JP3182462B2 - Displacement detector - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a displacement detecting device arranged in various electronic devices for detecting the position of a movable member of the electronic device.

[0002]

2. Description of the Related Art FIG. 6 shows a configuration of a conventional displacement detecting device.

In FIG. 6, reference numeral 41 denotes an iRED which is a light emitting element, and 42 denotes a PSD which is a light receiving element. 43 is attached to a movable member (not shown);
It is a transmitting member that transmits the light beam projected from the RED 41 through the opening 43s. A holding member 44 holds the iRED 41 and the PSD 42 and shields them from external light.

FIG. 7 shows a state in which a movable member (not shown) to which the above-described transmission member 43 is attached is displaced in the direction of arrow A.

In this state, the position of the spot irradiated onto the PSD 43 is displaced by the movement of the opening 43s, and the displacement is obtained as an electric signal, from which the displacement of the movable member is detected. Become.

[0006]

However, in the above conventional example, the iRED 41 and the like used for the light emitting element include:
Since there is a directional characteristic as shown in FIG. 8 and the amount of light decreases toward the periphery, the transmitting member 43 is moved from the state of FIG.
When the displacement is made as shown in (1), the amount of light transmitted through the opening 43s decreases, and the linearity of the displacement signal from the PSD 42 with respect to the displacement significantly deteriorates.

Conventionally, such degradation in linearity has been improved by a circuit configuration as shown in FIG.

Namely, by spot irradiated onto PSD42, flows out two currents I _A and I _B from the terminal of the PSD42, after being current-voltage conversion respectively by operational amplifiers 71 and 72 are added by an operational amplifier 73, the sum The signal _{VA + B} is obtained. The sum signal V _{A + B} is controlled by the operational amplifier 74 so as to be substantially equal to the reference voltage V _ref set by the resistance voltage division. When the light flux around the iRED 41 as shown in FIG. The light amount of iRED 41 is automatically increased so that sum signal V
_The operation is performed so that _{A + B} becomes constant, and the linearity of the difference signal V _AB corresponding to the displacement obtained by the operational amplifier 75 is maintained.

In FIG. 9, V _CC is a power supply voltage.
_C = １ ／ · V _CC . Also, the sum signal V _{A + B} and difference signal V _AB is _{V A + B = V C +} g 1 (I A + I B) V AB = V C + g 2 (I A -I B). Here, g ₁ and g ₂ are constants.

Here, the condition for maintaining the linearity of the difference signal V _AB is that, in the configuration shown in FIG. 6, the light beam reaching the PSD 42 must be only the light beam transmitted through the opening 43 s of the transmission member 43. It is.

However, in practice, the luminous flux of the iRED 41 is irregularly reflected on the inner walls of the transmission member 43 and the holding member 44, and the scattered light reaches the PSD 42. This scattered light is PSD42
It is thought that it hits uniformly.

At this time, the sum signal V _{A + B} is V _{A + B} = V _c + V _s + V _n ≒ V _ref (constant value), where V _s is the PSD caused by the light beam transmitted through the opening 43s.
42, where V _n is the PSD 42 due to scattered light.
Is the output signal.

Each value at the displacement center position, that is, the opening 4
Assuming that the output signal of the PSD 42 due to the light flux transmitted through 3 s is V _so and the output signal of the PSD 42 due to the scattered light is V _no , the sum signal _{VA + B} becomes _{VA + B} = V _c + V _so + V _no = V _ref , The gain of the difference signal V _AB at an arbitrary position is expressed as V _s / V _so = {V _so − (V _n −V _no )} / V _{so with} respect to the displacement center position (1), and scattered light the output signal V _n by is proportional to the amount of IRED41.

Assuming now that the light quantity is ω times, the output signal V _n due to the scattered light is V _n = ωV _no , and the above equation (1) is expressed as follows.

V _s / V _so = 1− (ω−1) V _no / V _so
(1) 'Therefore, the linearity of the difference signal at this position is (ω-1)
V _no / V _so only deteriorated.

FIG. 10 is a diagram showing each signal at this time.
The horizontal axis represents the displacement of the movable member, and the vertical axis represents each output voltage described below.

In FIG. 10, reference numeral 81 denotes the cathode voltage of the iRED 41, that is, light emission amount information; 82, an ideal difference signal V _AB ; .

As can be seen from the above equation (1) ', V _no / V
_so (for example, the opening 43s of the transmission member 43)
When the transmitted light flux is increased by increasing the output, the output of the iRED 41 decreases, and the output due to the scattered light decreases. Therefore, V _no decreases, V _so increases _{, and} V _no / V _so decreases.
Although it is possible to improve the linearity of the difference signal V _AB ,
There is a problem that the obtained linearity is limited.

