JP2003348852A - Pwm control mechanism - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To carry out PWM driving even in a microcomputer which is not provided with a PWM driving function for driving a motor, coils, or the like on an arbitrary voltage or is only provided with a PWM driving function insufficient to too many mechanisms to be simultaneously controlled. <P>SOLUTION: The control terminals of a motor or the like are directly controlled using an interrupt function based on a timer, especially, an interrupt which occurs when a timer counter and a register match each other and an interrupt which occurs when a timer overflows, from among interrupt function usually provided in microcomputers. If the overhead of an interrupt is too large to provide an intended duty, the cycle time of the PWM is lengthened, and the influences of the overhead are minimized. <P>COPYRIGHT: (C)2004,JPO

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a driving mechanism for energizing and driving a driving mechanism such as a motor for driving film feeding, lens driving, etc. of a camera so that the driving becomes a predetermined speed and driving force. Control at a high speed to control the voltage to be equivalent to a predetermined voltage.

[0002]

2. Description of the Related Art Conventionally, a PWM signal generator has a binary timer counter composed of N bits (generally an integral multiple of nibble) for counting clock pulses such as a system clock, and the same bit length as the binary timer counter. (Register length), two registers A and B
And all bits of the binary timer counter and register A are compared bit by bit, and when the values of all bits match, the output becomes "1" and all bits of the binary timer counter are cleared to "0". Compares all bits of the digital comparator A and the register B which output "0" for each bit, and when all the bits match, the output becomes "1", and normally outputs "0". Digital comparator B. The coincidence output "1" of the digital comparators A and B is supplied to the input terminal of the T flip-flop, so that the T flip-flop is inverted for both the coincidence outputs of the comparators A and B.

Here, the value set in the register A is PW
The cycle time of M is determined, and the value set in the register B determines the PWM on time. At this time, the value set in the register A is made larger than the value in the register B. Assuming that the binary timer counter is a binary up counter, all bits of the counter are cleared to "0" when the binary timer counter is started, and the output of the T flip-flop is reset to "H".
When the binary timer counter is incremented by the clock pulse, the register B is smaller than the register A and therefore matches first, and the T flip-flop is inverted by the coincidence output of the comparator B and the output becomes "L". When the binary timer counter continues to increment and matches the register A, the T flip-flop is inverted by the match output of the comparator A, and the output becomes “H”. At this time, if all bits of the binary timer counter are cleared to "0" at the same time, the value matches the register B again, and the inversion of the T flip-flop is repeated. The output of the T flip-flop at this time is a PWM output whose cycle time is set by the register A and whose on-time is set by the register B.

In order to supply the PWM output to devices to be controlled, such as a motor, a moving coil, and an LED, an output destination is switched using a selector. When the number of devices to be controlled is three or four, only two ports are required to control switching, but as the number of devices increases, the number of autos for controlling switching needs to be increased accordingly. .

[0005] Instead of the register A and the comparator A of the PWM generator, an overflow output of a binary timer counter ("1" is output when an overflow occurs) can be used. In this case, the PWM cycle time is determined by the maximum value of the binary timer counter.

[0006]

However, in the prior art, a counter, a register, a comparator, a flip-flop, a selector, and the like are required to generate PWM and send it to the device. Today's general microcomputers have built-in timer counters, registers, and comparators, but other hardware circuits must be provided.

At this time, if the degree of freedom of the output destination is increased, the number of control ports increases, and a finite number of ports of the microcomputer is used more, so that other control becomes difficult. Also, if the number of control ports is reduced, the degree of freedom of the output destination is reduced, and if PWM cannot be output to the desired output destination, the hardware design must be redesigned.

[0008]

Means for Solving the Problems By directly turning on / off the control terminals of a motor or a coil by an interrupt caused by a match between a timer and a register of a general microcomputer or by an overflow of the timer, a flip-flop or the like is provided. PWM without using a PWM output selector
M drive is performed.

At this time, since the delay due to the interrupt overhead affects the duty so that the delay cannot be ignored in the microcomputer having a slow processing, the PWM control by the interrupt is performed in the standard cycle when the duty is large enough and the ON time is sufficient. When the duty becomes smaller and the ON time becomes shorter, the PW is set so that the cycle is lengthened to make the ON time longer and the influence of the interrupt overhead on the duty is reduced.
M control is performed.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A timer counter for counting clock pulses such as a system clock, registers A and B having the same bit length as the binary timer counter, and an interrupt generated when the timer counter and registers A and B match. And a microcomputer that generates an interrupt due to an overflow of a timer, and gradually changes the camera shake correction lens from a stopped state to a PWM depending on the magnitude of the camera shake.
There is driving means for driving, and the control terminal is turned on by an interrupt generated when the timer counter and the register A match or an interrupt generated when the timer counter overflows, and the timer counter and the register B match. The drive means is PWM-controlled by turning off the control terminal in response to an interrupt generated as a result.

