JPS5997160A - Automatic original feeder - Google Patents

Abstract

PURPOSE:To maintain the original stop position on original placing glass always constant by providing a part to be detected which moves while maintaining the matching position with the front end of an original and disposing a sensor for detecting the front end of the original near the down stream side of the front end of the original which stops at the set position. CONSTITUTION:Feeding of paper is started by upper and lower feed rollers 2, 3 and a notch 23b for synchronization is moved synchronously by a sensor 32 for synchronization by which a hole 23a for passage of detection light is matched with the front end of the original and the original is conveyed in this state on placing glass 15. When the hole 23a comes to the position right under a seal 27, the front end of the original is detected by a detection sensor 29, and counting of clock pulses is started. When a prescribed number of pulses are counted, a conveyance belt 23 stops and the original O stops at a set position S. Since the counting of the clock pulses is accomplished near the end of original conveyance, the stop position of the original is maintained always in a specified position with good accuracy.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field) The present invention relates to a document feeder used in a copying machine.

(Prior art) In a copying machine, a wide endless document conveying belt rotates between a document placement glass and conveys the document to be copied.11. - An automatic document feeder that is set on a document placement glass and remains stationary has been proposed in the past.

In such an automatic document feeder, the leading edge of the document goes between the document placement glass and the document transport belt.

There is a known device in which the detection is detected by a detection sensor, the detection unit immediately counts clock pulses, and based on the counted number, the drive of the document conveying belt is stopped so that the document remains stationary on the document placement glass.

Figure 1 shows 1. A conventional automatic document feeder of this type is shown. In this automatic document feeder 2, the stop claw 1 is rotated counterclockwise with respect to the position shown in the figure, and the overprint paper row 22 is spaced apart from the underprint paper roller 3.

In this state, the document O to be copied is inserted into the document table 4 in the direction of the arrow until it contacts the stopper claw 1. Then, the set sensor 5 detects the manually loaded state of document 0, and when the print button (not shown) of the copying machine is turned on at the same time as this detection, the motor 7 is turned on.
At the same time as the paper starts rotating, the clutch 9 and paper feed solenoid 12 are turned on.

Then, at the same time as the document conveyance belt (hereinafter referred to as belt and burr) 13 starts rotating, the top picture paper roller 2 moves to the bottom picture paper roller 3.
The stop claw 1 is brought into pressure contact as shown in the figure, and the stop claw 1 is rotated and retracted to the position shown in the figure to release the original stopping action. After that, the paper feed clutch 14 is turned on, the overprint paper roller 2 starts rotating, and as a result, the original 0 is directed between the belt 13 and the original placing glass (hereinafter referred to as the placing glass) 15. I will send it to you.

Then, when the leading edge of the document 0 is detected by the document leading edge detection sensor (hereinafter referred to as detection sensor) 6, a clock pulse is generated by the clock disk 8 and the photo interrupter 16, and the counting of this clock pulse is started. It's designed to make you feel like you're walking.

Next, the document 0 is placed between the lower part of the belt 13 and the placing glass 1.
5, and is transported from the right to the left between it and the mounting glass 15. Ru.

On the inside of the belt 15, a plurality of rollers 17 which are driven to rotate are in pressure contact with each other due to the elasticity of a spring (not shown). Depending on the configuration, belt 15 acts to increase document transport force.

As a result, the document is transported at the same speed as the circumferential speed of the belt.

Next, when the rear end of the document passes the set sensor 5, the paper feed clutch 14 is turned off and the rotation of the overprint paper roller 2 is stopped.

Here, as mentioned earlier, when the leading edge of the document is detected by the detection sensor 6 and a certain number of clocks are counted in response to the clock pulses generated by the clock disk 8 and the photo interrupter 16, the clutch 9 is activated. At the same time as the motor 7 is turned off, the motor 7 stops, thereby cutting off the drive to the belt 13.

On the other hand, the belt 13 is caused by this rotational inertia.

It continues to rotate slightly, and the document advances to the right. During this process, when the predetermined number of clock pulses has been counted, the brake 1o is turned on, thereby stopping the clutch shaft 18 instantly.

When the clutch shaft 18 stops, the drive roller 19 stops, and as a result, the belt 13 stops completely. In this state, the document is placed on the mounting glass 15 for exposure. It stops at the top position.

In addition, in the process of such an operation, the clutch 9 is turned off,
The timing of turning on the brake 10 is staggered to avoid the influence of the fall of the clutch on the rise of the two brakes, and thereby there is no possibility that the document stopping position will vary.

