JPH0743803A - Camera-shake preventing device - Google Patents

Abstract

PURPOSE:To provide a camera-shake detecting device capable of improving a vibration proof effect. CONSTITUTION:The camera-shake preventing device is equipped with detecting means 11, 12, 13, 15 and 16 detecting the inclinded angle of a camera, a camera- shake displacement storage part 19 storing the detected inclined angle at specified times, a predicting arithmetic part 20 predicting the quantity of camera- shaking occurring during the exposing operation of the camera, a deciding part 21 deciding that a current camera-shake quantity tends to decrease and a camera-shake quantity deciding part 23 permiting an exposure when a tendency to decreas is decided and a predicted camera-shake quantity is a prescribed value or below.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a camera shake prevention device.

[0002]

2. Description of the Related Art Conventionally, various types of image stabilizing devices used in cameras and the like have been proposed. For example, in Japanese Patent Application No. 4-149674 filed by the applicant of the present invention, it is arranged on the back surface of a camera, projects light toward a photographer, and receives reflected light from at least two points by a light receiving element. And a calculation means for calculating the difference between the reciprocals of the square roots of the photocurrents output from the light receiving elements, and the output of the calculation means is a camera shake signal. A camera shake prevention device for a camera is disclosed. The structure and operation of the technique disclosed in Japanese Patent Application No. 4-149674 will be described below.

A method for detecting camera shake will be described with reference to FIG.
Are arranged, and the face 3 of the photographer is located at a predetermined distance from the back surface of the camera 1. 2A at the start of shooting, and assuming that the face 3 hardly moves during shooting, the position of the camera 1 when the camera shake occurs is as shown in FIG.
It can be expressed as (b). That is, when there is camera shake, the rotation center of the camera 1 moves by x, and the camera 1 (tilt sensor 2) tilts by θ.

FIG. 3 is a diagram showing the relationship between the inclination sensor 2 and the face 3. In FIG. 3, 4 is a light projecting element,
Reference numerals 5 and 6 respectively denote sensors that receive the reflected light from the light projecting element 4 and convert it into an electric current. Here, the sensor 5, the light projecting element 4, and the sensor 6 are arranged in a line in the vertical direction of the face 3.

FIG. 4 is a block diagram of an electric processing system. 7 processes the photocurrent I _p1 from the sensor 5,
This is an arithmetic circuit for generating a voltage proportional to the value represented by the equation (1). Further, the arithmetic circuit 8 is for processing the photocurrent I _p2 from the sensor 6 similarly to the arithmetic circuit 7 to generate a voltage proportional to the value represented by the equation (2).

[0006]

[Equation 1]

[0007]

[Equation 2]

Reference numeral 9 is a drive circuit for driving the light projecting element 4. The differential amplifier 10 is for differentially amplifying the output voltages of the arithmetic circuits 7 and 8. Here, the output of the differential amplifier 10 becomes a voltage proportional to the value expressed by the equation (3), and this voltage is proportional to the inclination of the face with respect to the sensor surface.

[0009]

[Equation 3]

That is, the amount of change in the tilt angle θ can be obtained by obtaining the amount of change in the above equation (3).
With such a configuration, the tilt angle θ can be reduced at a low cost.
Can be detected. That is, the camera shake of the photographer can be detected from the temporal change in the relative inclination between the photographer and the camera body.

Conventionally, there have been many anti-vibration techniques for detecting a blur and driving a taking lens so as to correct the blur amount.
Since the cost is high and the camera is large, a simple anti-vibration technique for opening a shutter by detecting a timing with a small blur is well known in a compact camera or the like. For example, in Japanese Patent Application No. 4-011225 filed by the present applicant, discrete blur data X (i) and a prediction coefficient A set in advance are used.
A technique of calculating the sum of products of (i) and predicting the blurring after t _f from the present is disclosed. Current blur data is X (0)
And letting it be X (1) past by Δt and X (2) past 2Δt, the blur W after t _f is

[0012]

[Equation 4]

Here, Δt is preferably 8 to 12 ms,
Detailed description of the coefficient determination method and the like will be omitted here. A
It is assumed that (i) is stored in, for example, a non-volatile memory (E ² PROM) for each shutter speed. W calculated by the equation (4) or (5) is the displacement of the shake, and to predict how much the shake amount w has occurred from the present after t _f ,

[0014]

[Equation 5]

For example, the shutter speed is 1/60 (about 1
6 ms), and the blurring amount that occurs during 16 ms is the blurring amount during 8 ms from the shutter opening (the blurring displacement after 8 ms and the current zero).
The absolute value of the difference in blur displacement of ms) is used as a substitute. That is, t _f = 8 ms is set, and the shake amount w predicted while the shutter is open is predicted by the equations (4) to (6). If w is within a certain threshold, it is determined that the timing is appropriate for exposure, and the shutter is started. Since the amount of shake in the future is predicted, it is a technique with a high anti-vibration effect if the prediction can be performed completely.
If the shake prevention device of 49674 is used, the cost will be low.

Further, the present prediction method can flexibly cope with the case where the mechanical time lag from the shutter start signal output to the actual movement of the shutter is several ms. That is, if the time lag is 3 ms in the above example, w is 1
It is the absolute value of the difference between the predicted blur displacement after 1 ms and that after 3 ms.

Next, there are many anti-vibration techniques that use an angular velocity sensor as the shake detection means. For example, in Japanese Unexamined Patent Publication No. 3-92830 and US Pat. No. 5,150,150, angular velocities in two orthogonal directions applied to a camera are detected, a shutter operation is performed when the angular velocities in both directions are below a certain value, or the angular velocity is a certain value. A technique is disclosed that enables a shutter operation when the number is below and is decreasing.

