JP3452267B2 - Copier - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a copying machine in which a scanner is driven by a DC servo motor according to a velocity diagram.

[0002]

2. Description of the Related Art Generally, in a slit exposure type copying machine, a document is placed on a document table with the image surface to be copied facing down, and the document on the document table is scanned from below by a scanner. However, the original image is formed on the photoconductor. The scanner is driven by the DC servo motor at the time of exposure, moves forward from the home position, and moves forward. After the exposure is completed, the scanner is temporarily stopped and then driven by the DC servo motor to return (return). The DC servo motor is controlled by the servo controller.

By the way, in this copying machine, in order to obtain a copied image without blurring, it is necessary to start scanning a document after the scanner is driven by a motor to enter a forward movement section at a constant speed. For that purpose, an approach distance for running the scanner until the scanner stands up at a constant speed must be provided between the home position and the start edge of the original on the original table.

On the other hand, since downsizing of the copying machine is required,
There is a background that the run-up distance cannot be long and can only be about 20 mm, for example. Therefore, you can enlarge the original and
Enlarged copy function for copying, and reduced copy function for reducing and copying originals.
In a copying machine having a copying function, the approach distance is fixed even if the velocity diagram showing the velocity at the time of scanning and returning of the scanner changes. Therefore, when the velocity diagram of the scanner changes, the acceleration of the scanner is changed and the scanner is started up to a constant speed with a fixed approach distance.

In a copying machine having these functions, the change in the velocity diagram of the scanner is further increased, and the amount of change in the acceleration of the scanner is 1/2 of the acceleration according to the velocity diagram of the scanner at the time of copying, which is the standard. It changes up to about 4 times. Therefore, the servo control device changes the gain of the servo loop according to the velocity diagram of the scanner to stabilize the operation of the scanner. Then, when the target speed of the DC servo motor changes during enlargement copying or reduction copying, the servo control device switches between the servo loop gain at the time of forward movement of the scanner and the servo loop gain at the time of constant speed scanning of the scanner. It is performed at a predetermined position.

[0006]

In the above copying machine, when the target speed of the DC servo motor changes at the time of enlarging copying or reducing copying, the servo loop gain at the time of forward movement of the scanner and the constant speed scanning of the scanner. Since the switching with the servo loop gain at this time is performed at a predetermined position, it is impossible to obtain a good rising characteristic of the DC servo motor and it is not possible to appropriately control the speed of the scanner.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a copying machine which can improve the above-mentioned drawbacks, can obtain a good rising characteristic of a DC servo motor, and can perform an appropriate speed control of a scanner.

[0008]

In order to achieve the above object, the invention according to claim 1 is a scanner for scanning an original, a DC servo motor for driving the scanner, and the scanner for controlling the DC servo motor. In a copying machine having control means for switching the servo loop gain according to the speed diagram of FIG. 1, the control means 1 controls the servo loop gain when the scanner moves forward and rises and when the scanner scans at a constant speed, as shown in FIG. Switching with the servo loop gain is performed by the position address of the scanner that is predetermined by the target speed of the DC servo motor 2.
Depending on the target speed of the DC servo motor,
The position address of the scanner determined for
Depending on the target speed for expanding and copying the servomotor,
The determined position address of the scanner and the DC servo
Predetermined according to the target speed at the same-speed copying of the motor
Position address of the scanner, the DC servo mode
Pre-determined according to the target speed at the time of reduced copying
It is the position address of the scanner .

According to a second aspect of the present invention, a scanner for scanning an original, a DC servo motor for driving the scanner, and a DC servo motor are controlled to switch the gain of the servo loop according to the velocity diagram of the scanner. In a copying machine having control means, the control means switches between a servo loop gain at the time of forward rise of the scanner and a servo loop gain at the time of constant speed scanning of the scanner, and the speed of the DC servo motor is the DC servo. There line when it reaches the speed previously determined by the target speed of the motor, the target speed of the DC servo motor
The speed determined beforehand is the expansion of the DC servo motor.
Speed determined in advance by the target speed during large copying,
Depending on the target speed of the DC servo motor at the same size copying
Predetermined speed, reduction of the DC servo motor
It is a speed that is predetermined according to the target speed for copying.
It is those that.