However, even after taking such measures, it still remains.

There are some factors that cause the original stopping position to be inconsistent.

In the automatic document feeder using the clock control method described above, after the leading edge of the document is detected, the document is conveyed by the conveyor belt 13, and when a predetermined number of clock pulses are counted from the detection, a brake is applied to the belt, and the belt is stopped. In this case, the time for conveying the document by the belt includes the time for counting clock pulses.

Since the belt is driven by the frictional force between it and the drive roller 19, and the document is conveyed and cooled by the frictional force during the formation of the belt, slippage inevitably occurs between these belts. In particular, when transporting small-sized originals, the contact area between the belt and the original placing glass increases, which increases the load on the belt.

Along with this, the amount of slip between the belt and the drive roller increases.

Due to this slip phenomenon, the distance the document is moved is not synchronized with the number of clocks counted.

When the original is conveyed by the belt, there will be a slight delay, and the original stopping position will vary.

In this case, if the distance the document is transported after the clock pulse count is started is long, the amount of slip increases cumulatively, and this slip greatly affects the precision with which the document is stopped. Considering these points, if the document transport distance after the clock pulse count v starts is made shorter,
Clock pulses can be counted within a range where no slip occurs or the amount of slip is extremely small, and the document can be accurately stopped at the set position for exposure in synchronization with this count.

(Objective) The present invention was conceived in view of the above points. Q Aims to provide an automatic document feeder that can always keep the document stopping position on the document placement glass constant (Structure) The structure of the present invention will be explained below based on one embodiment. . It should be noted that, for the sake of convenience, the same reference numerals as in the conventional example are used for members used in this embodiment that achieve the same functions as those in the conventional example.

FIG. 2 shows a side view of an automatic document feeder according to a first embodiment of the present invention, and FIG. 3 shows a plan view of the device.

In both figures, two holes 23a, 23a for passing through the detection source are provided in the center of the document conveyance belt 23 at positions that divide the length of the belt into two.

On the other hand, the stay 24 passes through the left side of the conveyor belt 23.
is horizontally suspended on both side plates 25 and 26, and this stay 24
A black sticker 27 is pasted to face the mounting glass 15. Note that this seal 27 is larger than the hole 23a through which the detection light passes.

Reed, the optical scanner 28 of this copying machine has a document edge detection sensor (hereinafter referred to as detection sensor and M5) 29 or a sticker 27.
It is fixedly installed so as to face and be close to the mounting glass 15.

As shown in FIG. 7, the conveyor belt 23 is also provided with two synchronizing notches 23b that divide the length of the belt into two, and these two notches are provided above the belt. It is detected by a synchronization sensor 32. 2. This function will be described later.

Here, in FIG. 4, the set sensor 30 detects the original 0 inserted into the 1 manual feed set position, and
When the print button is pressed, the original is printed.

The upper and lower paper feed rollers 2 and 3 start feeding the paper.

When the document 0 is fed toward the belt 23, a hole 23a provided in the belt for passing through the detection source.

The upper and lower paper feed rollers 2,
3 and the belt 23, so that the leading edge of the document remains aligned with the hole 23a.
The original is conveyed over the placement glass 15.

During this conveyance, the detection sensor 29 (see FIG. 2) detects the conveyor belt 23 and is in an on state.

Next, when the hole 23a reaches the position (2) directly below the seal 27 as shown in FIG. 2, the detection sensor 29 reacts to the black seal 27 and turns on.

Details of this state are shown in FIG.

Thereafter, the leading edge of the document is immediately detected fL by the detection sensor 29, and counting of clock pulses starts from this point n. This function is achieved by the clock disk 8, the photointerrupter 16, a suitable counter, etc., as described in the conventional example.

Then, when a predetermined number of clock pulses have been counted, the conveyor belt 23 stops as described in the conventional example, and accordingly, the document O stops as shown in FIG. It stops at the set position S.

This stop layer, immediately K.

The optical scanner 28 starts traveling in the direction of the arrow, illumination scanning of the original is performed, and the photoreceptor (not shown) is exposed to light.

Fig. 8 shows a timing control diagram for controlling the operation of the conventional device, and Fig. 9 shows a timing control diagram for controlling the operation of the device of the present invention. A indicates the timing at which the leading edge of the original starts by the leading edge detection sensor 6 (see Figure 1).

n indicates the number of clock pulses, and t indicates the time required for conveying the document by the conveyance belt 13.

