JP2572855B2 - Paper detection device for automatic document feeder - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a paper detection device of an automatic document feeder (ADF, RDF) provided in a copying machine, for example.

(Prior art)

2. Description of the Related Art Conventionally, an automatic document feeder has a paper for detecting whether or not a document is present and confirming whether or not the document is guided to a predetermined transport path when setting a document, feeding a document, and discharging the document. A sensing device is provided.

This paper detecting device irradiates light from the light emitting element of the original sensor toward the original, receives light reflected on the original surface by the light receiving element of the original sensor, and sets a value detected by the original sensor as a value detected in advance. If the detection value is larger than the determination value, it is determined that the document is present.

By the way, as the number of times the automatic document feeder is used increases, the light emitting output of the light emitting element in the document sensor and the light receiving ability of the light receiving element gradually decrease, or the light emitting surface of the light emitting element and the light receiving surface of the light receiving element are reduced. Dust adheres,
The performance of each of the above elements will be reduced. At this time, since the detection level of the document sensor decreases, the difference between the detection level and a preset determination value decreases or the detection level falls below the determination value while the document is being detected. As a result, it is determined that there is no original despite the presence of the original, and a paper jam, that is, a jam may occur due to the double feed of the original by the automatic document feeder unit.

Therefore, in the case of such a situation, the conventional paper detection device suppresses the subsequent occurrence of a jam.
A decision value adjusting volume is provided, and the decision value can be artificially readjusted with this volume.

[Problems to be solved by the invention]

However, in the above-described conventional structure, every time a jam occurs, it is necessary to request a service person or the like to re-adjust the judgment value artificially, which makes the handling of the automatic document feeder complicated and complicated. However, there is a problem that the cost is increased by providing the volume.

[Means for solving the problem]

In order to solve the above-mentioned problem, the paper detection device of the automatic document feeder according to the present invention includes, as shown in FIG. 5, a document sensor that outputs different levels of detection values depending on the presence or absence of a document in a document feed path. In a paper detection device of an automatic document feeder, comprising: a document presence / absence determination means for comparing presence / absence of a document by comparing a detection value of the document sensor with a determination value. A document position detecting means for detecting the position of the document, and detecting the document at a position other than the detectable position and the detectable position by the document sensor based on each detection value of the document sensor. Judgment value setting means for setting a judgment value of presence / absence, jam counting means for counting the number of occurrences of jams in the document conveyance path, and counter for counting the cumulative number of documents conveyed in the document conveyance path And when it is detected from the count value of the jam counting means that the frequency of occurrence of the jam has become equal to or more than the predetermined value, until the cumulative number of conveyed sheets of the document becomes equal to or more than the predetermined value from the count value of the counter. A determination value update control means for controlling the determination setting means to update the determination value of the presence or absence of the document is provided.

(Operation)

According to the above configuration, the presence / absence of a document in the document transport path of the automatic document transport device is determined by comparing the detection value of the document sensor with the determination value by the document presence determination unit.

The above-described determination value is determined by the determination value setting unit when the document position detection unit detects that the document is at a position other than the detectable position and the detectable position by the document sensor. It is set based on. The set value at this time is an intermediate value between the detection value of the document sensor when the document is at the detectable position and the detection value of the document sensor when the document is at a position other than the detectable position, or the document sensor due to aging. Is set closer to the detection value when the document is located at a position other than the detectable position than the above-mentioned intermediate value in consideration of the deterioration of the detection function.

Then, for example, if the detection function of the document sensor deteriorates,
When the document presence / absence determination unit determines that there is no document even though the document is in the document transport path, a situation occurs in which a jam occurs in the transport path of the automatic document transport apparatus. In such a case, the judgment value change control means detects the presence or absence of the document by the judgment value setting means when it detects that the frequency of occurrence of the jam has exceeded a predetermined value from the count value of the jam counting means. Is controlled to be updated.
As a result, a new determination value is set. This determination value is set closer to the detection value of the document sensor when the document is at a position other than the detectable position, compared to the previously set determination value. Is suppressed.

