JPH0335228A - Device for controlling aperture quantity - Google Patents

Abstract

PURPOSE:To detect an exact aperture quantity even if a fluctuation in sensor characteristics is generated by fluctuations in magnetic sensors and a change in temp. by providing memories and a correcting circuit which obtains the relation between the magnetic sensor output and the aperture quantity in accordance with the value of magnetic sensors stored in the memories, corrects the same to a correct aperture quantity and outputs the same to a control circuit. CONSTITUTION:The output signal of a multiplexer 10 when an aperture 2 is fully opened and fully closed by driving a driving signal 5 is stored into the memory 12 and the memory 13 by the output signal of the control circuit 4. The signal freshly outputted from the magnetic sensor 6 to a multiplexer 10 is inputted through a buffer amplifier 11 to the correcting circuit 14. The relation between the output of the mag netic sensor and the aperture quantity is obtd. in accordance with the value stored in the memory 12 and the memory 13 in the correcting circuit 14 and, therefore, the magnetic sensor output is fitted into this relation from this buffer amplifier 11, by which the correction to the exact aperture quantity is made. The always exact aperture quantity is detected regardless of the fluctuation in the characteristics by the individual fluctuations in the magnetic sensors and the change in temp.

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention relates to an aperture amount control device, and in particular to an aperture amount control device in an automatic exposure mechanism that automatically controls the aperture to an appropriate aperture amount depending on the brightness of a subject. Regarding equipment.

[Conventional technology]

2. Description of the Related Art An imaging device that photographs a subject is equipped with an aperture mechanism that allows an appropriate amount of light to be taken into the imaging unit according to the brightness of the subject.

Early aperture mechanisms required manual adjustment of the aperture while looking at the exposure meter. However, in recent years, automatic exposure mechanisms have been used that automatically adjust an appropriate aperture amount depending on the brightness of the subject.

FIG. 3 is a block diagram showing a conventional aperture control device disclosed in, for example, Japanese Unexamined Patent Publication No. 54-98468. In the figure, (1) is the imaging lens, (2) is the imaging lens (
(1) is an aperture that adjusts the amount of light passing through the aperture (3) is this aperture (2)
) is a video processing system that converts the image passed through (3) into a video signal.
a) is an image sensor that converts the amount of light into an electrical signal, (
3b) is a video signal processing circuit that processes the output of the image sensor (3a). (4) is a control circuit that controls the aperture amount to be optimal based on the output of the video processing system (3) and the aperture amount of the current depression;
(5) is a drive device that drives the diaphragm (2) using an output signal from the control circuit (4).

(6) is a magnetic sensor that detects the lines of magnetic force of the drive device that change with the opening and closing of the aperture, and (7) is an amplifier that amplifies the output of the magnetic sensor (6).

Next, the operation will be explained. When the diaphragm (2) is opened and closed by the driving device (5), a magnetic sensor (6) detects the magnetic field lines of the driving device (5) that change as the diaphragm (2) opens and closes, and its output is amplified by an amplifier (7). The control circuit (4) controls the aperture amount output from the amplifier (7) and the video processing system (
In order to obtain the optimum exposure from the two values of the image signal of the subject outputted from the camera (3), the aperture (2) is driven by controlling the drive device (5).

[Problem to be solved by the invention]

Since the conventional aperture amount control device is configured as described above, due to the influence of variations in the characteristics of the magnetic sensor (6) for detecting the aperture amount among individual products and changes in temperature,
There is a problem in that the output of the magnetic sensor tends to vary, making it impossible to accurately detect the amount of aperture. For this reason, it has been difficult for the control circuit to appropriately control the aperture amount according to the brightness of the subject.

It is also possible to detect the amount of aperture using something other than a magnetic sensor, such as a sliding resistor or a photo encoder, but this poses problems such as being mechanically complex and making it difficult to miniaturize. .

This invention was made with the aim of solving the above-mentioned problems, and it is possible to accurately detect the amount of aperture even if characteristics change due to variations in the magnetic sensor that detects the amount of aperture or changes in temperature. The object of the present invention is to provide an aperture amount control device that can control the amount of aperture.

