JPH03107954A - Paper detector for automatic document feeder device - Google Patents

Abstract

PURPOSE:To facilitate the handling of a device, to dispense with a volume, and to attain cost reduction by performing such control that a judging value for the presence/absence of a document can be updated with a judging value setting means when it is detected that the frequency of occurrence of jamming exceeds a prescribed value from the count value of a jamming counter means. CONSTITUTION:A judging value update control means 24 performs the control so as to update the judging value for the presence/absence of the document with the judging value setting means 24 when it is detected that the frequency of occurrence of the jamming exceeds the prescribed value from the count value by the jamming counter means 24, then, a new judging value is set. Since the judging value is set nearer to the detection values of document sensors 7, 8 when the document is located at a position other than a detectable position, erroneous judgement by the document presence/absence judging means 24 can be suppressed. In such a way, it is possible to omit time and labor to adjust the judging value artificially, and to simplify the handling of the automatic document feeder device, and also, to dispense with, for example, the volume to adjust the judging value, and to realize the cost reduction.

Description

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

[Prior art]

Traditionally, automatic document feeders have been equipped with paper to detect the presence or absence of a document and to confirm whether the document is guided to a predetermined conveyance path when setting the document, feeding the document, and ejecting the document. A detection device is provided.

This paper detection device emits light from the light-emitting element of the document sensor toward the document, and receives the light reflected from the surface of the document by the light-receiving element of the document sensor. If the detection value is larger than the determination value, it is determined that there is a document.

By the way, the more times the automatic document feeder is used,
As a result, the light emitting output of the light emitting element and the light receiving ability of the light receiving element in the document sensor gradually decrease, and dust adheres to the light emitting surface of the light emitting element and the light receiving surface of the light receiving element, reducing the ability of each of the above elements. I will do it. At this time, the detection level of the document sensor decreases, so that while the document is being detected, the difference between the detection level and the preset determination value becomes small, or the detection level falls below the determination value. As a result, it is determined that there is no document even though there is a document, and a paper jam, that is, a jam, may occur due to double feeding of the document in the automatic document feeder section.

Therefore, in conventional paper detection devices, in order to prevent future jams when such a situation occurs, a volume is provided for adjusting the judgment value, and this volume is used to artificially reproduce the judgment value. It is adjustable.

[Problem to be solved by the invention] However, with the above conventional structure, each time a jam occurs,
It is necessary to rely on service personnel to manually readjust the judgment value, making handling of the automatic document feeder complicated, and increasing costs by providing a volume for adjusting the judgment value. There are problems.

[Means to solve the problem]

In order to solve the above-mentioned problems, the paper detection device of the automatic document feeder according to the present invention includes a document sensor that outputs detection values of different levels depending on the presence or absence of a document in the document conveyance path, as shown in FIG. In the paper detection device of the automatic document feeder, the document is located at a position where the document sensor can detect the document. and a document position detection means for detecting the document position, and a document position detection means that detects the document position based on each detection value of the document sensor when the document position detection means detects that the document is at a position that can be detected by the document sensor and a position other than the position that can be detected by the document sensor. A judgment value setting means for setting a presence judgment value, a jam counting means for counting the number of jams occurring in the document transport path, and detecting that the frequency of occurrence of jams has exceeded a predetermined value from the count value of the jam counting means. The present invention is characterized by comprising a determination value update control means for controlling the determination value setting means described in F to update the determination value of document presence or absence.

[For production]

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

The above judgment value is based on each detection value of the document sensor when the document position detection means detects that the document is in a position that can be detected by the document sensor and a position other than the detectable position. is set. The judgment value at this time is an intermediate value between the detection value of the document sensor when the document is in the detectable position and the value detected by the document sensor when the document is in a position other than the detectable position, or the value of the document sensor due to changes over time. In consideration of the deterioration of the detection function, the detection value is set closer to the detection value when the document is at a position other than the detectable position, rather than the above intermediate value.

