JPS633692A - Control device for mobile member - Google Patents

Abstract

PURPOSE:To perform the conveyance of mobile members quickly and to prevent step-out phenomena and noise, by switching the voltage to be impressed to a pulse motor either in forward or in backward movement. CONSTITUTION:The power supply voltage V1 has relation to V2 in inequality: V1<V2, either of which is selected respectively by transistors T1 and T2. When mobile substance goes astern in high speed while a pulse motor is being controlled in backward movement, the transistor T1 is switched OFF and the transistor T2 switched ON. In this way, the voltage V2 is impressed to a coil L of each phase of the pulse motor. when the mobile substance goes ahead in low speed while the pulse motor is being controlled in forward movement, the transistor T1 is switched ON, the transistor T2 switched OFF. Thus the voltage V1 is impressed to the coil L of each phase of the pulse motor.

Description

Detailed Description of the Invention (Hereinafter, blank) 3. Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a control device that drives a pulse motor to convey a moving member.

More specifically, the present invention relates to a control device suitable for driving a moving optical system of a copying machine, for example.

[Prior Art] DC motors and AC motors have been used as drive motors for conventionally known 8-dynamic optical systems or document scanning systems.

Therefore, the reason why the rotation of these motors stops during driving is not only a failure of the motor itself but also a case where some kind of failure occurs in the drive transmission system.

Therefore, in such a case, stop the electric drive of the motor,
Measures were taken to display an abnormality and notify the operator of the error, thereby eliminating the cause of the trouble.

[Problems to be solved by the invention] However, while performing servo control such as position control using an AC motor or DC motor can obtain sufficient drive torque, it is difficult to perform accurate control. There were drawbacks.

Therefore, it is conceivable to use a pulse motor instead of the DC motor or AC motor.

However, if we assume that a pulse motor is used as the main motor of a copying machine, for example, an impulse overload caused by an accidental impact may cause the pulse motor to stop rotating (step out), resulting in a loss of synchronization. The disadvantage is that it is no longer possible to return to the pulse rate. In other words, in the case of a DC motor or AC motor, it is possible to generate rotational torque again after the temporary overload disappears, but in a pulse motor, once such a step-out phenomenon occurs, the original rotation cannot be resumed. The disadvantage is that it cannot be returned.

Furthermore, in a copying machine using an AC motor, it is difficult to control the speed when changing the copy magnification, and in a case where a Dc motor is used, it is difficult to control the speed at startup and the stop position.

In order to avoid such drawbacks, it may be possible to improve controllability by using the above-mentioned pulse motor, but on the other hand, it would not only cause the above-mentioned step-out phenomenon due to insufficient torque, but also the generation of noise due to over-torque. Various shortcomings become apparent.

Therefore, in view of the above-mentioned points, an object of the present invention is to provide a control device configured to appropriately perform startup control and steady drive control of a pulse motor when driving a pulse motor to convey a moving member. It's about doing.

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a control device for reciprocating a moving member by energizing each phase coil of a pulse motor. A switching means is provided for switching the voltage applied to each phase coil.

[Operation] The voltage applied to the pulse motor is switched between forward motion and backward motion to perform appropriate drive control.

[Example] Hereinafter, the present invention will be described in detail based on Examples.

FIG. 1 is a sectional view of a copying apparatus to which the present invention is applied.

The copying apparatus according to this embodiment has a stepless magnification zoom function. When the user sets a desired magnification, the zoom lens 8 is driven by a lens drive motor (not shown) in accordance with the copy command. And the home position (
) IP) The zoom lens 8 is set at a magnification position that is a predetermined distance away from the position of the sensor 36.

When the zoom lens 8 is set, the copy drive motor 27
starts rotating. Then, a drum 24 formed of a photoreceptor using a photoconductor rotates in the direction of the illustrated arrow.

When the drum 24 rotates to the normal position, the original placed on the original platen glass 1 is illuminated by the illumination lamp 3 and the reflective "shape" 2, which are integrally formed with the first scanning mirror 4. The reflected light is scanned by the first scanning mirror 4 and the second scanning mirror 5.6. By moving the first scanning mirror 4 and the second scanning mirror 5.6 at a speed ratio of 1:0.5, it is possible to scan the original while keeping the forward optical path length of the zoom lens 8 constant. be.

