JPH04107580A - Moving speed controller for optical system of image reader - Google Patents

Abstract

PURPOSE:To speedily stabilize the moving speed of an optical system device at a specific constant value by setting the initial voltage for feedback control over the moving speed of the optical system device according to variance among the driving mechanisms of respective devices and variation in load with time. CONSTITUTION:A CPU 1 applies a startup voltage Vs to a motor 6 through a driver circuit 5 to increase the moving speed of the optical system device 11 quickly. When the moving speed reaches a specific value, the initial voltage Via based upon a mean value Vs in a RAM 3 is applied. Thus, the initial voltage Via applied to the motor 6 in the beginning of the feedback control corresponds to the load placed on the motor 6, so a transient state of the control is changed into a stable state speedily to speedily stabilize the optical system device 11 at the specific constant speed.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to an optical system movement speed control device for controlling the movement speed of an optical system device for reading and scanning an image in an image reading device in a copying machine or the like. Regarding.

(Prior Art) In an image reading device such as a copying machine that reads and scans a document image by moving an optical system device consisting of an irradiation lamp, a mirror, etc., the optical system is moved so that this scanning is performed at a predetermined constant speed. A speed control device performs feedback control of the motor that drives the optical system device. That is, for example, as shown in FIG.
is applied to quickly raise the speed to a predetermined speed, and when the optical system device reaches the predetermined speed -, the voltage applied to the motor is switched to an appropriate initial voltage v1, and from then on, the moving speed of the optical system device is detected. By adjusting the applied voltage while giving feedback, control is performed to maintain a predetermined constant speed.

(Problem to be Solved by the Invention) However, the load applied to the motor to move the optical system device is not necessarily constant due to irregularities in the drive mechanism of each device, and also changes due to aging during use. It is something. However, the conventional optical system movement speed control device cannot handle such load fluctuations.
The initial voltage v1, which is optimal for a standard load, is uniformly applied to the motor.

Therefore, for example, in the case of a device that applies a large load to the motor, when the applied voltage is switched from the startup voltage 3 to the initial voltage Vl, as shown in FIG.
, which is too low, causes the speed of the optical system to drop once, and it takes a long time for the speed to asymptotically approach and converge again to the predetermined speed, which is the target value, due to feedback control. In addition, when the load is small, as shown in Figure 6 (b), when the startup voltage 3 is switched to the initial voltage Vl, the initial voltage v1 is too high, causing a speed transient of the optical system. Since the response becomes oscillatory, it also takes a long time to converge to a predetermined speed by feedback control in this case.

For this reason, conventional optical system movement speed control devices speed up the processing speed of the CPU, etc. that performs feedback control so that the movement speed of the optical system device quickly stabilizes at a predetermined value even when the load fluctuates. This has caused the problem of increasing the cost of the device.

In view of the above circumstances, the present invention quickly stabilizes the moving speed of an optical system device to a predetermined constant value by adjusting the initial voltage according to variations in the drive mechanism of the optical system device and changes in load due to aging. An object of the present invention is to provide an optical system movement speed control device for an image reading device that can control the speed of movement of an optical system of an image reading device.

(Means for Solving the Problems) The optical system movement speed control device of the present invention applies an initial voltage to a motor that drives an optical system device for image reading and scanning, and controls the subsequent movement speed of the optical system device. An optical system movement speed control device for an image reading device that detects the movement speed and controls the optical system device to move at a predetermined constant speed by adjusting a voltage applied to a motor based on the movement speed. , applied voltage storage means for controlling the optical system device to move at a predetermined speed by applying a voltage to the motor, and storing the voltage applied to the motor during this control; The above object is achieved by including an initial voltage setting means for setting an initial voltage to be applied to the motor when moving the optical system device based on the applied voltage.