[0010]

According to the first aspect of the invention, the scanner is driven by the DC servo motor, and the document is scanned by the scanner. The control unit 1 switches the servo loop gain according to the velocity diagram of the scanner to control the DC servomotor 2, and switches between the servo loop gain when the scanner moves forward and rises and the servo loop gain when the scanner scans at a constant speed. the are performed by the position address of the scanner in advance determined by the target speed of the DC servo motor 2, DC servo
Scanner determined in advance by target speed of motor
The position address of is the eye when the DC servo motor is enlarged and copied.
The position of the scanner, which is predetermined by the velocity
Less, depending on the target speed of the DC servo motor at the same size copying
The position address of the scanner and the DC
Depending on the target speed during reduction copying of the servomotor,
This is the position address of the determined scanner .

According to a second aspect of the invention, the scanner is a DC.
The document is scanned by a scanner driven by a servo motor. The control means controls the DC servomotor by switching the gain of the servo loop according to the velocity diagram of the scanner, and switches between the servo loop gain at the time of forward movement of the scanner and the servo loop gain at the time of constant speed scanning of the scanner. , have rows when the speed of the DC servo motor has reached a speed that is predetermined by the target speed of the DC servo motor, or roughness by the target speed of the DC servo motor
The speed that has been finalized is determined when the DC servo motor is enlarged and copied.
Speed determined in advance by target speed, DC servo
Predetermined according to the target speed at the same-speed copying of the motor
To the target speed for the reduced copying of the DC servo motor
Therefore, the speed is determined in advance .

[0012]

FIG. 2 shows a target operating speed diagram of a DC servo motor according to an embodiment of the present invention. This embodiment uses a servo control device as shown in FIG. 4 in a well-known slit exposure type copying machine, and scans a document set on a document table with a scanner and scans the document image on a photoconductor. Image on. This photoconductor is uniformly charged by a charger, and then an electrostatic latent image is formed by exposure by forming an image of the original document. This electrostatic latent image is developed by a developing device and transferred to a transfer sheet by a transfer device. It is fixed by the fixing device. Such a copying operation is started by pressing the copy start key of the operation unit and is repeated for the set number of sheets.

Generally, the operation of the scanner is roughly divided into a scanning operation (scan operation) of moving forward and backward from a predetermined stop position to scan an original on the original plate, and returning to a predetermined stop position. It is divided into return operation. Scanner is D
It is driven by the C servo motor, and the drive control of this DC servo motor is performed by the servo control device. The servo control device switches the gain of the servo loop to G _{1 to} G ₇ sequentially at a plurality of predetermined position addresses of the scanner, rising time t ₁ during forward movement, constant speed (constant velocity) time t ₂ during forward movement, and reversal. Time ₃ , rising time at return t ₄ , constant speed time at return t ₅ , deceleration time at return t ₆ ,
Controlling the DC servo motor as follows the stop control time t _7.

That is, the servo control device drives the DC servomotor at the rising time t ₁ to move the scanner forward from the stop position to the position before the starting end of the document on the document table, thereby moving the scanner forward. The speed is raised to a constant speed, and at a constant speed time t ₂ , the DC servo motor is driven to move the scanner forward at a constant speed to scan the document on the document table.

Next, the servo controller decelerates the DC servo motor at the reversal time ₃ to decelerate and stop the scanner, and drives the DC servo motor at the return rising time t ₄ to return the scanner. Start up to a certain speed of time. Then servo control
The control device drives the DC servo motor at a constant speed time t ₅ at the time of return to move the scanner back at a constant speed at the time of return, and at the deceleration time t ₆ at the time of return the DC
Decelerate the servo motor. Further, the servo control device controls the DC servo motor to stop at a predetermined stop position during the stop control time t ₇ .

Further, this embodiment has the same size copy function, the enlargement copy function and the reduction copy function, and as shown in FIG. 3, the speed of the scanner is higher in the same size copy than in the enlarged copy. Reduction copying is larger than double copying. Therefore, the acceleration at the start-up of the scanner is set such that the acceleration a ₂ at the same size copying is made larger than the acceleration a ₁ at the enlarged copying and the acceleration a ₃ at the reduction copying is made larger than the acceleration a ₂ at the same size copying. There is a need. Further, in a high-speed copying machine, it is necessary to further increase the scanner acceleration to the return rise time t ₄ and the return deceleration time t ₆ . The magnitude of the acceleration of the scanner is proportional to the magnitude of the inclination in the velocity diagram of the scanner.

