JPH05238601A - Automatic document feeder provided with light detecting means - Google Patents

Abstract

PURPOSE:To simply and accurately detect the presence or absence of a document and eliminate complex adjusting work by providing a control means capable of varying detection conditions by means of a light sensor according to the photographic density of the document in an automatic document feeder provided with the light sensor detecting the presence or absence of documents. CONSTITUTION:Light sensors 1, 2 and 3 are provided down-stream of a paper supply roller, upstream of a paper drawing roller, and in a reversing transfer passage in rear of a transfer belt 6 respectively, and signals from the light sensors 1, 2 and 3 are input in the analog port of a micro computer 10 through amplifiers 7, 8 and 9 respectively. When the light receiving levels of the light sensors 1, 2 and 3 are read in a CPU 10 as signals meaning that there is a document, the light generation level is calculated by a light generation level calculator 10a based on the read light receiving level, the quantity of the light generation of the light sensors 1, 2 and 3 is adjusted by a light generation quantity controlling means 10b. That is, if the light generation level is low, the light generation quantity of the sensors 1, 2 and 3 is raised, and if high, the light generation quantity of the sensors 1, 2 and 3 is adjusted to the lowering side.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic document feeder for detecting the presence / absence of a document by light detecting means.

[0002]

2. Description of the Related Art In a conventional automatic document feeder for detecting the presence / absence of a document by an optical sensor of this type, the determination level of the optical sensor is adjusted in advance at the time of product shipment, and the actual document density is adjusted. No adjustment has been made to the detection conditions such as the judgment level and the light emission amount of the optical sensor.

[0003]

In the conventional automatic document feeder having the light detecting means, erroneous detection may occur when a dark document or a thin document is detected.

Further, level adjustment is required before shipment, which requires labor and time.

[0005]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned drawbacks of the prior art, in which the light of a light emitting element is applied to an original and the light reflected from the original is received by a light receiving element. In the automatic document feeder including the light detecting means for detecting the presence / absence of the original, the control means for varying the detection condition of the light detecting means according to the density of the original is provided.

[0006]

According to the above-described automatic document feeder, the presence or absence of the original can be easily and accurately detected because the detection conditions of the light detecting means, such as the light emission amount and the judgment level, are automatically adjusted depending on the density of the original.

Further, troublesome adjustment work can be omitted.

[0008]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a sectional view showing the schematic arrangement of an automatic document feeder according to the present invention. FIG.
FIG. 7B is a diagram illustrating a paper feed state, FIG. 7C is a transport state, FIG. 8D is a stop state, FIG. 8E is a paper discharge state, and FIG.

FIG. 2 is a circuit block diagram according to the present invention.

FIG. 3 is a control flowchart according to the present invention.

In the figure, reference numerals 1, 2 and 3 denote photosensors for detecting an original. Specifically, the light emitting element and the light receiving element are
A reflection type optical sensor is used in which light emitted from a light emitting element is reflected by a document and is received by a light receiving element.

Reference numeral 4 denotes the original document 2 placed on the original document table 21.
It is a paper feed roller for feeding 2.

Reference numeral 5 is a feed-in roller for feeding the fed original 22 to the conveyor belt 6.

The optical sensor 1 is provided on the downstream side of the sheet feeding roller, and the optical sensor 2 is provided on the upstream side of the drawing roller 4.

Further, the optical sensor 3 is provided in the backward reversing conveyance path of the conveyance belt 6.

The signals from the optical sensors 1, 2 and 3 are passed through amplifiers 7, 8 and 9, respectively, to a microcomputer (CP).
U) It is input to the analog port of 10.

The paper feed roller 4 and the take-in roller 5 are driven by a paper feed motor 13, and the conveyor belt 6 is driven by a conveyor motor 15.

The control of the motors 13 and 15 will be described. Slit disks 14 and 16 are directly connected to the paper feed motor 13 and the conveyance motor 15, respectively, and rotation pulses of the respective motors are counted by rotation sensors 17 and 18. The counted data is sent to the CPU through the comparators 19 and 20.
It is input to 10 interrupt input ports.