Further, the number of coincidence interrupts between the timer counter and the register A or the number of overflow interrupts of the timer are counted, and the control terminal is turned on once, but the control terminal is not turned on (X-1) times. Thus, the PWM cycle time is extended by X times, and the count set in the register B is increased by X times in accordance with this, thereby increasing the ON time of the control terminal. However, it is necessary to prevent the count multiplied by X from becoming larger than the timer register.

(First Embodiment) Hereinafter, the present invention will be described in detail based on the illustrated embodiment.

FIG. 1 is a block diagram showing a circuit configuration of a camera with an image blur correction function according to a first embodiment of the present invention, and FIG. 2 is a diagram showing an arrangement of each component.

In FIG. 1, reference numeral 1 denotes an MPU (microprocessing unit / microcomputer), which has an interrupt function by a timer and a timer coincidence register for detecting that the timer has reached a predetermined count. In addition, it has a function of an overflow interrupt generated when the timer overflows and a function of a coincidence interrupt 1/2 generated when the timer and the comparison register match. Reference numeral 10 denotes an 8-bit timer used for a timer interrupt of the microcomputer, which inputs a system clock supplied to drive the microcomputer or another clock, and increments the counter.

Reference numeral 2 denotes a vibration gyro for detecting vibration in the pitch direction.

Reference numeral 3 denotes a vibration gyro for detecting yaw direction vibration.

Reference numerals 4 and 5 denote amplifier circuits for amplifying the outputs of the vibrating gyroscopes 2 and 3 for the pitch and the yaw, respectively.

Reference numeral 6 denotes a correction lens driving device that drives the correction lens 14 to correct an image shift due to hand shake in the pitch direction or the like.

Reference numeral 7 denotes a correction lens driving device that drives the correction lens 14 to correct an image shift caused by camera shake in the yaw direction.

Reference numeral 12 denotes a power supply for driving a microcomputer and peripheral circuits.

Reference numeral 13 denotes an EEPROM or FlashMemo.
In a non-volatile memory such as ry, parameters and adjustment values for image stabilization control are recorded.

In FIG. 2, reference numeral 14 denotes an image correction lens for correcting an image shift caused by camera shake.

Reference numeral 15 denotes three springs supporting the correction lens.

Reference numeral 11 denotes a photographing range of a film (not shown) in which a subject image passing through the lens is photographed.

The outputs of the vibrating gyroscopes 2 and 3 are connected to the A / D conversion input terminal of the microcomputer 1 via the amplifier circuits 4 and 5.

In this embodiment, control is performed using the angular velocity of camera shake detected by the vibrating gyroscopes 2 and 3. That is, at a speed corresponding to the angular velocity of the camera shake, the correction lens 12 is moved in the direction opposite to the direction of the camera shake.
To compensate for camera shake. Specifically, the vibration gyro 2 that detects the angular velocity in the pitch direction
If an angular velocity in the direction is detected, this means that the camera has rotated downward. At this time, the moving lens 8 drives the correction lens 14 in the + direction. This will move the correction lens upward relative to the camera. Similarly, when the vibrating gyroscope 3 for detecting the angular velocity in the yaw direction detects the angular velocity in the + direction, this means that the camera has rotated to the right. At this time, the moving lens 9 drives the correction lens 14 in the + direction. This will move the correction lens to the left with respect to the camera. However, depending on the configuration of the lens, image shift correction may be performed by driving the correction lens in the negative direction.

FIG. 3 is a flowchart showing a sequence of camera shake correction.

In step # 1, camera shake correction is started. When the photographing preparation start switch (SW1) is pressed, camera shake correction is started.

At step # 2, the settings relating to the control port and the timer are initialized.

In step # 3, the data of the digital filter operation is initialized.

In step # 4, the voltage output obtained by amplifying the output of the gyro by A / D conversion of the microcomputer is digitized and taken in. There are two gyros, one for detecting the pitch direction and the other for detecting the yaw direction.

At step # 5, the gyro output corresponding to the angular velocity fetched at step # 4 is converted into angular displacement by digital calculation for correction.

In step # 6, a required duty value is calculated based on the angular displacement converted in step # 5.

If it is determined in step # 7 that the switch SW1 is kept depressed or the photographing operation is being performed and the exposure is being performed, the camera shake correction is not terminated and the operation proceeds to step # 4.
And continue the image stabilization. If the switch SW1 is released or the shooting is completed, the camera shake correction is completed and the process proceeds to step # 8.

At step # 8, the camera shake correction processing is completed.

FIG. 4 is a flowchart showing a process when an overflow interrupt of the timer occurs.

When the 8-bit timer 10 overflows, an overflow interrupt is generated and the process jumps to step # 10.

In step # 11, the timer match comparison register Tre
The drive duty DutyP in the pitch direction is set to g1. Here, since DutyP is a duty for the 8-bit timer, a value from 0 to 255 is set.

In step # 12, the timer match comparison register Tre
The drive duty DutyY in the yaw direction is set to g2.

In # 13, the drive control terminal con in the pitch direction
Turn on tPA / PB. At this time, when the moving coil is driven in the forward direction, only contPA is turned on, and contPB is kept off, and the coil is energized in the forward direction. When driven in the reverse direction, only contPB is turned on and contPA is turned off. The driving direction is controlled by applying a current in the opposite direction to the coil while keeping the current.

In # 14, the yaw direction drive control terminal cont
Turn on YA / YB. At this time, similarly to # 13, when the moving coil is driven in the forward direction, contYA
When only the coil is turned on and the cont YB is kept off, the coil is energized in the forward direction.
The drive direction is controlled by turning on only YB and leaving contYA off, and conducting current in the opposite direction to the coil.

At step # 15, the overflow interrupt process is completed, and the process returns to the normal process.

FIG. 5 is a flow chart showing the processing when the timer coincidence interrupt 1 occurs.

When the 8-bit timer 10 and Treg1 match, a match interrupt 1 is generated and the process jumps to # 20.

At step # 21, both contPA / PB are turned off to stop energization.

At step # 22, the coincidence interrupt 1 process ends, and the process returns to the normal process.

FIG. 6 is a flowchart showing the processing when a timer coincidence interrupt 2 occurs.

When the 8-bit timer 10 and Treg2 match, a match interrupt 2 is generated and the process jumps to # 30.

At step # 31, both contYA / YB are turned off to stop the energization.

At step # 32, the coincidence interrupt 2 process ends, and the process returns to the normal process.

In FIG. 4 of the present invention, the interrupt generated by the overflow of the timer is used. However, the number of bits of the timer can be sufficiently prepared, and another interrupt generated by the coincidence of the timer as shown in FIGS. If it is, PWM can be controlled by a timer coincidence interrupt instead of an overflow interrupt.

(Second Embodiment) The second embodiment of the present invention will be described in detail with reference to the drawings.

FIG. 8 is a diagram showing the PWM operation of the second embodiment.

Here, assuming that a microcomputer having a slow processing speed of about 8 μsec with an interrupt overhead (delay) is used and a 2 MHz clock is input to an 8-bit timer to perform PWM control, one cycle time of the clock is assumed. Is 0.5 μsec, so one cycle of PWM using an 8-bit timer is 128 μsec, which is about 8 kHz.
Can be output.

In this configuration, when PWM with a 50% duty is output as in (1), the counter of the timer is set to 2
50% of 56 counts (because it is an 8-bit timer)
By switching the control terminal of the coil when the count reaches 128, the duty becomes 50%. However, in this configuration, since the microcomputer has an interrupt overhead of 8 μsec, the count is increased from 128 counts to 16 counts (8 μsec).
By switching at 112 counts minus (0.5 μsec), the duty can be made 50%.

Similarly, in the case of outputting a PWM with a 25% duty as in (2), the duty is set to 25% by switching from 64 counts, which is 25% of 256 counts, by subtracting 16 counts from 48 counts. Can do things.

However, when PWM with a duty of about 5% is to be output as in (3), since 12 counts, which is 5% of 256 counts, is smaller than 16 counts of the interrupt overhead, the overhead is subtracted. It cannot be corrected.

Therefore, the cycle time is set to 8 as shown in (4).
The duty can be made 5% by switching the control terminal by multiplying the count by 12 and 8 counts, which is 5% of 256 counts, to 96 counts, and the effect of 16 counts for the interrupt overhead. Can be reduced.

The actual control flow will be described with reference to the drawings.

FIG. 7 is a flowchart showing a process when an overflow interrupt of the timer occurs according to the second embodiment.

When an overflow of the 8-bit timer 10 occurs, the process jumps to step # 40.

If the value of DutyP is larger than the predetermined value α in # 41, the process proceeds to # 42. Here, α indicates the overhead due to interruption.

At step # 42, match interrupt 1 is enabled.