[Means for Solving the Three Problems] The aperture amount control device according to the present invention includes an A/D converter that converts the output of a magnetic sensor into a digital signal, and a magnetic sensor that measures the aperture amount when the aperture is fully open and when the aperture is fully open. and a memory that stores the output via the A/D converter, and obtains the relationship between the magnetic sensor output and the aperture amount based on the value of the magnetic sensor stored in the memory, and newly inputs it. The present invention is characterized by comprising a correction circuit that corrects the output of the magnetic sensor to a corresponding appropriate aperture amount and outputs the corrected aperture amount to the control circuit.

[Effect]

In the aperture amount control device according to the present invention, the output of the magnetic sensor that detects the aperture amount is converted into a digital signal by an A/D converter. The purpose of converting the magnetic sensor output into a digital signal is to perform digital data processing within the subsequent correction circuit.

Then, a magnetic sensor detects the amount of aperture when the aperture is fully opened and when the aperture is fully opened, and the outputs are converted into digital signals and stored in a memory.

The correction circuit obtains the relationship between the magnetic sensor output and the aperture amount based on the output values of the magnetic sensor when the aperture is fully open and when the aperture is fully open, which are stored in the memory. The correction circuit is
Based on this relationship, the newly manually input magnetic sensor output is supplemented with the corresponding appropriate aperture amount and output to the control circuit, so even if there are variations in the characteristics of the magnetic sensor, the It is now possible to obtain a large aperture amount.

〔Example〕

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of a throttle amount control device according to the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram of an aperture control device according to an embodiment of the present invention. In the figure, (1) is an imaging lens, (
2) is an aperture that mechanically adjusts the amount of light passing through the imaging lens;
(3) is an image processing system that converts the image passing through the aperture (2) into an electrical signal, (3a) is an image sensor that converts the amount of light into an electrical signal, and (3b) is the image sensor that converts the output of the image sensor (3a). This is the video signal unit FJILI circuit that processes it. (4
) is a control circuit that controls the aperture amount to the optimum aperture amount based on the output of the video processing system (3) and the current aperture amount, and (5) is a control circuit that drives the aperture (2) using the output signal of the control circuit (4). It is a drive device that (6) is a magnetic sensor that indirectly detects the amount of aperture by detecting the magnetic lines of force of the drive device (5) that change as the aperture (2) opens and closes, and (7) is the output of the magnetic sensor (6). It is an amplifier that amplifies the (8) is a sample hold, and (9) is an A/D converter, which converts the analog output signal from the amplifier (7) into a digital output (No. J).

(10) is a multiplexer which switches output light according to a control signal from a control circuit (4). (11) is a buffer amplifier, and (12) is the given A/D converter (with the aperture fully open).
Memory 1 stores the output of the A/D converter (9) (13), and memory 2 stores the output of the A/D converter (9) when the aperture is fully open.
It is. (14) is a correction circuit that obtains the relationship between the aperture amount and the magnetic sensor output from the values of memory 1 (12) and memory 2 (13), and adjusts the output from the buffer amplifier (11), that is, the new magnetic sensor Correct the output from (6) to obtain an accurate aperture amount.

Next, the operation of this embodiment will be explained with reference to FIG.

Light from a subject (not shown) passing through an imaging lens (1) is divided into 52 nodes by an aperture (2) and converted into an electrical signal by an image sensor (3a). The converted electrical signal is processed by the video processing circuit (3b) and input to the control circuit (4). The control circuit (4) outputs a human input signal, that is, a signal to control the appropriate aperture amount according to the signal of the brightness of the subject, and drives the drive device (5) to open and close the aperture (2). let The magnetic sensor (6) detects magnetic lines of force of the drive device caused by opening and closing of the aperture. The output of the magnetic sensor (6) is amplified by the amplifier (7), and the sample hold (
8), the analog signal is converted into a digital signal by an A/D converter (9). The output of the magnetic sensor (6) converted into a digital signal is sent to a buffer amplifier (11) and memory 1 (12), which will be described later, by a multiplexer (10).
It is also possible to change the output light and send it to the memory 2 (13). The selection of the output light of the multiplexer (10) is as follows:
This is done by a control signal from a control circuit (4).