(Function) The applied voltage storage means first applies an appropriate voltage to the motor, and then feeds back the moving speed of the optical system device to adjust this applied voltage so that the optical system device moves at a predetermined speed. control. Furthermore, the voltage applied to the motor is detected and stored by this feedback control. The voltage applied by this feedback control increases as the load applied to the motor increases, and decreases as the load decreases. Therefore, the applied voltage storage means stores the optimum applied voltage to the motor according to this load variation. However, the load applied to the motor fluctuates due to variations in the drive mechanism of the optical system device and changes over time, and does not change significantly during use, so the processing by this applied voltage storage means is
For example, it is only necessary to perform this in the initial processing that is executed every time the power is turned on to the image reading device.

When the optical system device is actually scanned to read a document image, the initial voltage setting means adjusts the initial voltage based on the applied voltage stored by the applied voltage storage means. Then, since the initial voltage used to feedback control the moving speed of the optical system device is set according to the load size of each device, only a small amount of speed correction is required by control, and the speed of this optical system device is The movement quickly stabilizes at a predetermined constant value.

Note that, before applying the initial voltage to the motor, a rising voltage higher than this initial voltage may be applied so that the moving speed of the optical system device quickly rises.

(Example) The invention will now be described with reference to examples.

An embodiment of the present invention is shown in FIGS. 1 to 4.

This embodiment is an optical system movement speed control device used in a copying machine. As shown in FIG. 2, this copying machine moves an optical system that scans a document 13 placed on a document table 12 by moving an optical system device 11 that includes a copy lamp tta, a mirror 11b, etc. It is of type. In this case, the moving speed of the optical system device 11 must be a constant value determined by the copying magnification.

The optical system movement speed control device in the copying machine described above has a computer device equipped with a CPU, ROM 2, RAM 3, and interface 4, as shown in FIG. Also, an optical system device 11 is connected to an interface 4 in this computer device via a dry noise circuit 5.
A motor 6 for driving is connected. The dry noise circuit 5 is a D/A conversion circuit that applies an analog voltage corresponding to the digital signal sent from the CPUI via the interface 4 to the motor 6.
consists of a DC motor whose rotational speed is determined by the level of the voltage applied by the driver circuit 5 and the magnitude of the load on the drive mechanism of the optical system device 11. Further, a rotary encoder 7 is directly connected to this motor 6 via a rotating shaft, and the CPUI inputs the pulse signal outputted by the rotary encoder 7 via the interface 4, and calculates the rotation speed of the motor 6 from the pulse width. It is now detectable. Note that various other devices 8 in the copying machine are also connected to this interface 4.

In accordance with the program stored in the ROM 2, the CPU in the combination coater device inputs a pulse signal indicating the rotational speed of the motor 6 from the rotary encoder 7 via the interface 4, and sends a signal to the driver circuit 5 based on this input signal. By adjusting the voltage applied to the feed motor 6, feedback control of the moving speed of the optical system device 11 can be performed. Further, this CPUI performs input/output with various devices 8 via the interface 4, and also performs other controls of the copying machine. R in computer equipment
AM3 is used to temporarily store data and the like during control processing of the CPUI.

The operation of the optical system movement speed control device having the above configuration will be explained based on FIGS. 3 and 4.

First, as shown in FIG. 3, in the initial operation when the copier is powered on, the CPU
A signal is sent to the driver circuit 5 via the driver circuit 5, and a start-up voltage (2) is applied to the motor 6. Then, the motor 6 starts moving the optical system device 11 while rapidly increasing the rotational speed. At this time, the CPU 1 detects the rotational speed of the motor 6, that is, the moving speed of the optical system device 11, by inputting the output of the rotary encoder via the interface 4. When this detected speed reaches a predetermined speed, the signal to the driver circuit 5 is changed to apply the initial voltage Vi to the motor 6, and thereafter the voltage applied to the motor 6 is changed while feeding back the output of the rotary encoder 7. adjust. As a result, the optical system bag W111, after a rapid increase in speed at startup, converges to a predetermined constant speed and moves stably. However, as a result of this feedback control, if the load applied to the motor 6 is a standard value, the voltage applied to the motor 6 will be a standard value as shown by the line B in the diagram; If the load is large, a high applied voltage is required as shown by the line A in the figure, and if the load is small, a low applied voltage is sufficient as shown by the line C in the figure. When the movement of the optical system device 11 is completed in this way, the CPU returns it to the reference position again to complete the initial operation, and also sets the average value of the applied voltage during feedback control.
is calculated and stored in RAM3.