The reflected light image thus obtained passes through the zoom lens 8 and the fixed mirrors 9, 10, 11, and then forms an image on the drum 24 in the exposure section 35.

The drum 24 is previously charged (for example, negatively charged) by the primary charger 14, and then in the exposure section 35, the image irradiated by the illumination lamp 3 is exposed to slit light. The slit-exposed image on the drum 24 forms a D-electrode image, which is visualized as a toner image by the developing device 15 or 16.

The copying apparatus according to this embodiment has two developing units.

The - developing device 16 is a black developing device containing black toner, and the other developing device 15 is a color developing device containing color toner. When forming a black toner image using the black developing device 16, this developing device is in close contact with the surface of the drum 24 through a small gap. At this time, the color developing device 16 is separated from the tram 24 by a predetermined distance. Further, when performing color development, the color developing device 15 is in close contact with the drum 24, and the black developing device 16 is separated from the tram 24.

Transfer paper in the cassette 20 or manual feed tray 19
The transfer paper inside is fed into the apparatus by paper feed rollers 18 or 17 and then sent to registration rollers 37. The registration roller 37 feeds the transfer paper toward the photosensitive drum 24 at precise timing after a predetermined period of time has elapsed after a signal is sent from the sensor 33 that detects passage of a specific position in the optical system, and separates the transfer paper and toner. Match the tips with the image.

Next, while the transfer paper passes between the transfer %F electric device 22 and the drum 24, the toner image on the drum 24 is transferred onto the transfer paper. After the transfer is completed, the transfer paper is sent to the conveyance section, and further guided to a pair of fixing rollers 29, where it is fixed by pressure and heat.
Thereafter, it is discharged onto the tray 32.

After the transfer, the drum 24 is neutralized by a charger 25 for neutralizing static electricity, and is further equipped with a cleaner 26 composed of an elastic blade.
The surface is cleaned and the next cycle begins.

After cleaning by the cleaner 26, a process is performed to equalize the surface potential of the drum surface portion 39 by the static elimination lamp 12. Thereafter, the drum 24 rotates toward the primary charger 14 in order to execute the next copy cycle.

In order to control the image forming cycle described above at each point in time, a sensor 40 that optically detects the position of the clock board 40a that rotates with the rotation of the drum 24 is used.
This generates a drum clock pulse DC.

In addition, as a cycle executed prior to the copy cycle, the drum 24 is rotated for a predetermined time after the copy button is pressed or the power switch is turned on, and the static elimination lamp 12 is rotated for a predetermined time.
There is a step in which residual charges and memory images on the drum 24 are erased by a cleaner Z5, and the drum surface is cleaned by a cleaner Z5. This is called forward rotation. This previous rotation is drum 2
This is to appropriately set the sensitivity of 4 and to form an image on a clean surface. Note that the pre-rotation time can be automatically changed depending on various conditions.

As a processing cycle after completing the copy cycle for the number of sheets set using the numerical keys on the operation section, the drum 24
There is a step of cleaning the drum 24 by rotating the drum 24 and energizing the static eliminating lamp 12 and the cleaner 26 to erase the residual charge and memory image on the drum 24 as in the previous rotation. This is called post-rotation. This is done in order to electrically and physically clean the tram 24 and leave it alone.

The in-machine cooling fan motor 28 rotates in synchronization with the main motor 27. Conventionally, in order to erase the non-image area of the drum 24 (particularly the toner image of the non-image area when changing the magnification),
A separate blank exposure lamp or the like was provided to lower the potential on the drum. In this embodiment, this mechanism is improved and the pre-discharge lamp is shared. Specifically, when changing the magnification, a mechanism (not shown) mechanically linked to the movement of the zoom lens 8 moves the light-shielding plate (blank shutter plate) 41 in the front-rear direction in the figure to reach a predetermined magnification. set in the appropriate position. That is, during exposure of a predetermined reduced magnification image, unnecessary non-image areas in the front and rear directions of the image are exposed to the drum surface 42.
The light from the static elimination lamp 12 is irradiated to the exposed part of the part, and -
The potential applied to the drum surface by the charger 14 is lowered, thereby preventing the toner image from adhering to the drum surface by the developing devices 15 and 16.

