sensor is not present, the original for the optional sensor is not set. Size table (Fig. 6 (b), Fig. 7
(See (b)) is set (S312, 313).

If it is determined that the operator has pressed the start key, the state counter S is set to S = 2, and if it is determined that the operator has not pressed the start key, then FIG.
The display of (1) is performed to prompt the operator to select the presence or absence of the optional sensor (S314 to 316). When the state counter S = 2 in step S304, it is confirmed whether or not the document cover 2 is closed (S320). If it is not closed, the liquid crystal display LCD displays the screen shown in FIG. 25 (2) to prompt the operator to close the document cover 2 and set the state counter S = 0 (S321, 322).
When the document cover 2 is closed, the state counter S = 3 is set (S323).

In step S304, the state counter S =
In the case of 3, first, an initial signal is output to the CPU 1 (S330). Therefore, when it is confirmed in step S320 that the document cover 2 is closed, C
Initial processing will be started on the PU1 side. Then, the display of FIG. 25C is displayed on the liquid crystal display LCD (S3).
31), and informs the operator that the initial process is in progress. Then, the state counter S = 4 is set (S
332).

In step S304, the state counter S =
4 or state counter S = 5, original cover 2
It is always confirmed whether or not is closed (S339). When it is determined that the document cover 2 is opened, the liquid crystal display unit L
The display of FIG. 25 (4) is displayed on the CD (S341), and the operator is instructed to restart the operation of the initial process from the beginning. Then, the state counter S = 0 is set (S
342).

When it is confirmed in step S339 that the original cover 2 is closed, and when the state counter S = 4 in step S340, the flag A is confirmed (S34).
3). The flag A is a flag indicating that the timer A is counting. When the flag A is OFF, the flag A is set to ON (S344) and the timer A is started (S355). When the flag A is set to ON, it is confirmed whether the timer A has timed out (S346).

BUSY before timer A times out
If a pulse is input (NO in step S346, YES in step S347), the initial time is too short, so it is determined that an error has occurred, and the liquid crystal display LCD displays FIG. The operator is notified of the occurrence (S348). Then, the state counter S = 0 is set, the flag A is reset to OFF, and the timer A is reset (S349 to 351).

On the other hand, if it is determined in step S346 that the timer A has timed out, the flag A is reset to OFF, the timer A is reset, and the state counter S = 5 is set (S352 to 354). Step S
If it is confirmed in 339 that the original cover 2 is closed, and if the state counter S = 5 in step S340,
Confirm BUSY pulse input from CPU1 (S3
55). When the BUSY pulse is not input, the flag B indicating that the timer B is counting is confirmed (S365).

When the flag B is 0FF, the flag B is set to ON and the timer B is started (S
366-367). If the flag B is already ON, it is confirmed whether the timer B has timed out (S368). If the timer B has timed up, it is determined that an error has occurred because the initial process takes too long, and the liquid crystal 25 (6) is displayed on the display LCD to notify the operator of the occurrence of the error (S369). Then, the state counter S is set to 0, the flag B is reset to OFF,
The timer B is reset (S370-372).

If a BUSY pulse is input before the timer B times out in step S355, a sensor error is confirmed (S356) and an initial error is confirmed (S358). If there is no error, the display of FIG. 25 (7) is displayed on the liquid crystal display LCD to notify the operator that the initial process has been normally completed. And
Set the state counter S = 0 (S360, 36
2).

On the other hand, if it is determined in step S355 that a sensor error has occurred, the display in FIG. 25 (5) is displayed, and if an initial error occurs, the display in FIG. 25 (8) is displayed on the liquid crystal display LCD. The operator is notified of the occurrence of each error (steps S357 and 359), and the state counter S = 0 is set (S361). 25 (5), the sensor No. Is indicated by a square, but in reality, C
The number of the faulty distance sensor unit is displayed based on the error position code transferred from PU1. After that, the flag B is reset (S363), and the timer B is reset (S364).

In step S304, the state counter S =
If 0, it is checked whether a key other than the clear key has been pressed (S305), and when it is determined that a key other than the clear key has been pressed, the state counter S = 1 is set (S306, 307). , The liquid crystal display LCD is returned to the initial mode initial screen (FIG. 25 (1)) (S308, 309).

In this way, the initial mode processing is sequentially performed according to the value of the state counter S. When the clear key is pressed by the operator after or during the initial processing, the initial mode is ended and the copy mode is restored. (S310). In the above embodiment, in step S310, when the clear key is pressed by the operator in the initial mode, the initial mode is canceled, but no key operation is accepted during the initial processing. You can

Further, in the above embodiment, the manuscript cover 2 is rotatably attached, and the sleep mode processing is performed when the manuscript cover 2 is closed at the specified angle or less. The method of opening and closing is not limited to this. For example, the original cover may be moved in parallel to open and close. Further, in the above embodiment, the present invention has been described using the copying machine in which the image of the original is exposed on the photosensitive drum PC via the optical system, but the present invention is not limited to this, and the image of the original is not limited to this. It goes without saying that the present invention can be applied to a device that converts digital data using a line sensor. Specifically, a CCD line sensor is provided on a slider that moves along the document glass, and a contact type document reading device that reads the document image by moving the slider or a CCD line sensor is fixedly provided on the device body. At the same time, the present invention can be applied to a document reading apparatus in which an image of a document is guided to a CCD line sensor via a reflection mirror provided on a slider that moves along the document glass.

