JP4536865B2 - Blur detection device and imaging device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a shake detection apparatus and an imaging apparatus , and more specifically, a shake detection apparatus that detects a shake using a mechanical shake detection sensor and a focus detection imaging device , and an imaging including the shake detection apparatus. Relates to the device .
[0002]
[Prior art]
In a conventional vibration isolation system, a mechanical sensor such as a vibration gyro-type angular velocity sensor that uses the Coriolis force generated in the vibrator is used as a shake detection sensor, and a part of the photographic lens or its A configuration is employed in which a correction optical system attached to the front surface is driven to correct blur.
[0003]
Further, as disclosed in Japanese Patent Application Laid-Open No. 58-4109 and Japanese Patent Publication No. 5-10603, a blur is detected using an automatic focus detection device, and the correction optical system is driven based on the detection result. The configuration is also known. In this method, the amount of camera shake is calculated by performing a correlation operation on imaging data at different times output from an imaging device (hereinafter referred to as an AF sensor). There are cases where an imaging element is used for photographing and a sensor dedicated for automatic focus detection is used.
[0004]
[Problems to be solved by the invention]
In a configuration in which a mechanical sensor such as a vibration gyro is used for shake detection, an output offset that varies with temperature or the like becomes a problem. This offset can be removed by inputting the sensor output to an analog high-pass filter. However, this method has a problem that a considerable time is required until the output is stabilized because the time constant of the analog high-pass filter is large.
[0005]
Also, when the photographer pans, even the camera operation intended by the photographer is included in the sensor output, so let's correct the blur by driving the correction optical system with the shake detection output at this time. Then, the correction optical system is excessively driven, and the panning effect intended by the photographer cannot be obtained.
[0006]
In view of these problems, an object of the present invention is to provide a shake detection device in which an output offset of a mechanical shake detection sensor quickly converges while using a mechanical shake detection sensor.
[0007]
It is another object of the present invention to provide a shake detection device that can obtain a panning effect intended by a photographer , and an imaging device including the shake detection device .
[0008]
[Means for Solving the Problems]
A shake detection device according to the present invention is a device that detects a shake of an imaging device that detects a focus by a photoelectric conversion unit, and includes a first shake detection unit that mechanically detects a shake of the imaging device, first offset adjusting means, and the second offset adjusting means comprising a high pass filter to adjust the offset of the output of the first vibration detection unit, the photoelectric conversion means for adjusting the offset of the output of the first vibration detection unit A second blur detecting unit that detects image blur from the temporally different outputs, and when the imaging device is determined to be stationary according to the output of the second blur detecting unit , the second blur According to the output of the detection means, the offset adjustment amount of the first offset adjustment means is controlled to select the output of the first offset adjustment means, and it is determined that the imaging apparatus is not stationary. When it is characterized by comprising a control means for selecting the output of the second offset adjusting unit.
[0009]
An imaging device according to the present invention includes the above-described shake detection device .
[0010]
【Example】
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[0011]
FIG. 1 shows a schematic block diagram of an embodiment of the present invention. Reference numeral 10 denotes a CPU that controls the sequence of the entire camera, such as lens driving and exposure. The CPU 10 also executes calculation related to photographing such as exposure calculation, distance measurement calculation, and calculation related to blur detection. Reference numerals 12a and 12b denote angular velocity sensors which are mechanical camera shake sensors, which detect camera shake angular velocities in the horizontal direction and vertical direction of the camera, respectively. 14a and 14b are detection circuits for converting the outputs of the angular velocity sensors 12a and 12b to corresponding voltage values, respectively. 16a and 16b are transducers in the angular velocity sensors 12a and 12b based on the detection outputs of the detection circuits 14a and 14b, respectively. , 18a and 18b are offset adjustment circuits for adjusting the offsets of the outputs of the detection circuits 14a and 14b, and 20a and 20b are respectively integrated with the angular velocity signals whose offsets are adjusted by the offset adjustment circuits 18a and 18b. And an integrating circuit for converting the angular displacement signal.
[0012]
Reference numeral 22 denotes a correction optical system for optically correcting blur, reference numeral 24 denotes a correction optical system drive circuit for driving the correction optical system 22, and reference numeral 26 denotes a photographing optical system. Reference numeral 28 denotes an AF sensor that converts an optical image obtained by the correction optical system 22 and the photographing optical system 26 into an electric signal, and is arranged orthogonal to the horizontal and vertical directions in order to measure a distance measuring point in the photographing screen. It consists of two line sensors. A sensor control circuit 30 controls the AF sensor 28 and outputs a signal corresponding to the subject distance to the CPU 10 based on the detection result of the AF sensor 28.
[0013]
In this embodiment, the image data of the AF sensor 28 is also used for blur detection. The sensor control circuit 30 supplies the imaging data from the AF sensor 28 to the CPU 10, and the CPU 10 detects a shake based on the imaging data.
[0014]
FIG. 2 shows an example of the imaging area in the shooting screen. Reference numeral 32 denotes an imaging area used to detect horizontal blur, and reference numeral 34 denotes an imaging area used to detect vertical blur. In the present embodiment, the CPU 10 detects blurring in the horizontal direction and the vertical direction using the imaging data from the AF sensor 28 corresponding to the imaging areas 32 and 34, respectively, and based on the detection result, the offset adjustment circuit The offset adjustment amount in 18a and 18b is controlled.