When the image exposure is completed, the light shielding plate 41 is driven to the position 43 in the figure by a solenoid (not shown), and the light from the static elimination lamp 12 is reflected by the light shielding plate 41 and irradiated onto the drum surface portion 42. Therefore, at timings other than image exposure, the surface potential of the drum 24 applied by the negative M electric device 14 can be lowered to prevent toner images from adhering.

Next, the operation of the sensor group necessary for copy control will be described. Reference numeral 44 shown in FIG. 1 is an optical transmission type photointerrupter that detects the presence or absence of transfer paper placed on the manual feed tray 19, and works together with a paper detection lever 45. A photointerrupter 47 detects the presence or absence of transfer paper in the cassette 20, and similarly works in conjunction with the paper detection lever 46 to perform detection.

Three sensors are arranged at predetermined positions in the transfer paper conveyance system. That is, the sensor 21 is a photo interrupter that detects paper feeding mistakes and paper jams in the paper feeding section, the sensor 23 is a sensor that detects paper jams up to the transfer section, and the sensor 31 is a sensor that detects paper jams near the fixing section and the ejection section. This is a sensor for detecting. Each of these sensors is a photoelectric transmissive type photointerrupter that detects the movement of a rotatable lever as the transfer paper passes.

Using the position of the zoom lens home position sensor 36 as a reference, the position of the zoom lens 8 corresponding to the variable magnification is determined. Further, sensors 33 and 34 are sensors related to the optical system and copy control. That is, the sensor 34
33 is a photo interrupter provided at a predetermined position corresponding to the stop position (home position) before starting, and 33 is an image tip sensor for determining the reference position at which the optical system actually exposes the document on the platen glass 1. . These sensors 33,
The signals from 34 are used as reference conditions for controlling the stoppage of each optical system, operating the paper feed roller, controlling the lighting of the document illumination lamp, and controlling the operation of the registration rollers.

FIG. 2 is a plan view of the main body operating section of the copying machine shown in FIG. 1. In the figure, 60 is a numerical key for setting the desired number of copies, and when this key is pressed, a two-digit number is displayed on the copy number display 61. The numeric display 61 displays °1'' when the power is turned on or when the clear key 59 or the like is pressed.
It also functions as a stop key, and operates as a stop key while copying continues. Therefore, it operates as a clear key for clearing the number display 61 when copying is stopped.

56 is a copy key for starting the copy operation, but when copying is impossible (for example, during wait, jam,
If there is no toner, no paper, no key counter, self-diagnosis is activated, etc.), the press will not be recognized.

54 is a ready display LED, which lights up when the copy key 56 can be pressed manually. 55 is a weight display LED, which flashes when copying is not possible.

52 is a preheating key, and when this preheating key is pressed, the device automatically enters the preheating mode, and the preheating display LED 53 blinks. When this preheating key 52 is pressed during standby, all the indicators on this operation unit except for the preheating display LED 53 turn off, and a function is activated to lower the fuser temperature by a predetermined value from the control temperature during copying and maintain it. Execute. Note that even if the preheating key 52 is not pressed, if no key on the operation unit is pressed for a predetermined period of time after copying is stopped, or if the OF (optional) cover cannot be opened, the preheating mode is automatically entered.

Reference numeral 51 denotes a reset key, and by pressing this key, the previously set copy mode can be returned to the standard mode (same size, number of copies "°1", cassette mode).

72 is a paper selection key. Usually the cassette display LED
74 is lit to indicate the cassette selection mode, but when this paper selection key 72 is pressed, the manual feed mode LED 7
3 lights up, and the cassette display LED 74 goes out. Then, when the key 72 is pressed again, the cassette mode is selected. In this copying apparatus, when the manual feed mode is selected from the cassette mode, the mode is automatically switched to the manual feed mode by driving a specific solenoid (not shown).

