JP2894774B2 - Camera shake prevention camera - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a camera shake prevention camera provided with a camera shake detection unit.

"Prior art and its problems" Especially when performing hand-held shooting with a camera, when the camera is incompletely held, when shooting a dark subject with a slow shutter, or when the photographer shoots while moving, the camera shakes light. Axis shake is easy to occur. The image in which the camera shake has occurred is extremely unsightly because the image flows. Despite the fact that the degree of camera shake varies greatly depending on the photographer's experience and skill, conventional cameras will turn on the lamp in the viewfinder when the shutter speed falls below a predetermined shutter speed at most. Only the coping function of the prompt was installed.

[Object of the Invention] The present invention informs the photographer that the blurring has occurred in the photographing optical axis more accurately, and furthermore, even if the blurring occurs in the photographing optical axis, a photograph free from image blurring is obtained in practical use. The aim is to get a camera.

[Summary of the Invention] The present invention, when the optical axis of the taking lens is blurred due to camera shake of the photographer, releases the shutter after the optical axis swings or stops, or alerts the photographer by issuing an alarm It was completed based on the idea of doing.

The present invention basically includes a camera shake detecting means for detecting the swing angular acceleration or angular velocity of the optical axis of the photographing lens, and after the camera shake detecting means detects the maximum camera shake, the output becomes an allowable level. The camera shake attenuation detecting means detects that the following conditions have occurred, and the shutter is released on condition that the camera shake attenuation detecting means detects that the camera shake is at an allowable level and that the shutter release switch is on. This is a camera shake prevention camera designed to be released.

The camera shake attenuation detection means detects and holds the maximum peak value of the output of the camera shake detection means, and detects and holds the maximum peak value holding circuit having a discharge characteristic of an appropriate time constant and the minimum peak value of the camera shake detection means. A minimum peak value holding circuit having a discharge characteristic with an appropriate time constant; a differential amplifier for obtaining differential outputs of the maximum peak value holding circuit and the minimum peak value holding circuit; A comparison circuit that compares a reference value corresponding to the shake amount and outputs a shutter operation enable signal when the output of the differential amplifier becomes smaller than the reference value corresponding to the allowable camera shake amount.

The shutter operation enable signal from the comparison circuit can cause the shutter to output a release signal on the condition that the shutter release switch ON signal is simultaneously output.

In addition, if the comparison circuit issues a warning signal to the camera shake alarm device from when the camera shake detection means detects the maximum camera shake until the shutter operation enable signal is output, the occurrence of camera shake can be accurately determined. Let the photographer know.

"Examples of the Invention" The present invention will be described below with reference to illustrated examples. 1 to 3 show a first embodiment of the present invention.
The camera 11 is equipped with an angular acceleration sensor 13 for detecting the shake (oscillation angular acceleration) of the optical axis O of the taking lens 12.
The shutter 14 is provided on the photographing lens 12.

The output voltage corresponding to the shake of the optical axis O detected by the angular acceleration sensor 13 is input to the maximum peak value holding circuit 15 and the minimum peak value holding circuit 16, and the maximum output and the minimum output are held. FIG. 2 shows the maximum peak value holding circuit 15.
And a general configuration example of the minimum peak value holding circuit 16, in which the held maximum peak value and minimum peak value are discharged by a time constant determined by the capacitors 15c, 15c, 16c and the resistors 15r, 16r. .

This maximum peak value holding circuit 15 and the minimum peak value holding circuit
The 16 outputs 15a and 16a are respectively input to the differential amplifier 17, and the amplified difference output 17a is input to the comparison circuit 18. The comparison circuit 18 compares the differential output 17a with the reference voltage Vref.
And if the differential output is greater than this Vref, L
(0), if smaller, H (0) is output. This comparison circuit
The output of the signal 18 is output together with the release switch signal that is turned on (H, 1) when the shutter release button 19 is pressed.
The AND circuit 20 supplies a shutter release signal to the shutter 14 when both the outputs are H.

