JPH02215632A - paper feeding device - Google Patents

Abstract

PURPOSE:To appropriately maintain feed timing of a paper sheet to a process part by constituting the device to institute the time after rotation of a paper sheet feeding roller up to detecting the paper sheet with a sensor and the rotating time of the paper sheet feeding roller based on the distance from a paper sheet feeding part to the sensor. CONSTITUTION:The remaining time required to reach a paper sheet feeding distance containing a decided resist quantity in a timing roller 3 is searched, based on the time which a paper sheet 7 fed from a paper sheet feeding part 5 reaches a sensor 4, and rotation of paper sheet feeding rollers 1, 2 are stopped when the resist time is lapsed after arrival of the paper sheet 7 to the sensor 4. Hereby, the fed paper sheet 7 always generates a decided shaped flexure on its front end part, and is carried always in appropriate condition to a copying process part 26 at rotation of the timing roller 3. By this constitution, even though paper feeding speed varies due to variation with lapse of time, the paper sheet 7 is always fed with a constant resist quantity of the timing roller 3.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application The present invention relates to a paper feeding device used in an apparatus having a paper transport section, such as an image forming apparatus.

2. Description of the Related Art In an image forming apparatus such as a copying machine, a copy image or the like is formed in an image forming section on a sheet fed from a paper feeding section. In order for this image forming section to accurately form an image at a predetermined position on the paper, the paper must always be guided to the image forming section at the appropriate timing.This means that processes other than image formation must be performed on the paper. The same applies to other processing devices. Therefore, with conventional paper feeding devices,
A timing roller is provided in a paper conveyance path from a paper feed section to a processing section such as an image forming section, and paper is fed from the paper feed section to the non-rotating timing roller at a timing earlier than a predetermined timing.

Next, after the leading edge of the paper comes into contact with the timing roller, the rotation of the paper feed roller is stopped, and the paper is stopped with the leading edge deformed into a loop shape, and when the timing roller starts rotating, the leading edge of the paper is securely fixed by its elastic force. From this state, the timing roller starts rotating at a predetermined timing so that the paper is guided to the processing section at an appropriate timing.

(C) Problems to be Solved by the Invention As described above, in a paper feeding device equipped with a timing roller, the elastic force generated on the paper is change,
When the timing roller starts rotating, the appearance of the leading edge of the paper sandwiched between the rollers changes, so this registration amount must be kept constant in order to optimize the timing of transporting the paper to the processing section. However, conventional paper feeding devices do not take into account the change in paper feeding time from the paper feeding section to the timing roller over time (the time from the start of paper feeding until the rotation of the paper feeding roller stops is always constant). Therefore, when the frictional force between the paper feed roller and paper changes due to changes over time such as wear on the surface of the paper feed roller and the paper feed speed changes, the amount of paper registration at the timing roller changes. Therefore, there is a problem in that the timing of transporting the paper to the processing section cannot be kept constant.

An object of the present invention is to keep the registration amount of paper at the timing roller constant by changing the paper feeding time based on the paper feeding speed between the paper feeding section and the timing roller, and to prevent the paper from reaching the processing section. An object of the present invention is to provide a paper feeding device that can maintain proper conveyance timing.

(d) Means for Solving the Problems The paper feeding device of the present invention feeds paper from the paper feeding section to the timing roller by rotation of the paper feeding roller. a sensor disposed between the paper feed rollers and detects the paper, and a sensor that detects the paper, and controls the rotation of the paper feed roller based on the time it takes for the sensor to detect the paper after the paper feed roller rotates, and the distance from the paper feed section to the sensor. A rotation time setting means for setting the time, and the following are provided.

That is, as shown in FIG. 1, when a paper feed start signal is supplied to the drive unit, the paper feed roller rotates, and the paper is fed from the paper feed unit to the timing roller.

The paper feeding start signal is also supplied to timer A of rotation time setting means. This timer A measures the time until the paper reaches the sensor after the start of paper feeding. When the sensor detects the leading edge of the paper, the time t1 measured by timer A is supplied to the calculation section. The calculation unit calculates the remaining time t2 required until the paper stops with a certain amount of registration as shown by the broken line in the figure, based on the distance r from the paper feed unit to the sensor and the time t1 (
, 2. Set this time t2 in timer B. When timer B measures time t2, a paper feed stop signal is supplied from the signal generator to the drive unit, and the drive of the paper feed roller is stopped.

