JPH0486730A - Vibration proof device for camera - Google Patents

Abstract

PURPOSE:To improve minimum resolution for controlled vibration by analogically obtaining the output of difference between the displacement amount of blurring with respect to absolute space and the displacement amount of the inclination of a correction optical means, digitally calculating the output of the difference and obtaining output for control of the correction optical means. CONSTITUTION:A floating body 4 which can be freely rotated is disposed in liquid 3 filling up an outer jacket 2. Signal light from a light emitting element 6 is reflected on the surface of the floating body 4 and made incident on a light receiving element for detecting a position 5. Then, it is changed by a current outputted by the element 5 and the movement of the floating body 4 when the body 4 is relatively rotated with respect to the jacket 2. On the other hand, the displacement amount of the angle of a variable apex angle prism 41 which is used as the correction optical means is also detected by the same method as a blurring detection means. Then, the difference between the displacement output of the blurring of the blurring detection means and the output of the displacement of the angle of the prism 41, that means, the output of the difference between the displacement amount of the blurring with respect to the absolute space and the displacement amount of the inclination of the correction optical means is analogically obtained. Thereafter, the output of the difference is digitally calculated and the output for control of the correction optical means is obtained. Thus, the minimum resolution for controlled the vibration is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Application of the Invention) The present invention provides camera shake detection means for detecting the amount of shake displacement of a camera body with respect to absolute space, and correction optics for varying the optical path incident on a photographic lens with respect to the optical axis. means, a position detection means for detecting the amount of tilt displacement of the correction optical means with respect to the optical axis, a driving means for electrically driving the correction optical means, digitally calculating the input output, and calculating the calculation result. The present invention relates to an improvement of a camera image stabilization device including a digital control means for controlling the driving means based on the present invention.

(Background of the invention) A conventional device of this type is shown in FIG.

In FIG. 6, a floating body 4 supported around a predetermined rotation axis is placed in an outer cylinder 2 containing a liquid 3.
In this state, if the outer cylinder 2 that moves together with the camera rotates by θIN relative to the absolute space, the floating body 4 inside remains stationary in the absolute space due to the inertia of the liquid 3, so the floating body 4 is relatively has rotated with respect to the outer cylinder 2.

Therefore, by detecting this amount of rotational displacement using the camera shake detection means as shown in the figure, as a result, the operational amplifier 1
The amount of shake displacement of the camera can be extracted from the output of 6. On the other hand, as a correction optical means for removing image blur, 41
It uses a variable apex prism in which a liquid with a constant refractive index is sealed inside, as shown in Figure 2, and can freely expand and contract around a predetermined rotation axis.

Here, when the amount of angular displacement of this variable apex angle prism 41 around a predetermined rotation axis is θ0tlT, and the refractive index of the internal liquid 3 is n, the incident light from the subject after passing through this variable apex angle prism 41 is The displacement angle θX of the light with respect to the optical axis is expressed as θx=<n-1)θ011T.

Therefore, if the shake displacement with respect to absolute space is detected by the above-mentioned camera shake detection means and the apex angle of the variable apex angle prism 41 is varied by an angle proportional to this shake displacement, even if the camera body shakes, the distance from the subject will always be maintained. Incident light can be guided to the same position on the film surface 42, and camera shake can be suppressed.

In FIG. 6, the amount of angular displacement (the amount of tilt displacement with respect to the photographic lens 40) of the variable apex angle prism 41 is extracted from the output of the operational amplifier 56 using a position detection means. Incidentally, since most of the configuration of each part in this FIG. 6 is the same as the configuration in FIG. 1 which will be described later, the details thereof will not be described in this FIG.

In this digital control method, the CPU 100
Inside the CPU 100, the internal sampling timer 101 performs A/D conversion at regular intervals, and converts the above-mentioned deflection displacement amount with respect to the absolute space and the angular displacement amount of the variable apex angle prism 41 into digital data. This data is digitally subtracted, the resulting value is multiplied by an appropriate coefficient, and the result is transferred to the PWM timer 103.

The output of the PWM timer 103 is converted into an analog value by a low-pass filter composed of a resistor 112° and a capacitor 111, and is applied to the drive coil 98, which is a driver circuit of the variable apex angle prism 41.

Therefore, according to this method, digital feedback control is performed on the drive coil 98 so that the output of the camera shake detection means and the output of the variable apex angle prism 41 (output of the position detection means) are equal.

However, in the device having the above-mentioned conventional configuration, the amount of deflection displacement with respect to absolute space and the amount of angular displacement of the variable apex angle prism 41 as a correction optical system are separately determined by A/
Feedback control of the actuator system was performed by D conversion and digital subtraction, but in this configuration, depending on the resolution of the A/D converter 102,
There has been a major problem in that the controllable stroke range and its minimum resolution are limited.

