JPH0799561A - Original reader - Google Patents

Abstract

PURPOSE:To easily revise a detection size and addition of a sensor by using a size detection control circuit independently of a main body control circuit so as to execute the processing of discriminating a size of an original from plural sensor outputs. CONSTITUTION:A CPU1 for detecting a size of an original provides an output of a LED signal and a clock signal CLK to each sensor. Each sensor unit outputs distance information sets OUTF1-OUTF3 and OUTC1, OUTC2 synchronously with the signal CLK. The CPU 1 compares the distance information received from each sensor unit with a threshold level stored in an EEPROM to discriminate the presence of the original. A table is stored in the CPU1 in advance and the CPU1 discriminates the size of the original by collating the table and the original presence information. Furthermore, the CPU1 generates 4-bit original size codes DATA 0-3 depending on the discriminated size and transfers them to a main body control CPU2.

Description

Detailed Description of the Invention

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. More specifically, the present invention relates to a document reading device having a function of automatically detecting the size of a document.

2. Description of the Related Art Conventionally, in a document reading apparatus used in a copying machine or the like, a plurality of reflection type photosensors are provided below a document table, and a document at a detection position of each sensor is opened with a document cover pressing the document open. It is known that the presence or absence of the document is detected and the document size is detected from the combination of the detection results. For example, in the copying machine described in Japanese Patent Laid-Open No. 4-66968, a plurality of sets of sensors each consisting of a light emitting element and a light receiving element are provided below the document table, and a signal generated in accordance with the amount of light received from each sensor is copied. It is input to the input port of the main body control CPU that controls the operation of the main body of the machine. Then, the main body control CPU detects the state of each port in a series of operation control, determines the document size from the detection result, and controls the copying operation.

As described above, in the conventional document reading apparatus, the output of the sensor is directly fetched into the main body control CPU, and the processing such as the determination of the original size is performed in the operation control of the main body control CPU. Was there. By the way, in order to meet the user's request and usage area, it is desired that the detectable document size (detection size) can be easily changed and increased. However, in the conventional apparatus, the document size is discriminated in the control program of the main body control CPU. Therefore, in order to change or increase or decrease the detection size, not only a document size detecting sensor is added, but also the control program of the main body of the apparatus is changed. Also needs to be changed. For this reason,
It was virtually impossible to change the detection size of a device once shipped to the market or add a detection sensor. Further, a distance sensor including a light emitting element such as an LED and a position detecting element (hereinafter referred to as PSD) has been known in recent years and is expected to be widely applied, but it has not been adopted as a document size detecting sensor. Further, even if a high-precision sensor such as a distance sensor is used as a document size detecting sensor of a conventional document reading apparatus, the amount of data to be processed becomes large, which adversely affects the operation control of the apparatus body such as a decrease in processing speed. There was a problem. The present invention has been made in view of the above problems,
An object of the present invention is to provide a document reading device having a document size detecting function that can easily change the detection size and add a document size detecting sensor and does not adversely affect the operation control of the apparatus body.

In order to achieve the above object, the present invention provides a document table on which a document is placed, a plurality of sensors for detecting the document on the document table, and outputs of the plurality of sensors. A size detection control circuit having size determination means for determining the document size based on the signal, and output means for outputting document size data corresponding to the document size determined by the determination means, and a document from the size detection control circuit A main body control circuit for controlling the operation of the main body based on the size data. In order to detect the presence or absence of the document with high accuracy, the invention according to claim 2 is a distance sensor in which the sensor is a combination of a light emitting element and a position detecting element, and a signal indicating the distance from the sensor to the detection target. Is output as an output signal.

According to the structure of the present invention, a plurality of sensors detect a document at a plurality of locations on the document table. Then, the size detection control circuit determines the document size based on the output signal of each sensor, and transfers the document size data indicating the determined document size to the main body control circuit. The main body control circuit takes in the original size data transferred from the size detection control circuit, recognizes the original size, and controls the operation of the apparatus main body. In this way, the processing for determining the document size from the output result of each sensor is performed by the size detection control circuit provided separately from the main body control circuit, and the main body control circuit only takes in the original size data.

