JP2721385B2 - Exposure control device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an exposure control device for an imaging device,
In particular, it is suitable for use in devices capable of automatic and manual exposure operations.

(Background Art) In recent years, the development of video equipment such as a video tape recorder (hereinafter abbreviated as VTR) has been remarkable, and in particular, an automatic exposure adjusting device has become standard equipment especially in a camera-to-camera VTR. .

FIG. 5 shows a typical example of an exposure control method conventionally used in such a camera-integrated VTR.

The amount of light incident from the optical system 1 is adjusted by an exposure adjusting mechanism (hereinafter referred to as an iris) 2 to form a subject image on an image sensor 3. The signal obtained from the image sensor 3 is input to a camera signal processing circuit 4 where it is subjected to processing such as gamma correction, separated into a luminance signal and a chrominance signal. Is converted into a television signal. The image luminance signal Y obtained before the gamma correction obtained by the camera signal processing circuit 4 is subjected to integration processing by an integrator 6 and an arithmetic unit 7 generates a difference signal from a reference value 8. The difference signal is used as an exposure control signal, and the driver 9 and the actuator 10 control the iris 2 (exposure adjusting aperture mechanism) so that the relationship between the output of the integrator 6 and the preset reference value 8 becomes constant. The opening amount is controlled.

(Problems to be Solved by the Invention) However, in the conventional automatic exposure apparatus, the exposure of the subject intended by the photographer may not always be appropriate.

For example, when the subject is illuminated by a light source, which is a so-called backlight, or when only the subject is illuminated in a dark place, the video camera averages a wide area including the background area other than the subject. Due to the photometry, the subject is underexposed in the former case and the subject is overexposed in the latter case.

Therefore, in a video camera with an automatic exposure device,
If the photographer determines that the exposure is not as intended,
There has been proposed a camera having a manual exposure control unit capable of switching from an automatic exposure operation state to a manual exposure operation state and setting an exposure state intended by a photographer.

However, in these apparatuses, when switching between the automatic exposure operation and the manual exposure operation, there has been a problem that the aperture state operates discontinuously before and after the switching operation, resulting in an unnatural screen.

(Means for Solving the Problems) The present invention has been made with a view to solving these problems, and according to the invention described in claim (1), an automatic control for automatically controlling the aperture is provided. Mode switching means for switching between an exposure control mode and a manual exposure control mode for manually controlling the aperture; and when the mode switching means switches from the automatic exposure control mode to the manual exposure control mode, the exposure control immediately before the switching is performed. The value is held as the initial value in the manual exposure control mode, and when the mode is switched from the manual exposure control mode to the automatic exposure control mode, the aperture value in the manual control mode immediately before the switching is set as the initial value, An exposure control device comprising: a control unit for shifting to a control mode.

According to the invention described in claim (2) of the present application,
A camera system comprising a lens unit and a camera to which the lens unit is detachable, wherein the camera switches between an automatic exposure control mode for automatically controlling an iris and a manual exposure control mode for manually controlling an iris. A mode switching unit, a computing unit that computes exposure control information based on a video signal level in the automatic exposure control mode, an operation unit that manually operates the aperture in the manual exposure control mode, and a mode switching unit. The information of the selected exposure control mode, the exposure control information calculated by the calculating means in the automatic exposure control mode, and the operation information of the operation section in the manual exposure control mode, respectively, to the lens unit. Camera-side control means for transmitting, and the lens unit includes an aperture and the camera. Receiving the respective control information transmitted from the camera-side transmission unit, and when the mode switching unit switches from the automatic exposure control mode to the manual exposure control mode, the exposure control value immediately before the switching is held. When the mode is switched from the manual exposure control mode to the automatic exposure control mode as an initial value in the manual exposure control mode, the mode is shifted to the automatic exposure control mode using the aperture value in the manual control mode immediately before the switching as the initial value. A camera system including a lens-side control unit is characterized.

According to the invention described in claim (3) of the present application,
A lens unit used in the camera system described in claim (2) is characterized.

According to the invention described in claim (4) of the present application,
A camera used in the camera system described in claim (2) is characterized.