Here, the operation of the correction circuit (4) will be explained.

First, the drive device (5) is controlled by the output signal of the control circuit (4).
) to fully open the aperture (2).

The output signal of the multiplexer (10) at that time is stored in memory 1.
(12). In addition, the output signal of the multiplexer (10) opposite to the fully closed aperture (2) is transferred to the memory 2 (1).
3). The preparation operations up to this point are performed in advance.

Next, when detecting the aperture amount, add a new magnetic sensor (6
) is outputted from the multiplexer (IO) to the correction circuit (14) through the buffer amplifier (11). In the correction circuit (14), memory 1 (12
) and the value stored in memory 2 (13), the relationship between the output of the magnetic sensor and the aperture amount is determined, so the magnetic sensor output from the buffer amplifier (11) is applied to this relationship to obtain accurate information. It is possible to correct the aperture amount.

FIG. 2 is a diagram illustrating the correction operation in this correction circuit. The horizontal axis represents the aperture position indicating the amount of aperture, and the vertical axis represents the magnetic sensor output to show the relationship between the two.

VO on the vertical axis is the output (value stored in memory 1) of the magnetic sensor (6) when the aperture (2) is fully open, and Vc is the output (value stored in the memory 1) when the aperture (2) is fully open. (value stored in memory 2). The line connecting Vc and vO indicates the relationship between the magnetic sensor output of the sensor and the actual aperture position.

Here, assuming that the magnetic sensor output from the buffer amplifier (11) is VO, the accurate aperture direct position θ, that is, the aperture amount can be easily determined by simply comparing it with the relationship shown in FIG. These processes are performed by digital data processing.

In this way, the corrected and accurate squeezing amount is output to the control circuit (4), and the optimal squeezing amount can be controlled together with the output signal from the video processing system (3).

As described above, the aperture amount control device of this embodiment is able to always accurately detect the aperture amount regardless of individual variations in the magnetic sensor, so it can be combined with the video signal from the video processing system It is now possible to control the optimum aperture amount using the control path.

〔Effect of the invention〕

As explained above, the aperture amount control device according to the present invention,
Store the magnetic sensor outputs when the aperture is fully open and when the aperture is fully open: c! By correcting the aperture amount based on the relationship between the output of the magnetic sensor and the aperture amount obtained by the correction circuit, it is possible to always obtain accurate information regardless of individual variations in the magnetic sensor or characteristic fluctuations due to temperature changes. Detecting the amount of aperture has become n1 capable.

[Brief explanation of drawings]

FIG. 1 is a block diagram of an aperture amount control device according to an embodiment of the present invention, FIG. 2 is a diagram illustrating a correction operation in a correction circuit, and FIG. 3 is a block diagram of a conventional aperture amount control device. In the figure, (2) is the aperture, (3) is the video processing system, and (4) is the aperture.
) is a control circuit, (5) is a drive device, (6) is a magnetic sensor, (12) is memory 1, (13) is memory 2, (14)
is a correction circuit. In addition, in the figures, fixed symbols indicate the same or corresponding parts.

Claims (1)

[Scope of Claims] An image processing system that processes the light passing through the aperture into a signal and outputs it, a drive device that mechanically opens and closes the aperture to vary the amount of aperture, and a drive device that detects the amount of aperture of the drive device. A magnetic sensor that
A control circuit for controlling the aperture to an optimum aperture amount based on the output of the magnetic sensor and the video output of the video processing system, an A/D that converts the output of the magnetic sensor into a digital signal.
a converter; a memory that detects the aperture amount when the aperture is fully open and when the aperture is fully closed using the magnetic sensor and stores the output thereof via the A/D converter; and a correction circuit that obtains the relationship between the magnetic sensor output and the aperture amount based on the value, corrects the newly input magnetic sensor output to a corresponding appropriate aperture amount, and outputs the corrected aperture amount to the control circuit. Aperture control device featuring: