JP2003029316A - Position controller and control method used for image pickup device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make perform precise control even if the characteristics of a system to be controlled have variance and to enable the controller to be of a high-density mounting. SOLUTION: A hole sensor 14 is controlled so that a constant current flows to a constant-current circuit 28, and outputs an output signal corresponding to the angle of rotation of a meter 13 when the meter 13 rotates. An adder 22 adds together the output signal from the hole sensor 14 and an offset voltage held in a PID arithmetic circuit filter arithmetic circuit 25 through a DAC 26. An amplifier 23 amplifies the signal from the adder 22. An arithmetic circuit 25 is supplied with parameters recorded in a ROM 32 through a microcomputer 31 so that an aperture diameter 11c reaches a target value. A driver circuit 29 performs the impedance conversion of the supplied voltage value and the impedance is applied as a driving voltage to a meter coil 30.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a position control device and method used in an image pickup apparatus suitable for controlling an iris of an image pickup section and a zoom lens.

[0002]

2. Description of the Related Art In recent years, a VTR integrated video camera and a digital still camera (hereinafter collectively referred to as a "digital camera") have been reduced in weight and size. Various parts that make up a digital camera are mounted in high density, and the weight and size of the digital camera have been reduced. As described above, as the weight and the size of the digital camera are reduced, the weight and the size of the imaging unit are also reduced. For example, the iris and ND filter for adjusting the amount of light are also reduced in weight and size, and the iris and ND filter themselves are becoming smaller. As the iris itself becomes smaller, the amount of change in the amount of light with respect to the amount of movement of the iris becomes larger, so that more precise control is required.

[0003]

However, in the iris control circuit, that is, the servo circuit, circuit characteristics such as gain and filter characteristics are set by resistors and capacitors.
There is a problem that it is not possible to adjust to the optimum characteristics according to the change of the state such as when the characteristics of the controlled object vary.

Further, since the circuit is composed of resistors and capacitors, there is a problem that the number of parts cannot be reduced, that is, high-density mounting becomes difficult.

Further, the zoom function incorporated in many digital cameras is also being reduced in weight and size. Therefore, the amount of change in the angle of view with respect to the amount of movement becomes large, so that there is a problem that it is not possible to adjust to the optimum characteristic according to the change in state, such as when the characteristics of the control target vary due to the operation of the digital camera. there were.

Therefore, an object of the present invention is to provide a position control device and method for use in an image pickup device which enables precise control even if variations occur in the characteristics of the controlled object and enables high-density mounting. Especially.

[0007]

According to a first aspect of the present invention, there is provided a position control device for use in an image pickup device, the position control device having an actuator for displacing an object to be controlled, and a sensor for detecting a position of the actuator. A memory that stores a parameter for calculating a drive signal for driving the actuator, a control unit that changes the parameter according to a detection signal output from the sensor, and an arithmetic unit that calculates the drive signal using the changed parameter. And a position control device for use in an image pickup device.

According to a sixth aspect of the present invention, there is provided a position control method for an image pickup apparatus, comprising a actuator for displacing a controlled object and a sensor for detecting the position of the actuator, and a drive signal for driving the actuator. An image pickup device characterized in that a parameter for calculating is stored in a memory, the parameter is changed according to a detection signal output from the sensor, and the drive signal is calculated using the changed parameter. This is the position control method used.

The sensor has an actuator and a sensor for detecting the position of the actuator and the object to be controlled by the actuator, and a parameter for calculating a voltage used when generating a drive signal for driving the actuator is stored in a memory. Since the setting of the parameter can be freely changed according to the detection signal output from the device, it is possible to set the optimum characteristic according to the variation or the change in the state of the actuator.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described below with reference to the drawings. It should be noted that components having the same function throughout the drawings are designated by the same reference numerals to avoid duplication of description. First, in order to facilitate this description, an example of the iris will be described with reference to FIG. Iris is 2
Comprised of a pair of diaphragm blades 11a and 11b, a meter (actuator) 13 for generating power, an arm 12 for transmitting the power of the meter 13 to the diaphragm blades 11a and 11b, and a Hall sensor 14 for detecting a rotation angle of the meter 13. To be done.

In order to adjust the light quantity L of the incident light to a desired light quantity, each of the diaphragm blades 11a and 11b is provided with a cutout portion. An opening diameter 11c is formed by these notches. By changing the rotation angle of the meter 13, the diaphragm blades 11a and 11b are slid in the directions opposite to each other, and the size of the opening diameter 11c is changed. The meter 13 may or may not be spring-biased. In this way, the amount of light supplied to the lens 15 is adjusted by changing the rotation angle of the meter 13. As an example, the light amount L supplied to the imager 16 via the lens 15 is
When it is desired to adjust the light amount La, the aperture diameter 1 shown in FIG.
When it is desired to control the rotation angle of the meter 13 to have a size of 1c and to adjust the light amount Lb, the rotation angle of the meter 13 is controlled to have a size of the opening diameter 11c shown in FIG. 1B.

