JPH06271147A - Paper sheet conveying device - Google Patents

Abstract

PURPOSE:To carry out the optimum sensor adjustment according to respectie modes to be performed with allowance. CONSTITUTION:The switching of a first mode for initializing light emitting amount control data to be stored into an EEPROM 22 to a second mode for timely renewing the light emitting amount control data initialized by the first mode is instructed by a mode switching switch 23, and the upper limit values-of the light emitting amount control data are set into the different values by a CPU unit 20 on the basis of the mode instruction state of the first mode and the second mode according to the instructions.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sheet conveying device for conveying a sheet to a predetermined position, and more particularly to a sheet conveying device provided with a detecting means for detecting the conveyed sheet.

[0002]

2. Description of the Related Art Conventionally, a sheet conveying device has a
A detection means for detecting the presence / absence of a sheet to be conveyed, for example, a light emitting element and a light receiving element are arranged so as to face each other, and the output voltage of the light receiving element is monitored to determine the presence or absence of the sheet.

Further, the presence or absence of paper is determined by monitoring the output level of a reflection type sensor in which a light emitting element and a light receiving element are paired on the conveying path.

FIG. 13 is a schematic diagram showing an example of a sheet detecting circuit in a conventional sheet conveying apparatus.

In the figure, 3 is composed of a sensor circuit, a photodiode and a phototransistor.

R1 is a resistor, R2 is a load resistor, and when the original conveyed on the conveying path is a semi-transparent sheet, the output voltage V ₀ is the presence of the sheet, the output level is the threshold V TH or more, and the sheet is the sheet. The output level is set to VL or less in the absence state. The output voltage V ₀ is input to the CPU 11 via the A / D converter 12. CPU11 output voltage V
The digitally converted output data of ₀ is constantly monitored to determine its operating state.

FIG. 14 is a diagram showing a paper out detection state variation characteristic of the sensor 3a shown in FIG. 13, where the horizontal axis represents time and the vertical axis represents the output voltage V ₀ .

As shown in this figure, with no paper initially,
The output voltage V ₀ of the light receiving element, which was less than VL, fluctuates with the passage of time as shown by the broken line in the figure due to paper dust adhering to the light receiving element portion as the sheet is conveyed and the light amount of the light emitting element decreasing.

The sheet detecting operation in the conventional sheet conveying apparatus will be described below with reference to the flow chart shown in FIG.

FIG. 15 is a flow chart for explaining the sheet detecting operation in the conventional sheet conveying apparatus. Note that (1)
~ (5) shows each step.

First, the CPU 11 determines whether or not a sheet (not shown) is being transported on the sheet transport path (1), and if YES, executes a predetermined sheet transport sequence (5). In addition,
When the CPU 11 is not in the carrying operation, the output voltage V ₀ of the light receiving element (phototransistor) when there is no paper is always A /
While monitoring the output of the D converter 12 (2), when the output voltage V ₀ becomes equal to or higher than the threshold value V TH (V ₀ ≧ V TH), the output voltage V ₀ is Since the output level VH with paper was approached due to the decrease in the light amount of the light emitting element, it was judged that the paper detection capability had deteriorated (3), the error signal / error display was output (4), and the timing shown in FIG. I had a service person urge you to clean the sensor or replace the sensor.

[0012]

However, when it is necessary to detect a semi-transparent sheet such as the second raw sheet at the same time by the transmissive sensor in the sheet conveying apparatus, the sensor output level judgment for determining the presence or absence of the sheet is performed. If the threshold value is constant, bother to place a semi-transparent paper on the transport path and set the resistance value of the load resistor so that the output voltage is above a certain voltage level VH and the voltage level without paper is below a certain voltage VL. Is required to determine or adjust the operating point of the sensor circuit, which complicates the sensitivity adjustment work of the sensor, and sets the operating point of the light-receiving sensor to the complete saturation area or cutoff area. There was a problem that I could not do it.

By the way, the sensor adjusted in this manner also has paper dust accumulated on the light-receiving surface of the light-receiving element when it is used for a long period of time, or the output of the light-receiving element in the absence of paper due to a decrease in the light amount of the light-emitting element. The voltage level is rising. Then, if the output voltage level of the light receiving element rises in the absence of paper, the delay time from the passage of the paper to the detection of the paper will not be constant, and the control of the paper conveying device will be hindered.

Normally, the voltage value in the absence of paper is read by the CPU by the A / D converter. When the voltage rises above a certain level, the CPU outputs an alarm or error indicating that the sensor is in a defective state, and the service person has to perform sensor cleaning or sensor replacement, so the maintenance and inspection work load is very heavy and serviceability is poor. There was a problem that it was bad.

Therefore, by providing the LED current varying means and making the sensor operating points uniform, the passage of the paper from
The delay time (sensor response) until the actual paper detection can be controlled to be constant, and the sensor cleaning interval can be extended, so that the serviceability is significantly improved. Furthermore, since it is not necessary to pass a large LED current unnecessarily, it is possible to extend the life of the LED.

However, for example, when mounting the sensor during assembly, cleaning the sensor, replacing the sensor, or the like,
If the optical axis of the sensor's light-receiving part and the light-emitting part are misaligned, it will be necessary to turn on more light than necessary.
Originally, when paper dust is accumulated on the light-receiving surface of the light-receiving element or the output level of the light-receiving element rises without paper due to a decrease in the light amount of the light-emitting element, there is no adjustment margin and adjustment becomes impossible. There were also points.