[0083]

As described above, in the document reading apparatus according to the present invention, when the document cover is closed to a specified amount or less, the distance sensor measurement operation such as the power supply to the distance sensor is stopped. Since the processing is performed, the power consumption of the device can be reduced and the life of the distance sensor can be extended.

Further, the processing for discriminating the original size from the output value of each distance sensor is performed by the original size detection circuit provided separately from the reading operation control circuit, and the reading operation control circuit fetches the original size data and performs the reading operation. Since the above control is performed, even when the detection size is changed or the distance sensor is added, it can be easily performed without adversely affecting the control of the reading operation. In addition, in comparison with a mechanism that determines the size of the original by detecting the amount of light, in terms of the detection life of the sensor and floating of the original,
It is possible to greatly improve the specifications.

[Brief description of drawings]

FIG. 1 is a perspective view showing a document reading unit provided on an upper portion of a copying machine main body according to an embodiment of the present invention.

FIG. 2 is a side sectional view of the document reading unit shown in FIG. 1 as seen from the direction of arrow X.

FIG. 3 is a diagram showing a configuration of a distance sensor unit and how light is emitted and received.

FIG. 4 is a diagram showing a configuration of a sensor control circuit incorporated in the distance sensor unit.

FIG. 5 is a diagram illustrating a state in which a distance sensor unit is installed.

FIG. 6 is a diagram showing a relationship between an arrangement of a distance sensor unit for Japan and a document size.

FIG. 7 is a diagram showing a relationship between an arrangement of a distance sensor unit for Europe and a document size.

FIG. 8 is a diagram showing a relationship between another arrangement of a distance sensor unit for European destinations and a document size.

FIG. 9 is a top view showing an operation panel of the copying machine main body.

FIG. 10 is a block diagram showing a control unit of the copying machine main body.

FIG. 11 is a time chart showing the timing at which the clock signal CLK issued by the original size detecting CPU 1 and the LED signal and the output signal from each sensor are fetched.

FIG. 12 is a diagram showing a correspondence relationship between a document size and a document size code.

FIG. 13 is a time chart showing the transfer timing of a document size code.

FIG. 14 shows a fault sensor No. It is a figure which shows the corresponding relationship between and an error position code.

FIG. 15 is a characteristic diagram of sensor output values from the distance sensor unit at the initial stage and after 50,000 hours.

FIG. 16 is a characteristic diagram of sensor output values for a white original and a gray original.

FIG. 17 is a flowchart showing a main routine of control of a document size detecting CPU 1.

FIG. 18 is a time chart showing the data transfer timing in the initial mode.

FIG. 19 is a flowchart showing a main routine of control of the main body control CPU 2.

FIG. 20 is a flowchart showing a document size reading subroutine of the main body control CPU 2.

FIG. 21 is a flowchart of an initial mode subroutine of the main body control CPU 2.

FIG. 22 is a continuation of the flowchart of FIG.

FIG. 23 is a continuation of the flowchart of FIG. 22.

FIG. 24 is a continuation of the flowchart of FIG. 23.

FIG. 25 is a liquid crystal display LC in the initial mode.
It is a figure which shows the display of D.

[Explanation of symbols]

 1 Copying Machine Main Body 2 Original Cover 5 Angle Detection Mechanism 7 Original Plate FD1-3, CD1-CD2 Distance Sensor Unit CPU1 Original Size Detection CPU CPU2 Main Body Control CPU

Claims (1)

[Claims] 1. A manuscript table on which a manuscript is placed, a manuscript cover which is openably and closably mounted on the manuscript table, and a plurality of manuscripts on the manuscript table corresponding to the size of the manuscript placed on the manuscript table. A plurality of distance sensors that are arranged facing each other at predetermined positions and measure distances in the respective predetermined position directions, and information of distances measured by the plurality of distance sensors, based on information about the distances An original presence / absence determining means for determining the presence / absence, an original size determining means for determining the size of an original placed on an original plate based on the determination result of the original presence / absence determining means, and the original size determining means A document size detection circuit including a document size data output unit for outputting document size data, a document cover opening / closing amount detection unit for detecting the opening / closing amount of the document cover, and a document cover opening / closing amount detection unit. The stage, when the document cover is detected to be open to more than a predetermined amount,
The document size data output means outputs the document size data and controls the reading operation of the document, and the document cover opening / closing amount detecting means closes the document cover more than the predetermined amount. And a distance measuring stop means for stopping the distance measuring operation of the distance sensor when detected.