In this iris, the rotation angle of the meter 13 is proportional to the size of the opening diameter 11c, and the Hall sensor 14 outputs a detection signal according to the rotation angle of the meter 13. By observing the detection signal of the hall sensor 14, the size of the opening diameter 11c can be servo-controlled. That is, in this embodiment, the hall sensor 14 is used as a position sensor for the iris.

An embodiment of position control to which the present invention is applied will be described with reference to FIG. In the hall sensor 14,
The reference voltage Vcc is supplied and is controlled by the constant current circuit 28 inside the digital servo circuit 21 so that a constant current flows. This constant current circuit 28 is a PID (proportionality / integration: integration / differentiation: differentiation) operation circuit via a D / A converter 27.
It is controlled by a control signal supplied from the filter calculation circuit 25. When the meter 13 rotates, the hall sensor 14 outputs a detection signal according to the rotation angle. The detection signal from the Hall sensor 14 is supplied to the adder 22. The detection signal supplied to the adder 22 is, for example, several hundred mV.

In the adder 22, the detection signal from the hall sensor 14 and the offset voltage supplied from the PID operation circuit / filter operation circuit 25 via the D / A (Digital to Analog) converter 26 are added. Adder 2
The addition result of 2 is supplied to the amplifier 23. Amplifier 23
Then, the signal from the adder 22 is amplified, and the A / D (Anal
og to Digital) converter 24. A / D
The converter 24 converts the supplied signal into a digital signal and supplies the digital signal to the PID operation circuit / filter operation circuit 25.

In the PID arithmetic circuit / filter arithmetic circuit 25, E is adjusted so that the opening diameter 11c becomes a target size.
EPROM (Electrically Erasable and Programmable
The parameters stored in the Read Only Memory) 32 are supplied by serial communication via the microcomputer 31, and the optimum output voltage is calculated. At this time, the microcomputer 31 and the digital servo circuit 21 are
Commands, parameters, data, etc. can be mutually communicated by serial communication. Similarly, both the microcomputer 31 and the EEPROM 32 can mutually communicate commands, parameters, data, etc. by serial communication.

The voltage value calculated by the PID calculation circuit / filter calculation circuit 25 is supplied to the driver circuit 29.
In the driver circuit 29, the supplied voltage value is impedance-converted and applied as a drive voltage to the meter coil 30. The meter 30 rotates by an angle according to the drive voltage applied to the meter coil 30.

The operation of the digital camera at startup will be described in detail. The D / A converters 26 and 27 are adjusted so that the detection signal of the hall sensor 14 when the iris is fully open and fully closed matches the conversion range of the A / D converter 24. At this time, the offset voltage supplied to the adder 22 and the control signal supplied to the constant current circuit 28 are optimally set. The adjustments of the D / A converters 26 and 27 are performed in the manufacturing process, and the adjusted values are stored in the EEPROM 32 as parameters.

As an example, the parameters stored in the EEPROM 32 are the PID operation circuit / filter operation circuit 2
5 is a gain and a filter coefficient used in FIG. The parameters stored in the EEPROM 32 are supplied to the digital servo circuit 21 via the microcomputer 31 each time it is activated. In the PID arithmetic circuit / filter arithmetic circuit 25, the driver circuit 29 is supplied with a voltage value such that the iris opening diameter 11c becomes a desired size. In the driver circuit 29, the drive voltage is applied to the meter coil 30 as described above, the meter 13 rotates, and the opening diameter 11c becomes a desired size.

When the operation of the digital camera is stopped,
The voltage to fully close the iris is the PID calculation circuit.
It is output from the filter calculation circuit 25 to the driver circuit 29, and the iris is fully closed. When the meter 13 is spring-biased toward the fully closed direction, this control is unnecessary.

The operating characteristics such as the stability of the iris against disturbance and the operating speed can be controlled by the parameters used for the operation of the PID operation circuit / filter operation circuit 25. This parameter is stored in the EEPROM 32 as described above.