The present invention has been made in order to solve the above problems, and is a sheet detecting means having a light emitting portion and a light receiving portion for detecting the presence or absence of a sheet conveyed to a predetermined position on a conveying path. In a paper transporting apparatus having the above, it is possible to provide a paper transporting apparatus that can perform optimal sensor adjustment according to each mode with a margin by controlling the adjustment mode of the paper detecting unit so that the adjustment mode can be switched step by step according to the usage status. To aim.

[0018]

SUMMARY OF THE INVENTION A first sheet conveying device according to the present invention comprises a reading means for reading output data from a light receiving portion, and the reading data read by the reading means within a predetermined range. A light amount control unit for controlling the light emission amount of the light emitting unit, a storage unit for storing the light emission amount control data output by the light amount control unit, and a first mode for initializing the light emission amount control data stored in the storage unit. And a mode switching means for instructing switching between the light emission amount control data initialized by the first mode and a second mode for timely updating, and the mode switching means for instructing the first mode or the second mode. Control means for setting the upper limit values of the light emission amount control data to different values based on the state.

In the second sheet conveying device according to the present invention, the control means initializes the light emission amount control data when the read data exceeds the upper limit value of the light emission amount control data set in the first mode. Is configured to be prohibited.

In the third sheet conveying device according to the present invention, the control means initializes the light emission amount control data when the read data exceeds the upper limit value of the light emission amount control data set in the second mode. Is configured to be prohibited.

A fourth sheet conveying device according to the present invention is a reading unit for reading output data from the light receiving unit, and a light emission amount of the light emitting unit so that the reading data read by the reading unit falls within a predetermined range. A light amount control means for controlling,
Storage means for storing light quantity data according to the light quantity received by the light receiving section; and a first storing means for storing the initial value of the first light quantity data according to the light quantity received by the light receiving section in a state where the sheet detection sensor does not cover the sheet. 1 mode, a second mode in which the storage unit stores second light amount data according to the amount of light received by the light receiving unit in a state where the paper is applied to the paper detection sensor, and a first mode stored in the storage unit.
And a third mode for determining the threshold value for determining the presence / absence of a sheet on the basis of the light amount data and the second light amount data, and for instructing switching between the third mode for detecting the presence / absence of the sheet conveyed on the conveying path. First mode control means for controlling execution of the first mode, the second mode, and the third mode based on the mode instruction state of the instruction means is provided.

A fifth sheet conveying device according to the present invention controls a reading unit for reading output data from a light receiving unit and a light emission amount of the light emitting unit so that the reading data read by the reading unit falls within a predetermined range. Light amount control means, storage means for storing light amount data according to the light amount received by the light receiving part, and initial value of the first light amount data according to the light amount received by the light receiving part when the paper is not applied to the paper detection sensor. A first mode for storing in the storage means, a second mode for storing in the storage means second light quantity data according to the quantity of light received by the light receiving section in the state where the paper is applied to the paper detection sensor, and the storage means A threshold value for determining the presence / absence of a sheet is determined on the basis of the first light amount data and the second light amount data stored in A determination unit based on the instruction state of the mode data stored in the storage means,
Based on the determination result of the determination means, the first instruction mode,
A mode control means for controlling execution of the second mode and the third mode is provided.

[0023]

According to the first aspect of the invention, the first mode for initializing the light emission amount control data stored in the storage means by the mode switching means and the light emission amount control data initialized by the first mode are timely. Since the switching means is instructed to switch to the second mode to be updated, and the control means sets the upper limit values of the light emission amount control data to different values based on the first mode or the second mode instruction state according to the instruction,
It is possible to adjust the sensor within the range corresponding to each mode.

In the second invention, the control means prohibits the initialization of the light emission amount control data when the read data exceeds the upper limit value of the light emission amount control data set in the first mode. It is possible to limit the sensor adjustment range in the first mode.

In the third invention, the control means prohibits the initialization of the light emission amount control data when the read data exceeds the upper limit value of the light emission amount control data set in the second mode. It is possible to limit the sensor adjustment range in the second mode.

In the fourth invention, the first mode control means corresponds to the first mode, the second mode and the third mode instructed by the instructing means, and the first mode, the second mode, Since the execution of the third mode is controlled, the original paper detection means can be individually adjusted according to the first to third modes, so that the paper detection means can stably detect the paper. Become.

In the fifth invention, the judging means automatically judges the instructed states of the first mode, the second mode and the third mode based on the data stored in the storing means, and based on the judgment result. The first mode control means is the first mode,
Since the execution of the second mode and the third mode is controlled, the original paper detection means can be automatically adjusted according to the first to third modes, so that the paper detection means stably detects the paper. It becomes possible to do.

[0028]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a sectional view showing the construction of a sheet conveying apparatus showing an embodiment of the present invention, which corresponds to the case where it is applied to a copying machine, for example.

In FIG. 1, reference numeral 1 denotes a copying machine, which exposes a document conveyed from a sheet conveying device 2 to a predetermined position of a platen to copy the document image on a recording medium. Reference numerals 3a and 3b denote non-contact type transmissive sensors (hereinafter, simply referred to as sensors) each including a light receiving portion and a light emitting portion. In addition,
The sensor 3a detects a document conveyed from the document table 4 to the conveyance path 5, and the sensors 3b and 3c detect the presence or absence of the document on the conveyance path 5. A conveyance control unit 6 communicates with a controller unit (not shown) of the copying apparatus 1 to control document conveyance.