Further, in Japanese Unexamined Patent Publication No. 4-265958, angular velocities applied to the camera in two orthogonal directions are combined, the maximum value of the combined waveform is detected, and the shutter is started with a delay of a predetermined time from the timing of the maximum value. The technology is disclosed.

[0019]

DISCLOSURE OF THE INVENTION Problem to be Solved by the Invention
In the prior arts of No. 2830 and JP-A No. 4-265958, the shutter operation can be performed at the timing when the current blur is small or at the timing when the blur is likely to be small during the future exposure, and the future blur is predicted. Since it is not a thing, it is quite possible that the blurring during the opening of the shutter actually changes from that at the time of detection.

It is generally considered that the hand shake has a frequency of 20 Hz or less, so that even a short cycle can be considered to be 50 ms. So in the worst case it's one
It is also necessary to consider that the blur suddenly changes in about 12 ms of / 4. It is fully conceivable that the blur displacement will change significantly during exposure at shutter speeds of 1/15 and 1/30 sec even with slower frequency blur. However, since the prior art enables the shutter operation aiming at an area near the peak of blurring or a flat portion where the blurring speed is small, if the blurring tends to decrease and the shutter operation is performed within a certain value, Anti-vibration effect can be expected to some extent.

However, in an actual camera, there is a mechanical time lag of about several ms from the CPU outputting the shutter start signal to the actual operation of the shutter.
Considering this time lag, shutter control based on the current shake amount without prediction involves some risk. Also, the angular velocity sensor is currently expensive and difficult to use for image stabilization of the camera.

By the way, according to the blurring prediction method disclosed in Japanese Patent Application No. 4-011225, the larger the value of t _f (that is, the slower the shutter speed), the larger the absolute value of the coefficient A (i) becomes. Has the drawback that the noise associated with is large. This is because the noise component contained in X (i) is multiplied by A (i) and added, as can be seen from the equation (5). When the same prediction method is used, it is possible that the blurring amount is judged to be within the threshold even though the blurring amount is not actually within the threshold due to the adverse effect of noise associated with the prediction. If there is an increasing tendency, the shutter may start at the timing when the blur amount is large.

The present invention has been made in view of the above problems, and is made in Japanese Patent Application Nos. 4-149674 and 4-149674.
In a shake prevention device that can be realized at low cost by combining -011225, the shake amount is not predicted when the shake is increasing, the shake is decreasing, and only when the shake speed is within the threshold value. It is an object of the present invention to provide a camera shake prevention device for a camera capable of improving the image stabilization effect by performing the above-mentioned operation and starting the shutter when the predicted amount of shake is within the threshold value.

[0024]

In order to achieve the above object, a camera shake preventing apparatus of the present invention detects a tilt angle of a camera and a tilt angle detected by the detecting means. Storage means for storing every predetermined time,
Prediction means for predicting the amount of camera shake that occurs during the exposure operation of the camera using the tilt angle stored in this storage means, determination means for determining that the current camera shake amount is in a decreasing tendency, and this determination And a permitting unit that permits the exposure when the amount of camera shake predicted by the predicting unit is less than or equal to a predetermined value.

[0025]

That is, in the camera shake preventing apparatus of the present invention, the tilt angle of the camera is detected, and the detected tilt angle is stored every predetermined time. Next, the stored tilt angle is used to predict the amount of camera shake that occurs during the exposure operation of the camera, and it is determined that the current amount of camera shake tends to decrease. Then, when it is determined that the current camera shake amount is in a decreasing tendency and the predicted camera shake amount is equal to or less than the predetermined value, the exposure is permitted.

[0026]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a camera shake prevention device according to the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram of a camera shake prevention device according to the first embodiment. In the figure, the light emitting element 12 is driven by a drive circuit 14 and projects light onto the face 3 serving as a target surface. First
The second light receiving elements 11 and 13 receive the light reflected by the face 3. The output of the first light receiving element 11 is supplied to the 1 / (I _p1 ) ^1/2 arithmetic circuit 15 and the second
The output of the light receiving element 13 is 1 / (I _p2 ) ^1/2 arithmetic circuit 1
6 is supplied. Then, the differential amplifier circuit 17 is
/ (I _p1 ) ^1/2 arithmetic circuit 15 and 1 / (I _p2 ) ^1/2 16
The differential amplification calculation is performed by receiving the output of.

Then, the output is input to the A / D converter 18 and converted into a digital signal. The output of the A / D conversion unit 18 is stored in the shake displacement storage unit 19 at fixed intervals for a fixed time. In general, the shake displacement storage unit 19 stores shake displacement digital data from the present to several tens ms past. The shake amount prediction calculation unit 20 predicts the shake amount during exposure according to equations (5) and (6). Prior to the prediction, the prediction coefficient A (i) corresponding to the shutter speed determined by the photometric calculation (not shown) or the manual input is read from the E ² PROM (not shown).

Then, the blur reduction tendency determining unit 21 determines whether or not the current blur is in a decreasing tendency, and when it is increasing, the blur amount determining unit 23 does not perform the blur determination. Alternatively, when it is determined that there is a decreasing tendency that blurring prediction is not performed before the determination, the blurring speed determination unit 22 further determines whether or not the current blurring speed is within a certain threshold. When it is determined that the blurring speed is within the threshold value, the blurring amount determination unit 23 determines whether the predicted blurring amount is within a certain threshold value, and the shutter is started only when it is within the threshold value. If the blurring speed determination is not performed, the shutter is started only when the blurring tendency is decreasing and the predicted blurring amount is within the threshold value.

