JPS6351937B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a document feeding device for a copying machine having a conveyor belt, and more particularly to a document feeding device for a copying machine whose operation timing can be precisely controlled.

The first document feeder uses a conventional conveyor belt.
FIG. 2 shows an outline of document jam detection. Further, a timing chart of signals in each part of FIG. 2 is shown in FIG. 3.

In FIG. 1, 1 is a document, 2 and 2' are lamps made of light emitting diodes, 3 and 3' are document detection sensors, 5 is a conveyor belt for the document, 24 is an ejection gate, and 25 is an entrance gate. Note that 2' and 3' act as document detectors for detecting jams.

Next, we will explain the operation of such a conventional device in the second and third stages.
This will be explained using figures.

Lamp 2' with document 1 placed at the document entrance
When the light is cut off, the output signal a of the document detection sensor 3' changes from L level to H level. The H level of the signal a is applied to a counter 102 used as a timer for detecting document feeding errors, and enables the counter 102 to count. The counter 102 sequentially counts the pulse signal b of the pulse oscillator 101 which is oscillated at a constant period.

Next, when the trailing edge of the document 1 passes the document detection sensor 3', that is, when the time t required for the document 1 to normally pass the document detection sensor 3' has elapsed, the document detection sensor 3' turns on the lamp 2' again. As a result, the output signal a of the document detection sensor 3' becomes "L" level, and the counter 102 is cleared.

However, if a jam occurs while the document 1 is being fed, the counter 102 continues counting even after the time t has elapsed, as shown in FIG. Tatsu and
A jam signal d is output.

As described above, in the conventional device, the timing at which the output signal of the counter 102, that is, the jam signal d becomes "H" level, is set to be delayed by Δt after time t has elapsed. The time period Δt is set to absorb variations in the operating time of the clutch that transmits power to the document conveyance belt 5, variations in the drive speed of the conveyance belt 5, and the like.

As described above, in conventional document feeders, even if the size of the document is known, the document will continue to be It was necessary to allow some time between the time when the edge is expected to finish passing and the time when the jam signal is output. For this reason, detection of document feeding errors is delayed, causing damage to the document.

In addition, in conventional devices, in order to align the registration of the original, the conveyor belt is driven for longer than the necessary time, or the leading edge of the original is moved past the registration position, and after the registration position is detected, Then, the conveyor belt was rotated in the reverse direction again at low speed, and the registration position of the document was adjusted. For this reason, there was a drawback that a complicated mechanism was required.

SUMMARY OF THE INVENTION An object of the present invention is to enable accurate and quick detection of misfeeding of a document, and to control various parts related to the document feeding at accurate timing. It is in.

The present invention provides one or more belt position display indicators between the indicators indicating the stopping position of an endless belt for document feeding, and also includes a sensor that can continuously detect these indicators, and a counter that counts signals detected by the indicators. The present invention is characterized in that the original feeding and related mechanisms are controlled by controlling the operation of the original feeding device or the main body of the copying machine in accordance with the output signal from the counter.

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

FIG. 4 is a perspective view of a document feeder, particularly a semi-automatic document feeder (hereinafter referred to as SADH), which is an embodiment of the present invention. In the figure, 1 is the original,
2, 2' are lamps, 3, 3' are document detection sensors, 4
is a conveyor belt drive clutch, 5 is a conveyor belt, 6 is a conveyor belt drive clutch,
is the first notch (index) used to detect the stop position (BELT HOME position) of the conveyor belt 5,
7a to 7d are second notches (indices) for generating timing signals during document feeding; 8a and 8b;
9a and 9b are light emitting elements facing the sensors 8a and 8b, and 14 is a main drive system.

Note that the width L ₁ of the first notch 6 is equal to the width of the sensor 8a,
The width L ₂ of the second notches 7 a to 7 d is smaller than the above-mentioned distance 1 . Further, in this embodiment, a case is shown in which one document is sent by a half-circle of the conveyor belt. Therefore, two sets of cutouts having the same pattern are arranged symmetrically around the conveyor belt. Furthermore, the conveyor belt 5 is driven by a main drive system 14 that drives the main body of the copying machine.
The power is controlled by connecting and disconnecting the clutch 4.