The parameters used for the operation of the PID operation circuit / filter operation circuit 25 are the values adjusted in the above manufacturing process, that is, the parameters stored in the EEPROM 32. Corrections are made according to the operating environment such as humidity and changes over time. The digital servo circuit 21 constantly observes the response characteristic of the iris with respect to the applied voltage through the hall sensor 14. The data from the hall sensor 14 is transmitted to the microcomputer 31 by serial communication.
In the microcomputer 31, the digital servo circuit 2
The parameters stored in the EEPROM 32 are corrected on the basis of the data received from 1. The corrected parameters are transmitted to the digital servo circuit 21 by serial communication.

More specifically, when the resistance value of the meter coil 30 rises due to the temperature rise in the operating environment, the same drive voltage as before the temperature rise is supplied from the driver circuit 29 to the meter coil 30. However, the current flowing through the meter coil 30 decreases. That is, the magnetic flux density decreases. (Current flowing through meter coil 30) =
(Output voltage of driver circuit 29) ÷ (Resistance value of meter coil 30)

Since the torque generated by the meter 13 is proportional to the current flowing through the meter coil 30, the torque generated by the meter 13 decreases as the temperature of the usage environment rises. Therefore, in order to make the opening diameter 11c a desired size, it is necessary to compensate for this decrease. Therefore, in the microcomputer 31, the parameters used in the PID operation circuit / filter operation circuit 25 are corrected so that the drive voltage output from the driver circuit 29 increases. Then, the corrected parameters are supplied to the digital servo circuit 21 by serial communication.

When the resistance value of the meter coil 30 decreases due to the temperature decrease, even if the same drive voltage as before the temperature decrease is supplied from the driver circuit 29 to the meter coil 30, the current flowing through the meter coil 30 does not change. Increase.
That is, the magnetic flux density increases. Therefore, meter 1
The torque generated in 3 increases. Therefore, opening diameter 11c
In order to obtain a desired size, it is necessary to suppress this increase. Therefore, the microcomputer 31 is arranged so that the drive voltage output from the driver circuit 29 becomes small.
In, the parameters used in the PID calculation circuit / filter calculation circuit 25 are corrected. And
The corrected parameters are supplied to the digital server circuit 21 by serial communication.

As described above, the parameters used for the calculation in the PID calculation circuit / filter calculation circuit 25 can be freely changed. Therefore, the parameter can be freely changed, so that even if the characteristic of the controlled object varies, that is, the resistance value of the meter coil 30 changes and the current flowing through the meter coil 30 changes, the size of the opening diameter 11c can be changed. A desired size can be easily obtained.

The change in the torque generated by the meter 13 and the change in the load on the diaphragm blades 11a and 11b are not limited to the temperature, but the parameters used in this embodiment are corrected by observing the detection signal from the Hall sensor 14. As a result, it is possible to detect the change in the torque generated by the meter 13 and the change in the load on the diaphragm blades 11a and 11b, so that the parameters can be freely changed according to the operating state of the iris.

Here, an example of changing the gain will be described as an example of changing the parameters described above with reference to the flowchart of FIG. In step S1, it is determined whether or not the iris has been operated. When it is determined that the iris is operated, the control shifts to step S2, and when it is determined that the iris is not operated, the control of step S1 is repeated until the operation of the iris is detected. As described above, the hall sensor 1 detects the movement of the iris.
It may be judged based on the detection signal from 4 or PID
The determination may be made based on the voltage value supplied from the arithmetic circuit / filter arithmetic circuit 25 to the driver 29. Further, it may be determined whether or not the iris is driven based on both of them.

In step S2, it is determined based on the detection signal from the hall sensor 14 whether or not the meter 13 does not stop at a desired position but exceeds the desired position, that is, whether it overshoots. When it is determined that the overshoot has occurred, the control shifts to step S5, and when it is determined that the overshoot has not occurred, the control shifts to step S3. In step S5, the gain is reduced. And
The control returns to step S1.

In step S3, it is determined whether the meter 13 has reached the desired position 20 msec or more after the iris is operated, or whether the meter 13 has not reached the desired position 20 msec or more. To be judged. That is, in this step S3, in order to stop the meter 13 at a desired position after operating the iris, 20 msec
It is determined whether the above delay has occurred. If it is determined that a delay of 20 msec or more has occurred to stop the meter 13 at a desired position after operating the iris,
When the control moves to step S4 and it is determined that the meter 13 has reached the desired position in less than 20 msec, step S1
Control returns to. In step S4, the gain is increased. Then, the control returns to step S1.

In this way, the gain is changed when it is detected that the desired position has not been reached within a predetermined time or overshoot. If the gain is not changed, in the case of overshoot, the overshoot state gradually deteriorates and eventually oscillation occurs, so that an accurate light amount cannot be supplied to the lens 15 and the imager 16. This kind of iris oscillation
It can be suppressed by changing the gain.

If the desired position has not been reached within the predetermined time, more time than necessary is required for the iris to operate accurately, so the light quantity is supplied to the lens 15 and the imager 16 for a long time. This causes damage to the imager 16.

Further, as the iris oscillation, for example,
The voltage value output from the digital servo circuit 21 may be the cause, or the spring when the meter 13 is biased by the spring may be the cause. However, the Hall sensor 14 causes the rotation angle of the meter 13 and the diaphragm blade 1 to
Since the gain can be changed by detecting the positions of 1a and 11b, oscillation can be suppressed. That is, in this embodiment, the gain can be changed to change the oscillation point.

Specifically, when an overshoot is detected from the detection signal supplied from the Hall sensor 14 when the iris is changed, the gain is, for example, 1 dB.
Lower. By reducing the gain by 1 dB, overshoot is suppressed when the iris is changed next time. If overshoot is detected again even if the gain is reduced once, the gain is reduced again until the overshoot is suppressed.

When the iris is changed and it is detected from the detection signal supplied from the hall sensor 14 that the target position is not reached within a predetermined time, the gain is increased by 1 dB, for example. By increasing the gain by 1 dB, the target position is reached within a predetermined time when the iris is changed next time. Further, if it is detected that the target position is not reached within the predetermined time even if the gain is increased once, the gain is increased again until the target position is reached within the time.

Here, as an example of the gain change amount, 1d
Although it is set to B, it may be 2 dB. Setting this gain change amount to a large value may cause hunting, and setting it to a small value may reduce the number of times (time) in order to suppress overshoot or to reach a desired position within a predetermined time. Therefore, the amount of change may be such that the overshoot can be suppressed or the desired position can be reached within a predetermined time by changing the gain once or twice. It should be noted that the amount of change in the gain is set by appropriately selecting an optimum value according to the device (meter 13) as the load.

Further, if oscillation occurs when the aperture diameter 11c is minimized, it has a great effect on the amount of light obtained from the incident light. Therefore, when the aperture diameter 11c is minimized, the oscillation will occur even if the gain is changed. The amount of change in gain may be set so as not to occur.

The amount of change in gain may be changed depending on the target size of the opening diameter 11c. For example, when the aperture diameter 11c is set to a minimum size, a slight change in the aperture diameter 11c has a great influence on the amount of light obtained from the incident light at that time. Is set to a small value and the maximum size of the aperture diameter 11c is set as a target, even if the size of the aperture diameter 11c is subtly changed, the light amount obtained from the incident light at that time is not significantly affected. , The gain variation is set to a large value. In this way, the change amount of the gain may be set to be optimum for the target opening diameter 11c. Further, the amount of change in gain may be set stepwise according to the size of the opening diameter 11c, and the gain may be switched depending on the size of the opening diameter 11c for use.

The amount of change in gain may be changed depending on the size of overshoot, that is, the distance over the target position. For example, when it is detected from the detection signal from the hall sensor 14 that the target position has overshooted only at a position that is less than a predetermined distance, the amount of change in gain preset as a standard is used to set the target position. When it is detected from the detection signal from the hall sensor 14 that the overshoot has occurred to a position that is equal to or greater than a predetermined distance, the change amount of the gain preset as a standard may be changed to a larger value. .

In this embodiment, the meter 13 may or may not be spring-biased.
If the meter 13 is not spring biased, the opening diameter 11c
The current supply to the meter coil 30 is stopped until the meter 13 is rotated to a predetermined size and then the size of the opening diameter 11c is changed. When the meter 13 is spring-biased, it is necessary to constantly supply current to the meter coil 30 in order to maintain the opening diameter 11c at a constant size.

Next, another embodiment to which the present invention is applied will be described with reference to the drawings. First, in order to facilitate the description of the other embodiments, an example of a zoomable lens unit will be described with reference to FIG. In this lens unit, a linear motor is used to drive the view angle changing lens and the focus adjusting lens. The magnetic circuit 101 on the fixed side of the linear motor is composed of a magnet and a yoke, and on the moving side, a driving linear motor coil 102 for moving the view angle changing lens 105 and a drive for moving the focus adjusting lens 111. And a linear motor coil 108 for. The magnetic circuit 101 is provided with a partition plate 101a.

As shown in FIGS. 5A and 5B, the view angle changing lens 105 is fixed to the lens fixing plate 131.
The lens fixing frame 104 is provided so as to surround the lens fixing plate 131. The lens fixing plate 131 is shown in FIG.
As shown in B, the base 103 and the magnet 106 for position detection are connected. The base 103 is also connected to the linear motor coil 102. MR (Magn
The eto resistance sensor 107 is fixed so as to maintain a distance t with the magnet 106 as shown in FIG. 5B. The base 103 is connected to the linear motor coil 102 and the lens fixing frame 104, and the shaft 127 penetrates through the central portion of the base 103. In addition, the shaft 128 is provided so as to penetrate the lens fixing plate 131 at a position facing the shaft 127.
Is provided. The angle-of-view changing lens 105 has a shaft 12
Guided by 7 and 128, slidable.

Although not shown, the focus adjusting lens 111
Is fixed to the lens fixing plate. Lens fixing frame 110
Are provided so as to surround the lens fixing plate. A base 109 and a magnet 112 for position detection are coupled to the lesbian fixing plate. The base 109 is connected to the linear motor coil 108. The MR sensor 113 is fixed so that the distance t from the magnet 112 can be maintained. The base 109 is connected to the linear motor coil 108 and the lens fixing frame 110, and the shaft 127 penetrates through the central portion thereof. Further, a shaft 128 is provided so as to penetrate the lens fixing plate at a position facing the shaft 127. The focus adjusting lens 111 is guided by shafts 127 and 128 and is slidable.

The lens 122 is fixed to the frame 121, the imager 126 is fixed to the frame 125,
A lens 124 is fixed to the frame 123. Also,
Frames 121 and 125 have axes 127 and 128.
Is stuck.

As described above, by applying a current to the linear motor coils 102 and 108, a force is generated in the optical axis direction, and by moving the angle-of-view changing lens 105 and the focus adjusting lens 111, a zoom function is achieved. Can be realized.

The MR sensor 107 is the lens 1 for changing the angle of view.
By changing the position of 05, the A-phase sine wave Sa and the B-phase sine wave Sb having different phases by 90 degrees are output as shown in FIG. By processing the sine waves Sa and Sb, the position of the angle-of-view changing lens 105 can be accurately known. Therefore, this sine wave S
The position of the angle-of-view changing lens 105 can be servo-controlled using a and Sb.

Similarly, the MR sensor 113 outputs an A-phase sine wave Sa and a B-phase sine wave Sb having different 90-degree phases as shown in FIG. 6 as the position of the focus adjusting lens 111 changes. To do. By processing the sine waves Sa and Sb, the position of the focus conversion lens 111 can be accurately known. Therefore, the position of the focus conversion lens 111 can be servo-controlled using the sine waves Sa and Sb.

In FIG. 6, the MR sensors 107 and 11 are shown.
It is one cycle of the sine waves Sa and Sb outputted from No. 3, and is actually repeated by the stroke. The potential a in FIG. 6 is the switching level above the A phase, and the position b
Is the switching level below the A phase. Position c is the switching level above phase B obtained by interpolation, and position d
Is the switching level below the B phase obtained by interpolation.

Another embodiment of the position control to which the present invention is applied will be described with reference to FIG. Hereinafter, the position control of the angle-of-view changing lens 105 will be described for ease of description, but the position control of the focus adjustment lens 111 can also be performed by the same circuit and control.

The MR sensor 107 is supplied with the reference voltage Vcc. The MR sensor 107 includes the angle-of-view changing lens 10
When 5 moves, two sine waves Sa corresponding to the movement
And Sb are output. The MR sensor 10
The sine wave Sa and Sb detection signals from 7 are added by the adder 1
42 and 144.

In the adder 142, the sine wave Sa from the MR sensor 107 and P through the D / A converter 149.
The offset voltage supplied from the ID calculation circuit / filter calculation circuit 148 is added. The addition result of the adder 142 is supplied to the amplifier 143. In the amplifier 143,
The signal from the adder 142 is amplified and supplied to the A / D converter 146. In the A / D converter 146, the supplied signal is converted into a digital signal and supplied to the position calculation circuit 147.

In the adder 144, the sine wave Sb from the MR sensor 107 and P through the D / A converter 150.
The offset voltage supplied from the ID calculation circuit / filter calculation circuit 148 is added. The addition result of the adder 144 is supplied to the amplifier 145. In the amplifier 145,
The signal from the adder 144 is amplified and supplied to the A / D converter 146. In the A / D converter 146, the supplied signal is converted into a digital signal and supplied to the position calculation circuit 147.

In the position calculating circuit 147, the position information is standardized by the amplitudes of the supplied two-phase sine waves Sa and Sb. The calculation for obtaining this position information is constantly operating while the digital camera is used.
The obtained position information is supplied from the position calculation circuit 147 to the PID calculation circuit / filter calculation circuit 148.