FIG. 5 is a block diagram of the electric system in the first embodiment. In the figure, a sensor head amplifier 30 and a microcomputer 31 for sequence control are connected. Further, the sensor head amplifier 30 is connected with a light emitting element 32 and sensors 33 and 34 for detecting blur, that is, for detecting a tilt angle of the face. These light emitting element 32 and sensors 33, 34
Are all located on the back of the camera and the sensor 3
3, 34 are arranged in a line so as to sandwich the light emitting element 32.

On the other hand, the microcomputer 31 includes a warning display circuit 35, a date imprinting circuit 36, an aperture drive circuit 37, a mirror-up drive circuit 38, and a front curtain drive circuit 3.
9, trailing curtain drive circuit 40, shutter charge drive circuit 4
1. The winding drive circuit 42 is connected.

In this embodiment, the present invention is applied to a single-lens reflex camera, which has a diaphragm in the taking lens. The diaphragm drive circuit 37 is a circuit for driving the diaphragm. The shutter uses a focal plane shutter and has a front curtain and a rear curtain. The front curtain drive circuit 39 and the rear curtain drive circuit 40 are circuits for driving the front curtain and the rear curtain. Further, although not shown, normally, the light from the taking lens is guided to the upper finder optical system by a mirror, but at the time of photographing, the light from the taking lens is switched to the shutter direction by raising the mirror. The mirror-up drive circuit 38 is a drive circuit for raising the mirror.

The warning display circuit 35 is a warning display means when the camera shake is large and is provided in the finder. This warning display can be visually confirmed by looking through the finder. The detailed functions will be described later.

The shutter charge drive circuit 41 is a circuit for charging the spring inside the focal plane shutter mechanism. This shutter charge drive circuit 41
Is operated to perform shutter charging, and at the same time, initial mirror position driving (mirror down) and aperture initial position driving are performed.

FIG. 6 is a circuit diagram showing details of the inside of the sensor head amplifier 30 in the first embodiment. In the figure, a current source 51 supplies a current value I _ref , and the current source 51 includes diodes 52, 53, 54.
Are connected. Then, the current source 51 and the diode 5
Transistors 55 and 56 are connected to the connection point of 2. Here, assuming that the anode-side potential of the diode 52 is V ₁ , the formula (7) is obtained.

[0035]

[Equation 6]

[0036] where K is Boltzmann's constant, q is the unit charge of an electron, T is the absolute temperature, I _s is the reverse saturation current of the diode (transistor). Here, the photocurrents I _p1 and I _p1 are respectively applied to the emitters of the transistors 55 and 56.
_{Since p2} flows, the emitter potentials V ₂ and V ₃ of the respective transistors are as shown in equations (8) and (9), respectively.

[0037]

[Equation 7]

Further, buffer amplifiers 57 and 58 are connected to the emitters of the transistors 55 and 56, and if their outputs are V ₄ and V ₅ , then V ₄ = V ₂ , V ₅ = V ₃ ... ( 10) becomes. Further, 59 and 63 are transistors, and 60 and 64.
Is a diode. Assuming that the collector currents of the transistors 59 and 63 are I _c1 and I _c2 , respectively, equation (11)
Expression (12) is established.

[0039]

[Equation 8]

On the other hand, the V _ref generating circuit 69 is for generating V _ref , and the V _ref generated here is B _ref.
It is output to the outside through the two terminals and input to the C2 terminal of the microcomputer 31. The microcomputer 31, which will be described later, performs A / D conversion on the voltage input from the C2 terminal, and uses V _ref as the reference voltage of the A / D converter. That is, the potential from 0 V to V _ref is A / D converted by the specified number of bits.

Further, V _ref generator V _ref output from 69, after being divided by resistors 70 and 71, is input to the non-inverting input terminal of the buffer amplifier 72. Resistance 7 here
Since 0 and 71 have the same resistance value, the buffer amplifier 72
The output voltage V ₆ of V becomes V ₆ = (1/2) · V _ref (15) and is output from the B6 terminal to the outside.

Further, the transistors 61 and 62 are PNP transistors forming a current mirror for returning the current. Reference numeral 65 is a resistor having a resistance value R _L. Resistance 6
A current obtained by subtracting the collector current of the transistor 63 from the output current of the transistor 62 flows through the transistor 5. Here, since the collector current of the transistor 62 is equal to I _c1 , the potential V _{7 at} the upper end of the resistor 65 is V ₇ = (1/2) V _ref + (I _c1 −I _c2 ) · _RL ... (16 ).

Further, this connection line is connected to the operational amplifier 66.
It is input to the non-inverting input terminal of. The operational amplifier 66 is a non-inverting amplifier, and its amplification factor is determined by the resistors 67 and 68. The resistance values of the resistors 67 and 68 are set to R ₆₇ and R _68.
Then, the output voltage V ₈ of the operational amplifier 66 is (1
It is expressed as in equation 7).

[0044]

[Equation 9]

Here, the second term on the right side of the equation (20) is a voltage proportional to the equation (3). Here, the sensor 33,
Between the inclination angle θ of the face with respect to 34 and the above equation (3),
It has been experimentally confirmed that there is a relationship of equation (21).

