JPS6132222B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a paper detection device for a feeding device used in a copying machine.

In a copying machine, optical scanning of a document, charging ON/OFF, or development ON/OFF is performed depending on the length of the copying machine.

Generally, a method is used in which the passage of the trailing edge of a copy sheet being conveyed is detected, and specifically, a detection means is provided in the conveyance path of a paper feeder to configure the detection method. As an example of the detection mode, FIGS. 1 and 2 each show a paper feeding device equipped with a conventional detection means.

That is, what is shown in FIG.
An actuator b is disposed in the path of the paper conveyance path a, a detection switch c is similarly disposed on the widthwise side of the paper conveyance path a, and the detection means is configured such that these two are connected by a rotatable rotating body d. Based on the contact with the copy paper e being conveyed into the paper conveyance path a, the actuator b is rotated in the vertical direction, and the passage of the trailing edge of the copy paper e is detected by the detection switch c. This is how it was done. Note that f is a paper feed cassette, and g is upper and lower guides forming the paper transport path a. Further, i is a paper feed roller.

Furthermore, in the one shown in FIG. 2, photoelectric elements h and h are provided along the upper and lower directions of the paper transport surface during the paper transport path a, respectively, to constitute a detection means.
The passage of the trailing edge of the copy paper e being conveyed into the paper conveyance path a is detected based on the presence or absence of transmitted light. In addition, in FIG. 2, the first
Components that are the same as those in the figures are given the same numbers and their explanations will be omitted.

However, in a case where such a detection unit is set limitedly in the path of the paper transport path a, at least the paper feed roller i is required as an element to achieve the detection of the trailing edge of the copy paper e. The distance from the paper feed section to the detection section must be equal to the sum of the length of the copy paper e, for example, a small paper transport path with a short distance from the paper feed section to the transfer section. A problem arises in that a detection unit cannot be installed in the copying machine.

Furthermore, with the detection means in which actuator b is disposed in the paper conveyance path a as shown in FIG. It can also cause losses.
Further, in the detection means formed by disposing photoelectric elements h, h in the path of the paper conveyance path a as shown in FIG.
Although there is no problem with paper jams, for example, when trying to detect copy paper e that is thin and has strong transparency that allows light to pass through, it is extremely difficult to detect the trailing edge of copy paper e. Have difficulty.

This invention was made in view of the above-mentioned circumstances, and its purpose is to use the paper feed roller as a detection unit to avoid the risk of paper jams and to ensure that any paper being fed can be quickly detected. It is an object of the present invention to provide a sheet detecting device for a feeding device that is particularly useful for small-sized copying machines and is capable of detecting the trailing edge.

An embodiment of the present invention will be described below with reference to FIG. Reference numeral 1 in the figure indicates a paper feeding device installed in a copying machine (not shown), and this paper feeding device 1 is roughly divided into a paper feeding mechanism 2 and a paper feeding cassette 16. The explanation is as follows.

That is, 3 in the figure is a driven shaft, and in the center of this driven shaft 3, three rollers 4 made of, for example, a rubber material are arranged in parallel along the axial direction, and constitute the paper feed roller 12. There is. The drive system for this paper feed roller 4 is constructed by providing a drive transmission gear 5a at one end of the driven shaft 3, and meshing this drive transmission gear 4 with a drive gear 5b driven by an external drive section. The rotation shaft of the drive gear 5b is transmitted to the driven shaft 3 via the drive transmission gear 5a, so that the paper feed roller 12 can be operated. In addition, a one-way clutch 6, which is a power disconnection means, is interposed between the drive transmission gear 5a of this drive system and the driven shaft 3, and the rotation of the rollers 4 of the drive transmission gear 5a in the direction of arrow A. It is set to transmit only motion. That is, roller 4...
... itself may be in a state where it is not restrained at all when rotating in the direction of arrow A.

