JPH0769638B2 - Method for preventing malfunction of paper detection in automatic document feeder - Google Patents

Description

The present invention relates to a method for preventing malfunction of paper detection in an automatic document feeder (ADF: RADF) installed in, for example, a copying machine.

[Prior Art] Conventionally, an automatic document feeder is provided with a document detecting means for detecting the presence or absence of a document and confirming whether the document is guided to a predetermined transport path or the like.

The document detecting unit includes a document detecting sensor including a light emitting unit that emits light toward the document and a light receiving unit that receives light reflected by the document. Compared with the predetermined judgment level in the adjustment process performed in the final stage,
If the detected value is higher than the determination level, it is determined that the document exists.

[Problems to be Solved by the Invention]

By the way, as a copying machine or the like equipped with such an automatic document feeder is used, the light emission output of the light emitting means in the document detection sensor may gradually decrease, or the light receiving ability of the light receiving means may gradually decrease. Become. Further, the adhesion of dust to the light-emitting surface of the light-emitting means or the light-receiving surface of the light-receiving means also reduces the performance of each of the above.

Therefore, the value detected by the document detection sensor when the document is present gradually decreases, and the difference between the detected value and the determination level becomes small, so that the document detection cannot be performed accurately. Further, if the detection value when there is a document falls below the determination level, document detection becomes extremely difficult. When such a situation occurs, it is determined that there is no document even though there is a document, and paper jams frequently occur in the automatic document feeder. Then, after such a situation occurs, a service person or the like adjusts the determination level adjusting volume to change the determination level.

[Means for Solving the Problems]

In order to solve the above-mentioned problems, a paper detection malfunction prevention method in an automatic document feeder according to the invention of claim 1 is provided.
A document provided with a document detecting means for illuminating the back side of the document and receiving the light reflected by the back side of the document, and comparing the detection value of the received light with a predetermined determination level to detect the presence or absence of the document. In the automatic transport device, each time the cumulative number of transported documents reaches a predetermined number, the detection value due to light reception with a document present and the detection value due to light reception without a document are measured, respectively. Based on the above, the determination level is automatically updated, and the detection value by the light reflected at the edge of the document is used for calculating the determination level in this update.

According to another aspect of the present invention, there is provided a method for preventing malfunction of paper detection in an automatic document feeder, which irradiates light on a back surface of a document and receives light reflected on the back surface of the document, and a detection value by the received light and a predetermined value. In the automatic document feeder including the document detecting means for detecting the presence / absence of a document by comparing the determination level with The detection value due to light reception in the absence of the original is measured, and the determination level is automatically updated based on these detection values, and at the time of this update, the level change of the detection value is monitored. It is characterized in that the detected value after a lapse of a fixed time from the start of the level change is used for calculating the determination level in the update.

[Action]

According to the configuration of claim 1, even if the detection value when there is a document gradually decreases due to deterioration of the document detection sensor or the like,
The automatic update of the judgment level that takes into consideration the deterioration of the detection sensor every time the cumulative number of conveyed documents reaches a predetermined number, and the detected value when there is a document is below the judgment level in the subsequent document detection. Can be avoided,
This makes it possible to accurately detect the presence or absence of the document. Of course, it is possible to save the trouble of the service person adjusting the judgment level. Further, since the detection value by the light reflected at the edge of the document is used for calculating the determination level in this update, the reliability of the paper detection malfunction prevention method can be improved. That is, when a character or the like is written in a portion of the document illuminated by the light, the reflected light becomes weak, and this does not reflect the deterioration of the capability of the document detecting means. Although it is impossible to set and update the judgment level by using this method, it is possible to obtain a detection value that reflects the capability of the document detection unit, because the edge of the document is often a white background with few characters written on it. Therefore, the judgment level can be updated based on the deterioration of the capability of the document detection sensor.

Further, according to the configuration of claim 2, since the level change of the detected value is monitored at the time of updating, and the detected value after a lapse of a fixed time from the start of the level change is used for the calculation of the determination level in the updating, in this case Also, the reliability of the paper detection malfunction prevention method can be improved. That is, the rising portion of the detection value by the document detection means is not used, and the subsequent stable detection value is used for the determination level calculation.