Further, if the frequency of occurrence of the jam becomes equal to or more than the predetermined value before the cumulative number of originals conveyed in the original conveyance path becomes equal to or more than the predetermined value, the determination value update control means determines that the occurrence of the jam is less than the detection capability of the original sensor. The determination value setting means is controlled so that the determination value is determined to be due to the decrease, and the determination value of the document presence / absence is updated. That is, the determination value update control unit does not update the determination value of the presence or absence of the document when the frequency of occurrence of the jam is greater than or equal to the predetermined value after the cumulative number of documents transported in the document transport is equal to or greater than the predetermined value. In this case, the judgment value setting means is controlled.

This makes it possible to accurately determine whether the occurrence of a jam is due to a decrease in the detection capability of the document sensor based on the cumulative number of documents transported. Then, the judgment value of the presence or absence of the original can be updated.

In this apparatus, as described above, the determination value of the presence or absence of the document is automatically updated only when the detection capability of the document sensor is reduced, so that no manual operation is required, and the presence or absence of the document due to the deterioration of the document sensor is eliminated. Can be prevented as much as possible.

Embodiment An embodiment of the present invention will be described below with reference to FIGS. 1 to 4.

As shown in FIG. 4A, the automatic document feeder 1
It is arranged on a platen glass 3 of the copying machine body 2. The automatic document feeder 1 is provided with a draw-in roller 5 and a paper feed roller 6 on the document feed-in side, and a document set detection sensor 7 as a document sensor is provided near the draw-in roller 5. A paper feed detection sensor 8 as a document sensor is provided between the paper feed roller 6 and the paper feed roller 6. The draw-in roller 5 and the paper feed roller 6 are driven by a paper feed motor 15 (see FIG. 3).

A transport belt 9 is stretched over transport rollers 10 and 10 at the center main body of the automatic document transport apparatus 1, and a paper discharge roller 11 is provided on the document discharge side. Transport roller 10
One of the driving rollers 10 drives the transport belt 9, and the transport roller 10 and the discharge roller 11 are driven by a transport motor 16 (see FIG. 3). In the vicinity of the paper discharge roller 11, a paper discharge detection sensor 12 as a document sensor is provided.

When the attracting roller 5 swings downward, the roller 5 comes into pressure contact with a document D set on the document carrying table 4, and the document D is rotated by the attracting rotation of the roller 5 as shown in FIG. As shown, it is guided to the paper feed roller 6. Then, as shown in FIG. 3C, the original D is guided between the original platen glass 3 and the transport belt 9 by the feed roller 6,
The original D is guided to a predetermined position on the original platen glass 3 as shown in FIG. 2D by driving the transport belt 9 in the direction of the arrow in FIG. 2C. Copying is performed in this state, and after completion of the copying, the transport belt 9 is moved to the state shown in FIG.
The document D is driven in the direction of the arrow in
11 and is discharged out of the automatic document feeder 1 as shown in FIG.

The feed motor 15 and the transport motor 16 are driven by a motor drive circuit 17 controlled by a microcomputer 24, as shown in FIG.
The microcomputer 24 constitutes document presence / absence determination means, document position detection means, determination value setting means, jam counting means, and determination value update control means. The rotating disks (not shown) of the respective motors 15 and 16 are respectively fixed with slit disks 18 and 19 so as to rotate together with the motors. The rotation of these slit disks 18 and 19 includes, for example, a photo interrupter. These are measured by the rotation sensors 20 and 21, respectively. The analog signal is digitized by the comparators 22 and 23 and input to the interrupt input port of the microcomputer 24. The microcomputer 24 measures the pulse interval of the analog signal detected by the rotation sensors 20 and 21 based on the digital signals input from the comparators 22 and 23. If the measured pulse interval is longer than the specified interval,
If the rotation speeds of the rotation speeds 15 and 16 are lower than the specified speed, the microcomputer 24 sends a square wave having a large ON duty ratio (= pulse width / pulse period) to the motor drive circuit 17 by the PWM method (pulse width modulation method). Output. The motor drive circuit 17 to which such a square wave is input is connected to each motor 15
・ The rotation speed of the motor is increased by increasing the energization time to 16. Conversely, if the measured pulse interval is shorter than the specified interval,
When the rotation speeds of the motors 15 and 16 are higher than the specified speeds, the microcomputer 24 outputs a square wave having a small ON duty ratio to the motor drive circuit 17 so that
The motor is controlled so as to reduce the rotation speed of the motor by shortening the energization time to 15 and 16. Thus each motor 15
・ The rotation speed of 16 will be controlled to be always constant. The microcomputer 24 constitutes document position detecting means together with the slit disks 18 and 19 and the rotation sensors 20 and 21. That is, the microcomputer 24 detects the document position based on the number of rotation pulses of each of the motors 15 and 16.