PID arithmetic circuit / filter arithmetic circuit 148
Then, using the signal from the position calculation circuit 147, the optimum output voltage for reaching the target position of the angle-of-view changing lens 105, which is given from the microcomputer 31 by serial communication, is calculated. At this time, the microcomputer 3
1 and the digital servo circuit 141 can mutually communicate commands, parameters, data, and the like by serial communication. Similarly, the microcomputer 31 and the EEP
Also with the ROM 32, commands, parameters, data, and the like can be mutually communicated by serial communication.

PID operation circuit / filter operation circuit 148
The voltage value calculated in step 3 is supplied to the driver circuit 151. In the driver circuit 151, the supplied voltage value is impedance-converted and applied as a drive voltage to the linear motor coil 102. The angle-of-view changing lens 105 moves according to the drive voltage applied to the linear motor coil 102.

The operation when the digital camera is started will be specifically described. The sine waves Sa and S of the MR sensor 107 from the wide end having the maximum angle of view to the tele end having the minimum angle of view.
The D / A converters 149 and 150 are adjusted so that b matches the conversion range of the A / D converter 146. At this time, the offset voltage supplied to the adders 142 and 144 is optimally set. The adjustment of the D / A converters 149 and 150 is performed in the manufacturing process, and the adjusted values are respectively used as parameters in the EEPR.
It is stored in the OM32.

As an example, the parameters stored in the EEPROM 32 are the PID operation circuit / filter operation circuit 1
Gain and filter coefficients used at 48. The parameters stored in the EEPROM 32 are supplied to the digital servo circuit 141 via the microcomputer 31 every time the system is activated. In the PID calculation circuit / filter calculation circuit 148, a voltage value with which the angle-of-view changing lens 105 is at the target position is supplied to the driver circuit 151. In the driver circuit 151, the drive voltage is applied to the linear motor coil 102 as described above, the lens 105 for changing the angle of view moves, and the target position is reached.

When the operation of the digital camera is stopped,
A voltage for setting the angle-of-view conversion lens 105 to a predetermined position is output from the PID operation circuit / filter operation circuit 148 to the driver circuit 151, and the angle-of-view conversion lens 105 moves to a predetermined position.

Further, the operating characteristics such as the stability of the lens position against the disturbance and the operating speed can be controlled by the parameters used for the operation of the PID operation circuit / filter operation circuit 148. This parameter is stored in the EEPROM 32 as described above.

PID operation circuit / filter operation circuit 148
The parameter used in the calculation of the above corresponds to the value adjusted in the above manufacturing process, that is, the parameter stored in the EEPROM 32, and corresponds to the use environment such as temperature and humidity during the use of the digital camera and the change over time. The correction is applied. The digital servo circuit 141 uses the MR sensor 10
7, the response characteristic of the linear motor 101 with respect to the applied voltage is constantly observed. The data from the MR sensor 107 is transmitted to the microcomputer 31 by serial communication. In the microcomputer 31, the EE based on the data received from the digital servo circuit 141
The parameters stored in the PROM 32 are corrected. The corrected parameters are transmitted to the digital servo circuit 141 by serial communication.

More specifically, if the resistance value of the linear motor coil 102 rises due to, for example, an increase in operating environment temperature, the same drive voltage as before the temperature rise is supplied from the driver circuit 151 to the linear motor coil 102. However, the current flowing through the linear motor coil 102 decreases. That is, the magnetic flux density decreases. (Current flowing through the linear motor coil 102) = (Output voltage of the driver circuit 151) / (Resistance value of the linear motor coil 102)

The torque generated by the linear motor 101 is
Since it is proportional to the current flowing in the linear motor coil 102, the torque generated in the angle-of-view changing lens 105 decreases due to the increase in the operating environment temperature. Therefore, in order to make the opening diameter 11c a desired size, it is necessary to compensate for this decrease. Therefore, in the microcomputer 31, the parameters used in the PID operation circuit / filter operation circuit 148 are corrected so that the drive voltage output from the driver circuit 151 increases. Then, the corrected parameters are supplied to the digital server circuit 21 by serial communication.

When the resistance value of the linear motor coil 102 decreases due to the temperature decrease, even if the same drive voltage as before the temperature decrease is supplied from the driver circuit 151 to the linear motor coil 102, the linear motor coil 10
The current flowing through 2 increases. That is, the magnetic flux density increases. Therefore, the torque generated by the linear motor 101 increases. Therefore, in order to set the view angle changing lens 105 to the target position, it is necessary to suppress this increase.
Therefore, in the microcomputer 31, the parameters used in the PID operation circuit / filter operation circuit 148 are corrected so that the drive voltage output from the driver circuit 151 becomes smaller. Then, the corrected parameters are supplied to the digital servo circuit 141 by serial communication.