Therefore, in this embodiment, the servo controller increases the gain of the servo loop during the forward rise time t ₁ , the return rise time t ₄ , and the return deceleration time t ₆ to increase the system (servo loop). Responsiveness of
It is designed to make it easy to follow rapid changes in speed of the scanner. In addition, the servo control device has a forward rise time t ₁
Switched, by performing at the location address of the pre-determined scanner by the target speed of the forward-movement a constant speed time t ₂ of the DC servo motor, smooth the servo loop gain and the forward servo loop gain of the constant speed time t ₂ during Performs various scanner operations.

FIG. 4 shows a digital servo control apparatus of this embodiment for obtaining the operation speed diagram of the DC servo motor as described above. This digital servo control device includes a DC servo motor 11 for driving a scanner, an encoder 12 attached to the DC servo motor 11, a count of a position address of the scanner by counting the number of feedback pulses from the encoder 12, and an encoder. A microprocessor (CPU) 13 that has an internal timer that measures the period of the feedback pulse from 12 and that performs PI calculation according to the period, and a PWM pulse whose duty ratio is changed according to the calculation result of this microprocessor 13. Programmable timer 14 for outputting
, Frequency divider 15, level shift circuits 16 and 17, field effect transistors 18 to 21, and diodes 22 to 2
5, to have the AND gate 26,2 7.

The field effect transistors 18 and 19 are CPUs.
13 output ports 1 and 2 to level shift circuits 16 and 1
ON / OFF is controlled by an input signal inputted via 7, and AND gates 26, 27 are turned ON / OFF by an input signal inputted from output ports 1 and 2 of CPU 13 to turn on a PWM pulse from programmable timer 14. Pass through at times. The field effect transistors 20 and 21 are turned on by the PWM pulse from the AND gates 26 and 27.

When the field effect transistors 18 and 21 are turned on at the same time, the DC servo motor 11 is fed from the power supply and rotates forward at a speed corresponding to the PWM pulse from the AND gate 27, thereby moving the scanner forward, thereby causing the field effect. When the transistors 19 and 20 are turned on at the same time, power is supplied from the power supply and reverse rotation is performed at a speed corresponding to the PWM pulse from the AND gate 26 to move the scanner back.
The encoder 12 detects the rotation of the DC servo motor 11 and generates a feedback pulse proportional to the rotation speed of the DC servo motor 11, and the frequency divider 15 frequency-divides the feedback pulse from the encoder 12 and sends it to the CPU 13.

The CPU 13 counts the position address of the scanner by counting the number of feedback pulses input from the encoder 12 via the frequency divider 15 with an internal timer which also functions as an address counter, and the encoder 12 frequency divider. The period of the feedback pulse input via 15 is measured by the internal timer. And C
The PU 13 obtains control data for rotating the DC servomotor 11 at a speed according to the speed diagram by performing PI calculation (calculation of proportional control and integration) with the period of the feedback pulse measured by the internal timer.

In this case, in order to realize the above velocity diagram, the CPU 13 determines the forward rising time t ₁ , the constant speed time t ₂ , the reversal time t from the position address of the scanner counted by the internal timer during the processing of the control program. ₃ , control constants for rise time at return t ₄ , return constant speed time t ₅ , return deceleration time t ₆ (P gain, I gain)
PI calculation is performed based on G1 to G6 and the cycle of the feedback pulse, and the programmable timer 14 is controlled according to the calculation result to change the duty ratio of the PWM pulse to control the DC servomotor 11. Where C
The PU 13 switches the servo loop gain to optimum values G1 to G6 at each time t _{1 to} t ₆ according to the velocity diagram of the scanner.

FIG. 5 shows a DC servo motor control flow of the CPU 13. The CPU 13 sets the servo loop gains G1 and G2 of the forward rise time t ₁ and the constant forward speed t ₂ before the scanning of the scanner to optimum values according to the target velocity diagram, and , Rise time t
Set the position (scanner position address) at which the servo loop gain of _{1 and} the servo loop gain of constant speed time t ₂ during forward movement should be switched according to the target speed of constant speed time t ₂ during forward movement of the DC servo motor. By doing so, the rising characteristic of the DC servo motor at the time of switching the servo loop gain is improved to a favorable rising characteristic, and the speed control of the scanner is appropriately performed.