〔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 platen glass 3 of the copying machine body 2. A document input side of the automatic document feeder 1 is provided with a call-in roller 5 and a paper feed roller 6, and a first document detection sensor 7 is provided near the call-in roller 5 and a call-in roller 5 and a paper feed roller. A second document detection sensor 8 is provided between the second document detection sensor 8 and the second document detection sensor 6. The pickup roller 5 and the paper feed roller 6 are driven by a paper feed motor 15 (shown in FIG. 3).

At the central body of the automatic document feeder 1, a conveyor belt 9 is provided so as to be stretched around the conveyor rollers 10 and 10 so as to move in the direction of the arrow in the figure. One of the transport rollers 10 forms a drive unit for driving the transport belt 9, and the transport roller 10 is a transport motor 16 (shown in FIG. 3).
It is designed to be driven by. A paper discharge roller 11 is provided on the document discharge side of the automatic document feeder 1, and a third document detection sensor 12 is arranged near the paper discharge roller 11.

When the pickup roller 5 swings downward, it comes into contact with the document D placed on the document carry-in table 4, and the document D
Is guided to the paper feed roller 6 as shown in FIG. Then, as shown in FIG. 3C, the document D is guided by the paper feed roller 6 between the platen glass 3 and the conveyor belt 9, and is conveyed to the conveyor belt 9 as shown in FIG. And is guided to a predetermined position on the platen glass 3. Copying is performed in such a state, and after the copying is completed, the document D is conveyed by the discharge roller 11 as shown in FIG. 7E, and the document automatic conveying device 1 as shown in FIG. Will be discharged to the outside.

As shown in FIG. 3, the paper feed roller 15 and the carry motor 16 are driven and controlled by a motor drive circuit 17, respectively. Slit discs 18 and 19 are fixed to the rotary shafts (not shown) of the motors 15 and 16 so as to rotate together with them, and the rotation pulses of the slit discs 18 and 19 are applied to the rotation sensors 20 and 21. Are measured individually. Then, each measurement information is input to the interrupt input port of the microcomputer 24 via the comparators 22 and 23, and the microcomputer 24 measures the pulse interval and the like from the above measurement information. Then, from this measurement result, a square wave with a changed ON duty ratio is output to the motor drive circuit 17. With such a square wave, the rotation speeds of the motors 15 and 16 driven by the motor drive circuit 17 are controlled so that they are always constant (PWM method: pulse width modulation method). Specifically, when the measured pulse interval is longer than the specified interval, it is determined that the rotation speed of each motor 15 and 16 is slow, and the ON duty ratio of the square wave is increased, while the pulse is reversed. When the interval is shorter than the specified interval, it is determined that the rotation speeds of the motors 15 and 16 are high, and the ON duty ratio of the square wave is reduced.

The conveyance distance of the document D can be measured by the number of rotation pulses of the motors 15 and 16 or the time after the motors 15 and 16 are rotated.
You can judge whether you have reached August 12th.

The original detection sensors 7, 8 and 12 each include a light emitting means and a light receiving means (not shown). The light emitting means irradiates the back surface of the document D with the light receiving means and the light receiving means. The light reflected on the back surface of the document D is received. The outputs from the document detecting sensors 7, 8 and 12 are taken into the analog port of the microcomputer 24 in the analog form via the amplifiers 25, 26 and 27, respectively. The microcomputer 24 detects the presence / absence of a document by comparing the detection values output from the respective document detection sensors 7, 8 and 12 with a predetermined determination level. The microcomputer 24 and the above-mentioned document detection sensors 7, 8 and 12 constitute each document detection means.

In order to implement the paper detection malfunction prevention method in the automatic document feeder having the above configuration, as shown in FIG. 2, after the power is turned on, it is determined whether or not a document is set (S1). , If the original is set, it is judged whether the judgment level automatic setting mode is set (S
2). The setting of the determination level automatic setting mode is performed by the operator by key input from the display 30.

If the sensor automatic adjustment mode is set, the above-described document feeding → conveyance → sheet ejection is performed. Of these, the paper feeding operation is first started. In this paper feeding operation, the paper feeding motor 15 is driven and the pulse number measurement of its rotation is started (S3). It is determined whether or not the predetermined number a has been reached (S4).