After that, for example, if the detection function of the document sensor deteriorates, the document presence determination means determines that there is no document even though the document is in the document conveyance path, and a jam occurs in the conveyance path of the automatic document feeder. A situation like this occurs. In such a case, when the judgment value update control means detects that the jam occurrence frequency has exceeded a predetermined value from the count value by the jam counting means, the judgment value setting means sets a judgment value for the presence or absence of the document. is updated. A new determination value is thereby set. Compared to the previously set judgment value, this judgment value is set closer to the detection value of the document sensor when the document is at a position other than the detectable position. is suppressed.

In this device, the document presence/absence determination value is automatically updated as described above, so there is no need for human operations.
Erroneous determination of the presence or absence of a document due to deterioration of the document sensor can be prevented as much as possible.

〔Example〕

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

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

A conveyance belt 9 is passed around conveyance rollers 10 in the central main body portion of the automatic document conveyance device 1, and a discharge roller 11 is provided on the document discharge side. One of the conveyance rollers 10 serves as a drive unit for driving the conveyance belt 9, and the conveyance roller 10 and paper ejection roller 11 are driven by a conveyance motor 16 (see FIG. 3). ing. A paper discharge detection sensor 12 as a document sensor is provided near the paper discharge roller 11.

When the above-mentioned pull-in roller 5 swings downward, the roller 5 comes into pressure contact with the document tray set on the document loading table 4, and this document tray is rotated as shown in FIG. As shown, the paper is guided to the paper feed roller 6. Then, as shown in FIG. 3(c), the document is guided between the document table glass 3 and the conveyor belt 9 by the paper feed roller 6, and the conveyor belt 9 is driven in the direction of the arrow in FIG. As a result, the original is guided to a predetermined position on the original platen glass 3, as shown in FIG. 3(d). Copying is performed in the bent state, and after the copying is completed, the conveyor belt 9 is driven in the direction of the arrow in FIG.
1 and transported by C! '), the document is ejected to the outside of the automatic document feeder 1.

The paper feed motor 15 and the conveyance motor 16 are each 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. Each motor 1
Slit disks 18 and 19 are respectively fixed to rotating shafts 5 and 16 (not shown) so as to rotate together with the rotation shafts.
The rotations of these slit disks 18 and 19 are measured by rotation sensors 20 and 21 each having, for example, a photo ink club. The analog signal is digitized by comparators 22 and 23 and input to the interrupt input port of the microcomputer 24. microcomputer 2
4 measures the pulse interval of analog signals detected by the rotation sensors 20 and 21 based on the digital signals input from the comparators 22 and 23. If this measured pulse interval is longer than the specified interval, that is, each motor 15.
6 is slower than the specified speed, the microcomputer 24 outputs a square wave with a large ON duty ratio (-pulse width/pulse period) to the motor drive circuit 17 using a PWM method (pulse width modulation method). . The motor drive circuit 17 to which such a square wave is input increases the rotational speed of the motors by lengthening the time during which each motor 15 and 16 is energized. Conversely, if the measured pulse interval is shorter than the prescribed interval, that is, if the rotational speed of each motor 15, 16 is faster than the prescribed speed, the microcomputer 24 transmits a square wave with a small ON duty ratio to the motor. By outputting to the drive circuit 17, control is performed to reduce the rotational speed of the motors by shortening the energization time to each motor 15 and 16. In this way, the rotational speed of each motor 15, 16 is controlled to always be constant. Also,
The microcomputer 24 has the above-mentioned slit disk 18
19 and the rotation sensors 20 and 21 constitute a document position detection means. That is, the microcomputer 24
The document position is detected based on the number of rotation pulses of each motor 15 and 16.

Each of the above-mentioned sensors 7, 8, and 12 is equipped with a light-emitting element and a light-receiving element (not shown). It receives the reflected light and outputs it as an electrical signal. The output from each sensor 7, 8, 12 is sent to the amplifier 25, 26.
・The analog signals are taken in as they are to the analog port of the microcomputer 24 via the analog ports 27 and 27, respectively.

The microcomputer 24 controls each of the above-mentioned sensors 7, 8, and
12 and a predetermined determination value to determine the presence or absence of a document. Then, when there is a document, a signal is sent to the motor drive circuit 17 to drive the paper feed motor 15 and the conveyance motor 16. Further, as shown in FIG. 1, the microcomputer 24 performs a control operation as a judgment value setting means for setting a judgment value for determining the presence or absence of a document, and also performs a control operation as a judgment value setting means, as shown in FIG. It is configured to perform a control operation as a judgment value update control means for updating the judgment value when a jam occurs with a frequency exceeding . Furthermore, microcomputer 2
4 is connected to a display 30 for displaying the operating status of the automatic document feeder and for setting an automatic sensor adjustment mode.

In the above configuration, a control operation for setting a determination value for determining the presence or absence of a document in the microcomputer 24 will be explained based on FIG. 1.

When the power is turned on, it is determined whether or not an original is set (31), and if an original is set, it is determined whether the sensor automatic adjustment mode is set (31).
S2). The sensor automatic adjustment mode is set by the operator using the key on the display 3o.

In S2, if the automatic sensor adjustment mode is set, the paper feed motor 15 is activated, the lead-in roller 5 and the paper feed roller 6 are rotated, and the original on the original transport table 4 is transported. At this time, pulse number measurement is started simultaneously with the operation of the paper feed motor 15 (33). In a normal automatic document feeder, the position of the document is detected by each sensor 7, 8, and 12, but in this device, the document presence/absence judgment value is determined by the detection value when the document is present and the detection value when there is no document. Since the settings are based on the values, it is possible to judge whether or not the document has reached each sensor 7, 8, and 12, or whether the document has passed, based on the number of rotation pulses of each motor 15, 16. I try to do that.

That is, in S3, when the paper feed motor 15 is driven and measurement of the number of rotational pulses is started, it is determined whether the number of pulses has reached a predetermined number a (S4). This predetermined number a
The predetermined numbers b, c-d, which will be described later, are for each sensor 7, 8, and 1.
A predetermined value is stored in the microcomputer 24 based on the positional relationship between the two. In S4, when it is determined that the number of pulses has reached the predetermined number a, the document is moved as shown in Figure 4 (
Since the position shown in b) has been reached, the detection values of the original set detection sensor 7 and the paper feed detection sensor 8 are read (S5). As a result, a detection value is obtained from the sensors 7 and 8 when a document is present in the paper feed section of the automatic document feeder.

When this detected value is obtained, driving of the transport motor 16 is started, and measurement of the number of rotation pulses of the motor 16 is started (S6), and it is determined whether the number of pulses has reached a predetermined number (S7). ). When it is determined that the number of pulses has reached the predetermined number, the document feeder has reached the position shown in FIG. Start it (S8),
It is determined whether the copying of the original document has been completed or not based on whether or not this timer has reached the timer end (S9).

If the timer has reached the timer end in S9, driving of the transport motor 16 is started, and measurement of the number of rotational pulses of the motor 16 is started (SIO), and if the number of pulses has reached a predetermined number C or not. (S11).

Then, the detection value of the pulse number disconnection detection sensor 12 is read (S12).

As a result, a detection value is obtained from the sensor 12 when there is a document in the paper discharge section of the apparatus.

Furthermore, it is determined whether the number of rotation pulses of the transport motor 16 that is continuously measured has reached a predetermined number d (313).
, if it is determined that the predetermined number d has been reached, the document tray is at the position shown in FIG. The detected values of each sensor 7, 8, and 12 are read (315). As a result, detection values when there is no document can be obtained from each sensor 7, 8, and 12.

Based on the detection value when there is a document and the detection value when there is no document obtained from each sensor 7, 8, and 12 in this way, a judgment value Z for determining the presence or absence of a document is calculated (3
16). This judgment value Z is set between the detected value when there is a document and the detected value when there is no document, or when the document is detected more than the intermediate value, taking into account the decline in the document detection ability of each sensor 7, 8, and 12 due to changes over time. It is set closer to the detection value when there is no such thing.