(e) Effect In this invention, when the paper fed from the paper feeding section reaches the sensor, the timing roller moves the paper feeding distance including a certain amount of registration based on the distance between them and the time required during this time. The remaining time required to reach this time is determined, and paper feeding is stopped when this time has elapsed. Therefore, paper feeding is affected by changes over time such as wear on the surface of the paper feeding roller. Even when the speed changes, the paper feeding distance is kept constant by changing the paper feeding time, and the registration amount of the paper at the timing roller is always maintained constant.

(f) Embodiment FIG. 2 is a schematic diagram showing the configuration of a copying machine to which a paper feeding device according to an embodiment of the present invention is applied.

A photoreceptor drum 22 is rotatably supported inside the copying machine 21, and a charger 23 is provided on the outer periphery.
, a developing device 24, a transfer charger 25, and the like constitute a copying process section 26. A document table 27 is provided on the top surface of the copying machine 21, and an optical system device including a light source 28 is provided on the bottom surface of the document table 27. The optical system distributes the light reflected from the original by the light source 28 onto the surface of the photoreceptor drum 22 via a mirror and a lens. A paper cassette 8 containing paper 7 is attached to one side of the copying machine 21, and together with the paper feed roller 1 constitutes a paper feed section 5. A paper feed roller 2 and a timing roller 3 are provided between the paper feed section 5 and the copy process section 26, and constitute a paper conveyance path 6.

Prior to the start of the copying process, the paper feed rollers 1 and 2 are driven, and the paper 7 is transferred one by one from the paper feed section 5 to the copy process section 2.
Paper is fed in six directions. Before the start of the copying process, the timing roller 3 has stopped rotating, and the fed paper 7 comes to a stop with its front end brought into contact with the timing roller 3. When the copying process is started, the timing roller 3 rotates at a predetermined timing, the paper 7 is guided between the photoreceptor drum 22 and the transfer charger 25, and the developer image formed on the surface of the photoreceptor drum 22 is transferred. transcribed. A sensor 4 is provided between the paper feed roller 2 and the timing roller 3, and detects the fed paper 7.

FIG. 3 is a block diagram of the main parts of the control section of the copying machine.

Drivers 35 to 37 are connected to the CPU 3 i via an I10 interface 34. This driver 35
A main motor 38, a paper feed solenoid 39, and a timing roller clutch 40 are connected to each of the motors 37 through 37. The main motor 38 supplies rotational force to the photosensitive drum 22, paper feed rollers 1 and 2, and timing roller 3.

The paper feed solenoid 39 selects whether or not to transmit the rotation of the main motor 38 to the paper feed rows 1 and 2. The timing roller clutch 40 selectively transmits the rotation of the main motor 38 to the timing roller 3.

Furthermore, detection data from the sensor 4 is input to the CPU 3 i via the I10 interface 34.

The CP and U31 output control data to the drivers 35 to 37 according to a program written in the ROM 32 in advance. The drivers 35 to 37 drive the main motor 38, paper feed solenoid 39, and timing roller clutch 40 based on this control data. In addition, as shown in FIG. 4, memory areas MAR to MA3 of the RAM 33 connected to the CPU 31 are used for a measurement timer Tl (corresponding to timer A in FIG. 1) and a registration timer T2 (corresponding to timer B in FIG. 1). ) and is assigned to the registration flag Fl.

5 and 6 are flowcharts showing the processing procedure of the control section of the copying machine.

When the power is turned on to the copying machine 21, initialization (nl) such as clearing the inside of the RAM 33 is performed, and further, warming-up is executed to raise the heat roller (not shown) to a predetermined temperature (n2). Once completed, it will wait for you to press the print switch. When the print switch is operated (n3), the main motor 38
, the chargers such as the electrification charger 23 and the transfer charger 25 are driven, and a developing bias is applied to the developing device 24 (n4 to n6) 0 Then, the paper feeding solenoid 39 is driven to feed the paper (nl) , drives the copy lamp 28 to scan the image of the document placed on the document table 27 (n8, n9), and then drives the timing roller clutch 40 at a predetermined timing to rotate the timing roller 3 to scan the image of the document placed on the document table 27 (n8, n9). is transported to the copying process unit 26 (nlo). The predetermined driving timing of the timing roller clutch 40 is the timing at which the front edge of the developer image formed on the photosensitive drum 22 and the front edge of the paper coincide at the position of the transfer charger 25.

