JP2000047084A - Imaging device - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To detect a temperature of a lens system without using a temperature sensor dedicated to temperature detection, and to correct a deviation of a lens focus adjustment position due to a temperature. SOLUTION: An output voltage of a Hall element at a fixed aperture position utilizes a temperature characteristic that changes with a temperature change, and a Hall element 6 that converts a change in a magnetic field due to rotation of a magnet rotor 5 into a voltage is used for temperature detection. By utilizing this, the temperature of the lens system 1 is detected, and the deviation of the lens focusing position due to the temperature is corrected.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image pickup apparatus such as a silver halide film camera, an electronic still camera, and a video camera, and more particularly to an image pickup apparatus having a temperature correcting function of a lens focal position.

[0002]

2. Description of the Related Art FIG. 2 is a block diagram showing a configuration of a video camera which is a conventional imaging device. In FIG. 2, reference numeral 1 denotes a lens system for condensing a subject image, reference numeral 2 denotes an aperture for controlling the amount of light of the received subject image, and reference numeral 3 denotes a device which converts the subject image received via the lens system 1 into electric charges, and generates a charge signal. An image sensor 4 for outputting to the image processor 4 is a video processor for converting the charge signal input by the image sensor 3 into a video signal (VS signal) and outputting the signal, and 5 is installed on the aperture 2 and opens and closes the aperture 2 by rotation. A magnet element 6 is provided in the vicinity of the magnet rotor 5 and converts a change in a magnetic field due to rotation of the magnet rotor 5 into a voltage, and outputs a voltage to the amplifier 7 as a signal. An amplifier 8 amplifies the amplified signal and outputs the amplified signal to an A / D converter. The amplifier 8 converts the amplified signal input by the amplifier 7 into a digital signal, and outputs a Hall element output voltage signal (HS signal).
A / D converter that outputs as
Reference numeral 10 denotes a focus motor having lens position driving means for driving the focus lens 9 in the optical axis direction, 11 denotes a temperature sensor which is installed close to the lens system 1 and detects the temperature of the lens system 1, 12 denotes an aperture driving circuit, 13 is an aperture driving coil, 15 is a motor driving circuit, and 26 is a CPU.

The CPU 26 stops the diaphragm drive circuit 12 based on the VS signal input from the video processing unit 4, the HS signal input from the A / D converter 8, and the temperature of the lens system 1 input from the temperature sensor 11. It outputs a drive control signal (SD signal) and a lens position drive control signal (LS signal) to the motor drive circuit 13.

Hereinafter, the operation of the conventional image pickup apparatus, particularly, the operation of controlling the aperture, detecting the aperture value, and correcting the deviation of the lens focus adjustment position due to the temperature change of the lens system 1 will be described.

[0005] The optical image incident from the lens system 1 is formed on the image sensor 3 and converted into a charge signal, then converted into a VS signal in the video processing unit 4 and input to the CPU 26. The CPU 26 detects the level of the VS signal input from the video processing unit 4 in order to determine whether or not the amount of light of the subject image received by the image sensor 3 is appropriate, and adjusts the aperture 2 so that the VS signal is at the optimal level. Open and close to perform light intensity control. That is, C
When the level of the VS signal is low, the PU 26 sends the SD signal to the aperture driving circuit 12 so that the aperture 2 opens, and sends the SD signal to the aperture driving circuit 12 so that the aperture 2 closes when the level of the VS signal is high. The aperture driving circuit 12 is a CPU 26
The rotation of the magnet rotor 5 is controlled by controlling the current flowing through the aperture driving coil 13 in accordance with the input SD signal, and the aperture 2 is opened and closed.

The opening / closing amount of the aperture 2, that is, the aperture value, is
Is detected based on the position information of the magnet rotor 5 that drives the motor. The change in the magnetic field due to the rotation of the magnet rotor 5 is converted into a voltage by the Hall element 6 and converted into a signal as an amplifier 7.
Is output to The signal is amplified by the amplifier 7 and then input to the A / D converter 8 to be converted into a digital signal, which is input to the CPU 26 as an HS signal. CPU2
6 is provided with output voltage detecting means for detecting the output voltage of the Hall element 6 from the HS signal, detecting the output voltage of the Hall element 6 from the HS signal, and further detecting the output voltage of the diaphragm 2 from the output voltage of the Hall element 6. Detect aperture value. The aperture value is used as data for the aperture control and various other controls in the imaging apparatus.