The copying apparatus 1 executes a well-known electrophotographic process and is not directly related to the present invention, so its explanation is omitted.

FIG. 2 is a diagram showing an example of the first sensor control circuit provided in the conveyance control unit 6 shown in FIG.

In the figure, 20 is a CPU unit, for example, C
It consists of a single chip that contains a PU, ROM, RAM, timer, and so on. 21 is D / as a light emitting element current varying means
In the A converter, the converter output Vout is applied to the base of the transistor TR1 via the resistor R11 (resistance value RB). The emitter side of the transistor TR1 is connected to the photodiode 24 via the resistor R12. The optical signal emitted from the photodiode 24 is received by the phototransistor 25. 12 is A / D
Converter (functions as light receiving element voltage monitoring means)
Then, the output voltage is monitored via the load resistor R13 (resistance value RL) connected to the collector side of the phototransistor 25. An EEPROM 22 stores a light emitting element current adjustment value. Reference numeral 23 is a mode switch.
The forward current I applied to the photodiode 24
F is derived from the following equation (1). IF = (Vout-RB.IB-VBE-VF) / RF (1) Vout: D / A converter output voltage IB: Base current of transistor TR1 VBE: Base-emitter voltage of transistor TR1 VF: Photodiode 24 Forward voltage In the paper transporting device configured as described above, the first mode in which the light emission amount control data to be stored in the storage unit (EEPROM 22) by the mode switching unit (mode switching switch 23) is initialized, and the first mode An instruction to switch to a second mode in which the light emission amount control data initialized by the mode is updated in a timely manner, and a first mode in accordance with the instruction
Since the control means (CPU unit 20) sets the upper limit value of the light emission amount control data to different values (set according to the flowcharts shown in FIGS. 6 to 9) based on the second mode instruction state or the second mode instruction state, It is possible to adjust the sensor within the range corresponding to.

In the second invention, the control means prohibits the initialization of the light emission amount control data when the read data exceeds the upper limit value of the light emission amount control data set in the first mode. It is possible to limit the sensor adjustment range in the first mode.

In the third invention, the control means prohibits the initialization of the light emission amount control data when the read data exceeds the upper limit value of the light emission amount control data set in the second mode. It is possible to limit the sensor adjustment range in the second mode.

FIG. 3 is a diagram showing a first operation characteristic of the phototransistor 25 shown in FIG. 2, in which the vertical axis represents the collector-emitter voltage VCE of the phototransistor 25 and the horizontal axis represents the phototransistor 25. Photocurrent IL is shown.

As shown in FIG. 2, the photodiodes 2 are arranged at opposite positions separated by a certain distance.
4. In the paper detection sensor composed of the phototransistor 25, when the photocurrent IL is gradually increased,
From a certain point, the collector-emitter voltage VCE is the photocurrent I
It begins to decrease substantially linearly with the change in L, and from a certain point, the collector-emitter voltage VCE settles at a substantially constant value (collector-emitter saturation voltage VCE (SAT)).

Therefore, by setting the operating point of the sensor to A, it is possible to detect the paper without passing unnecessary LED current, and it is possible to reliably detect the semi-transparent paper in this linear region.

FIG. 4 is a diagram showing a second operation characteristic of the phototransistor 25 shown in FIG. 2, in which the vertical axis represents the collector current IC and the horizontal axis represents the collector-emitter voltage VCE of the phototransistor 25. Indicates.

In the figure, is a characteristic curve (I of collector current IC vs. collector-emitter voltage VCE) when the amount of light reaching the phototransistor 25 is used as a parameter.
C-VCE characteristic curve), the IC-VCE characteristic curve shows a state without paper, shows a semi-transparent paper state, and shows a plain paper state.

At this time, the sensor output (collector-emitter voltage VCE) is the load resistor R1 of the phototransistor.
Intersection point a, b with a straight line determined by the resistance value RL of 3
It is represented by c.

FIG. 5 is a characteristic diagram for explaining changes in the collector-emitter voltage VCE of the phototransistor 25 shown in FIG. 2, where the vertical axis represents the collector-emitter voltage VCE and the horizontal axis represents time.

In the figure, tr indicates the delay time from the passage of the paper until the sensor 3a for detecting the paper is turned on (from the rise of the first voltage VL to the threshold voltage VTH), and tf is the passage of the paper to the sensor. The delay time until 3a is turned off (from the fall of the second voltage VH to the threshold voltage VTH) is shown. For example, if the collector-emitter voltage VCE is controlled to be constant when there is no paper, the delay times tr and tf are equal to the phototransistor 2
5 is determined by the load resistor 13. Therefore, if the resistance value RL of the load resistor 13 is increased, the delay time t
r and tf become longer. The resistance value RL of the load resistor 13 is
It is selected and determined according to the transportation accuracy of the paper transportation device.

However, as the time passes, the photodiode 24
When the amount of light emitted from the sensor 3 decreases and the collector-emitter voltage VCE when there is no paper becomes higher than when it is normal, the response time of the sensor 3a also changes. When the initial response times are the delay times tr1 and tf1, the response time after the decrease of the emitted light amount due to the above-mentioned change with time is the delay time tr.
2, tf2 (tr1 <tr2, tf1 <tf2), and the response time of the sensor 3a also changes with the change in the emitted light amount. Therefore, the response characteristic of the sensor 3a can be kept constant by controlling the collector-emitter voltage VCE when there is no paper. Hereinafter, the first automatic adjustment control operation of the sheet sensor in the sheet conveying apparatus according to the present invention will be described with reference to the flowcharts shown in FIGS.