For example, if the number of A/D conversion bits is 8 bits and the angular range assumed for the amount of camera shake is ±2.5 degrees, the minimum resolution will be approximately 002 degrees, and the amount of image shake on the film 41 should be lower than this. It is impossible to do so.

Furthermore, in reality, even if the number of bits for A/D conversion is 8 bits, the accuracy is only about 7 bits at most, and due to quantization errors caused by digital calculations, this method has a minimum resolution of 002°. was almost impossible to achieve.

(Object of the Invention) An object of the present invention is to provide a camera image stabilization device that can solve the above-mentioned problems and improve the minimum resolution for image stabilization control of the device.

(Features of the Invention) In order to achieve the above object, the present invention provides a difference calculation means for calculating the difference between the output of the camera shake detection means and the output of the position detection means in an analog manner before the digital control means. , so that the output of the difference between the deflection displacement amount and the tilt displacement amount of the correction optical means with respect to absolute space is obtained in an analog manner, and then the difference output is calculated digitally to obtain an output for controlling the correction optical means. It is characterized by being made to obtain.

(Embodiments of the Invention) Hereinafter, the present invention will be described in detail based on illustrated embodiments.

FIG. 1 shows an embodiment of the present invention, and FIG. 2 is a flowchart showing a part of its operation.

In FIG. 1, a cylindrical outer cylinder 2 is filled with a liquid 3, and a floating body 4 that can freely rotate around a predetermined rotation axis is installed in the liquid 3. The floating body 4 is configured to be maintained at a predetermined position with respect to the outer cylinder 2 by a weak spring force exerted by a closed magnetic circuit constituted by a permanent magnet 1.

As explained in the conventional example in FIG.
Since the floating body 4 maintains a stationary state with respect to absolute space due to the inertia of the floating body 4, the floating body 4 rotates relative to the outer cylinder 2. Therefore, this relative displacement amount (shake displacement amount) can be detected by the camera shake detection means having the light emitting element 1 and the light receiving element 5 that move together with the camera.

In other words, the signal light emitted from the light emitting element 6 is reflected on the surface of the floating body 4 and enters the position detection light receiving element 5. As a result, if the floating body 4 rotates relative to the outer cylinder 2, the signal light is Since the incident position of the reflected light on the light receiving element 5 changes, the output current Ia of the light receiving element 5 changes.

and Ib change depending on the movement of the floating body 4. Output current I
a and Ib are operational amplifiers 10. Resistor 11゜Capacitor 1
2, a current-voltage conversion circuit and an operational amplifier 13
．． Resistance 14. The outputs are amplified by a current-to-voltage conversion circuit composed of a capacitor 15, and each output is sent to an operational amplifier 21. Adder circuit and operational amplifier 16 consisting of resistors 22, 23 and 24, 25. It is input to a subtraction circuit composed of resistors 17, 18, 19, and 20. The output of this adder circuit is the operational amplifier 26. Resistor 27, 2831, capacitor 29. The voltage is input to a 1RED driver circuit composed of a transistor 30, and feedback control is performed so that the output of the adder circuit becomes equal to the reference voltage KVC.

On the other hand, a variable apex angle prism 41 used as a correction optical means
The amount of angular displacement is also detected by the same method as the camera shake detection means. That is, a slit is provided between the light emitting element 44 and the light receiving element 43, which is linked to the movement of the variable apex angle prism 41, and the movement of the slit generates photocurrent forces tIc and Id from the light receiving element 43. do.

This photocurrent is applied to the operational amplifier 5 in the same manner as described above.
6. A subtractor circuit consisting of resistors 57, 58, 59, 60 and an operational amplifier 61. It is input to an adder circuit composed of resistors 62, 63, 64, 65, and the output of this adder circuit is an operational amplifier 66, resistors 67, 68, 71. capacitor 69
, the output of the adder circuit is always the reference voltage KVC.
is equal to

As described above, the output of the operational amplifier 16 represents the amount of shake displacement with respect to absolute space, the output of the operational amplifier 56 represents the amount of angular displacement of the variable apex angle prism 41, and the unit angle of the camera shake detection means output from the operational amplifier 16 The voltage value per unit and the variable apex angle prism 41 output from the operational amplifier 56
The voltage values per unit correction angle of the position detecting means are set in advance to be equal by the gain resistor described above.

Also, operational amplifier 80. By configuring a differential amplifier with resistors 81, 82.8384, operational amplifier 16
The subtraction between the output of the A/D converter 1 and the output of the operational amplifier 56 is performed in an analog manner, unlike the conventional method, and this output A/D converter 1
This is the input to 02.

Next, the actual digital control method will be explained using the flowchart shown in FIG.