In a normal automatic document feeder, the position of the document is detected by the document detection sensors 7, 8 and 12, but in the present invention, the judgment level is set to the detection value when the document is present and the detection value when the document is not present. Since it is set based on the document detection sensor 7/8/12
Whether or not the original document has arrived is determined based on the number of rotation pulses of the motors 15 and 16. Therefore, the predetermined number a and the predetermined numbers b, c, d described later
Has a predetermined value based on the positional relationship of the document detection sensors 7, 8 and 12.

Further, in the present invention, since the detection value by the light reflected at the end of the original is used for calculating the determination level, the front end or the rear end of the conveyed original is detected by each of the original detection sensors 7, 8 ... The predetermined numbers a, b, c, and d are set so that the number reaches 12.

When it is determined in step 4 that the number of pulses has reached the predetermined number a, the process proceeds to step 5 and the first and second document detection sensors 7 and 8 are operated (S5). At this time, the sensors 7 and 8 each obtain a detection value when the document exists based on the light reflected at the edge of the document.

When this detection value is obtained, the conveyance motor 16 is driven and the pulse number measurement of the rotation is started (S6), and then in step 7, it is determined whether or not the pulse number has reached a predetermined number b (step S6). S7). When the number of pulses reaches the predetermined number b, the driving of the paper feed motor 15 and the conveyance motor 16 is stopped and the timer is started (S8), and it is determined whether or not this timer reaches the timer end (S9). ), If the timer end is reached, go to step 10.

In step 10, the drive of the carry motor 16 is started and the pulse number measurement of the rotation is started (S10). Then, in step 11, 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, the process proceeds to step 12, and the third document detection sensor 12 is operated (S12). At this time, the sensor 12 obtains the detection value when the document exists based on the light reflected at the edge of the document.

Then, it is determined whether or not the number of pulses has reached the predetermined number d (S13), and if so, the driving of the carry motor 16 is stopped. Thereafter, in step 15, the document detection sensors 7, 8 and 12 are operated (S15). At this time, the detection values when there is no document are obtained by the document detection sensors 7, 8 and 12, respectively.

The determination level Z is calculated based on the above detection value when there is no document and the above detection value when there is a document (S16). The determination level Z is set, for example, between the detection value when there is a document and the detection value when there is no document, or a detection value when there is no document, rather than the middle.

Then, each time the cumulative number of transported documents reaches a predetermined number,
As described above, the detection value obtained by receiving light when the original is present and the detection value obtained by receiving light when the original is not present are measured, and the determination level is automatically updated based on these both detected values. Go. That is, as shown in FIG. 1, the number of originals conveyed by the automatic document feeder is added to calculate a cumulative number (S21), and when the cumulative number exceeds 100 (S22), The processing of steps 1 to 15 described above is executed. And step 5 of the steps 1 to 15
In reading the detection value by each document detection sensor in step 12, it is detected whether or not the detection value by the document detection sensor starts changing (S23), and if the detection value starts changing, the detection value is stabilized. The timer is started in order to obtain a fixed time for (S24). And
After a certain time elapses by this timer (S2
5), the detection value of the document detection sensor is read (S26), and the determination level is calculated and updated in the same manner as the processing of step 15 described above (S27). The publication of the document based on the updated determination level is performed on the 101st and subsequent documents.

Then, the cumulative number of sheets is cleared (S28), and the process returns to step 21. Therefore, the determination level is updated every time the cumulative number of sheets reaches a predetermined number.

According to the above configuration, even if the detection value when there is a document gradually decreases due to deterioration of the document detection sensor, etc., the deterioration of the detection sensor when the cumulative number of document conveyances reaches a predetermined number is taken into consideration. By automatically updating the entered judgment level, it is possible to avoid the situation where the detection value when there is an original document falls below the judgment level. It becomes possible to detect. Of course, it is possible to save the trouble of the service person adjusting the judgment level.

Further, since the detection value by the light reflected at the edge of the document is used for calculating the determination level in this update,
The reliability of such a paper detection malfunction prevention method can be improved. That is, if characters or the like are written in the portion of the document illuminated by light, the reflected light becomes weaker,
Since this does not reflect the deterioration of the original detection unit's ability, setting and updating the judgment level based on this reflected light would be a problem, but characters and the like are rarely written on the edges of the original and white background In many cases, it is possible to obtain a detection value that reflects the capability of the document detection unit, and it is possible to update the determination level based on a reduction in the capability of the document detection sensor.

