JPH0486736A - Angle displacement detection device for vibration proof device of camera - Google Patents

Abstract

PURPOSE:To improve a rising characteristic by providing a viscosity coefficient varying means which controls energizing to an electromagnetic means according to the differential value of the output level of a detection means and varies the coefficient of viscosity as viscous force acting between an outer jacket and a floating body. CONSTITUTION:Liquid fills up the inside of the outer jacket 21 and the floating body 22 is supported in the liquid so that it can be freely rotated with a rotating shaft 27 as a center. Then, a light projecting element 25 and a light receiving element 26 for optically detecting the movement of the floating body 22 are arranged. Besides, a yoke 23 constituting a closed magnetic circuit with the floating body 22 is arranged and a coil 24 is arranged between the yoke 23 part and the floating body 22. Then, the differential value of the relative displacement of the floating body 22 and the outer jacket 21, that means, a current in proportion to a relative speed is applied to the coil 24 and the viscous force of a sensor is electrically generated. Besides, the proportional constant thereof is varied according to the displacement output of the sensor. Then, the control of the energizing corresponding to the relative speed of the outer jacket and the floating body is executed and the viscous force acting between the outer jacket and the floating body is varied. Thus, the rising characteristic of a device is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Application of the Invention) The present invention relates to an improvement in an angular displacement detection device used in a camera vibration isolation device for preventing camera shake.

(Background of the Invention) Conventional camera anti-shake devices include patent application No. 63-12637.
There is a device using an angular displacement detecting device as described in No. 4, Japanese Patent Application No. 63-126375, etc., and the schematic structure of this type of vibration isolating device is shown in FIG.

In FIG. 6, a floating body 2 supported around a predetermined rotating shaft 3 in an outer cylinder 1 filled with liquid is installed.

Further, permanent magnets 4 are installed around this outer cylinder 1 so as to form a closed magnet path with the floating body 2 in order to maintain the floating body 2 at a reference position. In this state, if the outer cylinder 1 that is integrated with the camera rotates by θIN with respect to absolute space due to the influence of camera shake, the floating body 2 inside will rotate relative to absolute space due to the inertia of the liquid inside outer cylinder 1. In order to maintain a stationary state, the floating body 2 rotated relative to the outer cylinder 1. Therefore, it is possible to optically detect this amount of rotation using the light emitting element 5, which rotates as a unit like the camera, and the light receiving element 6, whose ratio of two outputs changes depending on the light incident position. As a result, an output corresponding to the rotation angle is generated in the sensor control circuit 13. Note that the section from the outer tube 1 to the light receiving element 6 and the sensor control circuit 13 correspond to an angular displacement detection device.

On the other hand, a known variable apex angle prism 9 is used as an optical means for correcting image shake. The variable apex angle prism 9 has a liquid having a constant refractive index sealed therein, and is configured to be able to expand and contract around a certain rotation axis as shown in FIG. Therefore, when the entrance surface on the subject side (right side in FIG. 6) of the variable apex angle prism 9 is rotated by θ0LIT with respect to the parallel position, the optical path of the light ray that enters the film surface 12 through the taking lens 11 will be the above-mentioned θOUT. and is rotated about the optical axis by an amount whose proportionality constant is determined by the refractive index of the liquid.

Therefore, by detecting the angular displacement with respect to absolute space using the above-mentioned sensor (light emitting element 6, light receiving element 6) and varying the apex angle of the variable apex angle prism 9 by an amount corresponding to this angular displacement, it is possible to always keep the distance from the subject. This allows the light to be guided to the same position on the film surface 12, thereby suppressing camera shake.

In FIG. 6, the apex angle of the variable apex angle prism 9 is optically detected using the light emitting element 7 and the light receiving element 8 in the same way as the angular displacement detection described above, and as a result, the apex angle is detected by the position detection circuit 14. A corresponding angular output is generated. Here, it is assumed that the output per unit input angle output from the sensor control circuit 13 and the output per unit optical axis angle output from the position detection circuit 14 are equal. The output of the sensor control circuit 13 and the output of the position detection circuit 14 are both input to the subtraction circuit 15, where they are subtracted, and the difference output is amplified by the amplifier circuit 16, and then the phase compensation circuit 17 is used to control the actuator system. Phase compensation is performed to prevent the loop from oscillating. Further, the output of the phase compensation circuit 17 is input to a driver 18, and this driver supplies current to the actuator 10, thereby driving the variable apex angle prism 9.