A sampling timer 101 inside the CPU 100 executes interrupt processing at regular intervals. By jumping from the main flow (not shown) to the interrupt flow and first setting the ADST output to "H" in step 200, A
/D converter 102 starts execution. The A/D converter 102 A/D converts the output of the operational amplifier 80, and sets the ADEND output to "H" when the A/D conversion is completed.

In step 201, the CPU 100 converts the A/D converter 1
When detecting that the ADHND output of 02 has become "H", the process immediately proceeds to step 202 and the ADST output is set to "L".
” and stops the A/D conversion operation. Next, in step 203, ADDATA converted into a digital value from the A/D converter 102 is transferred to register A in the CPIJ 100. In step 204, feedback control is performed. In order to set the loop gain for
03, the PWMST output is set to "H", and then in step 206 it is transferred to the PWM timer 103 as PWMDATA. CPU100 finally uses PWMST
The output is set to "L" and the interrupt processing by the sampling timer 101 ends.

Here, the PWM OUT output of the PWM timer 103 corresponds to PWM [1ATA] into which the "H" and "L" duty values are input using a clock with a constant cycle, so the resistor 112
, the level of the non-inverting input terminal of the operational amplifier 110 through the capacitor 111 becomes an analog voltage level corresponding to PWMDATA. Operational amplifier 11○, transistor 1
13. A push-pull type power amplifier circuit is configured in 114, so that the current value obtained by dividing the voltage applied to the non-inverting input terminal of the operational amplifier 110 by the internal resistance of the drive coil 98 is applied to the drive coil 98. , the variable apex angle prism 41 is driven by this current value.

As described above, the difference between the shake displacement output of the camera shake detection means and the angular displacement output of the variable apex angle prism 41 that is driven accordingly is obtained in an analog manner, and this difference signal is digitally amplified. Due to the configuration in which the variable apex angle prism 41 is driven by the value, the output of the camera shake detection means and the output of the variable apex angle prism 41 (position detection means) are approximately equal from low frequencies to frequencies at which the variable apex angle prism 41 can be driven. becomes.

FIG. 3 shows a second embodiment of the present invention, and FIG. 3 shows a flowchart showing a part of its operation.

In this embodiment, the processing circuit of the light receiving element 6, which is a shake detection sensor, and the processing circuit of the light receiving element 43, which is a position detection sensor of the variable apex prism 41, are used as both by switching in time series. It is something.

Next, the operation of this embodiment will be explained using the flowchart shown in FIG.

As explained in the first embodiment, in the interrupt processing of the sampling timer 101 that generates an interrupt at a constant cycle, first, in step 250, the CHG output of the CPU 100 is set to "H".
Therefore, the analog switch 92.93 is ON, the analog switch 91.94 is 0FFL, and the photocurrent I of the light receiving element 5 is
a and Ib are converted into predetermined voltages by a processing circuit. The processing method is the same as in the first embodiment, and in this state, the runout displacement output appears in the output of the operational amplifier X6.

The output of the operational amplifier 16 is connected through an analog switch 89 to a resistor 87. It is input to a low-pass filter composed of a capacitor 88, and this low-pass output is input to an operational amplifier 85.
．． It is input to a buffer amplifier composed of a resistor 86.

Subsequently, in step 251, the delay timer 104 in the CPU 100 waits for a period of time for the output of the operational amplifier 16 to sufficiently charge the capacitor 88, and then, in step 252, the CHG output is set to "L". This output causes the analog switch 89 to become FF, and as a result, the deflection displacement output is stored in the capacitor 88, and the operational amplifier 8
Output from 5.

Since the CHG output becomes "L", the analog switch 91.94 is turned on via the inverter 90, the analog switch 92.93 is 0FFL, and the photocurrent 1c and Id of the light receiving element 43 are converted into voltage by the processing circuit. be done. The angular displacement output of the variable apex angle prism 41 appears in the output of the operational amplifier 16 using exactly the same processing method.

Here, operational amplifier 80 and resistors 81, 82 83.84
In the differential amplifier circuit configured with the above, since the output of the operational amplifier 16 is subtracted from the output of the operational amplifier 85, the shake displacement output of the camera shake detection means and the angular displacement output of the variable apex angle prism 41 are subtracted. In step 253, the CPU
After waiting for the time until the output is stabilized by the delay timer 104 in l0o, ADST is activated in step 254.
A/D conversion is started with the output set to "H". Step 2
Since steps 54 to 261 are completely the same as those in FIG. 2 of the first embodiment, their explanation will be omitted.

FIG. 5 shows a third embodiment of the present invention, in which the output currents of the light receiving elements 5 and 43 are directly subtracted.