(Operation) By this, when switching between exposure control modes having different exposure control methods, the exposure information before switching can be held, and the switching state does not change discontinuously due to the switching operation. The switching of the exposure control mode can be performed smoothly.

In particular, when the mode is switched to the manual exposure control mode, by retaining the aperture information detection information immediately before the switching, it is possible to prevent the aperture state from becoming discontinuous before and after the switching, and to perform a smooth switching.

(Embodiment) Hereinafter, an embodiment of an exposure control device according to the present invention will be described in detail with reference to the drawings.

FIG. 1 is a block diagram showing a first embodiment of the automatic exposure apparatus according to the present invention. In the figure, the same components as those of the above-described conventional example are denoted by the same reference numerals, and description thereof will be omitted.

A subject image formed on an image pickup surface of an image pickup device 3 such as a CCD by a lens optical system 1 through an iris 2 is photoelectrically converted by the image pickup device 3 and output as an image pickup signal. The imaging signal is supplied to the processing circuit 4 and subjected to gamma conversion and the like, and the color signal C and the luminance signal Yγ are extracted as video signals and output from the camera unit in the form of a composite video signal or the like via an encoder 5 such as NTSC. .

The luminance signal Y, which has not been subjected to gamma conversion and is output from the camera signal processing circuit 4, is an integrating circuit for generating a control signal for controlling the iris 2 to obtain an appropriate exposure according to the luminance state of the screen. After being input to 6 and integrated, it is input to a calculator 7 and compared with a reference value 8 to generate a difference signal corresponding to the difference. The difference signal is supplied as an exposure control signal (iris control data) to the actuator 11 via the switch 9 and the driver 10, and the iris 2 is controlled.

Further, a signal outputted from an encoder 12 constituted by, for example, a Hall element for detecting the state of the iris 2, ie, the aperture value, is amplified to a predetermined level by a buffer amplifier 13 and supplied to an inverting input terminal of a differential amplifier 15. At the same time, the signal is supplied to a holding circuit 14 for holding the output signal of the buffer amplifier 13.

The output of the holding circuit 14 is added to the output of the DC voltage variable circuit 30 via the adder 16 and supplied to the non-inverting input terminal of the differential amplifier 15. The DC voltage variable circuits 30
Adder 16 according to the operation of UP switch 31 and DOWN switch 32
The level of the DC voltage supplied to is varied. That is, by changing the output voltage level of the DC voltage variable circuit 30, the DC voltage level supplied from the holding circuit 14 to the non-inverting terminal of the differential amplifier 15 is changed, and the aperture value held by the holding circuit 14 can be arbitrarily set. Can be changed to Details will be described later.

When the switch 9 is switched to the upper contact 9A as seen in the figure, the output of the arithmetic unit 7 is connected to the driver 10, and the iris 2 is automatically controlled by the iris control data signal output from the arithmetic unit. The control mode is set. When the switch 9 is switched to the contact 9B, the differential amplifier 15
Is connected to the driver 10, and the iris 2 is controlled by the output voltage of the above-described differential amplifier. In this state, as described above, the iris 2 can be controlled by varying the output of the differential amplifier by the addition output of the holding circuit 14 and the DC voltage variable circuit 30 input to the differential amplifier 15.
That is, the iris 2 can be manually controlled by operating the UP and DOWN switches 31 and 32 to vary the output voltage level of the DC voltage variable circuit 30.

On the other hand, the switch 17 is switched in conjunction with the switch 9, and when the switch 9 is switched to the contact 9A in the automatic exposure control mode, the switch 17 is switched to the contact 17A, and when the switch 9 is switched to the contact 9B in the manual exposure control mode. 17B respectively. When the switch 17 is switched to the contact 17A, a predetermined high-level control signal + B is supplied to each of the DC voltage variable circuit 30 and the holding circuit 14 to invalidate each operation. When the switch 17 is switched to the contact 17B, a low-level control signal is supplied to each of the DC voltage variable circuit 30 and the holding circuit 14, whereby the holding circuit 14 switches the switch to the manual exposure control mode. The output voltage of the buffer amplifier 13 corresponding to the aperture value at the time point is held and output to the adder 16. The DC voltage variable circuit 30 varies the DC voltage supplied to the adder 16 in accordance with the operation of the UP switch 31 and the DOWN switch 32, and stops the aperture based on the aperture value of the iris 2 held by the holding circuit 14. The value can be adjusted manually.