According to the above configuration, feedback control is performed so that the output of the sensor control circuit 13 and the output of the position detection circuit 14 are equal, and the light of the photographing optical system is accurately adjusted to the detected amount of camera shake. Corrections to the axes can be performed.

In the case of the configuration in the above conventional example, the floating body 2 is kept at a predetermined position in the outer cylinder 1 by a closed magnetic circuit constituted by the floating body 2 and the permanent magnet 4, and therefore the spring force around the rotation axis 3 of the floating body 2 is determined by this magnetic circuit,
In terms of the performance of the sensor alone, if the floating body 2 is stationary with respect to absolute space even in response to vibration signals with low frequencies, vibration isolation effects will be produced even to lower frequency levels. It is necessary to weaken the magnetic force of the closed magnetic circuit and reduce the spring constant itself.

However, if the performance of the sensor is extended to the low frequency side, the spring force will be very weak and the rise characteristics will be very poor. When the sensor is moved, a large force is applied to the sensor itself and the relative position of the outer cylinder 1 and the floating body 2 shifts greatly, but the force that returns the floating body 2 to its original initial position is due to the above spring force and the viscous force of the liquid. However, if this spring force is weak, the stabilization time will inevitably become longer. Therefore, the vibration isolation will not work until the floating body 2 returns to its initial position, and when performing a shooting operation using vibration isolation. There was a problem that the shutter time lag became extremely long.

(Object of the Invention) An object of the present invention is to provide an angular displacement detection device for a camera vibration isolator, which can solve the above-mentioned problems and improve the start-up characteristics of the device.

(Features of the Invention) In order to achieve the above object, the present invention controls energization to the electromagnetic means according to the differential value of the output level of the detection means,
A viscosity coefficient variable means is provided to vary the viscosity coefficient as a viscous force acting between the outer cylinder and the floating body, and energization control is performed according to the differential value of the relative displacement between the outer cylinder and the floating body, that is, the relative speed. , is characterized in that the viscous force acting between the outer cylinder and the floating body is made variable.

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

FIG. 1 shows a first embodiment of the present invention, which is expressed by combining both a mechanical configuration and an electrical configuration as an angular displacement detection device.

First, the mechanical components will be explained.

The inside of the cylindrical outer cylinder 21 is filled with liquid, and the floating body 22 is supported in the liquid so as to be able to freely rotate around a rotating shaft 27. Light emitting element 25 and light receiving element 2 for optical detection
Further, a yoke 23 forming a closed magnetic circuit with the floating body 22 and a winding coil 24 are disposed between the yoke 23 and the floating body 22.

Next, the electrical components will be explained.

The part A surrounded by the dotted line is a position detection part for detecting the position of the floating body 22 with respect to the outer cylinder 21, and detects the position of the infrared light emitted from the light emitting element 25 reflected by the floating body 22. This is the basic configuration for detection by the detection light receiving element 26. Light receiving element 26
As is known, the photocurrents Ia and Ib generated in the photodetector 2
The infrared light incident on the operational amplifiers 30. Resistance 31. A current-voltage conversion circuit composed of a capacitor 32, an operational amplifier 33, and a resistor 3
4. A current-voltage conversion circuit including a capacitor 35 converts the voltage into voltages Va and Vb. And this voltage Va, V
b is the operational amplifier 36. It is input to a differential amplifier consisting of resistors 37, 38, 39, 40, where (Va-Vb)
It is output as a difference signal of 41. resistance 4
It is also input to a summing amplifier composed of 2, 43, and 44, where it is output as a sum signal of (Va+Vb).

Since the sum signal (Va+Vb) is connected to the inverting input terminal of the operational amplifier 45 via the resistor 46, the operational amplifier 45. Feedback resistor 47 Current value detection resistor 49
．． Constant current type 1R composed of transistor 50
The ED driver circuit varies the current flowing to the light emitter 8 according to this sum signal (Va+Vb), and as a result, this sum signal (Va+Vb) is connected to the reference voltage KVC connected to the non-inverting input terminal of the operational amplifier 45. Negative feedback is controlled so that it is equal to . In addition, capacitor 48
is for phase compensation to prevent this feedback system from oscillating, and in combination with the resistor 47 determines the overall band.

As described above, if the photocurrent generated in the light receiving element 26 is always kept constant, the difference signal (Va-Vb) between the two outputs of the light receiving element 26 will be affected by changes in temperature, etc., variations in the elements, etc. It becomes possible to always correctly detect the relative position of the outer cylinder 21 and the floating body 22 without being influenced by the above.

