JPH04239671A - Paper feeder for image forming apparatus - Google Patents

Abstract

PURPOSE:To obtain a stable paper feed performance with a simple construction and at a low cost by a method wherein the conveying speed of paper is detected and paper feed timing is controlled based on the detected result. CONSTITUTION:Count values of an A counter 4 are taken into a conveying speed decision device 5 and compared with a count value (timing value) of standard conveying speed stored in a memory 3. When the actual speed is faster (when the count value of the A counter 4 is smaller than the standard timing value), the count value of the A counter 4 is subtracted from the standard timing value, and the result (difference) is stored in a B register 6. Then, a paper feed controller 2 adds the value stored in the B register 6 to the standard timing value to obtain an actual control timing, and performs paper feed according to the control timing obtained.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a paper feeding mechanism for an image forming apparatus such as a copying machine, and more particularly to a paper feeding mechanism suitable for a small, highly functional, and low-cost front-loading type copying machine.

0002

[Prior Art] Conventionally, paper feed control in copying machines, laser beam printers, etc. requires lower precision than optical system control, and so little consideration has been given to stabilizing paper feed performance. It wasn't. This is because desired accuracy can be guaranteed as long as the drive timing of the paper feed motor is accurate.

0003

[Problems to be Solved by the Invention] However, in recent years, the small and low-cost front-loading type (transfer paper is set at the lower front of the device and fed to the upper part where the photoreceptor is located during transfer) has become popular. (type) copiers,
The paper feeding path is long, which makes paper feeding accuracy a problem. For example, if variations in paper feeding performance occur due to variations in the machine's conveying force, changes in circuit performance due to temperature, errors in settings, etc., those errors will be magnified during paper feeding and the output (in a given time If the number of copies (number of copies) changes or goes out of the permissible range of the device, malfunctions such as false detection of a jam occur. Therefore, in such cases, it is necessary to stabilize the paper feed, but it is not acceptable to complicate the device and increase costs must be avoided, and the reality is that there is no optimal control method. Met. Based on such considerations, the inventors have investigated the following control techniques.

In other words, two methods for stabilizing paper feeding performance in devices with long paper feeding paths are to completely control and stabilize the paper feeding speed, and to wait for the paper to reach the optimum speed just before the main body feeds the paper. One possible method is to feed paper at the appropriate timing.

However, if a complete control circuit is introduced to realize the former technique, the device will become complicated and the cost will inevitably increase, so it cannot be applied to popular machines that pursue low cost. The latter technology is used in popular low-cost machines. When the copy key is pressed, the rotation of the main motor is uniformly transmitted to each part, conveying the paper with slippage, and refeeding the resist. It cannot be applied to a mechanism that uses paper as a shutter. That is, in a system based on a continuous and uniform sheet feeding operation, selective speed adjustment of only a portion is not allowed and cannot be applied. The present invention was made based on such consideration,
The purpose is to provide a new paper feed control mechanism that is simple and suppresses cost increases.

[0006]

[Means for Solving the Problems] The present invention provides a conveyance speed detection means for measuring the conveyance speed of paper discharged from a paper feed unit, and a paper feed timing control that controls the paper feed timing based on the detected conveyance speed. It is characterized by having means.

[0007]

[Operation] We have changed the conventional concept of controlling motor rotation and varying the conveyance speed to control the paper feeding timing according to the device condition (conveying force, temperature characteristics of the circuit, error in settings, etc.), and to set the paper feed timing at a specified point in time. The paper position is determined by feedback control, thereby stabilizing the paper feeding performance. That is, by slowing the paper feeding timing to a fast paper feeding system and giving early paper feeding timing to a slow paper feeding system, stable performance is always obtained as an output.

[0008]

Embodiments Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a diagram showing the main part configuration of an example of a copying machine to which the present invention is applied.

The present embodiment is a front-loading type copying machine in which a paper feed unit (PFU) 7 is located at the lower part of the front surface, and its operations are centrally controlled by a CPU 1. Further, when the copy key 18 is pressed, the rotation of the main motor M is transferred to the rollers 8, 9, 10 via the transmission mechanisms 13, 14.
, 11, 12, etc.,
The paper sent out from the PFU 7 is conveyed to the upper main unit, the image on the photosensitive drum 15 is transferred thereto, and the paper is discharged via the fixing unit 16. An intermediate photosensor 17 provided at an intermediate position of the paper feeding path is used to detect the paper feeding speed.

