JP3060755B2 - Polygon motor control device and control method thereof - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device and method for a polygon motor in a variable resolution laser printer.

[0002]

2. Description of the Related Art In recent years, laser printers whose resolution can be changed have been used. In this case, regarding a polygon motor directly connected to a polygon mirror that performs scanning with laser light, the resolution is changed by changing the rotation frequency of the polygon motor. Hereinafter, a conventional example will be described in detail with reference to the drawings. However, in order to facilitate understanding of the description of the configuration and operation, the same portions are denoted by the same reference numerals throughout the drawings, and redundant description thereof will be omitted.

FIG. 3 shows a block diagram of a conventional polygon motor control device. In the figure, reference numeral 1 denotes a scanning signal a specifying a specific resolution from among a plurality of resolutions from a higher-level model, and a control signal b having a resolution corresponding to the scanning signal a.
Here, for the sake of simplicity, the plurality of resolutions represent one of a plurality of high resolutions, and the rotation frequency of the polygon motor corresponding to this is represented by one of the plurality of resolutions.
The conditions of the scan signal is represented by called mode A at f _1, subject to the mode B and referred to two different rotation frequency f ₂ of the scanning signal of the polygon motor corresponding to the lowest resolution (f _1> f ₂₎ Explanation will be made using modes.

A driving unit 2 supplies / stops a driving power corresponding to a designated resolution to the driving coil 3 of the polygon motor 4 based on ON / OFF of a control signal b received from the control unit 1.

A braking circuit 5 is activated by a braking signal c output from the control unit 1 when the scanning signal a is turned off from the scanning in the mode A. As shown in FIG. The three diodes 51, 52, 53, which bypass the current supplied to each electrode of the coil 3 to the midpoint of the star connection, and connect the midpoint of the star connection to the ground via the resistor 55. And a control type switch 54 which is turned on / off on the line side.

[0006] The control type switch 54 receives the scanning signal a.
Is turned off (stops scanning) from mode A, the control unit 1
Refers to the time set in advance in the braking time setting unit 6 using a timer or the like, turns on the control type switch 54 only during the set time, and is supplied to each electrode of the drive coil 3 of the polygon motor 4. The current flowing to the ground wire side is bypassed to temporarily stop the rotation of the polygon motor 4 in the deceleration direction.

The set time is set so that the rotation of the polygon motor 4 when the set time elapses becomes close to the rotation frequency f _{2 of the} mode B. As a deceleration unit, a supply current or a supply voltage (not shown) of the drive unit 2 is previously set in a reverse phase (reverse rotation direction) based on a braking signal c output from the control unit 1 in addition to the unit using the braking circuit 5. There is also a means to supply for a set time.

Reference numeral 7 denotes a frequency detecting unit for detecting the rotation frequency of the rotating shaft of the polygon motor 4 using, for example, an optical sensor or the like. Reference numeral 8 denotes a reference frequency generator that outputs a frequency (f ₁ or f _2, etc.) corresponding to the designated mode according to a control signal from the controller ₁ , and 9 compares the outputs of the frequency detector 7 and the reference frequency generator 8. A PLL circuit (phase-locked loop circuit) that outputs the phase difference as an analog value, and controls the output of the drive unit 2 so that the output phase difference always becomes zero, thereby supporting a designated mode. Control in synchronization with the required rotation frequency of the polygon motor 4.

By the way, the polygon motor 4 can be synchronized in a relatively short time with respect to the control in the direction of increase of the rotation speed, for example, in about 10 seconds when the rotation speed rises from zero, but is controlled to the mode A. In order to synchronize from the rotating state to the lower rotation number of mode B in the deceleration direction, the centrifugal force and the inertial force acting in accordance with the mass and the arrangement distance of the member around the axis of the polygon motor 4 are set. For this reason, when the natural deceleration is performed without braking, it may take about one minute until the synchronization is achieved.

[0010] In other words, the same principle as that of the top music having a larger diameter than the top music having a smaller diameter is based on the same principle as that of the top music. The time setting unit 6 and the braking circuit 5 were provided.

FIG. 4 is a time chart of each part of the conventional block diagram, which will be described below with reference to FIG.
First scan signal a is input to the control unit 1, the time t ₁ ~t ₂
Mode A, is input in the mode B between time t ₄ ~t ₆ between,
As a result, in the same time zone, the control unit 1 converts the supply voltage or the supply current of the drive unit 2 into the drive signal b corresponding to the mode A and the mode B, and drives the drive coil 3.

[0012] brake signal c, the mode when the scanning signal a is finished in A, i.e. the time which is set to rise braking time setting unit 6 in time t ₂ (set corresponding to between time t ₂ ~t ₃ time To ), The rotation of the polygon motor 4 is braked by turning on the control type switch 54.