6 and 7 are flow charts showing an example of the first automatic adjustment control procedure of the paper sensor in the paper carrying apparatus according to the present invention. It should be noted that (1) to (32) indicate each step. Further, the sensor 3a will be described as an example, but the same applies to the sensors 3b and 3c.

First, the signal state of the mode selector switch 23 is checked to determine whether the first mode (normal adjustment mode) is instructed (1), and the interval timer (counter in the CPU section 20) counts. When (2) is completed, the interval timer is set (3), and it is judged whether the copying machine 1 is in operation (4). If YES, the process returns to step (2), and if NO, the paper transport device 2 Is in the standby state (5). If NO, the procedure returns to step (2). If YES, it is determined whether or not the sheet is not conveyed on the conveyance path 5 (6). )
, NO (with paper), return to step (2), YES
If there is no paper, the interval timer (CPU unit 20
Each time the counting of the internal counter) is completed, that is, the sensors 3a to 3c are automatically adjusted periodically, the CPU unit 20 first determines the sensor output value (collector-emitter voltage VCE when there is no paper). The A / D value of the A / D converter 12 is not less than the set voltage value V1 and not more than the set voltage V2 shown in FIG. 3 (V1 ≦ A / D value ≦ V2) so that the A / D change value is within a certain voltage range. ) Is determined (7)
, YES, the processing is terminated, and if NO, it is determined whether the A / D value of the A / D converter 12 is larger than the set voltage value V1 (A / D value of the A / D converter 12> V1). (8) If YES, D / A of the D / A converter 21
The A value is read (9) and the D / A of the D / A converter 21 is read.
The value is incremented (10) and the incremented D / A
The value is output (11), and the D / A value is EE, which is a non-volatile memory.
It is written in the PROM 22 (12). Next, the CPU section 21 determines whether the set value (D / A value) of the D / A converter 21 exceeds the upper limit value of the first mode (16), and Y
If it is ES, the set value of the D / A converter 21 is fixed to the upper limit value of the first mode, the D / A value is written in the EEPROM 22 which is a non-volatile memory (17), and the process is ended.

On the other hand, if the determination in step (8) is NO, the A / D value of the A / D converter 12 is the set voltage value V2.
Less than (A / D value of A / D converter 12 <V
2) It is judged whether or not (13), if NO, the process returns to step (7), and if YES, the D / A value of the D / A converter 21 is read (14), and the D / A of the D / A converter 21 is read. Decrement the value (15) and return to step (11).

As described above, in the sensor output adjustment value in the first mode, the collector-emitter voltage VCE of the phototransistor 25 at the operating point of the sensor 3a is a substantially constant value (the collector-emitter saturation voltage VCE). (SAT)) is adjusted so that the operating point A (see FIG. 3) becomes an inflection point of the characteristic. Further, the CPU section 21 is D
It is checked whether or not the set value of the / A converter 21 exceeds the upper limit value of the first mode, and if it is less than or equal to the upper limit value, the automatic adjustment of the sensor 3a is continued. In this judgment, if the set value of the D / A converter 21 exceeds the upper limit value, the D / A
The set value of the converter 21 is fixed to the upper limit value of the first mode, this is output, and the subsequent sensor automatic adjustment is not performed.

The upper limit value of the first mode is assumed to be stored in advance in the ROM of the CPU section 20 as a predetermined value. It is assumed that the upper limit value of the first mode and the upper limit value of the second mode described later are set to different values.

On the other hand, if the determination in step (1) is NO, first, the signal state of the mode changeover switch 23 is checked to determine whether or not the second mode (initial value setting mode) is instructed ( 18), it is judged whether or not the copying apparatus 1 is in operation (19), and if YES, the procedure returns to step (1), and if NO, it is judged whether or not the sheet conveying apparatus 2 is in the standby state (20). , NO, the process returns to step (1), and if YES, it is determined whether or not there is no paper being conveyed on the conveyance path 5 (21), and if NO (paper is present), step (1) If YES (no paper), the sensors 3a to 3c are automatically adjusted.
The CPU unit 20 displays the sensor output value (collector when there is no paper).
The A / D value of the A / D converter 12 is adjusted so that the A / D change value of the emitter-to-emitter voltage VCE falls within a certain voltage range.
Above the set voltage value V1 shown in FIG. 3 and below the set voltage V2 (V1
≤ A / D value ≤ V2) is determined (22), and A / D
It is determined whether the A / D value of the D converter 12 is larger than the set voltage value V1 (A / D value of the A / D converter 12> V1) (23), and if YES, the D / A converter 21
Reading the D / A value of (24), incrementing the D / A value of the D / A converter 21 (25), outputting the incremented D / A value (26), and storing the D / A value in a non-volatile memory. It is written in the EEPROM 22 (27). Then C
The PU unit 21 sets the set value of the D / A converter 21 (D / A
Value) exceeds the upper limit of the second mode
If (28), YES, the one that exceeds the adjustable upper limit value of the D / A converter 21, that is, the status indicating the sensor adjustment failure error state is set (29), and the process is terminated, but to that effect, the copying apparatus 1 You may control so that it may be notified and displayed.

On the other hand, if the determination in step (23) is NO, the A / D value of the A / D converter 12 is the set voltage value V2.
Less than (A / D value of A / D converter 12 <V
2) It is determined whether or not (30), if NO, the process returns to step (22), and if YES, the D / A value of the D / A converter 21 is read (31), and the D / A of the D / A converter 21 is read. Decrement the value (32) and return to step (26).

As described above, the CPU section 20 sets the second mode from the signal state of the mode changeover switch 23, the copying apparatus 1 is not operating, and the sheet conveying apparatus 2 is not conveying sheets. At the time, or when there is no paper on the conveyance path 5 (no paper), the automatic initial value setting of each sensor 3a to 3c is performed, so that the output value of each sensor 3a to 3c falls within a certain voltage range. , The value of the forward current IF of the photodiode 24 of the sensor 3a is changed, and D at that time is changed.
The correction value of the A / A converter 21 is stored in the nonvolatile memory E
Write to EPROM 22. At that time, when the value exceeds the predetermined adjustment upper limit value in the second mode, it is considered that there is no adjustment margin thereafter, and the sensor automatic initial value setting is not performed. In this case, the sensor automatic initial value setting is restarted by eliminating the poor sensor adjustment state and then instructing the second mode again with the mode changeover switch 23. The second automatic adjustment control operation of the sheet sensor in the sheet conveying apparatus according to the present invention will be described below with reference to the flowcharts shown in FIGS.

8 and 9 are flow charts showing an example of the second automatic adjustment control procedure of the sheet sensor in the sheet conveying apparatus according to the present invention. Note that (1) to (32) and (41)
~ (45) indicates each step. Further, the sensor 3a will be described as an example, but the same applies to the sensors 3b and 3c. Further, description of the same processes as those in FIGS. 6 and 7 will be omitted.
In addition, the transport control unit 6 according to the present invention is configured by a control board, performs an operation check in advance by itself, and a code that can determine that the control board is an initial product, for example, "FFH (hex ) ”Is EEPRO
It is assumed that it is written in a predetermined address of M22, for example, "00H (hex)".

First, when the control board is installed in the sheet conveying device 2 at the production factory or in the market and the power is turned on, the CPU section 20 executes the step (41), and the EEPRO is executed.
The data written in a predetermined address of M22, for example, "00H (hex)" is read, and the data is read as "FFH".
(Hex) "is determined (42), and if NO (if already installed and initial value setting is completed), return to step (1), execute the above-described processing, and if YES For example, the process proceeds to step (18) shown in FIG. 9, the initial value setting process is executed, and if the determination in step (22) is YES, data indicating that the initial value setting mode process is completed (for example, "FFH 00H (hexa) other than (hexa) ")
At a predetermined address of, for example, "00H (hex)" is written (45), and the process is ended.

In the above embodiment, the D / A converter 2
By changing the D / A value output from 1, each sensor 3a-3
The sensor 3 so that the output value of c is within a certain voltage range.
The value of the forward current IF of the photo diode 24 of a is changed so that the sensor output value (the A / D change value of the collector-emitter voltage VCE when there is no paper) falls within a certain voltage range. The A / D value of 12 is not less than the set voltage value V1 shown in FIG. 3 and not more than the set voltage V2 (V1 ≦ A / D value ≦
The case where the control is performed so as to be V2) has been described.
The resistor R12 shown in FIG. 2 is used as a variable resistor, and the resistance value RF is set to a resistance value RF1 by an electronic volume or the like not shown.
To RFN (RF1 <RF2 <... <RFN), the A / D value of the D / A converter 12 is set to a value equal to or higher than the set voltage value V1 shown in FIG. 3 or lower than the set voltage V2 (V1 ≦ A / D value). ≤
The same effect can be expected even with a configuration in which the control is performed so as to be V2).

In this case, the CPU section 20 shown in FIG.
When it is determined that the first mode (normal adjustment mode) is instructed from the signal state of the mode changeover switch 23, the CPU section 20 determines that the copying apparatus 1 is not in operation, or the sheet conveying apparatus 2 detects that the sheet is being conveyed. When not in transit, or in transport path 5
When there is no paper on the upper side (no sensor paper), a switching signal for switching the resistance value of the resistor R12 serving as the current limiting resistor of the photodiode 24 by one step is sent to the electronic volume, and the resistance value RF1 of the resistor R12. The resistance value R
The sensor is automatically adjusted periodically by changing to F2. Then, the CPU unit 20 changes the value of the forward current IF of the photodiode 24 of the sensor 3a by changing the set value of the D / A converter 21 so that the sensor output value falls within a certain voltage range. The D / A converter correction value of is written in the EEPROM 22, which is a non-volatile memory. The sensor output adjustment value at that time is the sensor 3
The operating point A is an inflection point of the characteristic where the collector-emitter voltage VCE of the phototransistor 25 starts to become a substantially constant value (the collector-emitter saturation voltage VCE (SAT)) (see FIG. 3). ) Will be adjusted.

Further, the CPU section 20 determines whether or not the set value of the D / A converter 21 exceeds the upper limit value of the first mode, and if it is less than or equal to the upper limit value, the automatic adjustment of the sensor 3a etc. is continued. With this determination, the set value of the D / A converter 21 is fixed to the upper limit value of the first mode, and this is output,
The subsequent sensor automatic adjustment is not performed. Note that the upper limit value of the first mode is stored in the ROM in the CPU unit 20 shown in FIG.