Next, a part B surrounded by a dotted line is an arithmetic control section for varying the parameters of the sensor in this embodiment. The difference signal (Va-
Vb) is an operational amplifier 81, a capacitor 82 . resistance 83
The output of this differentiating circuit is input to a selection switch 64. It is connected to the inverting input terminal of the operational amplifier 60 via the gain setting resistor 61, and the selection switch 65. It is also connected to the inverting input terminal of the operational amplifier 6o via the gain setting resistor 62.

The operational amplifier 60 becomes an inverting amplifier by means of a feedback resistor 63, and its output is input to a driver section C, which will be described later.

Further, the difference signal (Va-vb) from the operational amplifier 36 is connected to the inverting input terminal of the comparator 68 and the inverting input terminal of the comparator 69, and the outputs of the respective comparators become inputs to the Nant gate 67. Here, since the positive reference voltage Vc is connected to the non-inverting input terminal of the comparator 68 and the negative reference voltage -Vc is connected to the inverting input terminal of the comparator 69, the comparators 68, 69 . The Nandt gate 67 forms a window comparator. That is, the value of the difference signal (V a -V b ) is rVc ~ -V
When it is between cJ, the output of NAND gate 67 is “L”
When the voltage is higher than the reference voltage Vc or lower than the reference voltage -Vc, the output of the Nandt gate 67 becomes "H". Since the output of the Nant gate 67 is input to the gate control terminal of the analog selection switch 65 and also to the gate control terminal of the analog selection switch 64 via the inverter 66, the difference signal (Va-Vb) is rVc~ -VcJ
When it is between the two, the analog selection switch 64 is turned on and the resistor 61 is selected, and at other times, the analog selection switch 65 is turned on and the resistor 62 is selected.

Also, the part C surrounded by the dotted line is actually the winding coil 24.
The driver section for driving the operational amplifier 51. Transistor 52.53. A push-pull type constant current circuit is configured by the current detection resistor 54, and current can flow in either the X or Y direction indicated by the arrow in FIG. A current proportional to the output voltage of the operational amplifier 60 applied to the terminal is applied to the wire-wound coil 24 .

In the above configuration, by supplying a current proportional to the differential value of the difference signal (Va-Vb) corresponding to the relative position of the outer cylinder 21 and the floating body 22 to the winding coil 24, the floating body 22 and the yoke are connected as described above. A force based on the left-hand rule of framing is generated in the closed magnetic circuit composed of the outer cylinder 21 and 23, and this force is naturally proportional to the current value of the winding coil 24.
A force proportional to the differential value of the relative value of the floating body 22 is generated.

Next, the characteristics of the sensor in this embodiment will be explained using the frequency transfer characteristics.

The input I (S) indicates the displacement of the outer cylinder 21 with respect to the absolute space, and the output angular displacement 0 (S) detected by the sensor of this embodiment is the displacement R of the floating body 22 with respect to the absolute space. Since it is detected from the relative relationship between (S) and input angular displacement I (S), 0 (S) = I (S) −
R(S) -------(1) Represented by the formula.

Also, this output angular displacement 0 (S) is the relative angular displacement between the outer cylinder 21 and the floating body 22, and due to the liquid sealed in the outer cylinder 21,
A viscous force ηs proportional to the relative speed between the outer cylinder 21 and the floating body 22
O(S) occurs. On the other hand, the width of the yoke 23 is
If it is expanded infinitely in the direction of movement of the winding coil 24, the spring force due to the magnetic force should not be generated when the winding coil 24 is not energized, but in reality, the width of the twist 23 is finite. Therefore, the spring force KO(S) also acts, although the force is weak.Furthermore, in this embodiment, the outer cylinder 2 is
A new viscous force can be applied by passing a current proportional to the differential value of the relative displacement of the floating body 22 with respect to the floating body 1 into the winding coil 24 to generate force. Here, the viscous force ηCLSO(S) due to coil energization is the original viscous force ηS○(S)
The gain setting resistor 61. 62
By varying the value of , it is possible to generate any viscous force.

Considering the above force as the force acting on the floating body 22, the angular displacement R(S) of the floating body 22 with respect to the entire space is expressed by the following equation using the moment of inertia J of the liquid in the outer cylinder 21.

When the transfer characteristics of this embodiment are expressed using the above equations (1) and (2), the following equation is obtained.

Equation (3) above indicates the characteristics of a second-order bypass filter, and it is clear that the frequency characteristics can be varied by electrically controlling the viscous force.