[0013] Rotation frequency signal d of the polygon motor 4 the frequency detecting unit 7 detects a frequency on the vertical axis, a chart in which the horizontal axis represents time, the polygon motor 4 when the scanning signal a rises at time t ₁ after having reached rapidly up to the frequency f ₁ corresponding to the mode a, by comparing the outputs of the reference frequency generating unit 8 and the frequency detecting unit 7 by the PLL circuit 9 outputs the phase difference in analog values. Its analog value that is, the rotational frequency control signal e controls the drive unit 2 such that the zero synchronously controlling the rotation frequency of the polygon motor 4 to f ₁ by.

When the scanning signal a of the mode A ends at time t ₂ , the supply of the driving signal b is also stopped, and at the same time, the braking signal c rises at time t ₂ in the control unit 1 and is set in the braking time setting unit 6. only time to, to brake the rotation of the polygon motor 4 by short-circuiting the controlled switch 54 to terminal of the driving coil 3 by turning control to the ground side, when the lapse of the set time to that is, the rotational frequency in the time t ₃ It was a f _3, then left in a state of coasting deceleration to stop the braking control.

Next, when the scanning signal a of mode B is input at time t ₄ , the reference frequency generator 8 outputs the reference frequency f ₂ under the control of the controller 1, and the PLL circuit 9 outputs the reference frequency f _2. And outputs the phase difference between the rotation frequency signal d output from the frequency detection unit 7 as an analog value. In this case the rotational frequency of the polygon motor 4 is reduced by the braking action of the braking circuit 5, is higher than the rotation frequency f ₂ of the still mode B in the time t ₃ when passed a set time To, PLL
The rotation frequency control signal e output from the circuit 9 does not control the drive unit 2 until the phase difference becomes zero.

[0016] That is, the drive unit 2 waits until time t ₅ to drop to a frequency f ₂ where the output of the rotation frequency signal d corresponding to the mode B, synchronizes the rotation frequency of the polygon motor 4 to f ₂ at time t ₅ since The drive coil 3 is driven so as to perform the operation. Unlike at the end of mode A When the mode B of the scanning signal a at time t ₆ is completed, the drive unit 2 stops the supply of the drive power, the rotation frequency of the polygon motor 4 is in a state of coasting deceleration time t Stop rotation at ₇ .

[0017]

Immediately after scanning in mode A is completed, that is, when the scanning signal a in mode B is input to the control unit 1 before the rotation frequency signal d decreases and reaches f ₂ , driver 2 are governed by the rotational frequency decreasing direction by the action of the PLL circuit 9, can not drive the driving coil 3 to reduce the rotation frequency f ₂ of the mode B, there is a problem that the waiting time is generated.

In order to prevent this problem, the set time To should be set slightly longer. However, wide variation range by factors such as friction coefficients of the error or the rotation shaft of the mechanism of production is the value of the output f ₃ of the frequency detector 7 at the elapsed point of setting time To be predetermined, also, the setting time
There is a problem in that setting and adjusting the To individually for each device is extremely troublesome.

The present invention has been made in view of the above-mentioned conventional problems, and provides a polygon motor control device and a control method capable of shortening a start-up time required for switching from a high-resolution scanning state to a low-resolution scanning state. Aim.

[0020]

In order to achieve the above object, as shown in FIG. 1, a laser printer in which a desired resolution is selected by designating one of a plurality of modes is used. a mode for forming an image, corresponding to each of the mode for forming a low resolution image poly
A reference frequency generator 8 to output the reference frequency for driving the Gonmota, prior to correspond to each of the modes
A drive unit 2 for supplying power to the serial polygon motor 4, the deceleration unit for decelerating the rotation of the pre-Symbol polygon motor 4 (e.g.,
A braking circuit 5), a frequency detection unit 7 for detecting the rotational frequency before Symbol polygon motor, the rotation circumference of the polygon meter
There is no difference between the wave number and the reference frequency of the low resolution mode.
And a PLL circuit 12 that outputs a synchronization signal when the
Together with the low resolution mode from the mode for forming the high resolution image.
When switching to the mode for forming a resolution image,
Operating the deceleration means immediately after
Upon receiving the synchronization signal from the circuit 12, the deceleration means
The control unit 1 for ending the operation is provided .

As a control method, there are a plurality of modes.
The desired resolution is selected by specifying one of
Mode for forming high-resolution images of laser printers
And modes for forming low-resolution images
And output the reference frequency for starting the polygon motor
And from the mode for forming the high resolution image to the low resolution
When switching to the mode for forming images again,
Later, the polygon meter is decelerated and the
Rotonometer rotation frequency and reference for the low resolution mode
Detect the difference from the frequency, and when the difference disappears,
Control is performed to end the deceleration of the polygon meter.

[0022]

[Action] Control unit 11 in FIG. 1 and the time t ₂ when the scanning mode A is completed as shown in FIG. 2, reference frequency generator 8
The output with switching to a frequency f ₂ corresponding to the mode B, the brake signal controlled switch 54 is turned on controlled by c decelerates the polygon motor 4, the output frequency of the rotary signal d frequency detector 7 outputs At the time (time t ₈ ) when the frequency falls to f _2, the synchronizing signal f output from the PLL circuit 12 is input to the control unit 11, whereby the control unit 11 controls the control type switch 54 to turn off and decelerates the polygon motor 4. Release control.