Each of the sensors 7, 8, and 12 includes a light-emitting element and a light-receiving element (not shown). The light-emitting element irradiates light on the surface of the original D, and the light-receiving element emits light on the surface of the original D. Receives the light reflected by and outputs it as an electrical signal. The outputs from the sensors 7, 8, and 12 are taken as analog signals into analog ports of the microcomputer 24 via amplifiers 25, 26, and 27, respectively. The microcomputer 24 is provided with the above sensors 7 and 8
A function as document presence determining means for determining the presence or absence of a document by comparing a detection value based on the output of 12 with a predetermined determination value. When a document is present, a signal for driving the paper feed motor 15 and the transport motor 16 is sent to the motor drive circuit 17.

As shown in FIG. 1, the microcomputer 24 performs a control operation as a judgment value setting means for setting a judgment value for judging the presence or absence of an original, and as shown in FIG. When a jam occurs at a frequency exceeding the set reference before the cumulative number of documents conveyed exceeds the set reference, a control operation as a determination value update control unit for updating the determination value is performed. .
Further, the microcomputer 24 is connected to a display 30 for displaying the operation state of the automatic document feeder and for setting the automatic sensor adjustment mode.

A control operation of the microcomputer 24 for setting a determination value for determining the presence or absence of a document in the microcomputer 24 will be described with reference to FIG.

When the power is turned on, it is determined whether or not a document is set (S1). If the document is set, it is determined whether or not the sensor automatic adjustment mode is set (S1).
2). Set the sensor automatic adjustment mode on the display 30
This is performed by the operator by key input at.

In S2, if the sensor automatic adjustment mode is set, the feed motor 15 is operated, the attracting roller 5 and the feed roller 6 are rotated, and the document on the document carrying table 4 is conveyed. At this time, the pulse number measurement is started simultaneously with the operation of the paper feed motor 15 (S3). In a normal automatic document feeder, the position of a document is detected by each of the sensors 7, 8, and 12. However, in this device, the determination value of the presence or absence of a document is determined by a detection value when a document is present and a detection value when a document is not present. Since the value is set based on the value, it is determined whether or not the original has arrived at each of the sensors 7, 8, and 12.
Alternatively, it is determined whether or not the document has passed based on the number of rotation pulses of each of the motors 15 and 16.

That is, in S3, when the rotation pulse number measurement is started at the same time when the sheet feeding motor 15 is driven, it is determined whether the pulse number has reached the predetermined number a (S4). The predetermined number “a” and the predetermined numbers “b”, “c”, and “d” to be described later are determined by the microcomputer 24 based on the positional relationship between the sensors 7, 8, and 12.
Is stored in In S4, if it is determined that the number of pulses has reached the predetermined number a, since the document D has reached the position shown in FIG. 4B, the detection of the document set detection sensor 7 and the paper feed detection sensor 8 is performed. Read the value (S5). As a result, a detection value when a document is present in the sheet feeding unit of the automatic document feeder is obtained from the sensors 7 and 8.

