JP3080435B2 - Camera aperture control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an aperture control device for a camera such as a video camera and a still video camera.
The present invention relates to an aperture control device for a camera that detects an aperture value using a ball element.

[0002]

2. Description of the Related Art An aperture control device in which a hall element is provided in an iris motor for driving an aperture and an aperture value is detected by an output voltage of the hall element corresponding to the degree of opening of the aperture is, for example, an integrated type. Video camera VM-C1
It is publicly known as described in (Hitachi) Service Technical Data, Chapter 2, page 13. By the way, since the output signal of the Hall element has a large variation between the signal amount and the DC voltage offset, conventionally, the DC bias current of the Hall element is manually adjusted for each product and the signal amount is set to a design value. Together,
The DC voltage offset of the means for amplifying the output of the ball element is manually adjusted to cancel the DC voltage offset of the ball element.

[0003]

As described above, conventionally, the characteristic variations of the Hall elements are individually adjusted manually before the product is shipped, so that the number of adjustment steps is increased, and the adjustment error is large. For example, there is a problem that a correct aperture value cannot be detected in a small aperture state.

Accordingly, a technical problem to be solved by the present invention is to solve the above-mentioned problems of the prior art. The purpose of the present invention is to automate the adjustment of the voltage signal of the Hall element output, Accordingly, an object of the present invention is to provide a camera aperture control device capable of detecting an aperture value with high accuracy.

[0005]

SUMMARY OF THE INVENTION The present invention, in order to achieve the above object, the average E - is stored in the ROM in advance or EEPROM throttle voltage characteristics corresponding to the aperture value of Le element, whereas, mosquitoes at power-on to the camera, at least aperture O - Pung time and black - to store the two or more points of the stop voltage including time's the EEPROM, the stop voltage characteristic that has been said previously stored, the upper Symbol power up The current aperture value is corrected and calculated from the sometimes stored aperture voltage, and thereby, the adjustment of the variation of the Hall element is automated.

[0006]

As described above, the aperture voltage when the aperture is open and when the aperture is closed is individually stored for each camera, and the result and the aperture fixedly stored in advance in a ROM or the like are open.
The aperture value is obtained by calculation from the standard aperture voltage characteristic corresponding to the aperture value from the open to the closed, so it is not affected by variations in the signal amount or DC voltage offset for each hole element, and is always The correct aperture value can be obtained automatically.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIGS. FIG. 1 is an explanatory diagram showing a configuration of an aperture control device of, for example, a video camera according to the present embodiment. In FIG. 1, reference numeral 1 denotes a lens, 2 denotes an aperture, 3 denotes an image sensor, 4 denotes a signal processing circuit, and 5 denotes an image pickup device. Element drive circuit, 6 is an iris drive circuit, 7 is an iris detection circuit, 8 is an iris motor, 9
Is a hole element, 10 is an amplifier, 11 is an A / D conversion circuit,
12 is a microcomputer (microcomputer), 13 is EE
PROM (electrically erasable programmable read only memory), 14, 15, 1
6, 17 are resistors, 18 is a constant current source, and 19 and 20 are voltage sources.

Light passing through the lens 1 and the aperture 2 is incident on a light receiving surface of the image pickup device 3 and is photoelectrically converted by the image pickup device 3. The output signal of the image sensor 3 is sent to the signal processing circuit 4, subjected to appropriate processing such as amplification by the signal processing circuit 4, and then input to the iris detection circuit 7.
In the iris detection circuit 7, the output of the signal processing circuit 4 is subjected to detection processing, and a signal corresponding to the level of the detected signal is output to the iris drive circuit 6. The iris drive circuit 6 drives the drive coil 24 of the iris motor 9 by the output of the iris detection circuit 7,
The aperture of the stop 2 is controlled in accordance with the received light intensity.