[0019] (object of the invention) The purpose of the present invention, the output of the photoelectric conversion element according to scattered light, is to provide a displacement detecting device which can be so as not to deteriorate the linearity of the detected displacement.

[0020]

Means for Solving the Problems In order to achieve the above object, the present invention provides a light emitting element and light from the light emitting element, and receives light from two output terminals according to a light receiving position. The photoelectric conversion element whose output changes, and the light from the light emitting element is projected, and is displaced in accordance with the displacement of the detection target, and the light receiving position of the light from the light emitting element on the photoelectric conversion element is changed. a detected portion for changing a displacement detecting means for detecting a displacement of the detection target depending on the difference between the output signals from the two output terminals of said photoelectric conversion elements, a predetermined reference
Controlling the light emission amount of the light emitting element based on the voltage value , wherein the predetermined reference voltage is set so that the sum of output signals from two output terminals of the photoelectric conversion element is substantially constant.
A displacement detecting device having a light emitting amount adjusting means for correcting the amount of light emission of the light emitting element based on the value, adding the voltage value corresponding to the emission amount of the light emitting element to the predetermined reference voltage value
And a displacement detection device having reference voltage value changing means for changing the reference voltage value .

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the illustrated embodiments.

FIG. 1 is a block diagram showing the configuration of a photographing apparatus having a camera shake correction function provided with the apparatus according to the first embodiment of the present invention.

In FIG. 1, reference numeral 201 denotes a vibration gyro for detecting the angular velocity of the photographing device, and outputs an angular velocity signal a.

The above-mentioned angular velocity signal a is supplied to a signal processing circuit 202.
The signal b passes through a low-pass filter for removing noise and a high-pass filter for removing DC components, and is then integrated by the integration circuit 203 to obtain an angular displacement signal c of the imaging device.

Numeral 210 denotes a variable apex angle prism which is a beam deflection means, the apex angle of which is changed by an actuator 207.

The apex angle of the variable apex angle prism 210 is detected by an apex angle sensor 208, and an apex angle signal d is obtained by a signal processing circuit 209. The apex angle signal d and the angular displacement signal c are applied to the addition circuit 204 with opposite polarities, and a difference signal e is output. This difference signal e is supplied to the amplifier 205
The driving signal g is amplified by the driving circuit 206, and the actuator 207 is driven by the driving signal g obtained by the driving circuit 206. That is, the signal processing circuit 20
9 form a closed loop.

In this configuration, control is performed such that the difference signal e is always zero, and as a result, the apex angle signal d acts so as to coincide with the angular displacement signal c. That is, the light beam incident on the imaging optical system 211 is deflected by the variable apex angle prism 210 in accordance with the change in the angle of the photographing device, and the CCD 212
The image formed on the surface has no camera shake in which the angle change of the photographing device is corrected.

The shake correction system is composed of two systems, pitching (vertical direction in the screen) and yawing (horizontal direction in the screen). When distinguishing, the subscript "a" is used for yawing and the subscript "b" is used for pitching. Represented with

FIG. 2 is an exploded perspective view showing the mechanical structure of the variable apex angle prism 210 and its periphery.

In FIG. 2, reference numerals 301a and 301b denote transparent plates made of glass or plastic, 302a (not shown) and 302b denote frames to which the transparent plates 301a and 302b are bonded, and 303a (not shown) and 303b denote the above frame members. 302
Reinforcing rings 304a and 302b are bellows-like films connecting the frames 302a and 302b, and a liquid having a high refractive index (not shown) is sealed in a space formed by these films to form the variable apex angle prism 210. ing.

The variable apex angle prism 210 includes a frame 306a.
And 306b, and the respective surfaces are in the yaw axis (X-
X) and support pins 307a and 308a and 307b and 308b so as to be swingable about a pitch axis (Y-Y), and each support pin is screwed to a device fixing member (not shown). The yaw axis (XX) and the pitch axis (YY) are arranged in the center plane of the variable apex angle prism.

A flat coil 207-1a is fixed to one end of the rear frame 306a, and the permanent magnet 207-2a and the yoke 207-3a are opposed to both surfaces thereof.
And 207-4a are arranged to form a closed magnetic circuit,
The actuator 207 is configured.

A transmission plate 208-1a having a slit opening is attached to the frame body 306a, and a light emitting element 208-2a and a light receiving element 208-3 are provided on both sides thereof.
a is held and arranged by a holding member (not shown), and constitutes a vertex angle sensor 208. Light emitting element 208-2a
After being transmitted through the slit opening, the light beam emitted from the light source is irradiated to the light receiving element 208-3a.