FIG. 5 is a diagram for explaining the positional relationship between the conveyor belt 5 and the document 1 when the document 1 is sent onto the platen by the conveyor belt 5, 11a, 11
b is an imaginary line of the original, 12 is a registration position, and as shown, the leading edge of the original is aligned with the registration position 12.

FIG. 6 shows a drive circuit for the document feeder shown in FIG. 4, in which 21 is a control circuit for the main body of the copying machine, 22 is a shift register, and 23 is a flip-flop circuit. Other numerals indicate the same things as in FIG. 4. FIG. 7 is a timing chart of the signals shown in FIG.

Next, the operation of the above device will be explained. Now, if the copier starts copying, first the main drive system 1
4 begins to move. Then, when a document is placed in the SADH, that is, when the sensor 3 detects the document 1, the SADH start signal a is generated from the control circuit 21 of the copying machine main body at an appropriate timing.

When the SADH start signal a becomes H level (time t ₁ in FIG. 7), the reset signal for the shift register 22 becomes L level, and the shift register 22 becomes enabled. Furthermore, as the SADH start signal a rises to H level, the flip-flop 23 is set, and the belt clutch signal C becomes H level. As a result, the belt clutch 4 is connected and the conveyor belt 5 begins to rotate. At the same time, the exit gate (EXIT
GATE) signal d, and entry gate (ENTRY
GATE) signals e both go to H level, and the discharge gate 24 and entrance gate 25 are opened. This causes the document to begin to be drawn in.

When the conveyor belt 5 starts rotating, each of the second notches 7a to 7d sequentially crosses between the sensor 8a and the light emitting element 3, and a signal from the sensor 8a is input to the shift register 22. Therefore, the shift register 22 is shifted bit by bit. When the third notch 7c crosses between the sensor 8a and the light emitting element 9a, the signal from the shift register 22
T ₃ becomes H level (time t ₂ in FIG. 7), discharge gate signal d becomes L level, and discharge gate 24 is closed. Subsequently, when the fourth notch 7d crosses between the sensor 8a and the light emitting element 9a, the signal _T4 from the shift register 22 becomes H level (time _t3 in FIG. 7), and the entrance gate signal e becomes L level and the entrance gate 25 is closed.

When the belt 5 completes half a revolution, it enters the belt stop position (BELT HOME position) again. At this time, the first
The notches 6 are for the sensors 8a, 8b and the light emitting element 9.
It comes between a and 9b. Width of first notch 6 L ₁
Since is greater than the distance 1 between the sensors 8a, 8b, the light from the light emitting elements 9a, 9b enters the sensors 8a, 8b at the same time, and the sensors 8a, 8b shown in FIG. 6 are turned on at the same time. By this,
Both signals S ₁ and S ₂ become L level. Therefore, the signal h indicating the belt stop position becomes H level,
A reset pulse is input to the flip-flop 23. This resets the flip-flop 23. And the belt clutch signal c is L
level, and the belt clutch 4 is released (time t ₄ in FIG. 7).

After this, the SADH start signal a output from the control circuit 21 of the copying machine body becomes L level,
The setting of the original onto the platen is completed (time _t5 in FIG. 7). This completes the SADH start cycle, and then begins the exposure cycle (from time _t5 in Figure 7).
_t6 ).

When the exposure cycle ends, the SADH ejection signal (SADH EXIT signal) b is output from the control circuit 21 (time t ₆ in FIG. 7), and the ejection gate 24 and belt clutch 4 are driven at the same timing as described above. . Then, the exposed original is discharged.

In addition, in the above embodiment, the belt position was detected by providing a notch in the conveyor belt and detecting the notch with a transmission type sensor, but the belt position detection method is not limited to the above detection method. For example, it is also possible to print a mark on the back side of the belt and detect the belt position based on the difference in reflectance of the mark based on the color of the background of the belt.

As described above, according to this embodiment, the timing signal emitted from the notch of the conveyor belt is used to control parts related to the rotational movement of the conveyor belt, such as controlling the entrance gate and discharge gate, controlling paper feeding, or By using it for controlling the scan start of an exposure lamp, etc., these parts can be controlled at accurate timing.