When the value of DutyP is larger than the predetermined value α in # 43, the drive duty DutyP in the pitch direction is not so affected by the interruption overhead.
Is subtracted by α for the overhead, and is set in the timer match comparison register Treg1.

At # 44, the drive control terminal con in the pitch direction
Turn on tPA / PB. At this time, when the moving coil is driven in the forward direction, only the contPA is turned on and the contPB remains off, and when the moving coil is driven in the reverse direction, only the contPB is turned on and the contPA is kept off to change the driving direction. Control.

At step # 45, counterP is cleared to zero. However, when DutyP is larger than α, the counter is not used, but only cleared to zero.

If the value of DutyP is smaller than the predetermined value α in # 41, the flow proceeds to # 46.

If counterP is zero in # 46, the process proceeds to # 47.

At step # 47, match interrupt 1 is enabled.

If the value of DutyP is smaller than the predetermined value α in # 48, the influence of the overhead of the interrupt increases, and the cycle time is lengthened to reduce the influence. Here, in order to make the cycle time eight times, the drive duty DutyP in the pitch direction is made eight times and set in the timer match comparison register Treg1.

At # 49, the drive control terminal con in the pitch direction
Turn on tPA / PB.

In order to increase the cycle time eight times at # 50, c
Set counterP to 8.

At step # 51, counterP is decremented.

If counterP is not zero at # 46, the process proceeds to # 52.

At step # 52, the interrupt is prohibited so that the coincidence interrupt 1 does not occur.

At step # 51, counterP is decremented. Here, until the value of counterP becomes zero, the register Treg1 for timer match comparison and the drive control terminal co
No processing is performed on ntPA / PB. As a result, the cycle time can be increased eight times.

If the value of DutyY is larger than the predetermined value α in # 53, the process proceeds to # 54. Here, α indicates the overhead due to interruption.

At step # 54, the coincidence interrupt 2 is permitted.

If the value of DutyY is larger than the predetermined value α in # 55, the drive duty DutyY in the pitch direction is not so affected by the interruption overhead.
Is subtracted from the value corresponding to the overhead, and is set in the register for timer match comparison Treg2.

In step # 56, the drive control terminal con in the pitch direction
Turn on tYA / YB. At this time, when driving the moving coil in the forward direction, only contYA is turned on and contYB remains off, and when driving the moving coil in the reverse direction, only contYB is turned on and contYA is kept off, thereby changing the driving direction. Control.

At step # 57, counterY is cleared to zero. However, when DutyY is larger than α, zero is only cleared and counter is not used.

If the value of DutyY is smaller than the predetermined value α in # 53, the flow proceeds to # 58.

If the value of counterY is zero in # 58, the process proceeds to # 59.

At step # 59, the coincidence interrupt 2 is enabled.

If the value of DutyY is smaller than the predetermined value α in step # 60, the influence of the overhead of the interruption increases, and the cycle time is lengthened to reduce the influence. Here, in order to make the cycle time eight times, the drive duty DutyY in the pitch direction is made eight times and set in the timer match comparison register Treg2.

At # 61, the drive control terminal con in the pitch direction
Turn on tYA / YB.

In order to make the cycle time eight times in # 62, c
Set counterY to 8.

In step # 51, counterY is decremented.

If counterY is not zero in # 58, the flow proceeds to # 64.

In step # 64, the interrupt is prohibited so that the coincidence interrupt 2 does not occur.

In step # 63, counterY is decremented. Here, the counter Treg2 and the drive control terminal co until the counterY becomes zero.
No processing is performed on ntYA / YB. As a result, the cycle time can be increased eight times.

At step # 65, the overflow interrupt processing is completed, and the processing returns to the normal processing.

In FIG. 7 of the present invention, the interrupt generated by the overflow of the timer is used. However, the number of bits of the timer can be sufficiently prepared, and another interrupt generated by the coincidence of the timer as shown in FIGS. If it is, PWM can be controlled by a timer coincidence interrupt instead of an overflow interrupt.

In the second embodiment, the period of PWM is reduced from 8 kHz to 1 kHz in order to reduce the influence of the overhead of the interrupt. Become. Therefore, the frequency is reduced only in the area where the duty is small and the driving amount is small (low energy), and the frequency is not lowered in the area where the duty is large and the driving amount is large so that the driving sound of the coil is minimized. I have.

On the other hand, if the driving member returns to the atmospheric position if the driving is stopped even if the position is changed by the PWM driving, such as a camera shake correction lens as in the present invention, a frequency having a high audible frequency sensitivity is obtained. By increasing the duty to generate a drive sound, it is possible to generate a warning sound used when a camera error occurs without adding a component such as a speaker.

[0096]

As described above, according to the present invention,
PWM that outputs PWM by switching the output of a flip-flop circuit in accordance with a match between a timer and a register
It is not necessary to provide an output circuit and a selector for switching this PWM output to a desired drive mechanism.

Further, by changing the cycle time depending on the duty to be output, even a microcomputer having a large delay due to the overhead of an interrupt which is slow in processing can minimize the influence of the overhead on the duty.

Further, the PWM drive cycle (frequency)
Can be changed, and by performing PWM driving at a frequency having high sensitivity to human audible frequencies, a warning sound can be output without providing a speaker.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a circuit configuration of the present invention.

FIG. 2 is a layout diagram of components.

FIG. 3 is a flowchart illustrating a sequence of camera shake correction.

FIG. 4 is a flowchart showing processing when an overflow interrupt of a timer occurs.

FIG. 5 is a flowchart showing processing when a timer coincidence interrupt 1 occurs.

FIG. 6 is a flowchart illustrating processing when a timer coincidence interrupt 2 occurs.

FIG. 7 is a modified example of a flowchart showing processing when an overflow interrupt of a timer occurs.

FIG. 8 is a PWM output waveform according to the second embodiment.

[Explanation of symbols]

1 MPU (microcomputer) for controlling camera shake correction 2 Gyroscope for detecting angular velocity of camera due to camera shake in pitch direction 3 Gyroscope for detecting angular velocity of camera due to camera shake in yaw direction 4 Amplifier 5 for amplifying gyro output in pitch direction 5 Yaw direction 6 A motor driver that drives a moving coil that corrects camera shake in the pitch direction 7 A motor driver that drives a moving coil that corrects camera shake in the yaw direction 8 A moving coil 9 that corrects camera shake in the pitch direction 9 Yaw direction A moving coil 10 for correcting camera shake, an 8-bit timer 11 for controlling PWM, a range (aperture) in which a subject image passing through a lens is captured 12 a power supply for driving a microcomputer and peripheral circuits 13 control parameters and calculation coefficients, etc. Recorded EE
Non-volatile memory such as PROM 14 Correction lens 15 for correcting camera shake by moving the position Three springs supporting the correction lens

   ────────────────────────────────────────────────── ─── Continuation of front page    F-term (reference) 5C022 AB55 AC54 AC74                 5H007 AA04 BB00 DB12 DC00 EA06                 5H540 AA10 BA06 BB06 EE02 EE11

Claims (6)

[Claims] 1. A binary timer counter composed of N bits for counting clock pulses such as a system clock. Registers A and B having the same bit length as the binary timer counter. A microcomputer that generates an interrupt when the values coincide with each other; and a PWM drive unit that energizes and drives while the control terminal is on, and stops or short-circuits while the control terminal is off. PWM control of the driving means by turning on the control terminal by an interrupt generated by the coincidence of the timer counter and by turning off the control terminal by an interrupt generated by the coincidence of the timer counter and the register B. PWM control mechanism. 2. A binary timer counter consisting of N bits for counting clock pulses such as a system clock, a register having the same bit length as the binary timer counter, and an interrupt when the timer counter matches the register. It has a microcomputer that generates an interrupt when the timer counter overflows, and a PWM drive means that energizes and drives while the control terminal is on, and stops or short-circuits while the control terminal is off. The drive means is PWM-controlled by turning on the control terminal by an interrupt generated when the timer counter overflows and turning off the control terminal by an interrupt generated when the timer counter and the register match. PWM control mechanism. 3. The cycle time of PWM is counted by counting the number of interrupts of coincidence between the timer counter and the register A, and turning on the control terminal once, but not turning on the control terminal (X-1) times. 3. The PWM control mechanism according to claim 2, wherein the ON time of the control terminal is lengthened by increasing the count set in the register B by X times. 4. Counting the number of overflow interrupts of the timer, turning on the control terminal once,
1) The cycle time of PWM is extended by X times by not turning on the control terminal, and the ON time of the control terminal is extended by increasing the count set in the register by X times. The PWM control mechanism according to claim 2, wherein 5. The PWM driving means according to claim 3, wherein when the duty is controlled in a wide range, such as when driving a lens for correcting camera shake, the cycle time is lengthened when the duty is small. 4 PWM control mechanism. 6. A method of changing the frequency by controlling the cycle time of the PWM and performing the PWM drive at a frequency having high sensitivity to human audible frequency to use as a warning sound when an error occurs or an operation sound during the PWM drive. Claim 3
And the PWM control mechanism according to claim 4.