[0046]

[Equation 10]

Therefore, V at two different times
_{When 8} is obtained and the difference voltage is obtained, the difference voltage is proportional to the variation of the tilt angle between two different times. Here, the output of the operational amplifier 66 is output from the B1 terminal to the outside and from the C1 terminal of the microcomputer 31. The voltage input from the C1 terminal is A / D converted by an A / D converter inside the microcomputer 31.

Further, a resistor 73 for dividing V _ref ,
74, operational amplifier 75, transistor 76 and resistor 77
Is a drive circuit for driving the external light emitting element 32 with a constant current. Among them, the resistance values of the resistors ₇₃ and ₇₄ are R ₇₃ and R ₇₄ , respectively. In addition, the resistance value of the resistor 77 is set to R
₇₇ . Here, assuming that the direct current amplification factor H _FE of the transistor 76 is sufficiently high, the collector current of the transistor 76, that is, the drive current I _LED of the light emitting element 32 is (2
It is obtained as in the equation (2).

[0049]

[Equation 11]

Flow charts of the software of the embodiment are shown in FIGS. 7 (a) to 7 (d) and 8 (e) to (i).
In addition, the shake displacement waveform is shown in FIG.
It shows in (a). FIG. 8 (i) is a main routine, which will be described later, and is called after the mirror is raised in the series of operations of the camera. 7 (a)-(d) and 8 (e)-
(H) is the subroutine. In step S30 of FIG. 8 (i), initial settings are first made. The subroutine is shown in FIG. A / D conversion starts in step S42 of FIG. 7 (a). The A / D converter is finely resolution in order to reduce the noise by using the technique of the digital low-pass filter or smoothing, 0V to V _ref
A / D conversion is performed within the range of and the output is 2 bytes (integer part X _H , decimal part X _L 1 byte each).

Next, in step S43, the timer interrupt is permitted, and here, the interrupt routine of FIG. 7B is called every 2 ms. X _L in step S52 shown in FIG. 7 (b)
The lower byte of the A / D conversion result is stored in the variable of, and the upper byte is also stored in X _H in step S53. In step S54, an interrupt flag indicating the end of interrupt is set to 1.

Next, in step S44, the shutter speed is read out, and in the following step S45, the prediction coefficient A (i) stored in the E ² PROM for each shutter speed.
Read out. In step S46, the start address # V0 of the RAM area for storing the 2-byte digital data of the shake displacement
Is set to the data pointer. Here, since it is assumed that the data is read once every 2 ms and stored for 20 ms,
There are 11 bytes of data 20 ms past from the present and 1 byte has 2 bytes, so there is a 22-byte RAM area.
That is, # V0, # V0 + 2, # V0 + 4, ..., #V
Lower byte in 0 + 20, # V0 + 1, # V0 + 3, #
The upper byte is stored in V0 + 5, ..., # V0 + 21. Steps S47 to S49 are waiting for the timing at which the timer interrupt is applied.
0 μs is an appropriate dead time.

Only after the timer interrupt routine of FIG. 7B has been completed, the process can proceed to step S50. Step S5
0 is a subroutine of FIG. 7C, where X _L ,
The latest blur data stored in X _H is stored in RAM.
The RAM over flag is set to 0 in step S55.
And the latest data X _L and X _H in step S56~S59
Is stored in the RAM indicated by the data pointer. Step S
When shifting to 60, the data pointer points to the RAM in which the next latest data is stored. That is, in other words, it shows the RAM in which the oldest current data (20 ms ago) is stored.

In step S60, it is determined whether or not the data pointer has exceeded the address of the RAM area in which the data is stored. If it exceeds, the data pointer is reset to # V0 in the following step S61, and the RAM over flag is set to 1 in step S62.

Next, in step S51 of the subroutine of FIG. 7A, it is determined whether or not the RAM over flag is 1, and if it is not 1, steps S47 to S51 are repeated. That is, for the first 20 ms, the process of waiting without blur prediction until the RAM is filled with blur data is performed.

Next, in the main rune step S31 of FIG. 8 (i), the blur data stored in the RAM is read. FIG. 7D shows the subroutine. Step S
In 63 and S64, the shake data 20 ms before is read into X _2L and X _2H .

Next, where RA is the blur data 10 ms before
In order to determine whether the data pointer is stored in M, it is determined in step S65 whether the data pointer is larger or smaller than # V0 + 12. If it is determined to be large, the data 10 ms before is in the RAM addressed by the data pointer 11 and the data pointer 12, and therefore steps S66 and S67.
Then, these are read into X _1L and X _1H . If it is determined to be small, it is read in steps S68 and S69. Similarly, the current (latest) blur data is read into X _0L and X _0H in steps S70 to S74.

Next, in step S32 of FIG. 8 (i), the blur amount during exposure is predicted. FIG. 8E shows the subroutine. First, in step S75, the latest blur data and the prediction coefficient are multiplied. Then, the resulting upper byte is stored in W _H and the lower byte is stored in W _L. Here, the prediction coefficient is also 2 bytes, and the upper byte is A _0H and the lower byte is A _0L . The dots in the figure are decimal points. 10m
The same applies to the prediction coefficient before s, 20 ms. Step S7
In 6 and S77, the blur data of 10 ms before and 20 ms before are multiplied with the prediction coefficient and added with the result of the previous step. That is, the output W of step S77
_H and W _L are predicted displacement amounts during exposure. In the following step S78, the absolute value of the difference between the predicted displacement amount during exposure and the current shake displacement amount is calculated, and this is used as the predicted shake amount during exposure w
Store in _H and w _L.