Reference numeral 58 denotes a development switching key, and when this key 57 is pressed, a color developer is selected and the LED 57 lights up. When a color developer is selected, the color developer 15 is brought into close contact with the tram 24 by a transmission mechanism driven by the main motor and a specific solenoid (not shown) prior to the start of copying, and at the same time, the black developer 16 is brought into close contact with the tram 24. The drum 24 is removed. Immediately before the color copy mode ends, the color developer 15 is removed from the drum 24 again and the black developer 16 is brought into close contact with the drum 24. However, the color development LED continues to be lit. That is, in order to allow the user to easily replace the color developing device, the drum 2 is removed when copying is stopped.
The color developing device is removed from 4 to make it mechanically free.

71 is a copy density adjustment lever, 70 is an automatic exposure lever (A
E) Selection key 59 is an AE momo display LED. In the standard mode, the AE mode display LED 69 is lit. To cancel this AE mode, it is sufficient to press the AE key 70.

75 is a fixed magnification selection key. In standard mode, among the fixed variable magnification display LEDs 76, the same magnification display LED (1:1)
is lit, and each time key 75 is pressed, the magnification display LED
is A4-B4. B5-84. A3→A4. A3 →
You can move to B4 and select each magnification.

77 and 78 are zoom select keys. When this plus key 77 is pressed, the current magnification is displayed on the copy number display 61 (when displaying the magnification, 88"
In addition to the LED segment representing 188%, °1" and °%" of 188% are displayed), and as the button is pressed continuously, the number on the magnification display increases by one digit at predetermined time intervals. When the key 77 is released, the current magnification percentage is determined and the magnification display continues for a predetermined period of time. Thereafter, the previously set number of copies is displayed on the display 61. When the minus key 78 is pressed, the same function as the plus key 77 is executed, and the magnification percentage is subtracted one digit at a time. When these zoom select keys 77 and 78 are pressed, the zoom display LED 79 lights up. Zoom mode can be canceled by pressing the fixed magnification selection key 75 or the reset key 51.

83 is a magnification display key, and when this key is pressed, the copy number display 61 displays the magnification at that time.

However, the magnification is displayed only when this key 83 is pressed, and when the key 83 is released, the display returns to the copy number display.

80 is a key that functions only when an optional sorter is added. When the sorter is added, the LEDs 82 and 81 are turned off in the standard mode, and the mode is set to the tray mode. If the key 80 is pressed at this point, sorter mode 1, ED81 lights up, and sorter mode t, ED81 is selected. Furthermore, when this key 80 is pressed, the collator mode LED 82 lights up and the sorter mode LED 8
1 goes out (collator mode is selected). Further, when the key 80 is pressed, the LED 82 goes out and the mode returns to the tray mode.

Next, the warning display will be explained.

62 is a paper out LE [+ which blinks when there is no paper when the cassette or manual feed mode is selected.

63 is an LED that blinks when the toner in the developing device runs out. That is, when a toner sensor (not shown) provided in the developing unit detects the state of no toner and outputs a no-toner signal for a predetermined period of time, this LED 63 blinks.

Reference numeral 65 is an LED that indicates a state in which there is no key counter.

64 is an LED for indicating a jam, and when a jam occurs in the main body, the LED 67 and ED54 blink. Further, a document feeder is added (optional), and when a document jam occurs in the document feeder, the LED 66 and the LED 64 blink. Further, when a jam occurs in the sorter, the ED 68 and the LED 64 flash. However, when a document feeder is added, if a document remains on the platen glass or in the document transport path, an LE will be displayed to notify the user of this fact.
Only D66 blinks. Further, if the sorter is not properly attached to the main body, only the LED 6B blinks.

FIG. 3 is a control block diagram in the copying machine W shown in FIG. 1. FIG. 4 is a timing chart showing the timing of the various controls described above.

In FIG. 3, Ql and q2 are well-known one-chip microcomputers (hereinafter referred to as microcomputers). These microcomputers have a memory (ROM) that stores control programs, a memory (RAM) that temporarily stores control data such as flags, input/output data for setting the number of copies, performing sequence operations, and displaying. An I10 boat is included to read input and output data.

First, the microcomputer Ql will be explained.

