JPH0158092B2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to a paper feeding device.

2. Description of the Related Art An example of a paper feeding device conventionally used in, for example, a copying machine is shown in FIG. In this case, a cassette 1 containing sheets P is removably attached to a main body of a copying machine (not shown), and a conveying roller 2 is rotatably provided so as to come into contact with the topmost sheet of the sheets P. A driving force from a pulse motor (not shown) is transmitted to the conveying roller 2 so that the sheets P can be fed out one by one from the cassette 1. The paper P sent out from such a paper feeding device is transported until the leading end in the transport direction contacts the nip portion of a pair of registration rollers 3 provided in the copying machine main body (not shown), and even after the contact, the paper P is transported as shown in FIG. The conveying roller 2 is rotated slightly to create a slight slack as shown by the two-dot chain line in the first figure, and then the pulse motor is stopped. This is to align the leading edge of the sheet P in the conveying direction and to determine the timing for subsequent processing.

However, in such a paper feeding device, even if the pulse motor is stopped, the conveyance roller 2 over-rotates due to the inertia of the drive system from the pulse motor to the conveyance roller 2, and as a result, the There was a drawback that the paper P that came into contact with the nip portion of the registration roller 3 was bent or paper jammed.

The present invention has been made based on the above circumstances, and can prevent over-rotation of the conveyance roller due to inertia of a drive system including at least a conveyance roller and a pulse motor, and has a relatively simple structure. It is an object of the present invention to provide a paper feeding device that can improve the reliability of paper feeding.

The paper feeding device of the present invention will be described below with reference to the drawings.

FIG. 2 is a schematic longitudinal sectional front view of a copying machine having a paper feeding device according to an embodiment of the present invention. In the figure, reference numeral 5 denotes a document table fixed to the main body 6 of the copying machine, and an optical system driving device 7 is provided below the document table. This is so that the lamp 8 and the first movable mirror 9 move together to scan the surface of the document placed on the document table 5.
Furthermore, a second movable mirror 11 is provided for reflecting the reflected light from the first movable mirror 9 and making it incident on the lens 10 provided ahead of the reflected light. The optical path length from the movable mirror 9 of No. 1 to the lens 10 can be kept constant. Furthermore, a photoreceptor 12 is provided approximately in the center of the copying machine body 6, and the image of the original illuminated by the lamp 8 is transmitted to the photoreceptor through the optical system drive device 7, lens 10, and two fixed mirrors 13. The image is formed on the surface of 12. Further, the photoreceptor 12
A charger 14 is provided near the charger 1.
An electrostatic latent image is formed on the surface of the photoreceptor 12 charged by the photoreceptor 4 by the illumination during image formation. This electrostatic latent image is visualized by applying a developer to it by a developing device 15. Further, a paper feeding device 18 consisting of a cassette 16 containing paper P, conveyance rollers 17, etc. is provided on the side of the copying machine main body 6, and the paper P sent out from this device comes into contact with a pair of registration rollers 19. After being aligned and aligned, it is conveyed to the circumferential side of the developed image formed on the surface of the photoreceptor 12. Then, the developer constituting the developed image is transferred onto the transported paper P by the transfer device 20, and then fixed by the fixing device 21, and then transferred to the tray 22.
It is now being taken out. A cleaning device 22a is provided near the photoconductor 12, and the photoconductor 12 after the transfer is cleaned by this cleaning device.
Further, the two-dot chain line in the figure indicates the conveyance path of the paper P.

Next, the paper feeding device 18 will be explained in detail, including FIGS. 3 to 8. FIG. 3 is a schematic perspective view showing one embodiment of the paper feeding device of the present invention, FIG. 4 is an explanatory diagram showing the relationship between the rotation speed and rotation angle of the conveying roller, and FIG. 5 shows the control means of the device. The block diagram, FIG. 6 is an explanatory diagram showing the driving method of the pulse motor, and FIG. 7 is an explanatory diagram showing the relationship between the rotational speed of the pulse motor and time. In the figure, reference numeral 16 denotes a cassette that is removably attached to the copying machine main body 6, and paper P is stored inside. A conveying roller 17 is attached to the upper part of this cassette 16 so as to be able to rotate together with a shaft 23 which is rotatably supported, and the uppermost sheet of the sheets P is always in contact with this conveying roller 17. It's summery. Further, a drive gear 25 is provided at one end of the shaft 23 via a one-way clutch 24. Note that this drive gear 25 only moves the shaft 2 when rotating in the direction of the third arrow A due to the action of the one-way clutch 24.
It is designed to be able to transmit driving force to 3. A pulse motor 27 to which a motor gear 26 that meshes with the drive gear 25 is attached, and a control means 28 for controlling the pulse motor 27 are provided.

Next, this control means 28 will be explained in detail. The pulse motor 27 without using the control means 28
to move the conveyance roller 17 in the direction indicated by the third arrow A.
When the paper P is being fed in the direction of the third arrow B while being rotated in the
When the conveyance roller 17 is stopped, the conveyance roller 17 over-rotates due to the inertia of the drive system including the conveyance roller 17 and the like. In particular, by the action of the one-way clutch 24, the conveying roller 17 is integrated with the shaft 23 and can freely rotate in the direction of the third arrow A in the figure, so the amount of over-rotation is relatively large. Such over-rotation amount θr can generally be determined by strictly solving the equation of motion of the rotational motion system shown in equation (1).

d ² θ/dt ² =−Tf (1) In equation (1), θ is the rotation angle and Tf is the friction torque, which changes depending on the angular velocity and the like. As shown in FIG. 4, this control means 28 decelerates the transport roller 17 in a rotation angle range θd (hereinafter referred to as deceleration amount) larger than the overrotation amount θr of the transport roller 17 to absorb the overrotation. This is for controlling the pulse motor 27 so that the pulse motor 27 can be operated. As shown in FIG. 5, the control means 28 has a structure in which a processor 29, a ROM 30, a timer 31, an input port 32, and an output port 33 are connected by a data bus 34. A drive circuit 35 is connected to the pulse motor 27 and sequentially switches the current flowing through the stator winding of the pulse motor 27 based on the output signal from the output port 33. Note that the pulse motor 27 is connected to an external power source Vcc. The input port 32 is connected to an operation switch 36 so that driving of the pulse motor 27 is started based on a starting signal from the operation switch 36. The timer 31 is supplied with a clock signal 38 from a clock generation circuit 37, and a timeout signal 39 is supplied as an interrupt signal to the processor 29. If, for example, a two-phase excitation method is adopted as the driving method for the pulse motor 27 consisting of phases A, B, as shown in FIG. 5, a predetermined pulse interval (phase switching time ) Excite while sequentially switching phases at ti (t ₁ to _{t o} ) (the shaded area indicates the excitation phase)
Therefore, in the present control means 28, as shown in FIG. 7, the pulse motor 27 is accelerated for a predetermined time at startup, and decelerated for a predetermined time before stopping. In other words, the range (hereinafter referred to as deceleration section) Td corresponding to the deceleration amount θd of the conveyance roller 17
In order to reduce the rotational speed of the pulse motor 27 and stop it, the phase switching time t _i is set to be sequentially increased in this deceleration section Td. Such phase switching time t _i (t ₁ to _{t o} ) is divided by the clock cycle time t _c of the clock generation circuit 37, and each value thereof is t _i /t _c (t ₁ /t _c to t _o / t _c ) is stored in the ROM 30 as timer set data, and this timer set data t _i /t _c (t ₁ /t _c to t _o /t _c ) is sequentially transmitted to the aforementioned timer set data via the processor 29 and the data bus 34. It is set in the timer 31. Incidentally, the driving time of the pulse motor 27, that is, the cumulative value _o 〓 ⁱ⁼¹ t _i of the phase switching time _t i is set so that the paper P is conveyed to a predetermined position when the pulse motor 27 stops. .

Next, the operation of this paper feeding device will be described with reference to FIG. 8, which is a flowchart of driving the paper feeding device constructed in this way. First, when the operation switch 36 is turned on, the output signal is sent to the processor 2 via the input port 32.
Detected at 9. Then, the processor 29 controls a predetermined phase of the pulse motor 27 (pulse motor 2
For example, the stop position of No. 7 is always stored in the main memory of the processor 29, and the predetermined phase at this time is the phase corresponding to this stored position). When the phase is excited, the processor 29 is enabled to accept the interrupt and can detect the timeout signal 39 from the timer 31. At the same time, this processor 29 refers to the timer set data t _i /t _c stored in the ROM 30, and when the timer set data t _i /t _c is meaningful, that is, the pulse motor 27 is excited. At this time, the first timer set data t ₁ /t _c is set in the timer 31. and the timer 31
When a timeout occurs, the timeout signal 39 output from the timer 31 causes the processor 29 to accept an interrupt. Thereafter, the processor 29 processes the ROM 30.
setting the second timer set data t ₂ /t _c stored in the timer 31;
The excitation phases A and B are switched to phase B, and the excitation phase B and the phase are excited via the drive circuit 35. When the excitation phase is switched in this way, the rotor of the pulse motor 27 starts to start, and the paper P begins to be sent out in the direction of the third arrow B in the figure via the conveyance roller 17 and the like.

The order of excitation phase switching is based on the pulse motor 27.
The order is determined by the direction of rotation, and the order is as shown in FIG. In this way, processor 2
Set the timer data sequentially according to the program in step 9.
By setting t _i /t _c and sequentially switching the excitation phases as shown in FIG. 6, the pulse motor 27 is driven at a speed inversely proportional to the phase switching time t _i (t ₁ to _{t o} ). It will be done. In the deceleration section Td, the phase switching time t _i is set to increase sequentially, so the rotational speed of the pulse motor 27 is sequentially decelerated, and the conveyance roller 17 driven by the rotation of the pulse motor 27 is The vehicle is sequentially decelerated and stopped within a range corresponding to the deceleration amount θd. In this way, the conveyance roller 17 is stopped within the range of the deceleration amount θd, which is a rotation angle range larger than the overrotation amount θr.
The paper P can be accurately fed to a predetermined position without over-rotating the paper P, and the paper P can be prevented from being bent or jammed in the vicinity of the registration rollers 19.

In the above embodiment, a case has been described in which the conveying roller is stopped after deceleration, but the present invention is not limited to this, and the present invention can also be applied to a case where the conveying roller is decelerated to a predetermined speed and then continues to be driven. Various modifications can be made without changing the gist of the invention.

As is clear from the above description, in the paper feeding device of the present invention, it is possible to prevent over-rotation of the transport roller due to the inertia of the drive system including at least the transport roller and the pulse motor, and moreover, it is possible to prevent the transport roller from over-rotating in a relatively simple manner. This configuration has excellent effects such as improving the reliability of paper feeding.

[Brief explanation of drawings]

FIG. 1 is a schematic explanatory diagram showing a paper feeding device conventionally used in, for example, a copying machine, FIG. 2 is a schematic longitudinal sectional front view of a copying machine having a paper feeding device according to an embodiment of the present invention, and FIG. 3 is a paper feeding device of the same. A schematic perspective view of the device, FIG. 4 is an explanatory diagram showing the relationship between the rotation speed and rotation angle of the conveying roller, FIG. 5 is a block diagram showing the control means of the device, and FIG. 6 is a diagram showing the drive system of the pulse motor. FIG. 7 is an explanatory diagram showing the relationship between the rotational speed of the pulse motor and time, and FIG. 8 is an explanatory diagram showing a flowchart of driving the paper feeding device. 17... Conveyance roller, 18... Paper feed device,
27... Pulse motor, 28... Control means, 29
...Processor, 30...ROM, 31...Timer, 32...Input port, 33...Output port,
34...Data bus, 35...Drive circuit, 36...
...Operating switch, 37...Clock generation circuit, 3
8...Clock signal, 39...Timeout signal.

Claims (1)

[Scope of Claims] 1. A paper feed device that transports paper by a drive system including at least a transport roller and a pulse motor, comprising: a drive means for exciting the pulse motor and driving it to rotate; and switching the excitation phase of the drive means. and a timing signal output means for supplying a signal for switching the excitation phase to the control means, and the control means is configured to cause the timing signal output means to control the drive when the pulse motor is stopped. A paper feeding device characterized in that time is sequentially set so that the timing signal is output within a range of rotation angles greater than or equal to a rotation angle of the conveyance roller due to inertia of the system.