1 is a perspective view and a sectional view showing the upper portion (original reading portion) of a copying machine to which the present invention is applied. Copier body 1
A document glass 7 for placing a document is fitted on the upper surface of the document. The original placed on the original glass 7 is scanned and read by a first slider (not shown) holding an exposure lamp and a reflection mirror. Below the original glass 7, distance sensor units FD1 and FD for detecting the length of the original placed on the original glass 7 along the moving direction of the first slider (hereinafter referred to as the vertical direction).
2, FD3, and distance sensor units CD1 and CD2 for detecting a length in a direction perpendicular to the moving direction of the first slider (hereinafter, referred to as a lateral direction). Of these distance sensor units, the units FD3 and CD2 indicated by broken lines in the figure are optional. Further, an original cover 2 is attached to the upper portion of the main body 1 so as to be rotatable around its rear end. A white original pressing surface 6 is provided on the lower surface of the original cover 2, and the original pressing surface 6 can press the original against the original glass 7 when the original cover 2 is closed on the apparatus main body 1. The fact that the document cover 2 is closed in the apparatus body 1 is detected by the magnet 3a provided in the document cover 2 coming into contact with the reed switch 3b provided in the apparatus body 1. Further, the detection mechanism 5 detects that the document cover 2 is at a specified angle or less with respect to the apparatus body 1. The detection mechanism 5 may have various configurations such as an actuator provided on the document cover 2 and a photo interrupter on the apparatus body 1 side. An operation panel 4 is provided on the front end of the upper surface of the apparatus body. FIG. 2 shows each of the distance sensor units FD1 to 3 and C.
FIG. 3 shows a configuration of D1 and D2 and a control circuit built in each sensor unit. Each sensor unit has two LEDs 1,2
And one PSD are built in, and one sensor unit can detect two positions, a position illuminated by LED1 and a position illuminated by LED2. LEDs 1,2
Emits light according to the state of the LED signal input to the LED drive circuit. The distance to the DUT is P
It is detected by the detection position on SD. The analog detection signal of the PSD is converted into a digital signal by the signal processing circuit and then output in synchronization with the clock signal CLK. Further, each sensor unit is installed so that the light emitted from the LEDs 1 and 2 is obliquely applied to the document, and the PSD detects irregularly reflected light of the document. Further, as shown in FIG. 2C, the sensor unit is PS
The distance (H) between the D and the LEDs 1 and 2 is equal, and the PSD and the LEDs 1 and 2 are arranged in a substantially triangular shape. The reason that the PSD is equal to the distance between the LEDs 1 and 2 is to reduce the difference between the captured data at the two detection positions and prevent the variation in detection accuracy. FIG. 4 shows that the distance between the PSD and the LED 2 is 3
It is a graph which shows the relationship between a sensor-document distance and a sensor output value when 0 mm and the distance to LED1 are set to 60 mm which is twice that. Distance to actual document placement position 5
The output value of each sensor at 5 mm is about 60 DEC,
It becomes about 220 DEC, and it can be seen that there is a considerable difference in the detected values. As will be described later, this detection value is a reference value of a threshold value for determining the presence or absence of a document, and it is necessary to reduce the difference between the sensor detection values in order to eliminate variations in determination accuracy. Also, as mentioned above, PSD and two LEDs
Since the arrangement relationship with and is substantially triangular, the entire sensor unit can be made small, and the degree of freedom in mounting on the device is increased. Next, the arrangement of each distance sensor unit will be described. FIG. 5A shows the arrangement of the sensor units in the domestic device, and FIG. 5B shows the correspondence between the output of each sensor and the document size. "○" in Fig. 5 (b)
Indicates that a document has been detected, and “x” indicates that a document has not been detected. For domestic shipments, it is basically necessary to detect centimeter type document sizes, but foreign-affiliated companies are required to be able to detect inch type document sizes as well. Therefore, as shown in the figure, the standard sensor FD
1, 2 and CD1 can detect centimeter type originals, and can also detect inch type originals by additionally installing sensors FD3 and CD2.
Meet these demands. When the distance sensor is used for detecting the document size in this way, the distance sensor is not easily affected by the amount of light, so the machine life (for example, 5 years 24 hours * 3