As described above, in the automatic exposure control mode, the information of the aperture information detector that has not been used is activated and held immediately before switching to the manual control, and the manual exposure control is performed using the value as an initial value. The aperture value before and after switching does not change suddenly, and the connection is smooth.

Then, as described above, in this state, the DC voltage variable circuit 30
Is changed and the voltage input to the non-inverting input of the differential amplifier 15 via the adder 16 is shifted, whereby the held aperture can be changed arbitrarily.

Here, FIG. 2 shows a configuration diagram of the DC voltage variable circuit.
When UP switch 31 or DOWN switch 32 is pressed, U
When a predetermined power supply voltage is input to the P, DOWN counter 33, if the UP switch side is pressed, it is counted up and the iris 2 is driven in the opening direction. Driven in the closing direction. The output of the counter 33 is input to the D / A converter 34, converted into an analog voltage, and supplied to the adder 16. The reset signal generating circuit 35 generates a reset signal when the switch 17 is switched from automatic to manual, sets the output of the counter 33 to a preset reference value, and sets the D / A converter 34
Is set to 0.

With the above-described configuration, in the normal photographing state, if the switches 9 and 17 are switched to the contacts 9A and 17A, respectively, and the automatic exposure control mode is set, the iris driving actuator 11 is driven regardless of the UP and DOWN switches. The driver 10 controls the iris 2 by the iris control signal output from the arithmetic unit 7 so that the video signal level is constant.

When the switches 9 and 17 are switched to the contacts 9B and 17B, respectively, to switch to the manual exposure control mode, the output of the buffer amplifier 13 corresponding to the aperture value immediately before the switching operation is held in the holding circuit 14, and at the same time, the UP and DOWN switches The DC voltage for iris control supplied to the adder 16 can be adjusted in accordance with the operation of the iris, and the iris control voltage supplied to the non-inverting input terminal of the differential amplifier 15 is held in the holding circuit 14. The value can be changed as an initial value. And differential amplifier 15
Drives the driver 10 so that the level of the non-inverting terminal is equal to the DC voltage level supplied from the buffer amplifier 13, that is, the iris 2 can be manually adjusted to the aperture value set by the UP or DOWN switch. .

As described above, when switching from the automatic exposure control mode to the manual exposure control code, the aperture value immediately before the switching is retained, and the manual aperture control can be performed from the aperture value. As a result, a smooth and stable switching operation can be performed without discontinuous movement.

(Other Embodiment) Next, another embodiment of the present invention will be described with reference to FIGS. 3 and 4. FIG. In this embodiment, the present invention is particularly applied to a video camera in which a lens is replaceable.
The functions of the holding circuit 14, differential amplifier 15, adder 16, and DC voltage variable circuit 30 in the first embodiment shown in FIG. 1 are realized by a camera microcomputer.

FIG. 3 is a block diagram showing a configuration of a video camera with interchangeable lenses to which the present invention is applied. The same components as those in FIG. 1 are denoted by the same reference numerals, and description thereof will be omitted.

In the figure, LS indicates a lens unit and CM indicates a camera unit, which are connected by a mount part MT. Further, a data communication path 27 for exchanging data between the camera and the lens is formed by an electric contact (not shown) in the mount portion. And the camera unit
Communication between the CM and the lens unit LS is performed based on processing of a television signal on the camera unit side.
This is performed in synchronization with Vsync (vertical synchronization signal).

In the camera unit CM, the configurations of the image pickup device 3, the camera signal processing circuit 4, the camera encoder 5, and the integrator 6 are the same as those in FIG. In the present embodiment, the output of the integrator 6 is converted into digital information via an A / D converter 23 and then supplied to a camera-side control microcomputer (hereinafter referred to as a camera microcomputer) 20. The reference value 8 for iris control is also supplied to the camera microcomputer 20 via the A / D converter 26.