In addition, since the level change of the detection value is monitored at the time of updating, and the detection value after a lapse of a certain time from the start of this level change is used for calculation of the determination level in the updating, the reliability of the paper detection malfunction prevention method is also in this case. Can be improved. That is, the rising portion (transient state portion) of the detection value by the document detecting means is not used, and the subsequent stable detection value is used for the determination level calculation.

As a method of counting the cumulative number of sheets, after the judgment level automatic setting mode is set, the method of counting the cumulative number of sheets from the first original document, or after the power is turned on,
There is a method of counting the cumulative number of sheets by counting from the first original, or a method of counting the cumulative number of sheets regardless of the determination level automatic setting mode and power ON, but any method may be used. It is a thing.

〔The invention's effect〕

As described above, the paper detection malfunction preventing method in the automatic document feeder according to the first aspect of the present invention irradiates the back surface of the document with light and receives the light reflected by the back surface of the document, and receives the received light. In an automatic document feeder including a document detecting unit that detects the presence or absence of a document by comparing the detection value of the document and a predetermined determination level, a document is detected every time the cumulative number of document feeds reaches a predetermined number. The detection value obtained by receiving light and the detection value obtained by receiving light when there is no original are measured, and the determination level is automatically updated based on these detection values. This is a configuration that uses the detection value of the light reflected at the edge of the document.

According to a second aspect of the present invention, there is provided a method for preventing malfunction of paper detection in an automatic document feeder, which irradiates the back surface of a document with light and receives the light reflected by the back surface of the document. And a predetermined determination level are compared to detect the presence or absence of a document, and in an automatic document feeder, detection is performed by receiving light in the presence of a document every time the cumulative number of fed documents reaches a predetermined number. Value and the detection value by light reception in the absence of the original are measured, and the judgment level is automatically updated based on these detection values, and at the time of this update, the level change of the detection value is monitored. A configuration is used in which the detection value after a lapse of a fixed time from the start of this level change is used to calculate the determination level in updating.

Accordingly, even if the detection sensor is deteriorated, the presence or absence of the document can be accurately detected by reliably comparing the detection value with the determination level. Of course, it is not necessary to provide a volume for adjusting the judgment level, and the labor of the judgment level adjustment by the service person can be saved. In addition, the reliability of the paper detection malfunction prevention method can be significantly improved.

[Brief description of drawings]

1 to 4 show an embodiment of the present invention. FIG. 1 is a flowchart showing a method of using a stable detection value for calculating a judgment level. FIG. 2 is a flowchart showing a method of preventing malfunction of paper detection in the automatic document feeder. FIG. 3 is a block diagram showing a motor control means, a document detection means, and the like in the automatic document feeder. FIGS. 4 (a) to 4 (f) are explanatory views showing the manner of document conveyance in the automatic document feeder. 1 is an automatic document feeder, 7/8 and 12 are original detection sensors (original detection means), 24 is a microcomputer (original detection means), and 30 is a display.

Claims (2)

[Claims] 1. A document detection method for detecting the presence or absence of a document by irradiating the back surface of the document with the light reflected by the back surface of the document and comparing the detection value of the received light with a predetermined determination level. In the automatic document feeder equipped with the means, each time the cumulative number of transported documents reaches a predetermined number, the detection value by light reception with a document and the detection value by light reception without a document are respectively measured. The original is characterized in that the above-mentioned determination level is automatically updated based on both of these detection values, and that the detection value by the light reflected at the edge of the original is used for calculating the determination level in this update. Method of preventing malfunction of paper detection in automatic transport device. 2. A document detection method for irradiating light on the back surface of a document and receiving light reflected on the back surface of the document, and comparing the detection value of the received light with a predetermined determination level to detect the presence or absence of the document. In the automatic document feeder equipped with the means, each time the cumulative number of transported documents reaches a predetermined number, the detection value by light reception with a document and the detection value by light reception without a document are respectively measured. The determination level is automatically updated based on both of these detection values, and at the time of this update, the level change of the detection value is monitored, and the detection value after a certain time has elapsed from the start of this level change A method for preventing malfunction of paper detection in an automatic document feeder, which is used for level calculation.