Next, during the actual copying operation, as shown in FIGS. Rapidly increase movement speed. When this moving speed reaches a predetermined value, an initial voltage Vis based on the average value (2) stored in the RAM 3 is applied. If the load applied to the motor 6 has increased due to variations in the drive mechanism of the optical system device 11 or due to aging, the initial voltage Via will be higher than the initial voltage to some extent, as shown in FIG. . In addition, in the case of a standard load, as shown in FIG. 6(B), the initial voltage Via is the same value as the conventional initial voltage 1. Furthermore, if the load is small,
As shown in , the initial voltage Vta is a low value. Thereafter, the voltage applied to the motor 6 is adjusted without feeding back the output of the rotary encoder 7, and the same feedback control as described above is performed. As a result, optical system device 1
After the start-up voltage v3 is applied, the initial voltage via corresponding to the load on the motor 6 is applied, so the moving speed of No. 1 quickly reaches a predetermined constant value as shown in (A) to (C) of the same figure. The speed becomes stable.

As explained above, according to the optical system movement speed control device of this embodiment, the initial voltage (1) applied to the motor 6 at the beginning of feedback control. has a value corresponding to the magnitude of the load applied to the motor 6, so that the transient state of control can be quickly shifted to a steady state, and the optical system device 1111 can be quickly stabilized at a predetermined constant speed. Therefore, the burden on the CPU, which controls the moving speed of the optical system device 11, is reduced, and it becomes possible to use inexpensive elements with slow processing speeds.

(Effects of the Invention) As is clear from the above description, according to the optical system movement speed control device for an image reading device of the present invention, the initial voltages at the time of feedback control of the movement speed of the optical system device can be controlled respectively. Since the speed can be set according to variations in the drive mechanism in the device and changes in load due to aging, the moving speed of the optical system device can be quickly stabilized at a predetermined constant value. As a result, there is no need to use a high-speed processing device such as a CPU that performs feedback control, so it is possible to reduce the cost of the device.

4. Just 9F! 1 to 4 show one embodiment of the present invention, in which FIG. 1 is a block diagram showing the configuration of an optical system movement speed control device of a copying machine, and FIG. 2 is a block diagram showing the structure of the copying machine. A configuration diagram for explanation, Figure 3 is a time chart showing the relationship between the voltage applied to the motor and the moving speed of the optical system device during the initial operation of the copying machine, and Figures 4 (A) to (C) respectively. Time chart showing the relationship between the voltage applied to the motor and the moving speed of the optical system device during the copying operation of the copying machine, No. 5
6 and 6 show conventional examples, FIG. 5 is a time chart showing the relationship between the voltage applied to the motor and the moving speed of the optical system device under standard load, and FIG. 6 (A) (
B) is a time chart showing the relationship between the voltage applied to the motor and the moving speed of the optical system device when the load varies.

5... Driver circuit, 6... Motor, 7... Rotary encoder, 11... Optical system device.

that's all

Claims (1)

[Claims] 1. Applying an initial voltage to the motor that drives the optical system device for image reading and scanning, detecting the subsequent moving speed of the optical system device, and applying the voltage to the motor based on this moving speed. An optical system movement speed control device for an image reading device that controls an optical system device to move at a predetermined constant speed by adjusting an applied voltage to a motor, the optical system device moving at a predetermined constant speed by applying a voltage to a motor. The movement of the optical system device is controlled to move at a predetermined speed, and the movement of the optical system device is controlled based on the applied voltage storage means that stores the voltage applied to the motor during this control, and the applied voltage stored in the applied voltage storage means. An optical system movement speed control device for an image reading device, comprising an initial voltage setting means for setting an initial voltage to be applied to a motor at a time.