The pulse interval of the rotation sensors 17 and 18 is measured and the motor drive circuit 1 is based on the measurement result.
Square wave with 2 ON duty changed (PWM method)
Is output to control the rotation speed of the motor to be constant.

For example, when the measured time is longer than the reference time, it is determined that the motor speed is slow, and the ON duty is increased. On the contrary, when the measured time is short, the ON duty is decreased.

Next, the document detection control according to the present invention will be described with reference to the flow chart shown in FIG.

First, in step S1, it is determined whether or not the original 22 is set on the original table 21.

When it is determined that the original 22 is set, it is determined in step S2 whether various modes have been set.

When the mode setting is completed, copying is started by operating the copy start key, and in step S3 the paper feed motor 13 is turned on and the rotation sensor 17 counts the rotation pulse of the slit disk 14 attached to the motor 13. Start being done.

Next, in step S4, it is determined whether or not the counted number of pulses has reached a preset value A (indicating that the optical sensor 1 or 2 has been reached).

When it is determined that the count pulse number has become A, the light receiving levels of the optical sensors 1 and 2 are read into the CPU 10 as the presence of the original document in step S5.

Next, in step S6, the light emission level is calculated by the light emission level calculation means 10a based on the read light reception level.

When the original is dark, the light reflected from the original is small and the light receiving level is low. On the contrary, when the original is light, the light reflected from the original is large and the light receiving level is high.

Next, in step S7, the light emission amounts of the optical sensors 1 and 2 are adjusted by the light emission amount control means 10b. That is, when the emission level is low, the sensors 1, 2
The amount of light emission is increased, and conversely, when the amount is high, the amount of light emission is decreased.

When the light emission amounts of the optical sensors 1 and 2 are adjusted and set, next, in step S8, the carry motor 15 is turned on.
The original is conveyed and the rotation sensor 18 counts the rotation pulse of the slit disk 16 attached to the motor 15. In step S9, it is determined whether or not the counted number of pulses has reached a preset value B (indicating that the document stopper 7 has been reached).

When it is determined that the count pulse number has become B, in step S10, the paper feed motor 13 and the carry motor 15 are turned off, and the counting of the copy time is started.

Then, in step S11, it is determined whether or not the timing of the copy time has ended.

When it is determined that the time measurement is completed, in step S12, the conveyance motor 15 is turned on to convey the document, and the rotation sensor 18 starts counting the rotation pulse of the slit disk 16.

In step S13, it is determined whether or not the counted number of pulses has reached a preset value C (indicating that the sheet has arrived at the sheet discharge position).

When it is determined that the count pulse number has reached C, the sensor 3 detects the presence of paper, and therefore step S1
At 4, the light receiving level of the sensor 3 is read.

Subsequently, in step S15, the light emission level calculation means 10a calculates the light emission level based on the read light reception level of the sensor 3.

Then, in step S16, the light emission amount of the optical sensor 3 is adjusted by the light emission amount control means 10b.

When the amount of emitted light is low, the amount of emitted light is increased, and when it is high, the amount of emitted light is decreased.

When the light emission amount of the sensor 3 is adjusted, it is determined whether or not the number of pulses counted in step S17 has reached a preset value D (indicating that the pulse has been discharged onto the discharge tray). It

When it is determined that the count pulse number has reached D, the carry motor 15 is turned off in step S18.

With the above-mentioned structure, the light emission amount of the light emitting element of the optical sensor can be adjusted according to the actual density of the original, so that the presence or absence of the original can be accurately detected.

FIG. 4 is a control flowchart showing another embodiment of the present invention.

First, in step S101, the light receiving levels of the photosensors 1, 2 and 3 when the original is absent are read and stored in the first storage means (not shown) of the CPU.

Next, in step S102, it is determined whether or not the document is set on the document table 21.

When it is determined that the original 22 is set, it is determined in step S103 whether various modes have been set.

When the mode setting is completed, the copy is started by operating the copy start key, and step S104
At, the paper feed motor 13 is turned on, and the rotation sensor 17 starts counting the rotation pulses of the slit disk 14 attached to the motor 13.

In step S105, it is determined whether or not the counted number of pulses has reached a preset value A (indicating that the optical sensor 1 or 2 has been reached).

When it is determined that the count pulse number has become A, the light receiving levels of the optical sensors 1 and 2 when the original is present are read into the CPU and stored in the second storage means (not shown) in step S106. To be done.

Next, in step S107, the determination level (threshold level) of the optical sensor is calculated based on the received light level data with and without the original.
Is calculated by

Subsequently, the determination level calculated in step S108 is newly set as the thresholds of the sensors 1 and 2.

When the determination level is set, step S10
At 9, the transport motor 15 is turned on to transport the document, and the rotation sensor 18 counts the rotation pulses of the slit disk 16 attached to the motor 15.

Next, it is determined in step S110 whether or not the counted number of pulses has reached a preset value B (indicating that the document has reached the stopper 7).

If it is determined that the number of pulses has become B, the paper feed motor 13 and the carry motor 15 are turned off in step S111, and the counting of the copy time is started. When it is determined in step S112 that the time measurement is completed, the carry motor 15 is turned off in step S113.
When the document is conveyed to N and the document is conveyed, the rotation sensor 18 starts counting the rotation pulse of the slit disk 16.

Then, in step S114, it is determined whether or not the number of pulses has reached a preset value C (indicating that the sheet has arrived at the sheet discharge position).

When it is determined that the count pulse number has reached C, the light receiving level of the sensor 3 is read and stored in the second storage means because the sensor 3 detects that the document exists in step S115. It

Next, in step S116, the determination level of the optical sensor 3 is calculated based on the data stored in the first and second storage means.

The calculated judgment level is set as the threshold of the optical sensor 3 in step S117.

Next, in step S118, it is determined whether or not the count pulse number has become D (indicating that it has been discharged onto the paper discharge tray), and if so, step S1
At 19, the carry motor 15 is turned off.

As described above, the threshold of the optical sensor can be set based on the light receiving level when the original is actually present.

[0061]

According to the automatic document feeder of the present invention, since the detection condition of the light detecting means is automatically adjusted depending on the density of the document, the presence or absence of the document can be detected easily and accurately.

Further, troublesome adjustment work can be omitted.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a schematic configuration of an automatic document feeder according to the present invention, in which (a) is a document set state, (b) is a fed state, (c) is a conveyed state, and (d) is a stopped state. , (E) is a diagram showing a discharged state, and (f) is a diagram showing a discharged state.

FIG. 2 is a circuit block diagram according to the present invention.

FIG. 3 is a control flowchart according to the present invention.

FIG. 4 is a control flowchart of another embodiment.

[Explanation of symbols]

 1, 2 and 3 light detection means 10 control means

Claims (3)

[Claims] 1. An automatic document feeder including an optical detecting unit that detects the presence or absence of a document by irradiating the document with light from a light emitting element and receiving light reflected from the document by a light receiving element. Accordingly, an automatic document feeder including a light detecting means is provided with a control means for varying the detection condition of the light detecting means. 2. The light emitting level calculating means for calculating a light emitting level based on a light receiving signal of the light detecting means when the presence of an original is detected by the light detecting means, and the light emitting level calculating means. 2. The automatic document feeder including the light detecting means according to claim 1, wherein the light emission amount is controlled according to the light emission level calculated by. 3. The control means comprises means for reading and storing a light receiving signal of the light detecting means when the original is absent, and means for reading and storing a light receiving signal of the light detecting means when the original is present, 2. The automatic document feeder according to claim 1, wherein the original presence / absence determination level is set on the basis of a light receiving signal when the original is absent and when the original is present.