[0015]
A shake detection operation based on the output of the AF sensor 28 will be described. In this embodiment, a so-called phase difference detection type distance measuring system is used for camera shake detection. FIG. 3 shows the basic principle of distance measurement by the phase difference detection method. Incident light that has passed through the light receiving lens passes through the separator lenses 40 and 42 and forms an image on the line sensors 44 and 46 that are disposed at spatially different positions. By calculating the correlation between the two image signals Sa and Sb formed on the line sensors 44 and 46, the shift amount between the two images is calculated, and the defocus amount is determined.
[0016]
In this embodiment, the AF sensor for distance measurement is used for blur detection between distance measurement. At the time of shake detection, as shown in FIG. 4, the output Ta and Tb at different time points of one line sensor 44 are compared, and they are subjected to correlation calculation to calculate temporal image shift amount. Since the temporal image shift amount corresponds to the image blur amount due to camera shake, it is possible to detect camera shake. This basic principle itself is well known.
[0017]
In the present embodiment, the CPU 10 controls the offset adjustment amounts of the offset adjustment circuits 18 a and 18 b based on the image blur amount detected from the output of the AF sensor 28. FIG. 5 shows a flowchart of the shake detection / offset adjustment operation of this embodiment.
[0018]
Energization of the angular velocity sensors 12a and 12b is started (S1), and the AF sensor 28 is driven (S2). Based on the basic principle described above, the amount of image blur is detected using the image data captured by the AF sensor 28 (S3). The horizontal angular velocity component due to camera shake is calculated from the image blur amount detected by the AF sensor arranged in the horizontal direction, and the vertical angular velocity component due to camera shake is calculated from the image blur amount detected by the AF sensor arranged in the vertical direction. Is calculated (S4). Specifically, assuming that the angular velocity component is w, the focal length is f, the imaging time interval by the AF sensor is Δt, and the amount of image blur obtained in step S3 is Δx, w is approximately obtained by the following equation. I can do it. That is,
w = tan ⁻¹ (Δx / f) / Δt
According to the obtained angular velocity component w, the offset adjustment amounts of the offset adjustment circuits 18a and 18b are adjusted (S5).
[0019]
FIG. 6 shows a circuit example of the offset adjustment circuits 18a and 18b. Reference numeral 50 denotes an operational amplifier, and the output voltage of the detection circuits 14a and 14b is applied to the non-inverting input thereof. A resistor 52 is connected between the inverting input and the output of the operational amplifier 50. The control value output from the CPU 10 is converted into an analog value by the D / A converter 54 and applied to the inverting input of the operational amplifier 50 via the resistor 56. The CPU 10 applies to the D / A converter 54 a control value that causes the offset adjustment circuits 18a and 18b to output a voltage value equal to the angular velocity component obtained in S4. By using the D / A converter 54, the time required for offset adjustment can be greatly reduced as compared with the analog high-pass filter, and the desired offset can be set almost instantaneously.
[0020]
FIG. 7 shows a schematic block diagram of the second embodiment of the present invention. The same components as those in FIG. 1 are denoted by the same reference numerals. In the embodiment shown in FIG. 7, switches 60a and 60b; 62a and 62b are respectively provided between the detection circuits 14a and 14b and the offset adjustment circuits 18a and 18b, and between the offset adjustment circuits 18a and 18b and the integration circuits 20a and 20b. The offset adjustment circuits 18a and 18b and the analog high-pass filters 64a and 64b can be selected.
[0021]
FIG. 8 shows a circuit example of the analog high-pass filters 64a and 64b. A capacitor 70 and a resistor 72 are connected in series, and a voltage at the connection point is amplified by an operational amplifier 74.
[0022]
The CPU 10a has a function of switching the switches 60a and 60b; 62a and 62b in addition to the function of the CPU 10. FIG. 9 shows an operation flowchart of the embodiment shown in FIG.
[0023]
Energization of the angular velocity sensors 12a and 12b is started (S11), and the AF sensor 28 is driven (S12). Based on the basic principle described above, the amount of image blur is detected using the image data captured by the AF sensor 28 (S13). It is determined whether the camera is stationary based on the detected amount of image blur (S15). When the camera is stationary (S15), the CPU 10a connects the switches 60a and 60b; 62a and 62b to the offset adjustment circuits 18a and 18b, and applies a predetermined value as an offset adjustment control value to the offset adjustment circuits 18a and 18b. (S16). When the camera is stationary, the angular velocity output is naturally zero, so there is no need to estimate the angular velocity from the amount of blur. When the camera is not stationary (S14), the CPU 10a connects the switches 60a and 60b; 62a and 62b to the analog high-pass filters 64a and 64b, and adjusts the offset by the filters 64a and 64b (S17).
[0024]
In the embodiment shown in FIG. 7, it is only necessary that the camera stillness determination can be accurately performed by the shake detection using the AF sensor. Therefore, the risk of erroneous offset adjustment due to an error in the amount of blur detected using the image data of the AF sensor is reduced, and the offset can be adjusted with higher accuracy.