As described above, the parameters used for calculation in the PID calculation circuit / filter calculation circuit 148 can be freely changed. Therefore, since the parameters can be freely changed, the characteristics of the controlled object vary, that is, the resistance value of the linear motor coil 102 changes,
Even if the current flowing through the linear motor coil 102 changes, the angle-of-view changing lens 105 can be easily moved to the target position.

Although the change in the torque generated by the linear motor 101 is not limited to the temperature, the correction of the parameters used in this embodiment is generated by the linear motor 101 by observing the detection signal from the MR sensor 107. Since the change in torque can be detected, the parameters can be freely changed according to the operating state of the linear motor 101.

Here, an example of changing the gain will be described as an example of changing the parameters described above with reference to the flowchart of FIG. In step S101, it is determined whether or not the angle-of-view changing lens 105 has been operated. If it is determined that the angle-of-view changing lens 105 is operated, the control proceeds to step S102. If the angle-of-view changing lens 105 is not operated, the control of step S101 is performed until the angle-of-view changing lens 105 is operated. Repeated.
The detection of the operation of the angle-of-view changing lens 105 may be determined based on the detection signal from the MR sensor 107 as described above, or the PID calculation circuit / filter calculation circuit 148.
Alternatively, the determination may be made based on the voltage value supplied from the driver circuit 151 to the driver circuit 151. Further, it may be determined whether or not the iris is driven based on both of them.

In step S102, the MR sensor 107
Based on the detection signal from, it is determined whether the angle-of-view changing lens 105 does not stop at the desired position but exceeds the desired position, that is, whether or not it has overshot. When it is determined that the overshoot has occurred, the control proceeds to step S105, and when it is determined that the overshoot has not occurred, the control proceeds to step S103. In step S105,
Gain can be reduced. Then, the control returns to step S101.

In step S103, the linear motor 10
It is determined whether the angle-of-view changing lens 105 has reached the target position after 8 msec has passed after operating 1 or whether the angle-of-view changing lens 105 has not reached the target position even after 8 msec has passed. To be done. That is, this step S1
In 03, in order to stop the angle-of-view changing lens 105 at the target position after operating the linear motor 101,
It is determined whether a delay of ec or more has occurred. When it is determined that a delay of 8 msec or more has occurred in order to stop the angle-of-view changing lens 105 at the target position after operating the linear motor 101, the control proceeds to step S104,
When it is determined that the view angle changing lens 105 has reached the target position in less than 8 msec, the control returns to step S101.
In step S104, the gain is increased. And
The control returns to step S101.

In this way, the gain is changed when it is detected that the target position has not been reached within the predetermined time or overshoot. If the gain is not changed, in the case of overshoot, the state of overshoot gradually deteriorates and oscillation eventually occurs, so that an accurate angle of view and focus can be supplied to the lens 15 and the imager 16. Can not. Such oscillation of the zoom function can be suppressed by changing the gain.

Specifically, when the zoom is changed,
When overshoot is detected from the detection signal supplied from the MR sensor 107, the gain is lowered by, for example, 1 dB. By reducing the gain by 1 dB, the overshoot is suppressed when the zoom is changed next time. If overshoot is detected again even if the gain is reduced once, the gain is reduced again until the overshoot is suppressed.

Further, when it is detected that the target position is not reached within a predetermined time from the detection signal supplied from the MR sensor 107 when the zoom is changed, the gain is changed to
For example, increase by 1 dB. By increasing the gain by 1 dB, when the iris is changed next time, the target position is reached within a predetermined time. Further, if it is detected that the target position is not reached within the predetermined time even if the gain is increased once, the gain is increased again until the target position is reached within the time.

Here, as an example of the gain change amount, 1d
Although it is set to B, it may be 2 dB. If the amount of change in gain is set to a large value, setting hunting may occur, and if it is set to a small value, it takes a number of times (time) to suppress overshoot or reach the target position within a predetermined time. Therefore, changing the gain once or twice suppresses overshoot,
The amount of change may be such that it can reach the target position within a predetermined time. It should be noted that this gain change amount is set by appropriately selecting an optimum value according to the device (field angle changing lens 105) as a load.

The amount of change in gain may be changed depending on the size of overshoot, that is, the distance over the target position. For example, when it is detected from the detection signal from the MR sensor 107 that the target position has overshot only at a position that is less than a predetermined distance, the change amount of the gain preset as a standard is used to set the target position. When it is detected from the detection signal from the MR sensor 107 that overshoots to a position that is equal to or greater than a predetermined distance, the change amount of the gain preset as a standard may be changed to a larger value. .