Next, a method for detecting document feeding errors using the above embodiment will be explained with reference to FIG. When the leading edge of the document 1 blocks the light from the lamp 2' placed at the entrance of the document, the output signal a of the document detection sensor 3' becomes L.
Change from level to H level. H level signal a
is applied to the counter 102, the counter 10
2 becomes a countable state. On the other hand, on the side of the conveyor belt for conveying the document 1 onto the platen,
As mentioned above, since the second notches 7a, 7b, . . . for generating timing signals are provided,
When the conveyor belt starts rotating, light emitted from the light emitting element 9a passes through the cutouts 7a, 7b, . . . and intermittently enters the sensor 8a. Therefore, the signal b output from the sensor 8a becomes a pulse signal,
It is input to counter 102 as a clock signal.

Now, assuming that the size of the document to be sent onto the platen is determined, the rear edge of the document will be placed at the lamp 2'.
and the point in time when it passes between the document detection sensor 3',
By rotating the conveyor belt 5, the number of notches provided on the conveyor belt passing between the light emitting elements 9a and the sensor 8a can be made to correspond accurately. For example, between the time when the front edge of the document 1 blocks the light from the lamp 2 and the time when the rear edge passes between the lamp 2 and the document detection sensor, there are n cutouts provided in the conveyor belt and the light emitting element 9a. If it passes between the sensors 8a, the counter 102 will be n+1.
It is only necessary to set it so that the jam signal d is output when the count is counted. At this time, if the interval between the n-th notch and the (n+1)th notch is made small, jam detection can be performed more accurately and quickly than in the method using the conventional device.

The method of detecting a document feeding error according to the present invention as described above is to provide a notch in the side of the belt that conveys the document, detect this notch with a light emitting element and a sensor, and send the detected signal to a counter. Therefore, it is not related to the clutch operating time or the driving speed of the conveyor belt, which had to be taken into consideration in the conventional method. For this reason, the jam signal delay Δt quoted in the explanation of the conventional device
can be made smaller.

In addition, as shown in FIG. 5, when detecting a feeding error of documents 11a and 11b of different sizes, the length of the document in the feeding direction is set as shown in FIG. Original size setting device 20
may be provided, and the count number of the counter 102 may be changed in response to a signal from the setting device 20.

Further, to detect a document feeding error, a photoelectric detector 11 is placed at an appropriate position on the conveyor belt 5, as shown in FIG.
0, and the number of notches in the conveyor belt 5 until the document reaches the detector 110 is counted by the counter 10.
It is also possible to count by 2. In this case, if the count number exceeds the count number when the document is normally fed, which is known in advance, a jam signal is output from the counter 102.

As described above, according to the present invention, it is possible to detect a document jam using an index such as a notch provided in the conveyor belt. It is possible to quickly detect misfeeding of documents. Therefore, damage to the document due to jams can be minimized. Furthermore, since the conveyor belt is provided with an index for generating a timing signal during document feeding, the timing signal generated from this index can be used to control each component related to the rotational movement of the conveyor belt. can be controlled with precise timing.

[Brief explanation of drawings]

Fig. 1 is a schematic cross-sectional view of a conventional document feeder, Fig. 2 is a block diagram of a conventional document feed error detection device, Fig. 3 is a timing chart of waveforms of each part in Fig. 2, and Fig. 4 is a diagram of a conventional document feeding error detection device. A schematic diagram of an embodiment of the invention;
FIG. 5 is a front view of the conveyor belt, FIG. 6 is a block diagram of the control section of the embodiment, FIG. 7 is a timing chart of waveforms in each part of the block diagram, and FIG. 8 is a document feeding error according to the present invention. A schematic circuit diagram of the detection device. FIG. 9 is a schematic diagram of another document feeding error detection device. 1... Original, 2, 2'... Lamp, 3, 3'...
Original detection sensor, 5...Transport belt, 6, 7a~
7d...Notch, 8a, 8b...Sensor, 9
a, 9b...Light emitting element, 22...Shift register, 102...Counter, 110...Photoelectric detector.

Claims (1)

[Claims] 1. A document feed belt, a plurality of detectable markers provided on the belt, a marker detector that detects the markers according to rotation of the belt, and a registration position of the document. A document detection sensor provided between the document feed belt and the document feed belt can be preset with a value according to the document size, and while the document detection sensor is detecting the document, a number of signals equal to or greater than the preset value is detected. 1. A document feeding device for a copying machine, comprising a counter that outputs a jam signal when input from an index detector, and detects a mistake in document feeding. 2. The document feeding device for a copying machine according to claim 1, wherein the output of the index detector is used to control the operation timing of each component of the copying machine.