Next, a control operation in which the microcomputer 24 updates the determination value when a jam exceeding a set standard 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 conveyance device, the number of conveyed sheets is added to calculate the cumulative number of conveyed sheets (321). However, the counter for the cumulative number of sheets conveyed and the counter for the number of jam occurrences are unrelated to power ON, and are counted starting from the first document after the determination value Z is updated. Next, it is determined whether or not the number of jam occurrences is two or more (522), and if it is two or more, the determination value Z is updated according to the flowchart shown in FIG. 1 (S23). Here, if it is determined that a jam has occurred between 5i and 15 (S24), the number of jams is cumulatively added, and the process moves to 321 when the jam is removed and the apparatus is reused. Furthermore, after steps 31 to 16 have been performed without any jamming and the determination value Z has been updated, the counter that counts the cumulative number of transported documents is cleared (S26), and the number of times that a jam has occurred is counted. The counter is also cleared (S27), and the process moves to 321.

Further, if it is determined in S22 that a jam has occurred when the number of occurrences of a jam is less than two (32B),
The number of jams is cumulatively added up (S29), and it is determined whether or not the cumulative number of transported sheets counter exceeds, for example, 100 (S30). Then, the counter for the cumulative number of sheets transported is 1.
If it does not exceed 00, the program returns to S21 and continues, and if it exceeds 100, the cumulative conveyed sheet counter and jam counter are cleared in accordance with S26 and S27, and then the program moves to S21.

Furthermore, if the number of jams has occurred less than two times in S22 and it is determined in 328 that no jam has occurred, it is determined in S30 whether or not the counter for the cumulative number of conveyed sheets exceeds, for example, 100. be done.

〔Effect of the invention〕

As described above, the paper detection device of the automatic document feeder according to the present invention includes a document sensor that outputs a detection value of a different level depending on the presence or absence of a document in the document conveyance path, and a detection value and a judgment value of this document sensor. In a paper detection device of an automatic document feeder, the paper detection device includes a document presence/absence determining means for comparing and determining the presence or absence of a document; Judgment value setting means for setting a judgment value for the presence or absence of a document based on each detection value of the document sensor when the device detects that the document is at a position detectable by the document sensor and at a position other than the detectable position. , a jam counting means for counting the number of occurrences of jams in the document conveyance path; and when it is detected from the counted value of the jam counting means that the frequency of occurrence of jams has exceeded a predetermined value, the above-mentioned judgment value setting means This configuration includes a determination value update control means for controlling the presence/absence determination value to be updated.

Therefore, every time a jam occurs in the automatic document feeder, it is not necessary to request a service person to manually adjust the judgment value, and the handling of the automatic document feeder is simplified. This also has the effect of eliminating the need for a volume for adjusting the determination value and reducing costs.

[Brief explanation of drawings]

1 to 4 show one embodiment of the present invention. FIG. 1 is a flowchart showing the determination value setting operation in the automatic document feeder. FIG. 2 is a flowchart showing the 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 diagrams each showing the document conveying operation in the automatic document conveying device. 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
24 is a microcomputer (document presence/absence determination means, document position detection means, determination value setting means, jam counting means, determination value update control means),
18 and 19 are slit disks (document position detection means), 20
- 21 is a rotation sensor (original position detection means).

Claims (1)

[Claims] 1. A document sensor that outputs detection values of different levels depending on the presence or absence of a document in the document conveyance path, and a document presence/absence device that determines the presence or absence of a document by comparing the detection value of this document sensor with a determination value. a paper detection device for an automatic document feeder, comprising: a document position detection device for detecting that the document is in a position where the document sensor can detect the document; and a judgment value setting means for setting a judgment value of the presence or absence of the document based on each detection value of the document sensor when the document sensor detects that the document is at a position other than the detectable position; a jam counting means for detecting the occurrence of a jam, and when it is detected from the count value of the jam counting means that the frequency of occurrence of jams is equal to or higher than a predetermined value, control is performed such that the judgment value for document presence is updated by the judgment value setting means. What is claimed is: 1. A paper detection device for an automatic document feeder, characterized in that the paper detection device includes a judgment value update control means for controlling the update of a judgment value.