The Hall element 9 is disposed inside the iris motor 8, and the Hall element 9 converts a magnetic field generated in the iris motor 8 into a voltage and detects and outputs the voltage. A voltage corresponding to the rotation position of the iris motor 8, that is, the amount of aperture of the aperture 2, is output to the amplifier 10. Here, the bias current input terminal 26 of the hall element 9 is connected to the voltage source 20, and the bias current output terminal 25 of the hall element 9 is connected to the constant current source 18. Further, one output terminal 27 of the hall element 9 is connected to the amplifier 1 via the resistor 14.
The other output terminal 28 of the Hall element 9 is connected to the inverting input (minus input) of the amplifier 10 via the resistor 15. The inverting input of the amplifier 10 is connected to the voltage source 19 via the resistor 17, and the resistor 16 is connected between the output of the amplifier 10 and the inverting input. Therefore, the output voltage of the Hall element 9 is controlled by an amplifier (operational amplifier).
Amplified by the amplifier 10 with a predetermined amplification factor determined by the input side and the feedback side impedance of the A / D,
It is input to the D conversion circuit 11. The A / D conversion circuit 11 performs analog-to-digital conversion of the output (aperture voltage value) of the amplifier 10 and sends the digitized aperture voltage value to the microcomputer 12.

In this embodiment, the ROM in the microcomputer 12 or the EEPROM 13 read / written by the microcomputer 12 has an aperture voltage characteristic (standard aperture voltage) corresponding to an average aperture value of the hall element. Characteristics), that is, the diaphragm voltage values corresponding to the respective diaphragm values from the diaphragm open to the diaphragm close as shown by a characteristic curve S in FIG. 2 are stored in advance. Also, EEPROM
Reference numeral 13 denotes two or more aperture voltages (for example, a voltage Va at a point a in FIG. 2) at the time of adjusting the pre-shipment of the camera or turning on the power to the camera, including at least when the aperture is open and when the aperture is closed. (data including the voltage Vb at point b). The microcomputer 12 refers to the standard aperture voltage characteristic stored in advance and the aperture voltage stored at the time of adjustment before shipment or at the time of turning on the power by using a previously created arithmetic program, and the amplifier 1
The digitized aperture voltage value from 0 is calculated as the current aperture value as described later. The microcomputer 10
Is adapted to appropriately control the signal processing circuit 4, the imaging element driving circuit 5, and the like.

As described above, in this embodiment, the image pickup device 3
Is amplified by the signal processing circuit 4, and the amplified signal is detected by the iris detection circuit 7, and the iris drive circuit 6 drives the iris motor 8 according to the level of the detected signal to stop the diaphragm 2. To work. The aperture value is detected by converting a magnetic field generated when the iris motor 8 is driven into a voltage by the hall element 9, amplifying the voltage by the amplifier circuit 10, and converting the voltage into a digital signal by the A / D converter circuit 11. After that, the aperture voltage characteristic (characteristic curve S in FIG. 2) corresponding to the average aperture value of the hall element given in advance, and the aperture obtained at the time of adjustment before shipment or when the power is turned on are open. And point A in FIG. 2 to point A in FIG. 3 based on aperture voltages (for example, points a and b in FIG. 2) corresponding to different Hall element characteristics in each camera at the time of closing.
The microcomputer 12 performs data conversion so that the point b in FIG. 2 becomes the point B in FIG. 3, and the microcomputer 12 always calculates a correct aperture value by such a calculation method regardless of the characteristic variation of the Hall element. It has become. That is, specifically, when the aperture voltage is V, the inverse function of the characteristic curve S is f (V), and the symbol shown in FIG. 2 is used to represent the aperture value when the aperture voltage is V, the aperture value becomes f ((V−Vb) · (Vo−Vc) / (Va−Vb) + Vc). By doing so, a correct aperture value can always be obtained, and the accuracy of signal processing control and image sensor drive control can be improved.

In the above-described embodiment, the current aperture value is obtained in accordance with the aperture voltage characteristic corresponding to the average aperture value of the hall element. An aperture voltage characteristic corresponding to an aperture value for each hole element provided in each camera is measured in advance, and RO
M or EEPROM, and when the power of the camera is turned on, at least the aperture voltage when the aperture is open and when the aperture is closed is taken into, for example, an EEPROM, and the aperture voltage characteristic stored in advance at the time of the adjustment is used. The current aperture value may be calculated from at least the aperture voltage when the aperture is open and when the aperture is closed when the power is turned on. According to such an aperture value calculation method, it is necessary to measure and store an aperture voltage characteristic corresponding to each Hall element at the time of adjustment before shipment of a camera, but this is easy to automate, and adjustment by manual operation as in the past is required. Workability is much better than that which requires work. Furthermore, even if the characteristics of the Hall element change over time or the operating environment (temperature environment, etc.) changes from the time of measurement, the aperture will be closed when the power is turned on.
The aperture value at the time of closing is captured each time, and the current aperture value is determined from the aperture voltage characteristics stored in advance at the time of adjustment and the aperture voltage at the time of opening and closing at the time of power-on. Since the calculation is performed, a correct aperture value can always be obtained.