Next, in step S33 of FIG. 8 (i), it is determined whether or not the blurring tends to decrease. FIG. 8F shows the subroutine. First, in step S79, X
The absolute value of the difference between (0) and X (1) is stored in Y _0H and Y _0L ,
Similarly, in step S80, the absolute value of the difference between X (1) and X (2) is stored in _Y1H and _Y1L . In step S81, the decreasing tendency flag is reset, and in step S82, (Y
The magnitude relationship between _{0H ·} Y _0L ) and (Y _{1H ·} Y _1L ) is determined.
When (Y _{0H ·} Y _0L ) <(Y _{1H ·} Y _1L ), it is determined that there is a decreasing tendency, the decreasing tendency flag is set to 1 in step S83, and the process returns.

Next, in step S34 of FIG. 8 (i), the shake speed is determined. Even if this step S34 is omitted, a certain effect can be obtained, and whether or not to omit it is determined by the magnitude of the prediction noise in equation (5). FIG. 8 (g) shows the subroutine. First, in step S84, the speed threshold V _th is read from the E ² PROM. Here, V _th is the threshold of (Y _{0H ·} Y _0L ) obtained previously. The speed flag is reset at step S85, the step S86 is (Y _{0H ·} Y _0L) is prescribed or less than V _th, and setting the speed flag to 1 in seeing the step S87 when the following V _th To return.

Next, in step S35 of FIG. 8 (i), the amount of blurring is determined. FIG. 8 (h) shows the subroutine. Since FIG. 8 (h) has the same configuration as the subroutine of FIG. 8 (g), its description is omitted. The amount of shake is threshold B
When it is less than _th , the blurring amount is set to 1 and the process returns.

Next, in step S36 of FIG. 8 (i), it is determined whether or not the decreasing tendency flag, the speed flag and the blur amount flag are all "1". If YES, the timing is appropriate for exposure, so in step S41 a shutter start signal is output and the process returns. If NO, then in steps S37 to S40, steps S47 to S in FIG.
The same process as 50 is performed, and the process returns to step S31.

As described above, according to the configuration of the first embodiment described above, the shutter can be started only when the blurring tendency is decreasing and the blurring speed is small and the predicted blurring amount is less than a certain value.

The second embodiment of the present invention will be described below. In the first embodiment, the blur evaluation is performed by software, but in this embodiment, the decrease tendency and the speed are determined by hardware, and the blur amount is determined by the software as in the first embodiment. Figure 4 shows an example block diagram. In the figure, a decreasing tendency and speed determination circuit 43 is arranged between the sensor head amplifier 30 and the microcomputer 31. Further, here, the peripheral circuits 35 to 42 connected to the microcomputer 31 shown in FIG. 5 and the light emitting element 32 and the sensors 33 and 3 connected to the sensor head amplifier 30.
4 is not shown.

Operational amplifier 80, capacitor 81, resistor 8
Reference numeral 2 denotes a differentiating circuit, which outputs V ₉ when V ₈ is input.
Is the capacity of the capacitor 81 is C, and the resistance value of the resistor 82 is R
Then,

[0066]

[Equation 12] Becomes In exactly the same way, the output V ₁₀ of the operational amplifier 83 is

[0067]

[Equation 13] Becomes Expression (23) is the blurring speed, and the waveform is shown in FIG. 9 (b). Equation (24) is the shake acceleration, and its waveform is shown in FIG. 9 (c). Here, for the sake of simplicity, the shake displacement V ₈ where the acceleration is a linear expression is considered. Comparators 86 and 8
7 determines whether the blur velocity V ₉ is within the threshold.
The threshold is set by external resistors 88-91, and D
It is input from terminals 5 and D6. Buffer amplifier 92,
It is input to the non-inverting input terminals of the comparators 86 and 87 via 93. That is, when the threshold level V _th and the resistance values of the resistors _{88 to 91} are R ₈₈ , R ₈₉ , R ₉₀ , and R ₉₁ ,

[0068]

[Equation 14]

This timing chart is shown in FIG. 9 (d). The outputs of the comparators 86 and 87 are exclusive OR 9
4 is input. That is, when the output of 94 is "H", the speed is within the threshold. Next, the magnitude of V ₉ and V ₆ is determined. That is, the sign of the speed dV ₈ / dt is determined. When the output of the comparator 95 is "H", dV
₈ / dt is 0 <0, dV ₈ / dt when the "L">. Next, the magnitude of V ₁₀ and V ₆ is determined. That is, the sign of the acceleration d ² V ₈ / dt ² is determined. When the output of the comparator 96 is "H", d ² V ₈ / dt ² > 0,
When "L", d ² V ₈ / dt ² <0. The outputs of the comparators 95 and 96 are input to the exclusive OR 97.
That is, when the output of 97 is "H", the blurring tends to decrease.

Then, the exclusive OR 94 and 97 are ANDed 9
Enter in 6. That is, when the output of the logical product 96 is "H", the blurring speed is within the threshold and the blurring tends to decrease. These series of operations are performed by the analog switch 98.
And 99 are made conductive, and capacitors 81 and 84 are discharged. That is, the D3 terminal is set to "H" to start discharging, and after a fixed time, set to "L" to start a series of operations. Further, the output of the logical product 95 is input from the D4 terminal to the C4 terminal of the microcomputer 31.

FIG. 11 shows the main routine of the software of the second embodiment. Here, only the differences from FIG. 8 (i) will be described. In step S91, the above-mentioned capacitor is discharged. In step S92, it is determined whether the logic of the C4 terminal is "H", and only in the case of "H", the shift amount is predicted.
As in the first embodiment, the speed determination may be omitted depending on the magnitude of the prediction noise of the equation (5).