When the optical system device reaches the end of the document, the optical system is moved backwards.
1l), turn off the copy lamp 28 (n12), perform the above processes n7 to n12 continuously for the set number of copies, and when the operation for the set number of copies is completed, the developing device 24, charger 23, 25 and main The motor 38 is turned off (n14 to n16) and the state returns to the print switch operation standby state. To explain in detail the paper feeding process of nl in the above process, when the print switch is operated, as shown in FIG. After that, drive the paper feed solenoid 39 at a predetermined timing (n21) and rotate the paper feed rollers 1 and 2.Next, check the state of the registration flag F1 assigned to the memory area MA3 of the RAM 33 (n22), If this registration flag F1 is not set, the measurement timer T1 is started to measure the time t1 until the sensor 4 turns on (n 23. n 24
), when the sensor 4 is turned on, the registration time t2 is calculated from the time t1 measured by the timer TI according to the following formula (
n 25) - t 2 = (t 1 L/6) - tl In the above formula, i is the paper feeding distance from the paper feeding section 5 to the sensor 4, and L is the paper containing a certain amount of registration at the timing roller 3. The paper feeding distance is t1+t2, and the time required to feed the paper this distance is tl+t2. The process of n25 above is the process in the arithmetic unit shown in FIG.

The registration time t2 thus obtained is set in the registration timer T2 (n26), and the registration flag F1 is set (n27), and the process returns to n22. When the registration timer T2 times up, the paper feed solenoid 40 is turned off (n28, n29).

Based on the time t1 for the paper 7 fed from the paper feed section 5 to reach the sensor 4 through the above processing, the remaining time required for the timing roller 3 to reach a paper feeding distance that includes a certain amount of registration. A certain registration time t2 is determined, and when the registration time t2 elapses after the paper 7 reaches the sensor 4, the rotation of the paper feed roller 1.2 is stopped. As a result, the fed paper 7 always has a certain shape of flexure at its front end, and when the timing roller 3 rotates, it is always fed one shell to the copying process section 26 in an appropriate state.

In this embodiment, the registration time t2 is always calculated when feeding the paper 7, but the registration time is calculated every time a predetermined number of sheets are conveyed, and this registration time is stored in a battery-backed memory. It is also possible to store the registration time and feed the paper using the stored registration time until the next calculation. Further, the present invention can be similarly implemented in other devices that feed paper at a predetermined timing.

(Effects of the Phantom Invention According to this invention, even if the paper feeding speed changes due to changes over time, the paper can be fed while keeping the registration amount on the timing roller constant. It is possible to keep the paper sandwiched in a constant state and maintain the conveyance timing from the timing roller in an appropriate state.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the configuration of the present invention, FIG. 2 is a schematic diagram showing the configuration of a copying machine to which a paper feeding device according to an embodiment of the present invention is applied, and FIG. 3 is a diagram showing the control section of the copying machine. A block diagram of the main parts, Figure 4 shows the RAM that constitutes part of the control section of the copying machine.
FIG. 5 is a flowchart showing the processing procedure of the control section of the copying machine, and FIG. 6 is a flowchart explaining in detail the paper feeding process in the processing procedure of the control section of the copying machine. 1.2-Paper feed roller, 3-Timing roller, 4-Sensor, 5-Paper feed section, 7-Paper.

Claims (1)

[Claims] (1) In a paper feed device that feeds paper from the paper feed unit to the timing roller by rotation of the paper feed roller, a sensor is placed between the paper feed roller and the timing roller to detect the paper, and a paper feed roller is installed between the paper feed roller and the timing roller. A paper feeder comprising: rotation time setting means for setting the rotation time of the paper feed roller based on the time it takes for the sensor to detect the paper after rotation and the distance from the paper feed section to the sensor; Device.