When this detection value is obtained, the driving of the transport motor 16 is started, and the measurement of the number of rotation pulses of the motor 16 is started (S6), and it is determined whether or not the number of pulses has reached a predetermined number b (S7). ). When it is determined that the number of pulses has reached the predetermined number b, since the original D has reached the position shown in FIG. 4D, the driving of the feed motor 15 and the transport motor 16 is stopped, and the timer is started. The timer is started (S8), and it is determined whether or not the copying of the document D is completed based on whether or not this timer has reached the timer end (S9).

If the above timer has reached the timer end in S9, the drive of the transport motor 16 is started and the
Is started (S10), and it is determined whether or not the number of pulses has reached a predetermined number c (S11). When it is determined that the number of pulses has reached the predetermined number c, since the document D has reached the position shown in FIG. 4E, the detection value of the paper discharge detection sensor 12 is read (S12). As a result, a detection value when a document is present in the paper discharge unit of the apparatus is obtained from the sensor 12.

Further, it is determined whether or not the continuously measured number of rotation pulses of the transport motor 16 has reached a predetermined number d (S13). If it is determined that the predetermined number d has been reached, the document D 4 Since the discharge is completed at the position shown in FIG. 4F, the drive of the transport motor 16 is stopped (S14). After this,
In step 15, the detection values of the sensors 7, 8, and 12 are read (S15). As a result, a detection value when there is no original is obtained from each of the sensors 7, 8, and 12.

In this manner, a determination value Z for determining the presence or absence of a document is calculated based on the detection value when there is a document and the detection value when there is no document obtained from each of the sensors 7, 8, and 12 (S1).
6). The determination value Z is intermediate between the detection value when a document is present and the detection value when no document is present, or considering the deterioration of the document detection ability of each of the sensors 7, 8, and 12 due to aging, the document is more than the intermediate value. It is set closer to the detection value when there is no such value.

By the way, in general, when the number of times of use of the automatic document feeder increases, the light emitting output of the light emitting element and the light receiving ability of the light receiving element in the document set detection sensor 7, the paper feed detection sensor 8, and the paper discharge detection sensor 12 gradually decrease, Dust adheres to the light emitting surface of the light emitting element and the light receiving surface of the light receiving element, and the performance of each element is reduced. In a state in which the performance of each element is reduced, that is, in a state of a so-called temporal change, each sensor 7.8,.
Since the detection level of twelve is reduced, erroneous determination of the presence or absence of a document is likely to occur. Each of these sensors 7 and 8 that have changed over time
In 12, the document is detected as being out of document even though the document is present in the automatic document feeder unit.As a result, a paper jam, that is, a jam, occurs due to the double feed of the document to the automatic document feeder. Will do.

As described above, since the detection of the presence or absence of the original by each sensor 7, 8, 12 depends on the detection level of each sensor 7, 8, 12, the detection level of each sensor 7, 8, 12 is changed by the aging. Is decreased, the frequency of occurrence of jams also increases.

Therefore, in order to detect the presence / absence of a document in accordance with the detection level of the sensor that has changed over time, the number of occurrences of the jam is set in advance, and when the number of jams exceeds this set value, the determination for document detection is performed. You just need to update the value.

Next, a control operation in which the microcomputer 24 updates the judgment value when a jam exceeding the set reference occurs in the automatic document feeder will be described with reference to FIG.

First, when the power is turned on and a document is conveyed by the automatic document conveying apparatus, the number of conveyed sheets is added to calculate the cumulative number of conveyed sheets (S21). However, the counter for the cumulative number of conveyed sheets and the counter for the number of occurrences of jam are not related to the power ON.
After the determination value Z is updated, the calculation is started from the first document. Next, it is determined whether or not the number of occurrences of the jam is two or more (S22), and if it is two or more, the determination value Z is updated according to the flowchart shown in FIG. 1 (S2).
3). Here, during the processing from S1 to S15, it is determined whether or not a jam has occurred inside the ADF (S24). If it is determined that a jam has occurred, the determination value Z is updated and the Are accumulated (S25), and the process proceeds to S21 when the jam is removed and the apparatus is reused. In S24,
If it is determined that no jam has occurred, the process is performed from S1 to S16, and after the determination value Z is updated, the counter for counting the cumulative number of conveyed documents is cleared (S26), and the number of occurrences of the jam is reduced. The counting counter is also cleared (S2
7), proceed to S21.