The third embodiment will be described below. In this embodiment, as shown in FIG. 12, four light receiving elements 101 to 1 are arranged at equal intervals around one light emitting element 100 provided on the back surface of the camera.
04 is arranged, the light receiving elements 101 and 102 are connected to the first sensor head amplifier 105, and the shake displacement around the y-axis in FIG. Similarly, the light receiving elements 103 and 104 are connected to the second sensor head amplifier 106 and detect the shake displacement around the x axis.

FIG. 13 shows a connection diagram. The first sensor head amplifier 105 is exactly the same as that in FIG. 6, and the second sensor head amplifier 106 has a configuration in which the light receiving element drive circuit and the V _ref generation circuit are omitted from the first sensor head amplifier 105. In the figure, the peripheral circuits 35 to 42 shown in FIG. 5 are not shown. B of the second sensor head amplifier 106
A shake displacement signal corresponding to V ₈ in the equation (20) is output from the 7 terminal and input to the C5 terminal of the microcomputer 31. In this embodiment, shake displacements around both x and y axes are independently detected, and shake is evaluated based on the first or second embodiment, and shake evaluation results are OK for both X and Y axes. Start the shutter at the timing.
Since the blurring around the two axes is detected, it is possible to detect and evaluate the blurring with higher accuracy. Further, as disclosed in Japanese Patent Application No. 4-246846 as a modified example of this embodiment,
It is also possible to detect blurring around two axes with three light receiving elements.

Further, as disclosed in Japanese Patent Application No. 5-122789, prediction results may be combined in the form of x ² + y ² or | x | + | y | for blur evaluation. Fourth below
An example will be described. In the first to third embodiments, the blurring amount during exposure is calculated after predicting the blurring displacement, but in the fourth embodiment, the blurring displacement data during exposure is time-series blurring displacement data from the past to the present. And the predicted shake amount during exposure is directly calculated. Moreover, since the two axes are combined, the calculation result of equation (5) becomes the predicted combined blur amount during exposure. In this embodiment, the calculation of the equation (5) is performed only once, and the noise accompanying the calculation is reduced as compared with the third embodiment. 14
The main routine of the software of the embodiment is shown in FIG. Since there are many parts in common with FIG. 8 (i), only the differences will be described.

The combined blur amount B ₀ at the current time in step S94 is the blur amount between the present and the present and t _f ms past, that is, it is about the X axis as follows: B _0x = | (current blur displacement )-(5 t _f ms past shake displacement from present) | ... (27), and B _0y around the y-axis is similarly obtained. Here, B ₀ is multiplied by the equation (28). B ₀ = B _0x + B _0y (28) In some cases, B ₀ = B _0x ² + B _0y ² or

[0076]

[Equation 15] However, the formula (28) is sufficient to simplify the calculation.

Similarly, in steps S95 and S96, Δt + t _f ms past to Δt ms past and 2Δt + t _{f respectively.}
The combined blur amount around the two axes from ms past to 2Δtms past is calculated and stored in B ₁ and B ₂ . Where B ₀ , B ₁ , B
₂ byte data is desirable for 2. In step S97,
The combined blur amount w _xy after t _f ms from the present is predicted by the equation (29).

[0078] to determine whether or not there to _{w xy = A (0) ·} B 0 + A (1) · B 1 + A (2) · B 2 ... (29) step S98 in the downward trend. That is, the magnitude of B ₀ and B ₁ is determined. The case of B ₀ <B _{1 is} the case of a decreasing tendency.

In step S99, the speed of synthetic blurring is determined. | B ₁ −B ₀ | is determined to be within the threshold _value .
However, in the fourth embodiment, since it is calculated in the form of blurring amount, it is easier to determine whether B ₀ is within a certain threshold _value than the above determination. That is, when the current blur amount is large, even if it is determined that the predicted blur amount is within the threshold value, it is regarded as an erroneous determination due to noise and the shutter does not start.
Step S99 may be omitted depending on the magnitude of noise. In step S100, it is determined whether w _xy is within the threshold value. The subsequent steps are the same as those in the first embodiment, so the description thereof will be omitted.

Next, the operation of the camera when the embodiment of the present invention is applied to a single-lens reflex camera will be described. Figure 15
[Fig. 6] is a flow chart for explaining the operation when shooting is performed in the camera shake reduction mode. Although not shown in the camera in the same embodiment, a release switch (SW)
Is a two-stage stroke, the first release SW is turned on in the first stroke, and the second release SW is turned on in the second stroke.

First, in step S1, the first
The release SW is monitored, and if the first release SW is in the ON state, the process proceeds to step S2 to perform AF (autofocus) processing. The details of this AF are not directly related to the present invention, and thus the description thereof is omitted.

Next, in step S3, the second release SW is monitored. If the second release SW is on, the process proceeds to step S4 to perform photometry. Then, in step S5, a signal is output to the diaphragm drive circuit 37 to start diaphragm drive. And step S
At 6, a signal is output to the mirror-up drive circuit 38 to start the mirror-up. Succeedingly, in a step S7, it is detected that the diaphragm drive and the mirror up are completed. These end detections are performed by detecting the states of encoders (not shown).

Then, in step S8, the delay timer is started. The role of this delay timer will be described later. Next, in step S9, the shake amount is detected and predicted according to the above-described embodiment. In the subsequent step S10, the blur is evaluated. That is, when the blurring speed is within a constant value and tends to decrease, and the predicted blurring amount is within a constant value, the evaluation is OK. If the evaluation is not OK, it is determined that the timing is inappropriate for exposure, and the process proceeds to step S11.