For example, in the case of a video camera provided with an autofocus control means, when performing autofocus, the CPU 26 outputs an appropriate LS signal to the motor drive circuit 13 and controls the focus motor 10 to control the focus. The lens 9 is moved to an appropriate position. Also,
When a fixed focus is set, the focus lens 9 is moved to a predetermined position for back focus adjustment. Here, the lens focus adjustment position moves due to a temperature change of the lens system 1. Therefore, in the imaging apparatus, the temperature of the lens system 1 is detected, the amount of correction of the shift of the lens focus alignment position due to the temperature of the lens system 1 is obtained, and the focus lens 9 is moved in the optical axis direction by the lens position driving unit. In addition, the shift of the focal position of the focus lens 9 is corrected.
That is, the CPU 26 has a table (not shown) indicating the correction amount of the lens focus alignment position corresponding to the temperature of the lens system 1 detected by the temperature sensor 11, and based on the table, the lens focus is calculated from the detected temperature. The correction amount of the matching position is obtained. Further, the CPU 26 sets an appropriate LS for correcting a shift of the focus adjustment position according to the detected correction amount.
The signal is sent to the motor drive circuit 15. Motor drive circuit 15
Drives the focus lens 9 by driving the focus motor 10 based on the LS signal input from the CPU 26, and corrects the shift of the lens focal position.

[0008]

As described above, in the conventional imaging apparatus, a dedicated temperature for detecting the temperature of the lens system is used in order to correct the deviation of the lens focus adjustment position due to the temperature change of the lens system. Since the sensor is provided, there is a problem that the device becomes large and the cost increases.

SUMMARY OF THE INVENTION The present invention has been made in order to solve the above-mentioned problems, and it is an object of the present invention to detect a temperature of a lens system without providing a dedicated sensor and correct a shift of a lens focusing position due to a temperature change. It is an object of the present invention to provide an imaging device capable of performing the following.

[0010]

According to a first aspect of the present invention, there is provided an imaging apparatus for controlling an amount of light mounted in a lens system, a device for controlling the aperture, and An output voltage detecting means for detecting an output voltage of the Hall element of the Hall element in an imaging apparatus including a magnet rotor linked to an opening and closing operation and a Hall element for converting a change in a magnetic field due to the rotation of the magnet rotor into a voltage. Temperature detection means for detecting the temperature of the lens system based on the output voltage of the Hall element at the fixed position of the diaphragm detected by the output voltage detection means; and a lens position for driving a lens in the lens system in the optical axis direction. Driving means for driving the lens position driving means based on the temperature of the lens system detected on the basis of the detected temperature, and changing the temperature of the lens system. It is characterized in that so as to correct the deviation of the lens focal alignment position with.

[0011]

(Embodiment 1) FIG. 1 is a block diagram showing a configuration of a video camera which is an image pickup apparatus according to Embodiment 1 of the present invention. 1, the same reference numerals as those in FIG. 2 denote the same or corresponding parts, reference numeral 14 denotes an aperture fixing circuit, and reference numeral 16 denotes a CPU. The CPU 16 is a conventional CP.
Unlike U26, it has a temperature detecting means for detecting the temperature of the lens system 1 based on the output voltage of the Hall element 6 detected by the output voltage detecting means.

Hereinafter, the operation of the image pickup apparatus according to the first embodiment configured as described above, in particular, the operation of controlling the aperture, detecting the aperture value, and correcting the deviation of the lens focus adjustment position due to the temperature change of the lens system 1 will be described. Will be described.

An optical image incident from the lens system 1 is formed on the image pickup device 3 and converted into a charge signal, and then converted into a VS signal in the video processing unit 4 and input to the CPU 16. The CPU 16 detects the level of the VS signal input from the video processing unit 4 in order to determine whether or not the amount of light of the subject image received by the image sensor 3 is appropriate. Open and close. That is, the CPU 16
Sends the SD signal to the aperture drive circuit 12 so as to open the aperture 2 when the level of the VS signal is low, and sends the SD signal to close it when the level of the VS signal is high.
Send to 2. The iris drive circuit 12 controls the rotation of the magnet rotor 5 and opens and closes the iris 2 by controlling the current flowing through the iris drive coil 13 in accordance with the SD signal input from the CPU 16.