Here, the light emitting element 208-2a is, for example, i
An infrared light emitting element such as a RED, and a light receiving element 208-3a
Is a photoelectric conversion element such as a PSD whose output changes depending on the spot position of the received light beam. Then, the light emitting element 208-2a and the light receiving element 2 fixed to the device fixing member
08-3a according to the swing of the frame 306a.
08-1a, that is, when the slit opening moves, the spot position on the light receiving element 208-3a changes,
The swing angle (displacement amount) of the frame 306a, which is a movable member, can be extracted as an electric signal.

Next, a signal processing circuit 209 for performing signal processing of the apex angle sensor 208 will be described with reference to FIG.

In FIG. 3, reference numeral 1 denotes the light emitting element 208-.
IRED, which is a light emitting element corresponding to 2a, and PSD, which is a light receiving element corresponding to the light receiving element 208-3a. Reference numeral 3 denotes a transmission member having an opening 3s that transmits the light beam of the iRED1 and corresponds to a transparent plate 208-1a having a slit opening attached to the frame 306.

The light beam transmitted by the transmission member 3 above is irradiated onto PSD2, the current value I _A as a position signal from the two terminals of the PSD2, is output I _B, the current-voltage by each operational amplifier 4, 5 After the conversion, they are added by the operational amplifier 6 to obtain a sum signal _{VA + B.}

Further, the voltage V _ref to the voltage kV _x and a power source V _CC obtained a cathode voltage V _x resistance-dividing set resistance-divided by the iRED1 are summed by an operational amplifier 7 and 8, the voltage (V _ref + KV _x ). This voltage (V _ref + kV _x ) and the sum signal V _{A + B} are controlled by the operational amplifier 9 so that V _{A + B} ≒ V _ref + kV _x .

The operational amplifier 10 obtains a difference signal V _AB between the outputs of the two terminals of the PSD 2, which is the displacement output of the transmitting member 3.

In FIG. 3, V _cc is a power supply voltage,
_c = １ ／ · V _cc .

Now, the sum signal V _{A + B} is represented as V _{A + B} = V _c + V _s + V _n (where V _s is the output value of the PSD 2 by the light beam transmitted through the transmission member 3, and V _n is the apex angle PSD output levels of the scattered light inside the sensor 208), also for the sum signal V _{a + B} by the circuit as described above is controlled to _{V a + B = V ref +} kV x, V c + V s A relationship of _{+ V n ≒ V ref + kV} x.

[0042] Now, when put subscript 0 to each value of the displacement center position (other than constant), a relationship of _{V c + V so + V no} ≒ V ref + kV xo.

The relative gain is the center position of the difference signal V _{A + B} at an arbitrary _{position, V s / V so = {} V so - (V n -V no) + k (V x -V xo)} / V so ... is expressed as (2), the output value V _n by scattered light is proportional to the amount of iRED1, also, iR also the cathode voltage V _x of iRED1
It is proportional to the light amount of ED1.

[0044] Now, when the amount of light and has become _{ω-fold, V n = ωV no, V} x = ωV xo , and the equation (2) can be expressed in the following manner.

V _s / V _so = 1 − {(ω−1) (1−kV _xo / V _no ) V _no ｝ / V _so (2) ′ where “kV _xo / V _no = 1” Is set so as to be "." That is, by setting the output value of PSD2 due to the scattered light inside the apex angle sensor 208 and the cathode voltage of iRED1, that is, the light amount information of iRED1 as the voltage value, the above equation (2) ′ becomes “V _s / V _so = 1 ”, and the linearity with respect to the displacement of the displacement signal V _AB due to the change in the light amount of iRED1 is maintained.

As described above, by greatly improving the linearity of the displacement signal with respect to the displacement of the movable member of the displacement detecting device, the photographing device with a camera shake correction function shown in FIG. Since the angle change and the light beam deflection angle by the variable apex angle prism 210 can be made to correspond one-to-one, a good camera shake correction operation can be realized, and the danger of oscillation of the system due to the nonlinearity of the displacement detection device can be avoided. .

(Second Embodiment) FIG. 4 is a circuit diagram showing a configuration of a signal processing circuit according to a second embodiment of the present invention.

The configuration of FIG. 4 is obtained by replacing a part of the circuit of the signal processing circuit (see FIG. 3) in the first embodiment the digital, the cathode voltage V _x of iRED1 91 of A / The data is converted into a digital value by a D converter and input to the microcomputer 92. The microcomputer 92 performs an operation as shown in FIG. 5 according to the input value to obtain an output value. This output value is D /
The signal is converted into an analog value by the A converter 93 and applied to the + input terminal of the operational amplifier 94.