The microcomputer Ql mainly controls operations not related to sequences. The boat PA outputs a signal for controlling the lighting of the LED on the operation section. Keystrokes on the operating unit are detected based on the signals output from the matrix sense output boats PF (bins 50 to 54) and the signals input to the boats PD.

Signals for driving the stepping motor for driving the optical system of this copying apparatus are output from the 9th to 13th bins of the boat Pa. That is, by sending out a pulse drive pattern signal representing a predetermined frequency corresponding to each magnification ratio from the microcomputer Ql, the speed, forward and reverse rotation, etc. of the moving optical system are controlled.

A signal for switching the voltage applied to the optical system drive stepping motor is output from the 14th pin and 15th bin of the boat PB. That is, a control signal for switching the voltage applied when the optical system moves forward and when it moves backward is output from the 14 bins.

The 15th bin of the boat PB outputs an output signal for protecting the optical system, which serves to cut off the current to the optical system drive motor when an abnormality occurs in the optical system or when trouble occurs in the device.

The home position CIIP) signal of the zoom lens described earlier is input to the 16th pin of the boat PB.

17.18 pin of boat PC and 47 of boat PF
The 49th bin and the 37th pin of the boat AN are communication channels for transmitting and receiving data necessary for copy control to the other microcomputer Q2.

Each of the 19 and 20 pins of the boat PC has an optical system) IP
Signals from the sensor 34 and the image tip sensor 33 are input, and are used to determine the control timing of the optical system drive motor.

Signals used to drive the zoom lens drive stepping motor are output from bins 21 to 24 of the boat PC.

Zero-cross pulses corresponding to the power supply frequency are manually input to 26 bins of the microcomputer Ql, and are used to determine the read timing of the AE sensor signal level and other control timings.

In addition, it is an A/D conversion input boat with a built-in A/D converter (not shown) for the microcomputer Ql.
AE sensor 7 is installed in the 34th bin of boat AN (see Figure 1).
The signals from the system are input manually using an analog level.

Further, in order to control the heat roller (fixing roller) 29 of the fixing device to a predetermined temperature, the output signal of the thermistor 48 is manually input to the 35th bin of the boat AN.

A divided voltage (the resist VR signal for varying the registration roller drive timing described above) from a variable resistor (not shown) on the control board is manually applied to pin 36 of the boat AN.

The 38th pin of the boat AN has a signal for adjusting the leading edge margin on the transfer paper like the resist VR, the 39th pin has a signal for performing AE sub-control, and the 40th pin has a signal on the operation unit. Either a signal from the copy density adjustment lever 71 (see FIG. 2) or a signal from a volume 84 provided on the operating section is input to the bin 41 manually. This volume 84 is also called a "hidden volume" and is adjusted so that a proper image is always obtained when the sensitivity of the photosensitive drum 24 is shifted due to various conditions.

Next, the microcomputer Q2 that controls sequence operations will be explained.

In the microcomputer Q2, a signal is output from pin 1 of the boat PA for data transmission between the main body and a microcomputer (not shown) that controls the sorter when the sorter is attached as an option.

The 3rd bin of the boat PA sends a signal to drive a fan (not shown) for cooling the optical system, the 4th bin sends a signal to turn the halogen lamp on and off, and the 5th bin sends a signal to the main motor/ A signal to drive the AC fan/static elimination lamp is output.

A signal for turning the heater 30 on and off is output from the 6th bin of the boat PA. Thermistor information is input to the boat AN35 bin of the microcomputer Ql, and the information is sent to the microcomputer Q2 by serial communication, decoded by the microcomputer Q2, and 0N10FF of the heater 30 is thereby controlled.

The 7th bottle of the boat PA sends a signal to turn on a high voltage transformer (not shown) to 0N10FF, and the 8th bottle sends a signal to the developer 15.1.
6 outputs a developing bias signal for depositing toner onto the drum.

Bins 12 to 15 of port PB and 17. of port PC.
The 18th pin is a signal transmission channel for transmitting signals between the two microcomputers Ql and 02. A signal to reset the microcomputer Q1 is output from the 16th bin of port PB,
It is supplied to the reset port pin 28 of the microcomputer Ql.