[0023] Thus, the scanning signal of the time t ₈ previously mode B is the case where the incoming start time is earlier than in the case for a short time t ₂ ~t ₈ deceleration control time coasting deceleration. Further, when the scanning signal of the mode B to the time t ₈ after has arrived, the effect of the rotation frequency of the polygon motor 4 becomes faster boot time because they become f ₂ below.

[0024]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a block diagram of a polygon motor control device of the present invention, and FIG. 2 is a time chart of each part of the block diagram of the present invention. Hereinafter, FIG. 1 will be described with reference to FIG. FIG. 1 differs from FIG. 3 of the conventional example in that the braking time setting unit 6 in FIG. 3 is deleted and a circuit for inputting the synchronization signal f from the PLL circuit 12 to the control unit 11 is newly added. is there.

FIG. 2 differs from FIG. 4 in that the synchronization signal f
There are added, in that the synchronizing signal as braking signal c falls in the time t ₈ to occur. That is, when the scanning signal a mode A ends at time t _2, the control unit
11 switches the output of the reference frequency generating unit 8 from f ₁ to f _2. When the scanning signal a of the mode B is completed, the mode is switched according to the next input mode. At the same time braking circuit 5
The control type switch 54 is turned on to decelerate the polygon motor 4.

[0026] When the output reaches the frequency f ₂ corresponding to the mode B of the polygon motor 4 is braked frequency detector 7 (time t _8), PLL circuit 12 outputs a synchronization signal f, the control unit 11 Notify. The control unit 11 releases the ON control of the control type switch 54 based on the notification. as a result,
The rotation of the polygon motor 4 is in a state of natural deceleration.

[0027] When the scanning signal a mode B in the time t ₄ is input to the control unit 11, drive signal b to the driving section 2
There is inputted, the polygon motor 4 which has been reduced to a frequency f ₂ or less locking can be established in the mode B to start immediately. Also,
Scanning signal a mode B during the period from time t ₂ to time t ₈
Is input to the control unit 11, the waiting time for activation is small because the period of braking deceleration is short.

At the time when the scanning signal a of the mode B is completed (time t ₆ ), the control unit 11 stops the control of the reference frequency generating unit 8 and the driving signal b is also changed to the braking signal c.
Outputs neither the rotation of the polygon motor 4 is naturally decelerated, it stops at the time t _7.

Although not shown, when the mode B ends and the next scanning signal a changes to the mode A, the polygon motor 4 starts from the remaining rotation state or the stop state, so that a waiting time is generated. Is less.

[0030]

As is apparent from the above description, according to the present invention, there is an effect that the startup time when switching from mode A to mode B is reduced.

[Brief description of the drawings]

FIG. 1 is a block diagram of a polygon motor control device of the present invention.

FIG. 2 is a time chart of each part of the block diagram of the present invention.

FIG. 3 is a block diagram of a conventional polygon motor control device.

FIG. 4 is a time chart of each part of a conventional block diagram.

[Explanation of symbols]

 2 is a drive unit 4 is a polygon motor 5 is a braking circuit 7 is a frequency detection unit 8 is a reference frequency generation unit 11 is a control unit 12 is a PLL circuit

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-2-158359 (JP, A) JP-A-4-281380 (JP, A) JP-A-62-162547 (JP, A) (58) Survey Field (Int.Cl. ⁷ , DB name) H04N 1/04-1/207

Claims (2)

(57) [Claims] 1. A laser printer desired resolution is selected by specifying one of a plurality of modes, and mode of forming a high resolution image, each of the mode for forming a low resolution image Drive the polygon motor accordingly
Deceleration to decelerate the reference frequency generator for output the reference frequency for moving a drive unit for performing <br/> power supplied to the polygon motor corresponding to each of the modes, the rotation of the pre-Symbol polygon motor a frequency detector for detecting a unit, the rotational frequency before Symbol polygon motor, the low-resolution mode and the rotational frequency of the polygon meter
Outputs a synchronization signal when there is no difference from the reference frequency
And a low-resolution image from a mode for forming the high-resolution image.
When switching to the image formation mode,
From the PLL circuit.
The operation of the deceleration means ends when the synchronization signal is received.
A polygon motor control device, comprising: a control unit for controlling the operation of a polygon motor. 2. Designating one of a plurality of modes.
High resolution of laser printer where desired resolution is selected by
Mode for forming a high-resolution image and forming a low-resolution image
Start the polygon motor corresponding to each of the modes
Output a reference frequency for the low-resolution image from the mode for forming the high-resolution image.
When switching to the image formation mode,
Decelerates the polygon meter, and sets the rotation frequency of the polygon meter and the low resolution mode.
When the difference from the reference frequency is detected and the difference disappears
Controlling the polygon meter to end the deceleration of the polygon meter .