JPH0593673A - Camera jiggling detector - Google Patents

Abstract

PURPOSE:To reduce delay time of a signal caused for removing noise to detect camera jiggling in a circuit for detecting a jiggling signal using a light measuring output. CONSTITUTION:Brightness information wherein brightness of a certain part of a subject is detected as a light measuring region by a light receiving element 11 and converted into light current is subjected to signal conversion with logarithmic compression, differentiation, etc., in a signal conversion part 12. This converted signal is envelope-detected by an AM wave detector 13. Dc components of an output detected by the AM wave detector 13 are removed by a dc component removing part 14 and then the output is sent to a subtractor 15. In this subtractor 15, the output directly sent out from the AM wave detector 13 and the output from the dc component removing part 14 with the dc components removed are subjected to subtraction. An output obtained by the subtractor 15 is amplified by an amplifier 16 and obtained as a jiggling detector output.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a camera shake detecting device, and more particularly to a camera shake detecting device for detecting a shake by reducing a delay time of a signal generated for noise removal.

[0002]

2. Description of the Related Art Conventionally, as one for detecting mechanical movement (blur) of a camera, for example, Japanese Patent Laid-Open No. 57-102.
A device as described in Japanese Patent No. 616 is known. In this technique, the brightness of the subject is converted into a photocurrent by a light receiving element, and the converted current is further converted into a compression voltage by a diode. Then, the flicker noise due to the fluorescent lamp, which is superimposed on the blur signal, is removed by a band-emission filter (BEF), and when the voltage exceeds a predetermined voltage determined by the shutter speed, the LED emits light. Is becoming In this device, the light emission of the LED is used as a warning of the blur. Also, conventionally,
To remove the flicker noise due to the fluorescent lamp from the signal obtained by the light receiving element, a filter is used.

[0003]

However, according to the blur detecting device as described above, since the blur signal is delayed by the BEF, the warning cannot be issued when the blur actually occurs. Also, if there is a release, you may be able to take a picture with blurring.
That is, the filter has a delay time (generally a few ms to a few tens ms) which is inevitably generated on the principle, and it is impossible to detect the blur in real time. Therefore, when actually trying to mitigate or prevent blurring, it is necessary to predict the blurring, and it is not possible to accurately mitigate or prevent the blurring.

The present invention has been made in view of the above points, and even if there is flicker noise due to a fluorescent lamp, by shortening the delay time, it is possible to detect camera shake in substantially real time. An object is to provide a detection device.

[0005]

That is, a camera shake detection apparatus according to the present invention photoelectrically converts the brightness of an object,
A light receiving element that outputs a photoelectric conversion signal, a detection unit that performs envelope detection of the photoelectric conversion signal, a DC component removal unit that removes a DC component due to camera shake of the photoelectric conversion signal, and an output of the detection unit. And a subtraction unit for calculating the difference between the outputs of the DC component removal unit, and the camera shake is detected based on the output of the subtraction unit.

[0006]

The camera shake detection apparatus according to the present invention extracts only the noise component from the photometric output and removes the noise component from the photometric output. That is,
When the brightness of the subject is photoelectrically converted by the light receiving element and a photoelectric conversion signal is output, envelope detection of the photoelectric conversion signal is performed by the detection means, and a DC component due to camera shake of the photoelectric conversion signal is a DC component. It is removed by the removing means. Then, the difference between the output of the detection means and the output of the DC component removal means is calculated by the subtraction means, and the camera shake is detected based on the output of the subtraction means.

[0007]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram schematically showing the structure of a camera shake detection apparatus according to the present invention. In the figure, when a part of a subject is detected as a photometric area by the light receiving element 11, the output of the light receiving element 11 is sent to the AM detector 13 which performs envelope detection via the signal conversion unit 12. It The output of the AM detector 13 is sent to the subtractor 15 via the DC component removing unit 14 and directly to the subtractor 15. Then, the output of the subtractor 15 becomes the shake detection output via the amplifier 16.

In the shake detecting device having such a structure,
The light receiving element 11 detects the brightness of a part of the subject as a photometric region, and the brightness information converted into photocurrent is subjected to signal conversion by logarithmic compression, differentiation, etc. in the signal conversion unit 12.
Then, the converted signal is envelope-detected by the AM detector 13. The output detected by the AM detector 13 has a DC component removed by a DC component removal unit 14 and then a subtractor 15
Sent to. The subtractor 15 subtracts the output directly sent from the AM detector 13 and the output from the DC component removing unit 14 from which the DC component has been removed. The output obtained by the subtracter 15 is amplified by the amplifier 16 and is guided to, for example, a blur correction optical system as a blur detection output. The blur signal detected in this manner can alleviate or prevent the blur.

Next, a second embodiment of the present invention will be described with reference to FIGS. FIG. 2 is a block diagram showing the structure of a camera shake detection device according to the second embodiment of the present invention. In the embodiments described below, the same parts as those in the first embodiment described above are designated by the same reference numerals, and the description thereof will be omitted.

In the figure, the light receiving element 11 is a photodiode generally used for photometry of a camera. However, the photodiode is not limited to the photodiode as long as the brightness of a part of the subject can be obtained as a photocurrent. The output of the light receiving element 11 is logarithmically compressed by the logarithmic compression circuit 17 and sent to the differentiator 18. Thereafter, the output appropriately amplified by the preamplifier 19 is sent to the AM detector 13 via the point a.