The CPU 1 also has a paper feed control means 2 and a conveyance speed determination means 5 as functional blocks, and
The hardware includes an A counter (3) for counting the time until the fed paper reaches the intermediate photosensor 17, and a B counter (3) for storing the paper feeding timing instruction value.
It has a register (6) and a memory 3 that stores the standard transport speed of the device. The paper feed control means 2 is the transmission mechanism 1
3 and 14 to control the timing of paper feeding (and transfer, etc.), and the conveying speed determining means 5 compares the actual conveying speed with the standard conveying speed, and determines the optimum feeding speed from the result. The paper timing is determined and the paper feed timing instruction value is stored in the B register. Paper feed control means 2
controls the paper feeding timing according to the value of the B register.

Next, the operation (control procedure) of the apparatus shown in FIG. 1 will be explained using FIG. 2. When the copy button is pressed to start copying, the paper feed control means 2 first determines whether it is the first copy (the first copy), and if it is the first copy, the paper feed control means 2 The process moves to step 26 to determine the paper feed speed. That is, when the paper feed timing comes (step 26), the transmission mechanisms 13 and 14 are controlled to turn on the paper feed (step 27), and at the same time, a start signal ST is input to the A counter to start counting. (Step 28). Next, when the conveyed paper reaches the intermediate photosensor 17 and the sensor is turned on (step 29), a stop signal ST is input to the A counter 3 to stop counting (step 30). If copying is not completed (step 31), step 2
Returns to 0 and executes the copy routine for the second and subsequent copies.

That is, the count value of the A counter is taken into the conveyance speed determining means 5 and compared with the count value (timing value) of the standard conveyance speed stored in the memory 3 (step 21). As a result, if the actual conveyance speed is faster than the standard speed (that is, if the count value of the A counter is smaller than the standard timing value), the count value of the A counter is subtracted from the standard timing value, and the result (difference) is is stored in the B register (step 22)
. Next, the paper feeding control means 2 adds the value of the B register to the standard timing value to obtain the actual control timing, and executes paper feeding according to the timing (step 23). In addition, in step 21, if the actual conveyance speed is slower than the standard speed (that is, if the count value of the A counter is larger than the standard timing value), the standard timing value is subtracted from the count value of the A counter, and the result is (difference) is stored in the B register (step 24). Subsequently, the paper feeding control means 2 subtracts the value of the B register from the standard timing value to obtain the actual control timing, and executes paper feeding according to the timing (step 25). Thereafter, the transport speed detection routine of steps 26 to 30 is executed for each copy. However, the present invention is not limited to this, and the detection of the transport speed may be performed only for the first copy in the case of continuous copying.

FIG. 3 is a diagram showing an example of paper feeding timing when the control shown in FIG. 2 is performed. The top row shows the standard paper feeding timing, the middle row shows the case where the actual transport speed is higher than the standard speed, and the lower row shows the case where the transport speed is lower.

In this case, when the conveyance speed is high, paper feeding is started delayed from the standard timing by the difference period T1 from the standard value, and when the conveyance speed is low, conversely, the difference period T1 is delayed from the standard value.
Paper feeding starts at a timing 2 earlier. Through such timing control (adjustment), stable performance can always be obtained as an output.

[0015]

Effects of the Invention As explained above, the present invention has a long paper feeding path and is difficult to stabilize the paper conveyance speed.
By detecting the actual paper conveyance speed, determining the status of the device, and feeding back the results to the paper feeding timing to adjust errors, it is possible to consistently and stably feed paper with a simple configuration and low cost. It has the effect of achieving paper performance.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing a main part configuration of an example of a copying machine to which the present invention is applied.

FIG. 2 is a flowchart showing the operation (control procedure) of the device in FIG. 1;

FIG. 3 is a diagram showing an example of paper feeding timing when the control shown in FIG. 2 is performed.

[Explanation of symbols]

1 CPU 2 Paper feed control means 3 Memory 4 A counter 5 Conveying speed judgment means 6 B register 7 Paper feed unit (PFU) 8, 9, 10, 11, 12 Roller 13, 14 Transmission mechanism 15 Photoreceptor drum 16 Fusing unit 18 Copy key

Claims (2)

[Claims] 1. A paper feeding apparatus comprising: a conveyance speed detection means for measuring the conveyance speed of paper discharged from a paper feed unit; and a paper feed timing control means for controlling the paper feed timing based on the detected conveyance speed. A paper feeding mechanism in an image forming apparatus. 2. The image forming apparatus has a long paper feeding path, and the paper transport speed is not stabilized, and the transport speed detection means detects the paper transport speed for each paper feed. If the paper transport speed is slower than a preset standard speed, the paper feed timing control means feeds the paper at the standard paper feed timing by a time corresponding to the difference from the standard speed. 2. The paper feed timing is made faster, and when the paper conveyance speed is faster than the standard speed, the paper feed timing is made slower than the standard paper feed timing by a time corresponding to the difference from the standard speed. Paper feeding mechanism in an image forming apparatus.