On the other hand, the other end of the driven shaft 3 is provided with a detection device 7 that is paper trailing edge detection means. To explain this detection device 7, numeral 8 in the figure is a disk fixed to the end of the driven shaft 3, and this disk 8 is provided with a large number of slits 9 radially spaced at predetermined intervals. ing. A pair of photoelectric elements 11, 11 are provided on both sides of the disc 8 through the slit 9.
are provided facing each other to constitute a pulse generator 10. By this pulse generator 10, the paper feed roller 4 is controlled depending on the presence or absence of the slit 9...
It constitutes a non-contact detection section targeted at A detection circuit 1 is connected to this pulse generator 10.
3 are provided to constitute the detection device 7. In addition,
This detection circuit 13 will be explained later.

A paper conveyance means 14 is disposed at the next stage in the conveyance direction of the paper feed roller 12, which is configured to include such a detection device 7 and a drive system. This paper conveyance means is composed of, for example, a conveyance roller section already installed in the main body of the copying machine (not shown) or an electrostatic conveyance section of a photosensitive drum. Consists of 15. This paper conveyance means grips the copy paper 17, which is the paper to be fed into the paper feed cassette 16, which is fed one by one by the paper feed roller 12, and continuously conveys it to, for example, a transfer section. It is becoming possible to do so. Note that this paper conveyance means includes conveyance rollers 15, 15.
When the copy paper 17 is clamped and the system for clamping and conveying is established, the driving of the drive system of the paper feed roller 12 is set to stop based on the time required for continuation.

Next, the detection circuit 13 will be explained as shown in FIG.

That is, 11 in the figure is the above-mentioned photoelectric element 11,
At 11, the output sides of the photoelectric elements 11, 11 are connected to an integrator 18. Further, the output side of the integrator 18 is connected to an AND circuit 20 via an inverter 19. On the other hand, 21 in the figure is a timer (clock), one of the output sides of this timer 21 is connected to the above-mentioned integrator 18 via a delay circuit 22, and the other is connected to the above-mentioned AND circuit 20. The circuit configuration is such that output information is obtained from the AND circuit 20 based on the presence or absence of overflow within a certain period of accumulated information based on the output signal of the output signal. A signal is now available.

When feeding paper in a cassette using the paper feeding device 1 configured in this way, first the copy paper 17 is fed.
The paper feed cassette 16 containing the stacked sheets is mounted in a predetermined position as shown in FIG. Next, the user operates an operation section (not shown) of the copying machine. Then, the external drive section is operated in accordance with this operation, and the drive gear 5b
Rotate. This rotational movement passes through the drive transmission gear 5a, the one-way clutch 6, and the driven shaft 3 in this order, reaches the rollers 4, and causes the rollers 4 to rotate. Based on the drive of this roller 4, the copy paper 17 is loaded one by one from the upper layer in the paper feed cassette 16.
As shown in FIG. 4, the paper is sent forward and reaches the transport rollers 15, 15 which are already in operation.
After the front end of the copy paper 17 is clamped by the conveyance rollers 15, 15 as shown in FIG. The drive system stops. Next, the copy paper 17 is continuously held and conveyed forward by conveyance rollers 15, 15, and reaches, for example, a photosensitive drum. During this clamping and conveyance, the rollers 4 are driven to rotate by friction with the copy paper 17 being conveyed based on the structure of the one-way clutch 6.

On the other hand, in the detection device 7, the disk 8 has been rotating since the start of paper feeding, and pulse signals based on the presence/absence of the slits 9 are sequentially output from the photoelectric elements 11, 11 to the integrator 18. ing. Similarly, the timer 21 outputs clock pulses indicated by A in FIG. 8 to the delay circuit 22 and the AND circuit 20, respectively. Then, the clock pulse is output from the delay circuit 22 to the integrator 18 as a reset signal shown by B in FIG. 8, and the pulse signal is integrated by the integrator 18 within a certain period of time. While the disk 8 is rotating, the integrated integrator output reaches the inverter 19 as an overflow signal shown as C in FIG. It is outputting.