In this case, as shown in FIG. 3, the CPU 13 causes the DC servo motor 11 to move forward at a constant speed time t _{2 when} the target speed is the forward speed constant speed t ₂ of the DC servo motor 11 at the time of enlargement copying. Since it is smaller than the target speed of t ₂ , the forward rise time t ₁ at the time of enlargement copying
The servo loop gain and the scanner location address D ₁ to perform switching between the servo loop gain of the constant speed time t ₂ during forward advancement rise time at the magnification at copying t ₁
Is set to be smaller than the scanner position address D _{2 at} which the switching between the servo loop gain of 1 and the servo loop gain of the constant speed time t ₂ during forward movement should be performed.

Further, the CPU 13 determines that the target speed of the constant forward speed t ₂ of the DC servo motor during reduction copying is larger than the target speed of the constant forward speed t ₂ of the DC servo motor during equal magnification copying. The servo position of the scanner position address D _{3 at} which switching between the servo loop gain of the forward rise time t ₁ at the time of enlargement copying and the servo loop gain of the constant speed time t ₂ at the time of forward movement at the forward rise time t ₁ at the same size copying is performed. larger set from the scanner location address D ₂ to perform switching between the loop gain G1 and the servo loop gain of the constant speed time during forward t ₂ G2.

When the copy start key is pressed by the input signal from the copy start key to start the copying operation, the CPU 13 outputs output signals from the output ports 1 and 2 to turn on the field effect transistors 18 and 19. The rotation of the DC servo motor 11 to start the forward movement of the scanner, and PI calculation is performed by the servo loop gain control constant (P gain, I gain) G1 at the forward rise time t ₁ and the cycle of the feedback pulse, The programmable timer 14 is controlled in accordance with the result of the calculation and P
DC by changing the duty ratio of the WM pulse
The forward rising time t ₁ of the servo motor 11 is controlled.

The CPU13 counts the position address of the scanner by counting an internal timer, which also serves as the number of the address counter of the feedback pulse input via the frequency divider 15 from the encoder 12, the position of the scanner address is When the scanner position address reaches the set scanner position address by determining whether or not the set scanner position address is reached, the servo loop gain is set to the servo loop gain G at the forward rise time t _1.
Servo loop gain G from 1 to constant speed time t ₂ when moving forward
2 switch. Thereafter, the CPU 13 switches the gain of the servo loop as described above, and the DC servo motor 11
To control.

In this embodiment, the switching between the gain G1 of the servo loop at the forward rise time t ₁ of the scanner and the gain G2 of the servo loop at the constant speed scanning time t ₂ of the scanner is switched in advance according to the target speed of the DC servo motor 11. Because the position address of the determined scanner is used, DC
A good start-up characteristic of the servo motor 11 can be obtained, and appropriate speed control of the scanner can be performed.

FIG. 6 shows a CPU according to another embodiment of the present invention.
The DC servo motor control flow of is shown. This example
In the above-described embodiment, the CPU 13 determines in advance the switching between the servo loop gain G1 of the scanner forward rise time t _{1 and} the servo loop gain G2 of the scanner constant velocity scanning time t _{2 according} to the target speed of the DC servo motor 11. Instead of using the scanner's location address,
The switching of the servo loop gain G1 at the scanner forward rise time t _{1 and} the servo loop gain G2 at the constant speed scanning time t ₂ of the scanner is a speed at which the speed of the DC servo motor 11 is determined in advance by the target speed of the DC servo motor 11. It is something to do when you reach.

That is, the CPU 13 calculates the speed of the DC servo motor 11 from the period of the feedback pulse from the encoder 12 measured by the internal timer, and calculates the DC
When the speed of the servo motor 11 reaches a speed predetermined by the target speed of the DC servo motor 11 (speed corresponding to the target speed of the DC servo motor 11), the servo loop gain G1 of the forward rise time t ₁ of the scanner
And the servo loop gain G of the uniform scanning time t ₂ of the scanner
Switch to 2.

In this embodiment, the switching between the servo loop gain G1 at the scanner forward rise time t _{1 and} the servo loop gain G2 at the scanner constant speed scanning time t ₂ is performed by changing the speed of the DC servo motor 11 to the DC servo motor 1.
Since the process is performed when the speed that is determined in advance by the target speed of 1 is reached, a good rising characteristic of the DC servo motor 11 can be obtained, and appropriate speed control of the scanner can be performed.