[0025]
FIG. 10 shows a schematic block diagram of the third embodiment of the present invention. The same components as those in FIG. 1 are denoted by the same reference numerals. Reference numeral 80 denotes a panning detection circuit that detects panning. In addition to the function of the CPU 10, the CPU 10b controls offset adjustment in the offset adjustment circuits 18a and 18b as follows in accordance with the detection result of the circuit 80.
[0026]
In order to detect the intentional panning of the photographer, for example, a panning photographing mode switch operated by the photographer when performing panning photographing may be provided, and it may be determined whether the panning is intentional panning according to the operation state. Then, the output of the angular velocity sensor and the blur detection result by the AF sensor may be compared to determine whether panning shooting is performed.
[0027]
At the time of panning shooting, the CPU 10b determines the offset adjustment amounts of the offset adjustment circuits 18a and 18b based on the image blur amount detected from the output of the AF sensor 28. Specifically, an angular velocity component due to camera shake is calculated from the output of the AF sensor 28. Since the image blur amount obtained by the AF sensor is a relative blur amount with respect to the subject, the blur amount due to panning is not included. The CPU 10b applies to the offset adjustment circuits 18a and 18b a control value such that the output of the offset adjustment circuits 18a and 18b matches the shake detection result (an angular velocity component not including the panning component) using the AF sensor 28. Thereby, the angular velocity component by panning can be removed from the outputs of the angular velocity sensors 12a and 12b.
[0028]
As an example of the focus detection imaging device, a line sensor arranged in a cross shape has been described as an example, but a two-dimensional area sensor may be used.
[0029]
The case where there is one image data obtained in each of the horizontal and vertical directions has been described as an example. The image blur amount may be calculated from the image, and the angular velocity component may be calculated and the camera stationary may be determined.
[0030]
【The invention's effect】
As can be easily understood from the above description, according to the present invention, the output offset of the mechanical shake detection sensor can be quickly converged. By switching the plurality of offset adjusting means according to the situation, the output offset of the mechanical shake detection sensor can be converged quickly and with high accuracy. Furthermore, it is possible to remove the blur component due to panning included in the output of the mechanical shake detection sensor during panning shooting so that the panning effect intended by the photographer can be obtained.
[Brief description of the drawings]
FIG. 1 is a schematic block diagram of a first embodiment of the present invention.
FIG. 2 is a diagram illustrating a distance measuring area in a shooting screen.
FIG. 3 is a schematic diagram showing the basic principle of AF distance measurement.
FIG. 4 is a schematic diagram illustrating a basic principle when blur detection is performed using an AF sensor.
FIG. 5 is a flowchart of shake detection / offset adjustment of the embodiment shown in FIG. 1;
FIG. 6 is a circuit example of offset adjustment circuits 18a and 18b.
FIG. 7 is a schematic block diagram of a second embodiment of the present invention.
FIG. 8 is a circuit example of analog high-pass filters 64a and 64b.
FIG. 9 is a flowchart of shake detection / offset adjustment of the second embodiment.
FIG. 10 is a schematic block diagram of a third embodiment of the present invention.
[Explanation of symbols]
10, 10a, 10b: CPU
12a, 12b: Angular velocity sensors 14a, 14b: detection circuits 16a, 16b: drive circuits 18a, 18b: offset adjustment circuits 20a, 20b: integration circuit 22: correction optical system 24: correction optical system drive circuit 26: photographing optical system 28: AF sensor 30: sensor control circuit 32: horizontal blur detection imaging area 34: vertical blur detection imaging area 40, 42: separator lens 44, 46: line sensor 50: operational amplifier 52: resistor 54: D / A converter 56: resistors 60a, 60b, 62a, 62b: switches 64a, 64b: analog high-pass filter 70: capacitor 72: resistor 74: operational amplifier 80: panning detection circuit

Claims (5)

An apparatus for detecting blur of an imaging apparatus that detects a focus by a photoelectric conversion means,
First blur detection means for mechanically detecting blur of the imaging device;
First offset adjusting means for adjusting the offset of the output of the first shake detecting means;
Second offset adjusting means comprising a high-pass filter for adjusting the offset of the output of the first shake detecting means;
Second blur detection means for detecting image blur from temporally different outputs of the photoelectric conversion means;
When it is determined that the imaging apparatus is stationary according to the output of the second shake detection unit, the offset adjustment amount of the first offset adjustment unit is controlled according to the output of the second shake detection unit. Control means for selecting the output of the second offset adjustment means when the output of the first offset adjustment means is selected and it is determined that the imaging apparatus is not stationary. Shake detection device. The shake detection device according to claim 1 , wherein the photoelectric conversion means is composed of line sensors orthogonal to each other. The shake detection apparatus according to claim 1 , wherein the photoelectric conversion means is a two-dimensional area sensor. The blur detection device according to claim 1 , wherein the second blur detection unit detects image blur at a plurality of points from an output of the photoelectric conversion unit. An imaging device comprising the shake detection device according to claim 1.

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