65 days * 5 years = 43800 hours: about 50,000 hours). D (= -log10 (reflectance of original)) 0.8 or more, original 5 mm above original glass 7
The required performance of m or more can be satisfied. This is because the conventional light amount detection type sensor has a life of 12000 hours and detects the original O.S. The specification is drastically improved with respect to D0.25 and the document floating regulation of 3 mm. Moreover, when using a light amount detection type sensor,
A circuit for turning the sensor on and off in synchronization with the main switch was necessary. FIG. 6 is a block diagram showing the control circuit. In FIG. 6, the document size detection unit is a single chip C
It has a PU1 and an EEPROM. The CPU 1 outputs an LED signal and a clock signal CLK to each sensor. Each sensor unit synchronizes with the clock signal CLK and outputs the distance information OUTF1, OUTF2, OUTF3, O.
It outputs UTC1 and OUTC2 (see FIG. 7). At this time, the LED signal is O
N / OFF switching is performed, and accordingly, the LEDs 1 and 2 of each sensor unit are alternately turned on. Therefore, as the distance information OUTF1 to 3 and OUTC1 to OUTC2, a signal indicating the distance to the document at the irradiation position of the LED1 of each sensor unit and the LED2 are interlocked with the ON / OFF switching of the LED signal. A signal indicating the distance to the document at the irradiated position is alternately output. CPU1
Is the EEPR for the distance information input from each sensor unit.
The presence / absence of a document is determined by comparison with the threshold value stored in the OM. This EEPROM is provided in the CPU 1 because the CPU 1 performs all the processing relating to the document size determination, and C
This is because the PU2 (main body CPU) reduces the burden of main body control processing as a process of only fetching size data, and prevents the reliability of threshold data (distance data) from being reduced due to inter-CPU communication. CPU1 is shown in FIG.
The table of (b) is stored in advance, and the size of the document is determined by comparing this table with the document presence / absence information. Further, the CPU 1 generates a 4-bit original size code (DATA0 to 3) according to the determined original size (see FIG. 8) and transfers it to the main body control CPU 2. CPU2
Is a timing at which it is detected that the document cover 2 has reached the specified angle by the document cover specified angle signal from the detection mechanism 5, and the document size codes DATA0 to DATA3 from the CPU 1 are detected.
Latch and recognize the document size. CPU1 to CP
As shown in FIG. 9, the transfer of the document size codes DATA0 to U2 is performed in synchronization with the BUSY signal pulse. Next, the purpose of the initial processing will be described. Figure 10
Shows the output value of the distance sensor at the initial stage and after 50,000 hours. In the figure, point A is the proper installation position of the document, and point B is the position of the document cover 2 when data is latched. Basically, by setting the threshold value S between A and B, the sensor output value E of the portion where the document exists becomes equal to or more than the threshold value S when the data is latched, and the sensor output value X of the portion where there is no document exists. Is less than or equal to the threshold value S. Thus, it is possible to determine the size of the document by determining the presence or absence of the document based on the output of each distance sensor. Further, the output value after 50,000 hours shifts in the direction in which the output value decreases from the initial value. Therefore, even if a document at the correct position is detected,
The sensor output value decreases from E to F. When the original is floated 5 mm from the original glass 7, the initial output value is C, and the value is Y after 50,000 hours. That is, life 50
If you want to allow the document to float 5 mm after 000 hours,
A threshold value S is set between the output value Y when the original is floated by 5 mm for 50,000 hours and the output value X when the original is not present.
Should be set. As described above, the document size detection works well over the machine life of 50,000 hours. However, this is the case where the threshold value is not changed even after the initial setting. On the other hand, even when it is desired to allow the document to float by 10 mm, if the threshold value S is reset several times within 50,000 hours, it can be achieved with a sufficient margin between the threshold value S and the output value. Also, the manuscript is 10 mm in 50,000 hours
If a threshold value S is set in advance between the output value Z when the document is floating and the output value X when there is no original document in the initial stage, the floating 10 mm can be allowed after 50,000 hours without resetting the threshold value S. However, the margin between the threshold value S and the output values Z and X almost disappears. Therefore, the document cover 2
If an error occurs in the detection of the specified angle for the data latch due to the deformation with time, there is a risk of malfunction.
In view of such a point, in the present embodiment, the threshold S is reset by an operator's input or the like every certain period, and the reset of the threshold S is called an initial process. FIG. 11 is a flowchart showing the control of the CPU 1. The CPU 1 first confirms whether or not the initial signal from the CPU 2 is active (Low) (step S1). If the active (Low) of the initial signal is shorter than the specified time T, it is ignored as noise and the initial processing is not performed (step S
2). If the specified time T is set to about 0.5 sec, noise can be sufficiently removed and the processing speed is not affected. When the initial signal is judged to be active, B
The USY signal is set to low level (see FIG. 12), and the initial flag is written in the EEPROM (step S
3). Next, the threshold value of each sensor is calculated from each sensor data of each distance sensor and written in the EEPROM (step S5). At this point, the sensor data itself
Although the threshold value may be calculated in advance by writing it in the EPROM and determining the presence or absence of the original, it is desirable to write the threshold value after the calculation in the EEPROM in order to determine the presence or absence of the original at a higher speed. . Then, the initial flag is reset (step S6), and the initial mode ends. On the other hand, when the initial signal is inactive (Hi), the document size detection mode is set. First, check the initial flag (step S7),
If the initial flag is set, an initial error is determined (step S12). If the initial flag is reset, it is determined that the initial processing has been completed normally, so data is read from each sensor unit (step S8). Here, if the default value of the initial flag is set to the set state, the initial CPU 1 that has not been subjected to the initial processing can be treated as an initial error and can be distinguished from the one that has been subjected to the initial processing. Further, when the power is turned off in the middle of the initial mode, or when the initial signal becomes inactive, the threshold value in the EEPROM may be rewritten halfway and the threshold value may not be normal. Therefore, it is possible to check whether or not the initial mode is completed by resetting the initial flag only when the initial mode is normally completed. Next, each sensor data is compared with the threshold value S to judge the presence / absence of a document (step S9). The original size is determined by comparing this determination result with the original size table, and the original size is coded (step S
10) and transfers to CPU2 (step S11). Figure 1
3 is a flowchart showing the control of the CPU 2. In this flowchart, first, various initial settings are performed, the internal timer is started, and then it is determined whether or not the initial mode is set (steps S101 to S).
103). Subsequently, normally, a document size reading subroutine (step S104) is performed, and then a copying process (step S105) and the like are performed. When the initial mode is selected (YES in step S103), the initial signal is activated (Low level), and the initial mode subroutine (step S108) is executed. FIG. 14 shows a document size reading subroutine. When it is detected that the document cover 2 has reached the specified angle from the document cover specified angle signal from the detection mechanism 5 (step S201), the latch flag is confirmed (step S202). If the latch flag is reset, the latch flag is set (step S203) and the document size code is latched (step S204). When the latch flag is set, the document size code is not latched so that the document size data is not latched again after the document cover 2 is closed to the specified angle or less (step S20).
2). When the document cover 2 is opened beyond the specified angle, the latch flag is reset (step S205) to prepare for latching the document size data when the document cover 2 reaches the specified angle. FIG. 15 shows the initial mode subroutine. In this initial mode subroutine,
C while the CPU 1 is performing the initial processing
The processing in PU2 is shown. First, the initial signal is made active (Low) (step S301). Receiving this initial signal, the CPU 1 starts the initial operation. Next, it is determined whether or not a BUSY pulse is input from the CPU 1 (step S302), and if there is an input, it is determined that the initial processing has been normally performed, and a display to that effect is displayed (step S303). 5 if there is no input
count the sec timer (step S305),
If the count is up, it takes too much time for the initial processing, and the initial warning is issued (step S306). In step S304, the initial signal is made inactive (H
i).

As described above, according to the present invention, the processing for discriminating the document size from the outputs of the plurality of sensors is executed by the size detection control circuit independent of the main body control circuit. It is possible to easily change the detection size, change the arrangement of the detection sensors, and add the detection sensors without changing the main body control program accompanying the addition of the detection sensors. Further, even if a sensor whose processing of detected data is more complicated is adopted, the operation control of the apparatus main body is not adversely affected such as a reduction in processing speed.

[Brief description of drawings]

FIG. 1 is a perspective view of an upper portion of a copying machine to which the present invention is applied.

FIG. 2 is a diagram showing a configuration of a document size detecting distance sensor.

FIG. 3 is a block diagram showing a control circuit in the distance sensor.

FIG. 4 is a diagram showing output characteristics of a distance sensor.

FIG. 5 is a diagram showing a relationship between an arrangement of distance sensors for Japanese destinations and a document size.

FIG. 6 is a block diagram showing a control circuit of the copying machine.

FIG. 7 is a time chart showing a timing at which a document size detecting CPU fetches an output signal from a distance sensor.

FIG. 8 is a diagram showing a correspondence relationship between a document size and a document size code.

FIG. 9 is a time chart showing the transfer timing of a document size code.

FIG. 10 is a diagram illustrating a reference value for determining the presence or absence of a document.

FIG. 11 is a flowchart showing a main routine of control of a document size detecting CPU.

FIG. 12 is a time chart showing data transfer timing in the initial mode.

FIG. 13 is a flowchart showing a main routine of control of a main body control CPU.

FIG. 14 is a flowchart showing a document size reading subroutine of the main body control CPU.

FIG. 15 is a flowchart showing a part of an initial mode subroutine of the main body control CPU.

[Explanation of symbols]

 7 ... manuscript table FD1-3, CD1-CD2 ... distance sensor CPU1 ... size detection control circuit CPU2 ... body control circuit

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[Procedure amendment]

[Submission date] October 26, 1993

[Procedure Amendment 1]

[Document name to be corrected] Drawing

[Correction target item name] All drawings

[Correction method] Change

[Correction content]

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[Figure 6]

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 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Tatsuya Eguchi 2-3-13 Azuchi-cho, Chuo-ku, Osaka Inside Osaka Kokusai Building Minolta Camera Co., Ltd. (72) Shinya Kawanishi 22-22 Nagaike-cho, Abeno-ku, Osaka In Sharp Corporation (72) Keiichi Okada 22-22 Nagaikecho, Abeno-ku, Osaka City Sharp Corporation (72) Inventor Koichi Furuta 22-22 Nagaikecho, Abeno-ku, Osaka City Sharp Corporation

Claims (2)

[Claims] 1. A document table on which a document is placed, a plurality of sensors for detecting the document on the document table, size determining means for determining a document size based on output signals of the plurality of sensors, and A size detection control circuit having output means for outputting document size data corresponding to the document size determined by the determination means, and a main body control circuit for controlling operation of the main body based on the document size data from the size detection control circuit And a document reading device. 2. The sensor is a distance sensor including a combination of a light emitting element and a position detecting element, and outputs a signal representing a distance from the sensor to a detection target as an output signal. Document reader.