Current flows through the resistor 76 in the direction shown by the arrow, and the resistor 76
The potential on the light receiving element 5 side is VC-R, where the resistance value is R.
It is expressed as (I a + I b). This potential is passed through a buffer circuit including an operational amplifier 75 to the operational amplifier 21. The voltage is input to a subtraction circuit composed of resistors 22, 23, 24, and 25, and is subtracted from the reference potential VC by this subtraction circuit, so the output of the operational amplifier 21 becomes R(Ia+Ib).

As shown in the first embodiment, this potential is the reference voltage KVC
Feedback control is performed through the 1RED driver circuit so that it is equal to .

On the other hand, the light receiving element 43 has a polarity opposite to that of the light receiving element 5, and its output currents 1c and Id flow in the directions shown in the figure. Therefore, since a current flows through the resistor 78 in the direction shown in the figure, the potential on the light receiving element 43 side is R, where the resistance value of the resistor 78 is R.
Express it as (Ic+Id). This output is op amp 77
The voltage is applied to the 1RED driver circuit through a buffer amplifier composed of a 1RED driver circuit, and feedback control is performed through the 1RED driver circuit so that this potential becomes equal to the reference voltage KVC.

In this configuration, the difference current between the photocurrent Ia of the light receiving element 5 and the photocurrent Ic of the light receiving element 43 is the operational amplifier 10, the resistor 11. It is converted into a voltage by a current-voltage conversion circuit composed of a capacitor 12, and similarly the photocurrent Ib of the light receiving element 5 and the light receiving element 43 are converted into voltage.
The difference current between the photocurrent 1d and the photocurrent 1d of the operational amplifier 13. Resistance 14.
A current-voltage conversion circuit including a capacitor 15 converts the voltage into a voltage. Operational amplifier 16. Resistance 17, 18, 19
．． 20, the output of the operational amplifier 10 and the output of the operational amplifier 13 are subtracted, and as a result, the shake displacement output of the camera shake detection means and the angular displacement output of the variable apex angle prism 41 are subtracted. executed. The output of the operational amplifier 16 is subjected to A/D conversion in the same manner as in the first and second embodiments, and after digital calculation is performed, PWM
The variable apex angle prism 41 is driven through the D/A conversion output from the timer and low-pass filter.

According to each of the above embodiments, the output of the difference between the shake displacement output of the hand shake detection means and the angular displacement output of the variable apex angle prism 41 (position detection means) is calculated in an analog manner, and this output is
A/D conversion, that is, converting it to digital data and processing it, makes it possible to use A/D with a limited number of bits.
Even by using conversion, a sufficiently high control resolution can be obtained.

(Effects of the Invention) As explained above, according to the present invention, the difference calculation means for calculating the difference between the output of the camera shake detection means and the output of the position detection means in an analog manner is provided in the preceding stage of the digital control means. , so that the output of the difference between the deflection displacement amount and the tilt displacement amount of the correction optical means with respect to absolute space is obtained in an analog manner, and then the difference output is calculated digitally to obtain an output for controlling the correction optical means. By doing so, it is possible to improve the minimum resolution for vibration isolation control of the device.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing a first embodiment of the present invention, FIG. 2 is a flow chart showing a part of its operation, FIG. 3 is a block diagram showing a second embodiment of the present invention, and FIG. 5 is a flowchart showing a part of the operation, FIG. 5 is a block diagram showing a third embodiment of the present invention, and FIG. 6 is a block diagram of a conventional device of this type. l...Permanent magnet, 2...Outer cylinder, 3...
...Liquid, 4...Floating body, 5...Light receiving element, 6...Light emitter, 10.13.16.
...Operational amplifier, 11,14.17-20...
...Resistance, 12.15 ...Capacitor, 41
...Variable apex angle prism, 43... Light receiving element, 44... Light emitting element, 50.53.56.
...Operational amplifier, 51, 54.57-50...
...Resistance, 52゜55 ...Capacitor, 75
...Operation amplifier, 7678...Resistance,
80... operational amplifier, 81-84...
Resistor, 85...Operational amplifier, 86.87...
...Resistance, 88...Capacitor, 89.91
~94...Analog switch, 90...
・Inverter, 98... Drive coil, 100・
...CPU, 101...Sampling timer, 102...A/D converter.

Claims (1)

[Claims] (1) Camera shake detection means for detecting the amount of shake displacement of the camera body with respect to absolute space, correction optical means for varying the optical path incident on the photographic lens with respect to the optical axis, and tilt displacement amount of the correction optical means with respect to the optical axis. a position detecting means for detecting the correction optical means; a driving means for electrically driving the correction optical means; and a digital control means for digitally calculating input output and controlling the driving means based on the calculation result. The image stabilization device for a camera is characterized in that a difference calculation means for calculating in an analog manner the output of the difference between the output of the camera shake detection means and the output of the position detection means is provided before the digital control means. Anti-shake device for cameras.