FIG. 2 is for explaining how the actual signal output changes according to the above embodiment.

When a step signal like that shown in Fig. 2(a) is input as a camera shake signal input, the characteristics of this sensor are those of a second-order bypass filter, so the conventional signal output is the second-order bypass filter. As shown in Figure (b), when a signal is input, the sensor output changes following the input, and thereafter approaches the initial level according to the time constant of the sensor. Therefore, as the ability of the sensor for detecting camera shake is extended to the lower frequency side, the stabilization time TA becomes longer. FIG. 2(c) shows the signal output of the sensor according to the first embodiment, and shows the point at which the sensor output exceeds the reference level Vc (or -Vc) set in the part B of FIG. Since the analog switch 64 is 0FFL and the analog switch 65 is ON, the resistor 62 whose resistance value is smaller than the value of the resistor 61 is selected, and the overall gain is therefore large. The value of the viscosity constant ηCL increases due to energization. Therefore, while the sensor output exceeds Vc (or -Vc), since the viscosity constant is large, it tries to quickly approach the initial level, and after that,
Since the sensor output returns to the original viscosity constant when it becomes smaller than Vc (or -Vc), the vibration isolation at the low frequency level has the same ability as before, but the overall stabilization time TB has been reduced. This will significantly reduce the time compared to TA. In other words, it is possible to shorten the shutter time lag when performing a photographing operation using image stabilization.

FIG. 3 shows a second embodiment of the present invention, in which the viscosity constant is continuously varied in accordance with the output level.

Here, the position detection section A and the driver section C are the same as those in the first embodiment.

In this embodiment, the arithmetic control section Bl shows a method of continuously varying the value of the viscosity constant in accordance with the input difference signal (Va-Vb).

Operational amplifier 70. Resistors 71, 72. diode 73.7
4 is a known half-wave rectifier circuit, and when the level of the difference signal (Va-Vb) is lower than the ground potential connected to the non-inverting input terminal of the operational amplifier 70, Since the diode 73 is ON and the diode 74 is OFF, the anode side output of the diode 74 becomes equal to the ground potential. On the other hand, when the level of the difference signal (Va-Vb) is higher than the ground potential, the diode 73 is 0FFL and the diode 74 is ON.
Therefore, the anode side output of the diode 74 becomes an inverted output of the difference signal (Va-Vb).

Next, operational amplifier 79. The adder circuit composed of resistors 75, 76.7778 adds the difference signal (Va-Vb), the output of the half-wave rectifier circuit, and the negative reference voltage -Vc, and makes the values of resistors 71.72 equal. By setting the ratio of resistors 75 and 76 to 2=1, a known absolute value circuit is constructed, and by varying the value of variable resistor 77, it is possible to vary its DC bias level.

Next, the output of the absolute value circuit is an N-channel MOSFET 8 whose source is connected to the inverting input terminal of the operational amplifier 60.
Since it is input to the gate of 0, the equivalent resistance between the source and drain changes nonlinearly depending on the output of the absolute value circuit. Further, the difference signal (Va-vb) is sent to the operational amplifier 81. Capacitor 82. It is input to a differentiator circuit consisting of a resistor 83,
Its output is connected to a train of N-MOSFETs 80.

Since the feedback resistor 63 is connected to the operational amplifier 60, the gain determined by the equivalent resistance of the N-MOSFET 80 and the resistance value of the resistor 63 is varied according to the differential value of the difference signal (Va-Vb). The viscosity constant will be continuously varied.

FIG. 4 shows a third embodiment of the present invention, in which the viscosity constant is varied digitally, and FIG. 5 shows a flowchart thereof.

Here, regarding the position detection section A and the driver section C, the first.
This is similar to the second embodiment.

The arithmetic control section B2 plays a role in controlling digital control in this embodiment, and receives the input difference signal (Va-Vb
) into digital data.
．． A CPU 90 that performs overall calculations and state detection. CPU9
D/A that outputs analog data based on data from 0
Next, the operation of this embodiment, which is comprised of the converter 92, will be explained using the flowchart of FIG.

First, in step 98, constants are set in registers aot at and bl for differential operation.

Here, C corresponds to the capacitance value of capacitor 80 in FIG. 1, R corresponds to the resistance value of resistor 83 in FIG. This is set by the known S-7 conversion for converting to data on the time axis. Next, in step 99, the value of register W1 used for calculation is reset to "0". In the next step 100, A
/D control signal input, the A/D converter 91 generates a difference signal (Va-
Vb) starts A/D conversion.

Next, in step 101, it is determined whether the A/D conversion has been completed, and if the A/D conversion has been completed, step 1
Proceed to step 02 and take in the A/D converted result from the A/D converter 91 to register A in the CPU 90.6 Next, in step 103, the value of register A is stored as it is in register D, and in the next step 104. Check whether the value of this register D is positive or negative, and if it is positive, proceed to step 1.
If the value is negative, the sign is inverted in step 105 and the result is placed in register D, and the process proceeds to step 106.

In step 106, the value obtained by multiplying register b1 and Wl is subtracted from register A in which the A/D converted result is stored, and the result is stored in register W0. Next, the value obtained by multiplying registers ao and Wo by al and Wl is added and stored in register A. Furthermore, the value of register Wo is set to Wl. In step 107, memory data M (
D) to register K, but here memory data M
The value of (D) is set to increase as the value of D increases.

Next, in step 108, the value in register A as a result of A/D conversion is multiplied by the value in the above register, and the result is stored in register A, and in step 109, the value in register A is
/A converter 92. Next, in step 110, the D/A converter starts D/A conversion in response to a control signal input from the CPU 90, and in step 111, the D/A converter starts D/A conversion.
It is determined whether or not the conversion has been completed, and once the D/A conversion has been completed, the process returns to step 100.

Since the output of the D/A converter 92 is connected to the input section of the driver section C, a current proportional to the output of the D/A converter 92 is applied to the wire-wound coil 24.

In this way, the value of the proportional coefficient applied to the driver section C is selectively varied depending on the value of the difference signal (Va - Vb), that is, the viscosity constant as a sensor is changed from the sensor output (difference signal (Va - Vb) ).

According to each of the above embodiments, a current proportional to the differential value of the relative displacement between the floating body 22 and the outer cylinder 21, that is, proportional to the relative velocity, is applied to the winding coil 24 to electrically generate the viscous force of the sensor.
Since this proportionality constant is configured to be varied in accordance with the displacement output of the sensor, the rise and stabilization time as a sensor can be significantly shortened. This has the effect of shortening the shutter time lag of the camera.

In this embodiment, the wire-wound coil 24 is used as the electromagnetic force generating member, but the present invention is not limited to this as long as it generates electromagnetic force by controlling energization.

(Effects of the Invention) As explained above, according to the present invention, energization to the electromagnetic means is controlled according to the differential value of the output level of the detection means,
A viscosity coefficient variable means is provided to vary the viscosity coefficient as a viscous force acting between the outer cylinder and the floating body, and energization control is performed according to the differential value of the relative displacement between the outer cylinder and the floating body, that is, the relative speed. Since the viscous force acting between the outer cylinder and the floating body is made variable, it is possible to improve the start-up characteristics of the device.

[Brief explanation of the drawing]

Fig. 1 is a configuration diagram showing a first embodiment of the present invention, Fig. 2 is a time chart explaining signal output in this first embodiment, and Fig. 3 shows a second embodiment of the invention. 4 is a block diagram showing a third embodiment of the present invention, FIG. 5 is a flowchart showing the operation of the third embodiment, and FIG. 6 is a diagram showing a conventional camera equipped with this type of device. FIG. 2 is a schematic configuration diagram of a vibration isolator. 21... Outer cylinder, 22... Floating body, 23.
... Yoke, 24 ... Winding coil, 25
...Light emitter element, 26... Light receiver element, 2
7...Rotation axis, A...Position control unit, B
, B1. B2... Arithmetic control unit, C...
Driver part.

Claims (1)

[Claims] (1) A cylindrical outer cylinder in which liquid is sealed, a floating body that is placed in the liquid enclosed in the outer cylinder and held rotatably around a predetermined rotation axis, and the floating body and the outer cylinder. a detection means for detecting relative angular displacement of the cylinder around the rotational axis; and a detection means provided in a fixed relationship with the outer cylinder in a gap adjacent to the floating body in a closed magnetic path formed including the floating body, An angular displacement detection device for a camera vibration isolator, comprising an electromagnetic means for generating a viscous force between the outer cylinder and the floating body by an electromagnetic force, the angular displacement detection device for a camera vibration isolator comprising: Angular displacement for a camera vibration isolator, characterized in that a viscosity coefficient variable means is provided for controlling energization to the electromagnetic means to vary a viscosity coefficient as a viscous force acting between the outer cylinder and the floating body. Detection device.