On the other hand, when the CPU section 20 determines from the signal state of the mode changeover switch 23 that the second mode (initial setting mode) is instructed, the CPU section 20
The section 20 serves as a current limiting resistor of the photodiode 24 when the copying apparatus 1 is not in operation, when the sheet conveying apparatus 2 is not conveying sheets, or when there is no sheet on the conveying path 5 (no sensor sheet). The switching signal for switching the resistance value of the resistor R12 by one step is turned OFF, the resistance value of the resistor R12 is set to RF, and the forward current IF of the photodiode 24 is adjusted so that the sensor output value falls within a certain voltage range. It is changed, and the D / A converter correction value at that time is written in the EEPRPOM 22 which is a non-volatile memory. Since the resistance value RF> (RF1 // RF2), the forward current IF of the photodiode 24 in the second mode is smaller than the forward current IF in the first mode, so that the adjustment margin is maintained. .

At that time, when the value exceeds the predetermined adjustment upper limit value in the second mode, it is considered that there is no adjustment margin thereafter, that is, it is regarded as a sensor adjustment failure error state, and the sensor automatic initial value setting is performed. Prohibit
In this case, the second mode (initial value setting mode) is performed again after eliminating the sensor adjustment failure error state.
FIG. 10 is a diagram showing an example of the second sensor control circuit provided in the conveyance control unit 6 shown in FIG. 1, and the same components as those in FIG. 2 are designated by the same reference numerals.

In the figure, reference numeral 50 denotes a mode changeover switch, which is used to switch the contacts C1 and C2 from the ON / OFF state to the first to third positions.
To specify the mode. Reference numeral 51 is a switch for taking in sensor data. Hereinafter, the third automatic adjustment control operation of the sheet sensor in the sheet conveying apparatus according to the present invention will be described with reference to the flowchart shown in FIG.

In the sheet transporting device constructed as described above, the first mode control means (corresponding to the first mode, the second mode, and the third mode instructed by the instructing means (mode changeover switch 50)) The CPU unit 20) executes the first mode, the second mode, and the third mode, which will be described later.
Since the control is performed according to the flowchart shown in FIG.
An original sheet detection unit (sensor 3a) is used according to the third mode.
~ 3c) can be individually adjusted, so that the sensors 3a to 3c
The sheet c can be stably detected.

FIG. 11 is a flow chart showing an example of a third automatic adjustment control procedure of the sheet sensor in the sheet conveying apparatus according to the present invention. Note that (1) to (18) indicate each step. [First Mode Processing] First, the CPU section 20 determines from the signal state of the mode changeover switch 50 whether or not the contact C1 designated by the first mode is in the ON state (1), and if YES, the first mode Set (2). Here, the first mode is a mode in which the sensor is initialized in the state where there is no paper on the conveyance path 5, and which is set on the production line.

Next, in the CPU section 20, the switch 51 is turned off.
It is judged whether or not N is given (3), and if YES, the first
Enter the initialization mode that initializes the light intensity data of the light emitting part in the mode (4), and determine whether the result is normal (5), N
If it is O (abnormal), an error is warned (7) and the first mode is interrupted.

On the other hand, if the determination in step (5) is normal, that is, if the determination is YES, the CPU section 20 causes the forward current I so that the sensor output value falls within a certain voltage range.
F is changed, and the D / A converter correction value at that time is EE
Writing (6) to the PROM 22 and ending the processing. At that time, when the D / A converter correction value exceeds the predetermined adjustment upper limit value in the first mode, it is regarded as a sensor adjustment failure error state with no adjustment margin thereafter, and the sensor automatic initial value setting is prohibited. To do. In this case, the first mode (initial value setting mode) is performed again after eliminating the sensor adjustment failure error state. [Second mode processing] On the other hand, in the judgment of step (1), N
When it is O, the CPU section 20 uses the mode selection switch 5
From the signal state of 0, the contact C2 designated by the second mode is O
It is judged whether it is N state (8), and if YES, the second mode is set (9). Next, the CPU section 20 determines whether or not the switch 51 is turned on (10), and if YES, the CPU section 20 reads the sensor level of the sensor 3a etc. (11), but the second mode is also on the production line. The mode is set by (2), and it is premised that the semi-transparent paper is set on the transport path 5. Next, it is determined whether the read sensor level of the sensor 3a or the like is within a specified value (12). In this judgment, if the read sensor level is lower than the specified value, the read sensor level is the specified value due to the fact that no semi-transparent paper is set between the sensors or due to the diffusion effect of the semi-transparent paper. If the level is higher than the above, it is assumed that the optical axes of the photodiode 24 and the phototransistor 25 are largely deviated, and if the level does not fall within the specified value, an error is displayed.
(14) Stop the work in the second mode.

On the other hand, if the determination in step (12) is YES, that is, if the sensor level is within the specified value, the paper presence level value indicating the result is stored in the predetermined address of the EEPROM 22 (13), and the process ends. To do. [Third Mode Processing] On the other hand, if the determination in step (8) is NO, it is determined that the third mode is designated, and a threshold value for determining the presence or absence of paper is calculated (15). Here, the CPU unit 20
Paperless sensor level stored in the EEPROM 22 in the first mode (at the time of initial setting) and EEPR in the second mode.
The threshold value is calculated by reading the sensor level with paper stored in the OM22 and taking the arithmetic mean of these.
The calculated threshold value is stored in the RAM in the CPU unit 20. Next, the CPU section 20 determines whether or not automatic adjustment in the third mode is possible (16). When the copying apparatus 1 is not in operation, when the sheet conveying apparatus 2 is not conveying sheets, or when there is no sheet on the conveying path 5 (no sensor sheet),
Judge that automatic adjustment is possible (YES). Then, in the automatic adjustment mode of the third mode, the CPU unit 20 changes the set value of the D / A converter 21 so that the sensor output value falls within a certain voltage range, and thus the forward current of the sensor 3a or the like. IF is changed and the D / A converter correction value at that time is written in the EEPROM 22 which is a non-volatile memory (17). At the same time, the CPU unit 20
The sensor level after the correction is stored in the same address as the sensor level stored in the first mode on the EPROM 22, and the sensor level without paper is updated. After that, the calculation of the threshold value is performed by the updated sensor level.