In addition, in FIG. 9, ■ indicates the detection start timing of the seal 27, A indicates the document leading edge start timing by the document leading edge detection sensor 29, 11 indicates the clock pulse, and t indicates the timing for starting the detection of the document leading edge detection sensor 29.
The document conveyance time by n is shown in each case.

Comparing both figures, in the case of the device of the present invention (Fig. 9), the number of clocks counted (nl) is as follows in the case of the conventional example (Fig. 9).
(Fig. 8), it is extremely small.

In this case, the proportion of the count time to the document transport time is extremely small.

i.e., count of clock pulses)k, A(ffflfl
The conveyance distance of the document after starting from (Fig. 9) becomes extremely short, and therefore, as mentioned above, it is necessary to count clock pulses within a range where no slip occurs or the amount of slip is extremely small. In synchronization with this count number, the document can be accurately stopped at the set position for exposure.

This is because the hole 23 moves in alignment with the leading edge of the document.
The document leading edge detection sensor 29 that detects the detected portion as shown in a and the seal 27 that detectably cooperates with the sensor 29 are stopped at the set position S (see Figure 6). This is achieved by arranging it near the downstream side in the direction of movement.

Here, an example of a method for synchronizing the rotations of the conveyor belt 23 and the paper feed roller 2.degree. 3 in order to align the hole 23a with the leading edge of the document will be described below.

It has already been mentioned that the synchronization notch 231) is provided on one side edge of the conveyor belt 23 as shown in FIG. The conveyor belt 23 begins to rotate via the motor 8, clutch 9 (see FIG. 1), etc., and thereafter the synchronization notch 231) is detected by the synchronization sensor 32.

At this time, the upper and lower feed rollers 2 and 3 start rotating, and the document 0 is sent to the conveyor belt 23, so that the leading edge of the document meets the hole 23a at an opportune time.

By the way, the relationship between the positions of the holes 23a when the synchronization notches 23b are detected is set under the following conditions.

In FIG. 4, the diameter of the hole 23a is now Ll, and the distance from the position -12=C where the leading edge of document 0 is held in the belt to the inner edge of the rear end of the hole 23a is '(c''
Assuming that L2 is the distance from the leading edge of the document to the C position, and t is the distance from the leading edge of the document to the C position, the relationship between these positions is set as shown below.

(Lt Lt )<A<Lt By satisfying such conditions, the leading edge of the document
The detection holes 23a can be made to coincide with each other when the document is fed to the conveyor belt.

In the embodiment shown in FIG. 2, the document leading edge detection sensor 29
The seal 27 is placed on the side of the optical scanner 28, and the conveyor belt 2
It is installed on the side of the stay 24 in 3,
There is no problem in replacing the detection sensor 29 and the seal 27 with each other.

(Effects) According to the present invention, the detection of the leading edge of the document for starting clock pulse count a-n is performed near the end of document conveyance. The slip does not have any effect on the clock pulse count, and therefore, the stopping position of the document, which is controlled by the count, can be maintained at a constant position with high precision.

[Brief explanation of drawings]

FIG. 1 is a side view of a conventional automatic document feeder of a copying machine, FIG. 2 is a side view of an automatic document feeder according to an embodiment of the present invention, FIG. 3 is a plan view of the automatic document feeder of the same, and FIG. The figure shows a state in which a document is about to be fed toward the document conveyance belt in the automatic document feeder shown above, and FIG. Figure 6 is a diagram showing the state corresponding to the leading edge detection sensor.
FIG. 7 is a perspective view of the document conveying belt provided in the automatic document feeder, and FIG.
The figure is a timing control diagram for controlling the operation of a conventional device.
FIG. 9 is a timing control diagram for controlling the operation of the apparatus of the present invention. 15... Document placement glass, 23... Document transport bell) % 23a... Hole that closes the detected part,
29... Original edge detection sensor. 0... Manuscript 1 b- Re-en. l+-1to

Claims (1)

[Claims] When a document is conveyed between the document placement glass and the document placement glass by rotating an endless document conveyance belt and set on the document placement glass, the document edge detection sensor detects the document edge, and this Upon detection, a clock pulse count is started, and based on this count, the original is controlled to be stopped immediately. In an automatic document feeder of a copying machine, the document conveying belt is provided with a detected portion that is detected by a document leading edge detection sensor during this movement and moves in alignment with the leading edge of the document. The most important feature is that the document leading edge detection sensor for detecting the position of the document is disposed near the leading edge of the document stopped at the set position on the downstream side in the document moving direction. Automatic document feeder.