In this embodiment, the microcomputer Q2 acts as a mask, and at the same time resets Q2 itself when a data transmission error or other abnormality occurs between the two microcomputers Ql and 02.
We are taking safety measures to ensure that the system is also reset.

A signal from the jam detection paper ejection sensor 31 is manually input to the 19th pin (port PC) of the microcomputer q2. Same 2
The tram clock pulse that controls the sequence timing of this copying machine is manually input to the 0 bin. From the same bin 21, a signal for controlling the output of the bias voltage of the developing bias is outputted in the form of a pulse, and f/V (frequency/
A converter (voltage) converter transmits the converted analog voltage to a high voltage transformer (not shown). Such a high voltage transformer applies a developing bias voltage to the developer sleeve in response to the applied analog voltage.

The output signals of the optical HP sensor 34 and the image tip sensor 33 are input to pins 22 and 23 of the port PC, respectively, and are used as timing signals for sequence control.

A signal for controlling the voltage applied to the exposure lamp 3 is output from the 24th pin of the port I'C, similar to the developing bias control signal. This output signal is applied to the exposure lamp control circuit CVR via the f/V converter (applied as an analog voltage).

This CVR controls the voltage applied to the exposure lamp 3 in response to the manually applied analog voltage. That is, when the concentration adjustment lever 71 provided on the operation section is moved, a signal corresponding to the movement is manually sent to the 40 bins of the microcomputer Ql.
Furthermore, the signal is transmitted to the microcomputer Q2 via the transmission channel, and the signal is transmitted from the 24 bins of the Q2 to the CVR,
The exposure lamp voltage is thereby controlled so that an image density corresponding to the lever 71 can be obtained. In addition, this copying device
When the E mode is set, a part of the original is exposed during optical system bliscanning, the reflected light from the original is detected by the AE sensor 7 (see Figure 1), and the appropriate The voltage of the exposure lamp 3 is controlled so that the image density is obtained.

A microcomputer voltage detection signal is input to 26 bins of the microcomputer Q2 as a timing signal for updating the RAM of the microcomputer Q2 when a jam occurs. That is, the power supply for the RAM of the microcomputer Q2 is backed up by a capacitor, and in order to memorize the copy mode before the jam occurred before the microcomputer power is turned off, the 5-halt detection signal is read and the data is transferred to the RAM by the microcomputer command.

The 63rd pin and 64th bin of the microcontroller Q2 are
2 is connected to a capacitor (not shown) as a RAM backup power supply.

Port PD of microcomputer Q2 is used as a manual port. The signal from the separation sensor 23 (see FIG. 1) is input to the 62nd pin of this port, and the signal from the sensor 21 is input to the 61st pin. Both sensors 21, 23 are used to detect the above-mentioned jam. There are 2 cassettes in the 60th bin.
The signal output from the paper presence/absence detection sensor 47 in bin 0 is manually input to the bin 59, and the signal from the sensor 44 that detects the presence of paper in the manual feed tray 19 is manually input to the bin 59. A signal output from a sensor (not shown) for detecting the remaining amount of toner in the black developing device 16 is input to the 58th pin. This toner remaining amount detection is as described above.

The disconnection detection signal of the total counter is manually input to the 55th bin of the microcomputer Q2. As a result, as soon as the total counter, which is the basis of copying charges, breaks down, it is determined that copying is not possible.

Port PF of microcomputer Q2 is used as an output port. From pin 54 of port PF, total counter/
The count driving pulse of the key counter is output. In this copying apparatus, instead of incrementing the counter when the transfer paper passes the paper ejection sensor, the separation sensor 23
The counting timing is controlled so that the total counter counts up when the transfer paper (see FIG. 1) detects the transfer paper. This is because if the total counter is counted up at the conventional paper feeding timing, the count will continue to be counted up even when copying is not actually performed due to a paper feeding error, causing trouble to the user. In addition, if a count-up signal is sent when the transfer paper passes the paper ejection sensor, there will be an inconvenience that the count will not be counted if the user removes the key counter or total counter (or if the total counter is disconnected). Moreover, it has been difficult to prevent such inconveniences. Therefore, in this embodiment, in order to prevent such inconvenience, the counter is energized at the time when the separation sensor 23 detects the transfer paper. That is, if the key counter is removed immediately before the counter is driven or the total counter is disconnected, the developing bias is controlled to a predetermined value so that toner does not adhere to the latent image on the drum. This makes it possible to control the toner image so as not to transfer it to the transfer paper, thereby allowing the blank paper to be discharged outside the machine. Furthermore, by adopting such a configuration, even if a paper feeding error occurs, there is no need to count, so that the user is not inconvenienced.