FIG. 3 is a time chart showing an operation example of the camera configured as described above. When the camera 11 is held, the optical axis O of the photographing lens 12 fluctuates. The swing of the optical axis O includes a parallel movement component and a rotation movement component, but most of the rotation movement component causes image blur on the film surface. The angular acceleration sensor 13 outputs a voltage 13a proportional to the vertical angular acceleration of the rotational movement component of the optical axis O, and the maximum peak and the minimum peak of this output voltage are the maximum peak value holding circuit 15 and the minimum peak value holding circuit. Held by 16. The maximum and the minimum mean the maximum run-out in the vertical direction and the opposite direction.

The peak voltages 15a and 15b held by the maximum peak value holding circuit 15 and the minimum peak value holding circuit 16 are connected to a capacitor 15c.
While discharging according to the time constant determined by the capacitor 16c and the resistor 16r, and the difference
Is amplified by When this value 17a becomes lower than the reference voltage Vref, that is, when it is detected that the camera shake level has become equal to or less than the allowable value, the comparison circuit 18 outputs H (shutter operation enable signal).

Before the comparison circuit 18 outputs H, the shutter release button 19 is turned on, and even if H is input to the AND circuit 20, the shutter 14 is not released. That is, AND circuit 2
0 indicates that when the comparison circuit 18 outputs H and the shutter release button 19 outputs H, that is, on the condition that the camera shake is attenuated to an allowable level and the shutter release button 19 is on, To the release signal.
As described above, according to the present invention, the shutter is not released immediately after the shutter release button 19 is turned on, but is released on the condition that the camera shake is attenuated to a certain level or less.

The H signal (release enable signal) from the comparison circuit 18 is simultaneously supplied to a warning circuit 21 and, for example, a warning provided in a finder.
The LED 22 can be operated. Conversely, when the L signal is output from the comparison circuit 18, that is, in the section A of FIG. 3 from the occurrence of a camera shake exceeding the reference voltage Vref until the camera shake falls within an allowable level, the warning circuit is activated. The warning LED 22 may be operated via 21.

The reference voltage Vref may be fixed in a relatively inexpensive camera having a fixed shutter speed and fixed lens. However, in an auto-exposure camera in which the shutter speed is automatically set, and in a more sophisticated camera in which a photographer can select a shutter speed and a focal length (lens), it is desirable to set the reference voltage Vref according to these values. . For example,
The signal s proportional to the shutter speed (exposure time) and the signal f proportional to the focal length of the taking lens are shown in FIGS.
It can be input to the reference voltage generation circuit 23 shown in the figure, and the calculation result of Vref = K / (s × f) (K is a proportional constant) can be output as the reference voltage Vref. That is, as the exposure time is longer and the focal length is longer, image blur is more likely to occur, so the value of the reference voltage Vref is reduced.

The angular acceleration sensor 13 may be any as long as it can detect the shake of the optical axis O of the photographing lens 12, and for example, Japanese Patent Application No. 1-8431.
No. 8 (filed on April 3, 1989) can use the angular acceleration sensor proposed by the present applicant. Or the angular velocity sensor “EYK-G02C” manufactured by Matsushita Electronic Components Co., Ltd.
(Part number) can be used. This angular velocity sensor is
Utilizing the Coriolis force generated by the vibrating tuning fork, it is composed of a gyro signal detecting section in which two bimorphs are arranged in a T-shape, a tuning fork driving circuit, and a signal processing circuit.

The output of the angular acceleration sensor 13 is directly supplied to the maximum peak value holding circuit 15 and the minimum peak value holding circuit 16 as in the above embodiment.
Alternatively, the angular velocity may be converted into an angular velocity through an integrating circuit and then input to both holding circuits 15 and 16. The present invention
Since the difference between the maximum peak value and the minimum peak value of the angular acceleration or the angular velocity is used, in these cases, it is possible to remove the influence of the offset output of the angular velocity sensor or the integrating circuit satisfactorily.

FIG. 4 shows another embodiment of the present invention. This example is
It is characterized in that a pair of acceleration sensors 25 and 26 are used instead of the angular acceleration sensor 13 of the first embodiment. The acceleration sensors 25 and 26 are for detecting vertical acceleration applied to the camera 11 (photographing lens 12), and are installed as far as possible in the direction of the optical axis O. The outputs of the acceleration sensors 25 and 26 are respectively input to a differential amplifier 27, and the differential outputs are input to a maximum peak value holding circuit 15 and a minimum peak value holding circuit 16. Other parts are the same as those in the first embodiment, and the same parts are denoted by the same reference numerals.