In step S11, the count value of the delay timer started in step S8 is checked. If the count value is equal to or more than a certain value, the process proceeds to step S12 to display a hand shake warning. Then, in step S13, the first release SW is monitored. If the first release SW is OFF, the camera shake warning display is turned OFF in step S14, and the mirror is lowered in step S15, and then step S1.
Return to.

If the first release SW is in the ON state in step S13, it waits for the first release SW to be in the OFF state, and the process returns to step S1. If the count value of the delay timer is equal to or less than the fixed value in step S11, the process returns to step S9.

Here, the role of the delay timer is to limit the time in the exposure waiting state composed of steps S8, S9 and S10. That is, when the camera shake does not become small, the warning display means 35 in the viewfinder is activated after a certain period of time, and the release is disabled.

If the shake evaluation is OK in step S10, the process proceeds to step S16, and a date imprinting signal is output to the date imprinting means 36. Next, in step S17, a signal is output to the front curtain drive circuit 39 to start the front curtain. Next, in step S18, an exposure timer corresponding to the exposure movement is started according to the result of the photometry performed in step S4. Then, in the next step S19, the trailing curtain drive circuit 40
To output a signal to start the rear curtain.

Next, in step S20, a date imprinting timer is started. Here, the operation time T _D of the date imprinting timer is as shown in equation (30). T _D = T _DATE −T _EXP (30) Here, T _DATE is the time required for imprinting. See also T
_EXP is the time required for exposure, and steps S17 and S1
8, the time required for the sequence of S19.

Next, in step S21, a signal is output to the shutter charge drive circuit 41 to start shutter charge. Then, in step S22
To output a signal to the winding drive circuit 42 at
Start frame winding. Then, in step S2
In 3, the shutter charge and the winding end are detected, and if both are completed, then in step S24, the state of the first release SW is detected,
If the first release SW is OFF, the process returns to step S1.

When the present invention is applied to a compact camera having a lens shutter, steps S5, S6, S
There is no 7, S17, S19, S15, and after step S4, the AF lens is driven and the process proceeds to step S8. If the blur evaluation is OK, the shutter (sector) is processed after step S16.
To start.

The present invention can be variously modified. For example, as shown in Japanese Patent Application No. 4-281927, a level shift circuit is provided at the subsequent stage of either the first or second 1 / (I _p ) ^1/2 arithmetic circuit, and the level shift amount is set. The tilt angle detection range may be expanded without deteriorating the tilt angle detection resolution by arbitrarily controlling.

Also, as shown in Japanese Patent Application No. 4-346437, a circuit for demodulating the received photocurrent by causing the light emitting element to pulse light at a constant frequency in order to remove the influence of background light such as sunlight. May be provided. Further, although the tilt angle detecting device of Japanese Patent Application No. 4-149674 is cited as the blur detecting means, the present invention can be applied to any other tilt angle detecting device as long as it detects the tilt angle of the camera. is there.

[0093]

As described above in detail, according to the camera shake detection apparatus of the present invention, the shutter may start when the predicted shake amount is erroneously determined to be small due to the adverse effect of noise accompanying the prediction. The anti-vibration effect is improved.

[Brief description of drawings]

FIG. 1 is a block diagram of a camera shake detection device for a camera according to a first embodiment.

FIG. 2 is a diagram for explaining a conventional method for detecting camera shake.

FIG. 3 is a diagram showing a relationship between a tilt sensor and a face.

FIG. 4 is a block diagram of an electric processing system in a conventional camera.

FIG. 5 is a block diagram of an electric system according to the first embodiment of the present invention.

FIG. 6 is a circuit diagram showing details of the inside of the sensor head amplifier in the first embodiment.

FIG. 7 is the front part of the flowchart for explaining the operation of the first embodiment.

FIG. 8 is the rear part of the flowchart for explaining the operation of the first embodiment.

FIG. 9 is a diagram showing a blur displacement, a blur velocity, a blur acceleration, and waveforms of respective portions.

FIG. 10 is a configuration diagram of a second embodiment of the present invention.

FIG. 11 is a flowchart showing a main routine of the second embodiment.

FIG. 12 is a diagram showing one light emitting element and four light receiving elements arranged at equal intervals around the light emitting element on the back surface of the camera in the third embodiment.

FIG. 13 is a connection diagram of the third embodiment.

FIG. 14 is a flowchart showing a main routine of the fourth embodiment.

FIG. 15 is a flowchart for explaining an operation when shooting is performed in the image stabilization mode.

[Explanation of symbols]

11 ... 1st light receiving element, 12 ... light emitting element, 13 ... 2nd light receiving element, 14 ... drive circuit, 15 ... 1 / (I _p1 ) ^1/2 ,
16 ... 1 / (I _p2 ) ^1/2 , 17 ... Differential amplifier circuit, 18 ...
A / D conversion unit, 19 ... Blurring displacement storage unit, 20 ... Blurring amount prediction calculation unit, 21 ... Blurring reduction tendency judging unit, 22 ... Blurring speed judging unit, 23 ... Blurring amount judging unit.