[0032]

As described above, according to the first aspect of the present invention, a scanner for scanning an original, a DC servo motor for driving the scanner, and a velocity diagram of the scanner for controlling the DC servo motor. In the copying machine having a control means for switching the servo loop gain according to the DC servo control, the control means switches between the servo loop gain at the time of forward movement of the scanner and the servo loop gain at the time of constant speed scanning of the scanner. are performed by the position address of the scanner in advance determined by the target speed of the motor, the target speed Niyottea of the DC servo motor
The position address of the scanner determined from the
It depends on the target speed at the time of enlarged copying of the DC servo motor.
The position address of the scanner which has been determined by the caulking, the DC
Depending on the target speed of the servomotor at equal size copying,
Position address of the scanner determined by the
Pre-determined according to the target speed for the reduction copy of the Bo-Motor
Since the position address of the scanner is fixed, a good rising characteristic of the DC servo motor can be obtained,
Appropriate speed control of the scanner can be performed.

According to the second aspect of the present invention, the scanner for scanning the document, the DC servo motor for driving the scanner, and the DC servo motor are controlled to set the servo loop gain according to the velocity diagram of the scanner. In a copying machine having a control unit for switching, the control unit switches the servo loop gain at the time of forward rising of the scanner and the servo loop gain at the time of constant speed scanning of the scanner by changing the speed of the DC servo motor to the DC. There line when it reaches the speed previously determined by the target speed of the servo motor, depending on the target speed of the DC servo motor
The speed determined in advance by the DC servo motor
Speed determined in advance according to the target speed for enlarged copying
Depending on the target speed of the DC servo motor at the same size copying.
The speed determined in advance by the DC servo motor
Speed determined in advance by the target speed during reduced copying
Since it is, it is possible to obtain a good rise characteristic of the DC servo motor, it is possible to perform appropriate speed control of the scanner.

[Brief description of drawings]

FIG. 1 is a block diagram showing an invention according to claim 1.

FIG. 2 is a velocity diagram showing the relationship between the velocity and the movement position of the scanner in the embodiment of the present invention.

FIG. 3 is a diagram showing a speed and a loop gain switching position address in each copy mode of the scanner in the embodiment.

FIG. 4 is a block diagram showing a servo control device of the embodiment.

FIG. 5 is a flowchart showing a processing flow of a CPU in the servo control device.

FIG. 6 is a flowchart showing a processing flow of a CPU in a servo control device according to another embodiment of the present invention.

[Explanation of symbols]

1 control means 2 DC servo motor

Continuation of front page (51) Int.Cl. ⁷ identification code FI G05D 3/12 306 G05D 3/12 306R 13/62 13/62 E (58) Fields investigated (Int.Cl. ⁷ , DB name) G03B 27 / 50 G03G 21/00 G05B 13/02 G05D 3/12 305 G05D 3/12 306 G05D 13/62

Claims (2)

(57) [Claims] 1. A copying machine having a scanner for scanning an original, a DC servo motor for driving the scanner, and a control means for controlling the DC servo motor and switching a servo loop gain according to a velocity diagram of the scanner. In the above, the control means switches the servo loop gain at the time of forward rising of the scanner and the servo loop gain at the time of constant speed scanning of the scanner by the position address of the scanner determined in advance by the target speed of the DC servo motor. There line, the target speed of the DC servo motor
The position address of the scanner determined in advance by
Is the target speed for the magnified copy of the DC servo motor.
Therefore, the position address of the scanner determined in advance is
Depending on the target speed of the DC servo motor at the same size copying.
The position address of the scanner determined in advance,
Depending on the target speed at the time of reduction copying of the DC servo motor
A copying machine characterized in that it is a position address of the scanner determined in advance . 2. A copying machine having a scanner for scanning an original, a DC servo motor for driving the scanner, and a control means for controlling the DC servo motor and switching a servo loop gain according to a velocity diagram of the scanner. In the above, the control means switches the servo loop gain at the time of forward movement rising of the scanner and the servo loop gain at the time of constant speed scanning of the scanner by the speed of the DC servo motor being determined in advance by the target speed of the DC servo motor. There line when it reaches the speed that is, the DC Sir
Speed determined in advance by the target speed of the Bo-Motor
Depends on the target speed of the DC servo motor at the time of magnified copying.
The speed determined in advance by the DC servo motor
Speed determined in advance according to the target speed for 1x copying
Depending on the target speed of the DC servo motor during reduction copying.
A copying machine characterized by a predetermined speed .