The sensor output adjustment value during automatic adjustment is
At the operating point of the sensor 3a, the collector-emitter voltage VCE of the phototransistor 25 begins to become a substantially constant value (collector-emitter saturation voltage VCE (SAT)). The adjustment is made so that the operating point A becomes.

Further, the CPU section 20 checks whether or not the set value of the D / A converter 21 exceeds the upper limit value of the third mode, and if it is below the upper limit value, the automatic adjustment of the sensor 3a etc. is continued. Based on this judgment, the D / A converter 21
If the set value of exceeds the upper limit, the D / A converter 2
The set value of 1 is fixed to the upper limit of the third mode, this is output, and the automatic sensor adjustment thereafter is prohibited.

It is assumed that the upper limit value of the first mode is stored in the ROM in the CPU section 20 as a predetermined value.

After the automatic adjustment in step (17) is completed, the normal paper detection operation is performed (18), but the A / D converter 12
The paper determination is performed by comparing the sensor level from 1 to the threshold value stored in the RAM in the CPU unit 20.

In the above embodiment, the case where the first to third mode designation states are determined based on the designation state by the mode changeover switch 50 has been described, but the data written in the predetermined address of the EEPROM 22 shown in FIG. It is also possible to control so that the first to third mode designation states are automatically determined according to the flow chart shown in FIG.

That is, in the paper transporting apparatus configured as shown in FIG. 10, the determining means (CPU section 20) determines whether the first mode, the second mode, or the like based on the data stored in the storage means (EEPROM 22). The figure which determines the instruction | indication state of a 3rd mode automatically, and the 1st mode control means (CPU part 20) performs execution of a 1st mode, a 2nd mode, and a 3rd mode later based on this determination result. Since the control is performed according to the flowchart shown in FIG. 12, the original sheet detection means (sensors 3a to 3c) can be automatically adjusted according to the first to third modes, so that the sensors 3a to 3c stably detect the sheet. It becomes possible to do.

FIG. 12 is a flow chart showing an example of a fourth automatic adjustment control procedure of the sheet sensor in the sheet conveying apparatus according to the present invention. Note that (1) to (18) and (31) to (3
8) shows each step. The operations shown in steps (1) to (18) are the same as those in FIG.
The operations of 1) to (38) will be described.

The transfer control unit 6 according to the present invention is composed of a control board, performs an operation check in advance by itself, and during the operation check, it is possible to determine that the control board is an initial product, for example, "FFH ( Hex) "
It is assumed that it is written in a predetermined address of the PROM 22, for example, "00H (hex)".

First, when the control board is installed in the sheet conveying device 2 at the production factory or in the market and the power is turned on, the CPU section 20 executes the step (31), and the EEPRO is executed.
Data written in a predetermined address of M22, for example, "00H (hex)" is read, and it is determined whether the read data is "FFH (hex)" (32), and if YES (transport control unit) 6 is determined to be the initial part)
Execute the initial value setting mode process after step (2)
If it is O, it is judged whether or not the read data is, for example, "0FH (hex)" (33), and if YES, the processes in and after step (9) are executed, and if NO, the read data is, for example, "00H (hex)". (Hex) '' (34), YES
If so, the third mode is set (35) and the processes of step (15) and thereafter are executed. If NO, an error is displayed and the process ends (36).

On the other hand, when the initial value setting mode process is completed in step (6), the CPU section 20 stores the data "0FH (hex)" in a predetermined address of the EEPROM 22, for example, "00H (hex)".
(37), the next time the power is turned on, the determination in step (32) is NO, and the process proceeds to step (33). Similarly, when the second mode processing is completed in step (13),
The CPU unit 20 writes the data “00H (hexa)” to a predetermined address of the EEPROM 22, for example, “00H (hexa)” (3
8) At the next power-on, the determination in step (33) is NO, and the process proceeds to step (34).

[0075]

As described above, according to the first invention, the first mode for initializing the light emission amount control data to be stored in the storage means by the mode switching means and the first mode.
The switching of the light emission amount control data initialized by the second mode to a timely updating mode, and the control means controls the light emission amount based on the first mode or the second mode instruction state according to the instruction. Since the upper limit value of the data is set to a different value, the sensor can be adjusted within the range corresponding to each mode.

According to the second invention, the control means prohibits the initialization of the light emission amount control data when the read data exceeds the upper limit value of the light emission amount control data set in the first mode. The sensor adjustment range in the first mode can be limited.

According to the third aspect of the invention, the control means prohibits the initialization of the light emission amount control data when the read data exceeds the upper limit value of the light emission amount control data set in the second mode. The sensor adjustment range in the second mode can be limited.

According to the fourth aspect of the invention, the first mode control means corresponds to the first mode, the second mode and the third mode instructed by the instructing means, and the first mode and the second mode. ，
Since the execution of the third mode is controlled, the original sheet detection means can be individually adjusted in accordance with the first to third modes, so that the light amount control means can stably detect the sheet.