When the number of occurrences of the jam is less than two in S22, if it is determined that the jam has occurred (S28), the number of the jams is cumulatively added (S29), and the counter of the cumulative number of conveyed sheets exceeds 100, for example. Is determined (S
30). If the counter of the cumulative number of conveyed sheets does not exceed 100, the program returns to S21 and the program is continued. Move to.

Further, if it is determined in S22 that the number of occurrences of the jam is less than two, and it is determined in S28 that no jam has occurred, the counter of the cumulative number of conveyed sheets is set to 1 in S30.
It is determined whether or not it exceeds 00.

〔The invention's effect〕

As described above, the paper detection device of the automatic document feeder according to the present invention includes a document sensor that outputs different levels of detection values depending on the presence or absence of a document in the document feed path, and a detection value and a determination value of the document sensor. A document detection unit for detecting that a document is at a position detectable by a document sensor; and a document position detection unit. Determination value setting means for setting a determination value of presence or absence of a document based on each detection value of the document sensor when the document is detected at a position other than the detectable position and the detectable position by the document sensor; A jam counting unit that counts the number of occurrences of jams in the document conveyance path, a counter that counts the cumulative number of documents conveyed in the document conveyance path, and By cumulative transport number is detected from a predetermined value or more, when the occurrence frequency from the count value of jams counting means detects became a predetermined value or more,
A determination value update control unit that controls the determination setting unit to update the document presence / absence determination value is provided.

Therefore, every time a jam occurs in the automatic document feeder, the trouble of requesting a service person or the like to manually adjust the determination value can be omitted, and the handling of the automatic document feeder can be simplified. A volume for adjusting the determination value is not required, and the cost can be reduced.

Also, the judgment value is updated only when the frequency of occurrence of the jam becomes equal to or more than the predetermined value until the cumulative number of conveyed sheets of the original becomes equal to or more than the predetermined value. This also has an effect that the determination value can be accurately updated only when the detection capability is reduced.

[Brief description of the drawings]

1 to 4 show an embodiment of the present invention. FIG. 1 is a flowchart showing a determination value setting operation in the automatic document feeder. FIG. 2 is a flowchart showing a judgment value updating operation in the automatic document feeder. FIG. 3 is a block diagram showing the configuration of the automatic document feeder. FIGS. 4 (a) to 4 (f) are explanatory views showing a document conveying operation in the automatic document conveying apparatus. FIG. 5 is a block diagram corresponding to the configuration shown in the claims. 1 is an automatic document feeder, 7 is a document set detection sensor (document sensor), 8 is a paper feed detection sensor (document sensor), 12 is a paper ejection detection sensor (document sensor), 24 is a microcomputer (document presence / absence determination means, Document position detecting means, judgment value setting means, jam counting means, judgment value updating control means), 18.
19 is a slit disk (document position detecting means), and 20 and 21 are rotation sensors (document position detecting means).

Claims (1)

(57) [Claims] A document sensor for outputting a detection value of a different level depending on the presence or absence of a document in a document conveying path; a document presence / absence determining means for comparing the detection value of the document sensor with a determination value to determine the presence / absence of the document; In the paper detection device of the automatic document feeder provided with: a document position detecting means for detecting that the document is at a position detectable by the document sensor; and a document position detecting means for detecting the document by the document position detecting means. A determination value setting means for setting a determination value of presence / absence of a document based on each detection value of the document sensor when it is detected at a position other than the position; and a jam counter for counting the number of occurrences of a jam in the document conveyance path. Means, a counter for counting the cumulative number of documents transported in the document transport path, and detecting from the count value of the counter that the cumulative number of documents transported is greater than or equal to a predetermined value. By the time, when it is detected from the count value of the jam counting means that the frequency of occurrence of the jam has exceeded a predetermined value, the determination setting means controls the determination setting means to update the determination value of the presence or absence of the document. And a paper detecting device of the automatic document feeder.