From pin 52 of the output boat PF, paper feed rollers 17 and 18
A paper feed clutch signal for driving the register roller 37 is output from the 51st bin.

FIG. 5 is a diagram showing the applied voltage switching circuit in this embodiment,
FIG. 6 is a flowchart showing the voltage switching subroutine of this embodiment.

In FIG. 5, V and ■2 are V, <V.

The power supply voltages TI and T2, which have the following relationship, are drive transistors that select the applied voltage, respectively. L is a coil for one phase in the pulse motor, T3 is a pulse excitation 6n driver for rotationally driving the pulse motor, and Dl
is a Zener diode that eliminates the back electromotive force generated in the coil L when the drive pulse is switched from on to off.

Although this circuit is shown for one phase, in reality, circuits for a plurality of phases are required.

Next, the operation of this embodiment will be explained with reference to the flowchart shown in FIG.

In step a, it is determined whether a pulse motor drive flag set/reset by another subroutine program (not shown) for controlling the pulse motor is set. As a result, when the flag is in the reset state (No), the pulse motor is not driven and is deaf, so in step b, the transistor T1. Turn off T2. As a result, no voltage is applied to each phase coil of the pulse motor.

When the pulse motor drive flag is set (Ye
In step s), the pulse motor has just started to be driven or is in the process of being driven, so step C is executed. This step C is a step for determining the state of a forward flag that is set/reset by another subroutine program (not shown).

When the forward flag is reset (No), the pulse motor is in the reverse control state, so step d
Turn off transistor T1 at .

Turn on T2. As a result, voltage 2 is applied to each phase coil of the pulse motor.

Also, when the forward flag is set (Yes)
Since the pulse motor is under forward control in step e, the transistor TI is turned on and the transistor T2 is turned off. As a result, voltage 1 is applied to each phase coil of the pulse motor.

In this embodiment, in order to increase the copying speed, the speed when moving backward is further increased. For example, when scanning a document (when moving forward)
When moving backwards, the optical system is transported at more than three times that speed.

[Effects of the Invention] As described above, according to the present invention, since the voltage applied to the pulse motor is switched between the forward movement and the backward movement, it is possible not only to convey the member quickly but also to prevent step-out. It is possible to perform appropriate drive control while preventing phenomena and noise. For example, when the present invention is applied to a copying device,
It is possible to increase the conveyance speed when the optical system moves backward, thereby increasing the copying speed.

[Brief explanation of drawings]

1 is a sectional view showing an embodiment of a copying apparatus to which the present invention is applied; FIG. 2 is a plan view showing an operation panel of the copying apparatus shown in FIG. 1; and FIG. 4 is a timing diagram showing the control timing of the control block shown in FIG. 3, FIG. 5 is a diagram showing the switching control circuit in this embodiment, and FIG. 6 is a diagram showing the control block of the copying machine. 3 is a flowchart showing a control procedure to be executed by the embodiment. DESCRIPTION OF SYMBOLS 1... Original table glass, 3... Illumination lamp, 4... First scanning mirror, 5.6... Second scanning mirror, 8... Zoom lens, 15.16... Developing device , 24... Drum, 27... Main motor, 37... Registration roller, Ql, Q2... Microcomputer. VI V2 Figure 5 Figure 6

Claims (1)

[Claims] 1) A control device for reciprocating a moving member by energizing each phase coil of a pulse motor, comprising a switching means for switching the voltage applied to each phase coil during forward movement and backward movement. A control device characterized by comprising: 2) The control device according to claim 1, wherein a moving optical system of a copying machine is used as the moving member.