The output of the AM detector 13 is supplied to the subtractor 15 via the point b, the high pass filter (HPF) 20 and the point c, and is also directly supplied to the subtractor 15 via the point b. The output of the subtracter 15 is amplified by the main amplifier 21 via the point d, and then taken out as a shake detection output. Next, the operation of the second embodiment will be described with reference to FIGS.

By the light receiving element 11, a part of the subject,
In particular, the central area of the subject area projected onto the camera, where the main subject is highly likely to be present, is metered, and the brightness of this metered area is extracted and converted as a photocurrent signal. This photocurrent changes due to camera shake, and this is the basis of the shake signal. The photocurrent obtained by the light receiving element 11 is converted into a logarithmic compression voltage by the logarithmic compression circuit 17, and further converted into a change amount of the logarithmic compression voltage by the differentiator 18. This is the amount of change in photometric brightness caused by movement of the photometric area of the light receiving element 11 due to camera shake, and is a signal that is highly correlated with camera shake.

The signal thus obtained as the amount of change is
The preamplifier 19 differentiates the noise and shake signals that the logarithmic compression circuit 17 and the differentiator 18 have, and the next AM detector 13 facilitates envelope detection, so that the value can be adjusted to a predetermined value. Is amplified (for example, about 20 dB). As shown in FIG. 3A, the amplified waveform (point a) becomes waveform 2 in which flicker noise due to the fluorescent lamp is superimposed on blur signal 1. Here, when the flicker of the fluorescent lamp is small, the amplitude of the waveform 2 becomes small, and in a place without the fluorescent lamp, for example, outdoors, the waveform 2 coincides with the blur signal 1.

Next, the waveform 2 is A in the AM detector 13.
M detection (envelope detection) is performed. The output waveform (point b) by this AM detection is represented as a waveform 3 as shown in FIG. In this embodiment, the AM detector 13
As the circuit, a circuit having a simple configuration as shown in FIG. 4 is used. That is, the parallel circuit of the resistor 23 and the capacitor 24 is connected between the cathode of the diode 22 and the ground. The constant state of the unevenness of the waveform 3 is determined by the constants of the resistor 23 and the capacitor 24. Here, as the time constant of the resistor 23 and the capacitor 24 is larger, the unevenness of the waveform 3 is eliminated, and the flicker noise removal rate of the fluorescent lamp is improved. On the other hand, if the time constant is too large, it may not be possible to respond to the shake signal.
Therefore, even if the ideal constants of the resistor 23 and the capacitor 24 are determined, the waveform 3 does not sufficiently eliminate flicker noise.

Therefore, in the HPF 20, as shown in FIG. 3C, a waveform 4 (point c in FIG. 2) from which the DC component of the shake signal is removed is obtained from the waveform 3. Then, the waveform 4 and the waveform 3 are subtracted by the subtractor 15 to obtain a waveform 5 in which flicker noise is substantially removed, as shown in FIG. 2 point d). By the way, in the HPF 20, it is impossible to completely remove the flicker noise because of the delay time, but the HPF satisfying the delay time allowed to be considered that the flicker noise is sufficiently removed.
Is designable. Considering this, waveform 5
Is substantially the same as the blurring signal 1 originally desired to be detected. Waveform 5 obtained in this way is the main amplifier
It is amplified by 21 and output as a blur signal.

As described above, by substantially removing the flicker noise due to the fluorescent lamp, it becomes possible to detect the blur signal in substantially real time. Further, in this embodiment, there is no influence on the presence or absence of the fluorescent lamp, the frequency of the flicker noise due to the fluorescent lamp, the difference in the amplitude of the flicker noise depending on the type of the fluorescent lamp, and the like. Therefore, it is not necessary to switch or adjust the blur detection method for these detections or detection results, and it is possible to detect the blur with a simple circuit configuration.

[0018]

As described above, according to the present invention, there is provided a camera shake detection apparatus capable of performing substantially real-time shake detection by reducing the delay time even when there is flicker noise due to a fluorescent lamp. can do.

[Brief description of drawings]

FIG. 1 is a block configuration diagram schematically showing a configuration of a camera shake detection device according to the present invention.

FIG. 2 is a block configuration diagram showing a configuration of a camera shake detection device according to a second embodiment of the present invention.

3 (A), (B), (C) and (D) are waveform diagrams of respective signals at points a, b, c and d in FIG. 2, respectively.

FIG. 4 is a circuit diagram showing a configuration example of an AM detector shown in FIG.

[Explanation of symbols]

11 ... Light receiving element, 12 ... Signal conversion section, 13 ... AM detection section, 14 ...
DC component removing unit, 15 ... subtractor, 16 ... amplifier, 17 ... logarithmic compression circuit, 18 ... differentiator, 19 ... preamplifier, 20 ... high-pass filter (HPF), 21 ... main amplifier.

Claims (1)

[Claims] 1. A light-receiving element that photoelectrically converts the brightness of a subject and outputs a photoelectric conversion signal, a detection unit that performs envelope detection of the photoelectric conversion signal, and a DC component of the photoelectric conversion signal due to camera shake. And a subtraction unit for calculating a difference between the output of the detection unit and the output of the DC component removal unit, and the camera shake is detected based on the output of the subtraction unit. Camera shake detection device.