After that, during the conveyance process of the copy paper 17, when the trailing edge of the copy paper passes directly under the rollers 4, as shown in FIG. 6, the rotation of the rollers 4, which have been driven until now, stops. At the same time, the rotation of the disk 8 is also stopped, and the output of the pulse signals from the photoelectric elements 11, 11, which have been output since the start of paper feeding, is stopped.

Then, no pulse signal is input to the detection device 7, no overflow signal is output from the integrator 18, and a detection signal is output from the inverter 19 to the AND circuit 20.

As a result, the AND circuit 20 outputs a signal to stop the rotation of the roller 4 as indicated by E in FIG.
The rear end of will be detected.

Therefore, the trailing edge of any copy paper 17 can be reliably detected without requiring any obstruction to the paper transport path. Moreover, there is no danger of paper jams.

Furthermore, since the trailing edge of the copy paper 17 is detected based on the rotation and stoppage of the paper feed roller 12, the length of the paper transport path required for detection is kept to the minimum necessary, which is particularly useful for early trailing edge detection. At the same time, it is extremely useful for small-sized copying machines, and its effects are great.

In the above-mentioned embodiment, the paper feed cassette in which the copy papers are stacked is used to feed paper from the cassette, but the same effect as in the above-mentioned embodiment can also be obtained by manual paper feeding in which copy paper is fed one by one. be able to.

Further, in the above-described embodiment, a pulse generator made of a combination of a disk and a photoelectric element was used as the paper trailing edge detection means, but a pulse generator using an electromagnetic rotation sensor may also be used. For example, a generator as a detection element may be provided on the driven shaft, and stoppage of rotation of the paper feed roller may be detected by comparing the output of the generator with a threshold value.

As explained above, according to the present invention, the paper conveyance means is provided at the next stage in the conveyance direction of the paper feed roller,
The paper is conveyed in a continuous mode, and the paper feed roller is driven when the paper is conveyed by the paper conveyance means, and the paper trailing edge detection means detects the paper trailing edge based on the stopped state of the paper feed roller. Therefore, when detecting the trailing edge of a sheet, it is possible to reliably detect the trailing edge of any sheet of paper without requiring any obstruction to the sheet conveyance path. Moreover, there is no danger of paper jams.

Furthermore, since the trailing edge of the paper is detected based on the rotation and stoppage of the paper feed roller, the length of the paper transport path required for detection is kept to the minimum necessary length, which is particularly useful for early trailing edge detection, and is useful for example. It is extremely useful for small-sized copying machines, and its effects are great.

In addition, if the paper trailing edge detection means is constructed in a non-contact manner with respect to the paper feed roller, unnecessary load will not be applied to the paper feed roller, and there will be no disadvantage to the device itself. , it is possible to reliably detect the trailing edge of the fed paper.

[Brief explanation of the drawing]

FIGS. 1 and 2 are perspective views showing different conventional paper feeding devices, FIG. 3 is a perspective view showing an embodiment of the present invention, and FIGS. 4, 5, and 6 are perspective views of the paper feeding device. a perspective view showing each transition state;
FIG. 7 is a circuit diagram similarly showing the detection circuit, and FIG. 8 is an output signal line diagram showing each output signal inside the circuit and the output signal from the circuit. 6...One-way clutch (power intermittent means),
7...detection device (paper trailing edge detection means), 12...
Paper feed roller, 14...Paper conveyance means.

Claims (1)

[Scope of Claims] 1. A paper feed roller that feeds paper, and a paper transport means that is provided at the next stage in the feeding direction of the paper feed roller and receives and transports the paper that is fed by the paper feed roller. and a power intermittent means for causing the paper feed roller to follow the conveyance of the paper to be fed during conveyance by the paper conveyance means, wherein the paper feed roller is in a disconnected operating state by the power intermittent means. A trailing edge of the paper that is driven by the paper that is continuously transported by the paper transport means when the paper passes the paper feed roller and the paper feed roller stops rotating. A paper detecting device for a feeding device, comprising a detecting means. 2. Paper detection in a feeding device according to claim 1, wherein the paper trailing edge detection means is configured to detect the presence or absence of rotation of the paper feeding roller in a non-contact manner. Device.