According to each of the above embodiments, the light emitting device (iR
A light beam projected from the ED) is irradiated on a transmission member (transmission plate) provided on a member movable with respect to the imaging device (base), and the light beam transmitted by the transmission member is received by a light receiving element (PSD).
In the apparatus configured to receive light using the light emitting element and detect the amount of displacement of the movable member, the information on the amount of light emitted from the light emitting element is used as a control signal for obtaining linearity with respect to the displacement of the displacement signal obtained from the light receiving element In this manner, the output of the light receiving element due to the scattered light projected from the light emitting element and scattered by the inner wall of the transmitting member and the holding member of the light emitting element and the light receiving element does not deteriorate the linearity of the displacement signal with respect to the displacement of the movable member. Like that.

That is, since the light emission amount of the light emitting element is controlled based on the light emission amount information of the light emitting element, it is possible to greatly improve the linearity of the light receiving element output with respect to the displacement of the movable member. .

(Modification) In this embodiment, the transmitting member 3 having the opening 3s is used as a member attached to the movable member. However, the present invention is not limited to this, and it may be a reflecting member. In other words, even if a reflection member is attached to the movable member, and the light projected from the iRED 1 is reflected by the reflection member and guided to the PSD 3, the displacement output of the displacement output can be obtained by using the same circuit configuration. The linearity can be greatly improved.

(Correspondence between Invention and Embodiment) In the above embodiment, iRED1 is replaced by PSD2
Is the photoelectric conversion element of the present invention, the transmitting member 3 is the detected part of the present invention, the operational amplifier 10 and the like are the displacement detecting means of the present invention, the voltage _Vref is the predetermined reference voltage value of the present invention,
The operational amplifiers 6 and 9 serve as the light emission amount adjusting means of the present invention.
The voltage dividing resistor for generating the voltage kV _X and the operational amplifiers 7 and 8, or the A / D comparator 91, the microcomputer 92 and the D / A converter 93 are the reference voltage of the present invention.
Each corresponds to a value changing unit .

[0053]

As described above, according to the present invention,
If the output of the photoelectric conversion element due to scattered light is
Displacement that does not degrade position linearity
A detection device can be provided.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of a photographing apparatus with a camera shake correction function including a device according to a first embodiment of the present invention.

FIG. 2 is an exploded perspective view showing a mechanical configuration of the variable apex angle prism of FIG. 1 and its periphery.

FIG. 3 is a circuit diagram showing a configuration of a signal processing circuit of FIG. 1;

FIG. 4 is a circuit diagram showing a configuration of a signal processing circuit according to a second embodiment of the present invention.

FIG. 5 is a diagram showing an input / output relationship of the microcomputer of FIG. 4;

FIG. 6 is a cross-sectional view illustrating a configuration of a conventional displacement detection device.

FIG. 7 is a cross-sectional view showing a state when the transmission member is moved from the state of FIG.

FIG. 8 is a diagram illustrating directivity characteristics of a general light emitting element.

FIG. 9 is a circuit diagram showing a configuration of a conventional displacement detection device.

10 is a diagram showing each output value of the displacement detection device of FIG.

[Explanation of symbols]

 1,208-2a Light emitting element (iRED) 2,208-3a Light receiving element (PSD) 3 Transmission member 4-10,94 Operational amplifier 92 Microcomputer 208 Vertex angle sensor 209 Signal processing circuit

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-4-96031 (JP, A) JP-A-4-86735 (JP, A) JP-A-4-86736 (JP, A) JP-A-4-86735 86731 (JP, A) JP-A-4-86730 (JP, A) JP-A-3-172702 (JP, A) JP-A-1-134420 (JP, A) JP-A-3-172702 (JP, A) JP-A-2-247625 (JP, A) JP-A-2-27126 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) G03B 5/00 H04N 5/232

Claims (1)

(57) [Claims] 1. A light emitting element, a photoelectric conversion element for receiving light from the light emitting element, wherein an output from two output terminals changes according to a light receiving position, and light from the light emitting element is A detection target that is projected and is displaced in accordance with a displacement of a detection target to change a light receiving position of the light from the light emitting element on the photoelectric conversion element; and two output terminals of the photoelectric conversion element a displacement detecting means for detecting a displacement of the detection target depending on the difference between the output signals from a predetermined reference potential
Controlling the light emission amount of the light emitting element based on the pressure value , wherein the predetermined reference voltage value is such that the sum of output signals from two output terminals of the photoelectric conversion element is substantially constant. > A light emission amount adjusting unit that corrects the light emission amount of the light emitting element based on>, wherein a voltage value corresponding to the light emission amount of the light emitting element is determined by the predetermined base.
A reference voltage that changes the reference voltage value by adding to the reference voltage value;
A displacement detection device comprising pressure value changing means .