The opening / closing amount of the aperture 2, that is, the aperture value, is
Is detected based on the position information of the magnet rotor 5 that opens and closes. The change in the magnetic field due to the rotation of the magnet rotor 5 is converted into a voltage by the Hall element 6 and converted into a signal as an amplifier 7.
Is output to The signal is amplified by the amplifier 7 and then input to the A / D converter 8 to be converted into a digital signal, which is input to the CPU 16 as an HS signal. CPU1
Reference numeral 6 denotes output voltage detecting means for detecting the output voltage of the Hall element 6 from the HS signal, detects the output voltage of the Hall element 6 from the HS signal, and further detects the output of the aperture 2 from the output voltage of the Hall element 6. Find the value. The aperture value is
It is used as data for the above-mentioned aperture control and various other controls in the image pickup apparatus.

For example, in the case of a video camera provided with an autofocus control means, when performing autofocus, the CPU 16 outputs an appropriate LS signal to the motor drive circuit 13 and controls the focus motor 10 to control the focus. The lens 9 is moved to an appropriate position. Also,
When a fixed focus is set, the focus lens 9 is moved to a predetermined position for back focus adjustment. Here, the lens focus adjustment position moves due to a temperature change of the lens system 1. Therefore, in the imaging apparatus, the temperature of the lens system 1 is detected, the amount of correction of the deviation of the lens focusing position due to the temperature of the lens system 1 is obtained, and the focus lens 9 is moved in the optical axis direction by the lens position driving means. In addition, the shift of the focal position of the focus lens 9 is corrected.

Next, the operation of detecting the temperature of the lens system 1 in the imaging apparatus according to the first embodiment will be described. In the imaging apparatus according to the present embodiment, the temperature of the lens system 1 is detected based on the output voltage of the Hall element 6 at the fixed position of the diaphragm 2 detected by the output voltage detecting means, without using a temperature sensor dedicated to temperature detection. Do.

First, the CPU 16 sends an aperture drive control signal (SS) to the aperture fixing circuit 14 so that the aperture value of the aperture 2 becomes a fixed value (for example, a fully open position is an example of a fixed position of the aperture 2). Signal). Aperture fixing circuit 14
Controls the rotation of the magnet rotor 5 by controlling the current flowing through the aperture driving coil 13 in accordance with the SS signal input from the CPU 16, and drives the aperture 2 to a fixed position.

The temperature characteristics of the Hall element 6 will be described using the output voltage of the Hall element 6. The output voltage of the Hall element 6 is represented by the following (Equation 1). VH = Bic / (ent) (Equation 1) where VH is the output voltage of the Hall element 6, B is the magnetic flux density, Ic is the current flowing through the Hall element 6, e is the charge amount of the carrier, n is the carrier concentration, and t is Is the thickness of the Hall element 6. When the Hall element 6 is driven at a constant current, the output voltage VH changes as the carrier concentration changes with temperature. That is, when the Hall element 6 is driven at a constant current,
By fixing terms other than the carrier concentration, the temperature can be detected from the output voltage of the Hall element 6. Also,
When the Hall element 6 is driven at a constant voltage, the output voltage VH changes because the charge amount of the carrier changes with temperature. That is, when the Hall element 6 is driven at a constant voltage, the temperature can be detected from the output voltage of the Hall element 6 by fixing terms other than the charge amount of the carrier. In the imaging device according to the first embodiment, since the Hall element 6 is disposed close to the lens system 1, if the temperature characteristic of the Hall element 6 is used, the Hall element 6 is fixed at the fixed position of the diaphragm 2. The temperature of the lens system 1 can be detected using the output voltage.

The change in the magnetic field due to the rotation of the magnet rotor 5 when the diaphragm 2 is driven to the fixed position is converted into a voltage by the Hall element 6 and output to the amplifier 7 as a signal. The signal is amplified by the amplifier 7 and then input to the A / D converter 8 to be converted into a digital signal, which is input to the CPU 16 as an HS signal. C
The PU 16 receives the HS signal at the fixed position of the diaphragm 2 from the A / D converter 8 and detects the output voltage of the Hall element 6 from the HS signal by the output voltage detecting means. Further, the CPU 16 detects the temperature of the lens system 1 with reference to a table (not shown) for determining the temperature of the lens system 1 from the output voltage of the Hall element 6 at the fixed position of the diaphragm 2 prepared in advance. .