In this other embodiment, the lens closer to the imager 126 is used as the focus adjusting lens and the lens farther from the imager 126 is used as the angle-of-view changing lens. May be used as a lens for focus adjustment. That is, any device that can realize the zoom function may be used.

In this other embodiment, the position detecting magnets 106 and 112 are provided at positions facing the linear motor, but there is no problem if they are provided at the same position as the linear motor.

[0075]

According to the present invention, since the gain can be adjusted by comparing the current position and the target position with the digital servo circuit, the microcomputer, and the EEPROM, the device (meter or linear motor) serving as a load can be adjusted. ), That is, the parameter (gain) having the optimum characteristic can be appropriately changed according to the variation of the controlled object and the change of the state. Therefore, it is possible to suppress overshoot that greatly exceeds the target position and a state where the target position is not reached.

According to the present invention, at least 40 or more resistors and capacitors are conventionally used to set the servo parameters, but since the servo parameters can be stored in the EEPROM, the number of parts can be reduced. It can be reduced significantly. Furthermore, the mounting area can be significantly reduced, and the iris can be downsized. Moreover, since the number of parts can be significantly reduced, power consumption can be suppressed.

According to the present invention, the digital servo circuit,
With the microcomputer and the EEPROM, speed control as well as iris position control can be easily performed. Further, since the iris is controlled by the digital servo circuit, the microcomputer and the EEPROM, more precise control becomes possible.

According to the present invention, since the optimum characteristics can be set according to the variation of the controlled object and the change of the state, precise control becomes possible, and the lens barrel having the zoom function can be miniaturized. can do.

[Brief description of drawings]

FIG. 1 is a schematic view of an example in which the present invention is applied to an iris.

FIG. 2 is a block diagram of an embodiment of position control of the present invention.

FIG. 3 is a flowchart for explaining an embodiment of the present invention.

FIG. 4 is a schematic view of an example in which the present invention is applied to a zoom function.

FIG. 5 is a schematic view of an example in which the present invention is applied to a zoom function.

FIG. 6 is an example of the output of the MR sensor used in the present invention.

FIG. 7 is a block diagram of another embodiment of the position control according to the present invention.

FIG. 8 is a flowchart for explaining another embodiment of the present invention.

[Explanation of symbols]

13 ... Meter, 14 ... Hall sensor, 21 ...
・ Digital servo circuit, 22 ... Adder, 23 ...
Amplifier, 24 ... A / D converter, 25 ... PI
D operation circuit / filter operation circuit, 26, 27 ... D /
A converter, 28 ... Constant current circuit, 29 ... Driver circuit, 30 ... Meter coil, 31 ... Microcomputer, 32 ... EEPROM

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Claims (10)

[Claims] 1. A position control device for use in an image pickup device, comprising: an actuator for displacing an object to be controlled; and a sensor for detecting the position of the actuator, for calculating a drive signal for driving the actuator. A memory for storing parameters, a control means for changing the parameters according to a detection signal output from the sensor, and an arithmetic means for calculating the drive signal using the changed parameters. Position control device used in an image pickup device that operates. 2. The position control device used in the image pickup device according to claim 1, wherein the actuator is a meter. 3. The position control device used in the image pickup device according to claim 1, wherein the actuator is a linear motor. 4. The position control device used in the image pickup apparatus according to claim 1, wherein the parameters are a gain and a filter coefficient, and at least the gain is changed. 5. The control means, when it is determined that the actuator has greatly exceeded a target position based on the detection signal output from the sensor, lowers the gain and sets the detection signal output from the sensor to the detected signal. The position control device used in the image pickup device according to claim 4, wherein, when it is determined that the actuator has not reached the target position based on a predetermined time period, the gain is increased based on the actuator. . 6. A position control method used in an image pickup apparatus, comprising: an actuator for displacing an object to be controlled; and a sensor for detecting the position of the actuator, the method being for calculating a drive signal for driving the actuator. A parameter is stored in a memory, the parameter is changed according to a detection signal output from the sensor, and the drive signal is calculated using the changed parameter. Position control method. 7. The position control method used in an image pickup apparatus according to claim 6, wherein the actuator is a meter. 8. The position control method used in an image pickup apparatus according to claim 6, wherein the actuator is a linear motor. 9. The position control method used in an image pickup apparatus according to claim 6, wherein the parameters are a gain and a filter coefficient, and at least the gain is changed. 10. The gain is changed by decreasing the gain when it is determined that the actuator has largely exceeded a target position based on the detection signal output from the sensor. 10. The image pickup apparatus according to claim 9, wherein the gain is increased when it is determined that the actuator has not reached the target position within a predetermined time based on the detection signal. Position control method.