According to the fifth invention, the judging means automatically judges the instructed states of the first mode, the second mode and the third mode based on the data stored in the storage means, and the judgment result is obtained. Since the first mode control means controls the execution of the first mode, the second mode, and the third mode based on the first mode,
Since the original paper detection means can be automatically adjusted in accordance with the third mode, the light amount control means can stably detect the paper.

Therefore, there is an excellent effect that the optimum sensor adjustment according to each mode can be accurately performed with a margin.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a configuration of a sheet conveying device showing an embodiment of the present invention.

FIG. 2 is a diagram showing an example of a first sensor control circuit provided in the transport control section shown in FIG.

FIG. 3 is a diagram showing a first operation characteristic of the phototransistor shown in FIG.

FIG. 4 is a diagram showing a second operation characteristic of the phototransistor shown in FIG.

FIG. 5 is a collector of the phototransistor shown in FIG.
It is a characteristic view explaining the emitter voltage VCE change.

FIG. 6 is a flowchart showing an example of a first automatic adjustment control procedure of the sheet sensor in the sheet conveying apparatus according to the present invention.

FIG. 7 is a flowchart showing an example of a first automatic adjustment control procedure of the paper sensor in the paper carrying device according to the present invention.

FIG. 8 is a flowchart showing an example of a second automatic adjustment control procedure of the paper sensor in the paper carrying device according to the present invention.

FIG. 9 is a flowchart showing an example of a second automatic adjustment control procedure of the paper sensor in the paper carrying device according to the present invention.

FIG. 10 is a second view provided in the transfer control unit shown in FIG.
It is a figure which shows an example of the sensor control circuit of.

FIG. 11 is a flowchart showing an example of a third automatic adjustment control procedure of the sheet sensor in the sheet conveying apparatus according to the present invention.

FIG. 12 is a flowchart showing an example of a fourth automatic adjustment control procedure of the paper sensor in the paper carrying device according to the present invention.

FIG. 13 is a schematic diagram showing an example of a paper detection circuit in a conventional paper transport device.

14 is a diagram showing a paper out detection state variation characteristic of the sensor shown in FIG.

FIG. 15 is a flowchart illustrating a sheet detecting operation in a conventional sheet conveying apparatus.

[Explanation of symbols]

 3a sensor 12 A / D converter 20 CPU section 21 D / A converter 22 EEPROM 23 mode selector switch 24 photodiode 25 phototransistor

Claims (5)

[Claims] 1. A paper conveyance device having a paper detection unit having a light emitting unit and a light receiving unit for detecting the presence or absence of a paper sheet conveyed to a predetermined position on a conveyance path, and reading output data from the light receiving unit. A reading unit, a light amount control unit that controls the light emission amount of the light emitting unit so that the read data read by the reading unit falls within a predetermined range, and a storage unit that stores the light emission amount control data output by the light amount control unit. And an instruction to switch between a first mode for initializing the light emission amount control data stored in the storage means and a second mode for timely updating the light emission amount control data initialized by the first mode. And the upper limit value of the light emission amount control data is changed based on the mode switching means and the first mode or the second mode instruction state by the mode switching means. And a control means for setting the value to a certain value. 2. The control means prohibits initialization of the light emission amount control data when the read data exceeds the upper limit value of the light emission amount control data set in the first mode. 1. The sheet conveying device according to 1. 3. The control means prohibits the initialization of the light emission amount control data when the read data exceeds the upper limit value of the light emission amount control data set in the second mode. 1. The sheet conveying device according to 1. 4. A paper conveying device having a paper detecting means having a light emitting portion and a light receiving portion for detecting the presence or absence of a paper sheet conveyed to a predetermined position on a conveying path, and reading output data from the light receiving portion. Reading means, light quantity control means for controlling the light emission quantity of the light emitting section so that the read data read by the reading means falls within a predetermined range, and storage means for storing light quantity data according to the light quantity received by the light receiving section. A first mode in which the initial value of the first light amount data according to the amount of light received by the light receiving unit is stored in the storage means when the paper detection sensor is not covered with the paper; A second mode in which the second light amount data according to the light amount received by the light receiving unit is stored in the storage unit, and the first light amount data and the second light amount stored in the storage unit. An instruction unit for instructing switching between a third mode for detecting the presence or absence of a sheet conveyed on the conveyance path by determining a threshold value for determining the presence or absence of the sheet based on the data, and a mode instruction state of the instruction unit First based
And a first mode control means for controlling execution of the second mode, the third mode, and the third mode. 5. A paper conveyance device having a paper detection means having a light emitting portion and a light receiving portion for detecting the presence / absence of a paper sheet conveyed to a predetermined position on a conveyance path, and reading output data from the light receiving portion. A reading unit; a light amount control unit for controlling the light emission amount of the light emitting unit so that the read data read by the reading unit falls within a predetermined range; and a storage unit for storing the light amount data according to the light amount received by the light receiving unit. In the first mode in which the storage unit stores the initial value of the first light amount data according to the light amount received by the light receiving unit when the paper detection sensor is not covered with the paper, and when the paper detection sensor is covered with the paper. A second mode in which the second light amount data according to the light amount received by the light receiving unit is stored in the storage unit, and the first light amount data and the second light amount data stored in the storage unit. Based on the data stored in the storage means, a third mode for determining the presence / absence of a sheet conveyed on the conveyance path by determining a threshold value for determining the presence / absence of a sheet based on the light amount data is stored. A sheet conveying apparatus comprising: a determination unit for determining and a mode control unit for controlling execution of the first mode, the second mode, and the third mode based on the determination result of the determination unit. .