The CPU 16 has a table (not shown) showing the detected temperature and the correction amount of the lens focal position.
A correction amount of the lens focus position is obtained from the detected temperature. The CPU 16 outputs an LS signal to the motor drive circuit 15 based on the correction amount. The motor drive circuit 15
By driving the focus motor 10 in accordance with the LD signal input from the PU 16, the focus lens 9 is driven, and the displacement of the lens focal position is corrected.

In order to detect the temperature of the lens system 1, the stop 2
Is moved to the fixed position, the light amount of the image sensor temporarily deviates from the normal exposure amount that is optimal for photographing. Therefore, the operation of moving the diaphragm 2 to the fixed position is performed during a period in which there is no trouble in photographing. For example, in the case of a video movie that handles a moving image, the aperture 2 is moved to a fixed position at the moment when the power is turned on and an image is output, at the moment when switching from playback to the camera recording mode, or when the operation mode is during playback. What should I do? Needless to say, these periods may vary depending on the type of the imaging device.

As described above, in the first embodiment, in the imaging apparatus including the Hall element 6 that converts a change in the magnetic field due to the rotation of the magnet rotor 5 into a voltage, the output voltage for detecting the output voltage of the Hall element 6 Detecting means; temperature detecting means for detecting the temperature of the lens system 1 based on the output voltage of the Hall element 6 at the fixed position of the diaphragm 2 detected by the output voltage detecting means; And a lens position driving means for driving the lens position driving means based on the temperature of the lens system 1 detected based on the detected temperature. , The temperature of the lens system 1 is detected without providing a sensor dedicated to temperature detection, and the deviation of the lens focus adjustment position due to the temperature change is compensated. Can, it is possible to reduce the size and cost reduction of the imaging device.

[0023]

As described above, according to the present invention (claim 1), a diaphragm mounted in the lens system for controlling the amount of light, a device for controlling the diaphragm, and a magnet interlocked with the opening / closing operation of the diaphragm. In an imaging apparatus including a rotor and a Hall element that converts a change in a magnetic field due to rotation of the magnet rotor into a voltage, an output voltage detection unit that detects an output voltage of the Hall element, and an output voltage detection unit that detects an output voltage of the Hall element. Temperature detecting means for detecting the temperature of the lens system based on the output voltage of the Hall element at the fixed position of the diaphragm, and lens position driving means for driving a lens in the lens system in the optical axis direction. The lens position driving means is driven based on the temperature of the lens system detected based on the above, and the shift of the lens focus adjustment position due to the temperature change of the lens system is corrected. Therefore, the temperature of the lens system can be detected without providing a sensor dedicated to detecting the temperature, the displacement of the lens focus adjustment position due to the temperature change can be corrected, and the size and cost of the imaging apparatus can be reduced. .

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of an imaging device according to an embodiment of the present invention.

FIG. 2 is a block diagram illustrating a configuration of an imaging device according to a conventional technique.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Lens system 2 Aperture 3 Image sensor 4 Image processor 5 Magnet rotor 6 Hall element 7 Amplifier 8 A / D converter 9 Focus lens 10 Focus motor 11 Temperature detection sensor 12 Aperture drive circuit 13 Aperture drive coil 14 Aperture fixing circuit 15 Motor Drive circuit 16CPU 26CPU

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Shiro Sakurama, 8-1, Koshinmachi, Takamatsu-shi, Kagawa Prefecture Inside of Matsushita Hisashi Denshi Kogyo Co., Ltd. (72) Inventor Masanori Kanaoka, 1-8, Koshinmachi, Takamatsu-shi, Kagawa, Japan F-term in Electronic Industries Co., Ltd. (reference) 2H011 BA33 CA22 DA00 2H044 AH01 2H051 BA45 BA47 CD21 EA20 EB04

Claims (1)

[Claims] 1. A diaphragm mounted in a lens system for controlling the amount of light, a device for controlling the diaphragm, a magnet rotor interlocked with the opening and closing operation of the diaphragm, and converting a change in a magnetic field due to rotation of the magnet rotor into a voltage. An imaging device comprising a Hall element for converting, based on an output voltage detecting means for detecting an output voltage of the Hall element, based on an output voltage of the Hall element at a fixed position of the diaphragm detected by the output voltage detecting means. Temperature detecting means for detecting the temperature of the lens system; and lens position driving means for driving a lens in the lens system in the optical axis direction, wherein the lens position is detected based on the temperature of the lens system detected by the temperature detecting means. An imaging apparatus, wherein a driving unit is driven to correct a shift of a lens focus alignment position due to a temperature change of a lens system.