In this embodiment, the differential amplifier 27
Since the output difference between 25 and 26 is detected, the angular acceleration of the optical axis O can be detected excluding the influence of gravity on each acceleration sensor. Maximum and minimum peak value holding circuit 15
According to (16), since the difference between the maximum peak value and the minimum peak value is used, there is an advantage that the influence of the offset output of the differential amplifier 27 caused by the characteristic difference of each acceleration sensor is eliminated.

Note that the actual camera shake includes not only the vertical vibration but also the horizontal vibration, but generally, the vertical vibration tends to be larger. Therefore, sufficient practicality can be obtained by detecting only the vertical optical axis shake as in the embodiment, but since the camera shake is detected more strictly, the lateral acceleration can also be detected. For example, in FIG. 1, two pairs of components of an angular acceleration sensor 13, a maximum peak value holding circuit 15, a minimum peak value holding circuit 16, a differential amplifier 17, a comparing circuit 18, and a reference voltage generating circuit 23 are provided, If the sensor 13 is arranged to detect the angular acceleration in the horizontal direction and the outputs of the two comparison circuits 18 are input to the AND circuit 20, the shutter is released when the vertical and horizontal camera shake falls within the allowable value. be able to.

[Effects of the Invention] As described above, the camera shake prevention camera of the present invention releases the shutter when the camera shake occurs and waits until the magnitude of the camera shake falls within an allowable value. Even if blurring occurs, a photograph with less image blurring can be obtained. By using the fact that a shutter release enable signal indicating that the camera shake has fallen within the allowable value is output or not, a camera shake warning is issued to alert the photographer.

[Brief description of the drawings]

FIG. 1 is a system connection diagram showing an embodiment of a camera shake preventing camera according to the present invention, FIG. 2 is a circuit diagram showing a specific example of a maximum peak value holding circuit and a minimum peak value holding circuit, and FIG. FIG. 4 is a system connection diagram showing another embodiment of the present invention. 11… Camera, 12… Shooting lens, 13… Angular acceleration sensor, 14
... shutter, 15 ... maximum peak value holding circuit, 16 ... minimum peak value holding circuit, 17 ... differential amplifier, 18 ... comparison circuit, 19 ... shutter release button, 20 ... AND circuit, 21 ... warning circuit, 2
2 ... warning LED, 23 ... reference voltage generation circuit, 25, 26 ... acceleration sensor, 27 ... differential amplifier.

Claims (6)

(57) [Claims] 1. A camera shake detecting means for detecting a swing angular acceleration or an angular velocity of an optical axis of a photographing lens; a camera shake detecting means for detecting and holding a maximum peak value of an output of the camera shake detecting means and having a discharge characteristic with an appropriate time constant. A peak value holding circuit; a minimum peak value holding circuit which detects and holds the minimum peak value of the camera shake detecting means and has a discharge characteristic with an appropriate time constant; a differential output between the maximum peak value holding circuit and the minimum peak value holding circuit A differential amplifier that obtains the following; and compares the output of the differential amplifier with a reference value corresponding to the allowable camera shake amount, and operates the shutter when the differential amplifier output becomes smaller than the reference value corresponding to the allowable camera shake amount. An anti-shake camera, comprising: a comparison circuit that outputs a permissible signal. 2. The camera according to claim 1, further comprising a release control circuit for outputting a release signal to the shutter in response to a shutter operation enable signal of a comparison circuit and an ON signal of a shutter release switch. Camera shake prevention camera. 3. The camera according to claim 1, wherein the comparison circuit outputs a warning signal to the camera shake alarm device from when the camera shake detection means detects the camera shake until the shutter operation enable signal is output. Camera shake prevention camera which emits. 4. A camera shake preventing camera according to claim 1, wherein the reference value according to the allowable camera shake amount is set according to at least one of a set shutter speed of the camera and a focal length of the photographing lens. camera. 5. The camera according to claim 1, wherein the camera shake detecting means is an angular acceleration sensor. 6. The camera according to claim 1, wherein the camera shake detecting means comprises a pair of acceleration sensors installed at a distance from each other and a differential amplifier for detecting a differential output of the acceleration sensor. Anti-shake camera.