[0013]

As described above, according to the present invention, it is not necessary to manually adjust the variation of the Hall element, so that the adjustment error can be suppressed and the productivity can be improved.
Further, since it is possible to always obtain a correct aperture value, resulting to improve the signal processing precision of the drive control of the control and imaging device according to the aperture value, that Do is possible to control the aperture value of high accuracy. Sa
In addition, every time the power is turned on, at least when the aperture is open
And memorize two or more aperture voltages including when closing
The characteristics of the Hall element change over time or the operating environment
Even if is changed, the correct aperture value can always be obtained.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram illustrating a configuration of an aperture control device according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing aperture voltage characteristics.

FIG. 3 is an explanatory diagram showing aperture voltage characteristics.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Lens 2 Aperture 3 Image sensor 4 Signal processing circuit 5 Image sensor drive circuit 6 Iris drive circuit 7 Iris detector circuit 8 Iris motor 9 Hall element 10 Amplifier 11 A / D conversion circuit 12 Microcomputer 13 EEPROM 14, 15, 16 , 17 resistor 18 constant current source 19,20 voltage source

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Takuya Imade 292 Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa Pref. Video Media Research Laboratory, Hitachi, Ltd. (72) Tomoyuki Kurashige 292 Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa Address Hitachi Image Information System Co., Ltd. (72) Inventor Hiroyuki Tarumi 292 Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa Prefecture Hitachi Image Information System Co., Ltd. (56) References JP-A-59-232319 (JP, A) JP-A-2-187737 (JP, A) JP-A-3-144426 (JP, A) JP-A-3-144546 (JP, A) JP-A-61-11729 (JP, A) JP-A-2-224478 (JP , A) (58) Field surveyed (Int. Cl. ⁷ , DB name) G03B 7/091 G03B 7/10 G03B 9/02

Claims (3)

(57) [Claims] An iris motor for controlling an aperture of a lens, an iris drive circuit for operating the iris motor in accordance with a signal amount, and an iris motor provided for detecting an aperture value of the lens. A ball element, amplifying means for amplifying the output of the ball element, A / D converting means for converting the amplified output signal of the ball element into a digital signal, and a hole converting the digital signal into a digital signal. The output signal of the element
In throttle control system of a camera and a calculation means for calculating an aperture value from that throttle voltage, average ho - with advance are stored in advance in the storage means a stop voltage characteristics corresponding to the aperture value of Le element, power supply Input
For each, at least aperture O - Pung time and black - are stored before Symbol storing means stop voltage when's, the previously stored as stop voltage characteristics had been at least aperture Oh stored for each power-up - An aperture control device for a camera, wherein an aperture value is calculated from an aperture voltage at the time of opening and a time of closing. 2. The storage device according to claim 1, wherein the storage means for storing the aperture voltage characteristic corresponding to the average aperture value of the hall element is a ROM or an EEPROM, and at least the aperture stored at the appropriate timing is used. The storage means for storing the aperture voltage at the time of opening and closing is EEPROM.
An aperture control device for a camera. 3. An iris motor for controlling an aperture of a lens.
And an eye for operating the iris motor in accordance with the signal amount.
To detect the squirrel drive circuit and lens aperture value
A ball element provided inside the iris motor;
Amplifying means for amplifying the output of the element, and the amplified hole element
A / D conversion means for converting an output signal of the digital camera into a digital signal
And the output signal of the Hall element converted to a digital signal.
Calculation means for calculating an aperture value from an aperture voltage
In the aperture control device of the camera, when adjusting the aperture control device, a camera provided in the aperture control device is used.
-The aperture voltage characteristics corresponding to the aperture value of the
In addition to storing it in the storage means,
At least the aperture voltage when the aperture is open and when the aperture is closed
Store it in the storage means and store it in advance at the time of the adjustment.
The aperture voltage characteristics and the minimum stored at power-on
In both cases, the aperture is determined based on the aperture voltage when the aperture is open and when the aperture is closed.
Diaphragm of a camera, characterized in that the Values were adapted to calculate
Control device.