[Procedure amendment]

[Submission date] October 31, 1994

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0012

[Correction method] Change

[Correction content]

[0012]

[Equation 4]

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0026

[Correction method] Change

[Correction content]

[0026]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a camera shake prevention device according to the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram of a camera shake prevention device according to the first embodiment. In the figure, the light emitting element 12 is driven by a drive circuit 14 and projects light onto the face 3 serving as a target surface. First
The second light receiving elements 11 and 13 receive the light reflected by the face 3. The output of the first light receiving element 11 is supplied to the 1 / (I _p1 ) ^1/2 arithmetic circuit 15, and the output of the second light receiving element 13 is supplied to the 1 / (I _p2 ) ^1/2 arithmetic circuit 16. . Then, the differential amplifier circuit 17 is
(I _p1 ) ^1/2 operation circuit 15 and 1 / (I _p2 ) ^1/2 operation time
The output of the path 16 is received and a differential amplification operation is performed.

[Procedure 3]

[Document name to be amended] Statement

[Correction target item name] 0028

[Correction method] Change

[Correction content]

Then, the blur reduction tendency determining unit 21 determines whether or not the current blur is in a decreasing tendency, and when it is increasing, the blur amount determining unit 23 does not perform the blur determination. Alternatively, the blur prediction is not performed before the determination . When it is determined that there is a decreasing tendency, the blurring speed determination unit 22 further determines whether or not the current blurring speed is within a certain threshold. When it is determined that the blurring speed is within the threshold value, the blurring amount determination unit 23 determines whether the predicted blurring amount is within a certain threshold value, and the shutter is started only when it is within the threshold value. If the blurring speed determination is not performed, the shutter is started only when the blurring tendency is decreasing and the predicted blurring amount is within the threshold value.

[Procedure amendment 4]

[Document name to be amended] Statement

[Correction target item name] 0044

[Correction method] Change

[Correction content]

[0044]

[Equation 9]

[Procedure Amendment 5]

[Document name to be amended] Statement

[Correction target item name] 0056

[Correction method] Change

[Correction content]

Next, read data of the motion that is stored in the RAM in Meinru Chi down step S31 in FIG. 8 (i). FIG. 7D shows the subroutine. Step S
In 63 and S64, the shake data 20 ms before is read into X _2L and X _2H .

[Procedure correction 6]

[Document name to be amended] Statement

[Correction target item name] 0077

[Correction method] Change

[Correction content]

Similarly, in steps S95 and S96, ( Δt + t _f ) ms past to Δtms past and ( 2Δ
t + t _f ) ms past to 2Δtms past, and the combined shake amount around the two axes is calculated and stored in B ₁ and B ₂ . here,
2-byte data is desirable for B ₀ , B ₁ , and B ₂ . In step S97, the combined blur amount w _xy after t _f ms from the present is predicted by the equation (29).

[Procedure Amendment 7]

[Document name to be corrected] Drawing

[Name of item to be corrected] Figure 7

[Correction method] Change

[Correction content]

[Figure 7]

[Procedure Amendment 8]

[Document name to be corrected] Drawing

[Correction target item name] Figure 8

[Correction method] Change

[Correction content]

[Figure 8]

[Procedure Amendment 9]

[Document name to be corrected] Drawing

[Name of item to be corrected] Fig. 10

[Correction method] Change

[Correction content]

[Figure 10]

[Procedure Amendment 10]

[Document name to be corrected] Drawing

[Name of item to be corrected] Fig. 11

[Correction method] Change

[Correction content]

FIG. 11

[Procedure Amendment 11]

[Document name to be corrected] Drawing

[Name of item to be corrected] Fig. 14

[Correction method] Change

[Correction content]

FIG. 14

 ─────────────────────────────────────────────────── ─── Continued front page (72) Inventor Hideto Kitazawa 2-43-2 Hatagaya, Shibuya-ku, Tokyo Olympus Optical Co., Ltd. (72) Inventor Yoshinori Matsuzawa 2-43-2 Hatagaya, Shibuya-ku, Tokyo No. Olympus Optical Co., Ltd. (72) Inventor Toshiro Kikuchi 2-43-2 Hatagaya, Shibuya-ku, Tokyo Olympus Optical Co., Ltd.

Claims (4)

[Claims] 1. A detection means for detecting a tilt angle of a camera, a storage means for storing the tilt angle detected by the detection means at predetermined time intervals, and the tilt angle stored in the storage means. , A predicting unit that predicts the amount of camera shake that occurs during the exposure operation of the camera, a determining unit that determines that the current amount of camera shake is in a decreasing tendency, and this determining unit determines that the image is in a decreasing tendency,
A camera shake prevention device for a camera, comprising: a permitting means for permitting exposure when the amount of camera shake predicted by the predicting means is equal to or less than a predetermined value. 2. The detecting means includes a light projecting means for projecting light toward an operator of the camera, a light receiving means for receiving reflected light from the operator and outputting a photoelectric conversion signal, and the photoelectric conversion. The camera shake prevention device for a camera according to claim 1, further comprising: a calculation unit that calculates a tilt signal that indicates a relative tilt between the operator and the camera based on a signal. 3. The camera shake prevention device for a camera further comprises:
In addition to the above conditions, the permitting means performs exposure only when the camera shake speed is below a predetermined value by the speed judging means. The camera shake prevention device for a camera according to claim 1, wherein the device is permitted. 4. The detecting means has at least two tilt angle detecting means for independently detecting tilt angles around axes orthogonal to each other in the camera, and the storage means outputs from the tilt angle detecting means. It is possible to store at least two pieces of tilt angle information for each predetermined time interval, and the prediction means uses the tilt information stored in the storage means to calculate a combined blur amount for each predetermined time interval. And a combined camera shake amount predicting unit that predicts the amount of camera shake during the exposure operation using the calculated combined camera shake amount, and performs prediction based on the combined camera shake amount. A camera shake prevention device for a camera according to claim 3.