A switch 17 for switching between automatic and manual exposure control in FIG. 1 and UP and DOWN switches 31 and 32 for adjusting the exposure in the manual exposure control mode are provided on the camera unit CM side. Supplied.

The luminance signal Y output from the camera signal processing circuit 4 is input to the integration circuit 6 to generate a control signal for controlling the iris 2 so as to obtain an appropriate exposure according to the luminance state of the screen as in the first embodiment. A / D converter 23
Is taken into the camera microcomputer 20 via At the same time, the reference voltage 8 is also digitally converted by the A / D converter 26 and taken into the camera microcomputer 20.

The data taken into the camera microcomputer 20 performs a predetermined calculation to obtain iris control data corresponding to the difference, and the result is transmitted to the lens microcomputer 21 on the lens unit LS side via the data communication path 27. .

On the other hand, as for the lens unit LS, a lens side control microcomputer (hereinafter referred to as a lens microcomputer) 21 is provided, and an iris control calculated based on control information transmitted from the camera microcomputer 14 via a communication path 27 is provided. Data is supplied to the driver 10 via the D / A converter 24, and the actuator 11 is driven to perform iris control. Also, iris encoder
The aperture value data detected by 12 is also supplied to the lens microcomputer 21 after the output signal of the buffer amplifier 13 is also converted into a digital signal by the A / D converter 25.

The lens microcomputer 21 outputs the iris control data communicated from the camera microcomputer 20, is converted into an analog signal by the D / A converter 24, and drives and controls the iris 2 via the driver 20 and the actuator 11.

Therefore, in the automatic exposure control state, as described above, iris control data for controlling the iris 2 according to the difference between the average level of the luminance signal and the reference value 8 in the camera unit is calculated, and the lens unit is operated. The lens unit receives the data and drives the iris, so that the exposure state can be controlled so that the average level of the luminance signal always has a fixed relationship with the reference value 8.

Here, as in the first embodiment, it is assumed that the automatic exposure control mode is switched to the manual exposure control mode by the automatic / manual switch 17.

The operation state of the switch 17 is captured by the camera microcomputer 20, and the fact that the mode has been switched to the manual exposure control mode is transmitted to the lens microcomputer 21 via the data communication path 27.

Next, upon receiving the manual exposure control mode command, the lens microcomputer 21 outputs to the D / A converter 24 a control value for stopping the iris 2 from operating in the current state. The aperture value information indicating the aperture state of the iris 2 at that time is detected by the encoder 12, amplified by the buffer amplifier 13, converted to a digital value by the A / D converter 25, and taken into the lens microcomputer 21. . Further, the aperture value information taken into the lens microcomputer 21 is stored and held in a storage circuit in the lens microcomputer 21.

After a predetermined time, the value of the iris 2 is periodically updated in the same manner as described above by the encoder 12, the buffer amplifier 13, and the A / D converter 25.
To the lens microcomputer 21 via the
The iris control data is output from the lens microcomputer 21 by the control program described later stored in the memory 21 so that the values are compared with the values held in the storage circuit so that these values become equal. Is maintained in the state at the time of switching to the manual operation.

When the iris 2 is held in the above-mentioned manual exposure control mode, the value stored in the storage circuit via the data communication path 27 from the camera unit is specified by the UP switch 31 and the DOWN switch 32 in a specific range. The aperture value of the iris 2 can be arbitrarily set.

FIG. 4 shows a flowchart for explaining the iris control operation in this embodiment.

First, as processing on the camera unit CM side, as shown in FIG. 4 (a), # C1: a predetermined number of Vsyncs (vertical synchronization signals in the video signal) for setting the communication timing to the lens unit LS side ) Confirm input.

# C2: When a predetermined number of Vsyncs have been generated, a chip select signal is set.

# C3: Converts iris data from parallel to serial and sends it from the camera to the lens.

# C4: Reset the chip select signal.

In the above-described operation, if a predetermined number of Vsyncs are not input at C1, communication to the lens unit LS side is not performed, and the process shifts to C5 to perform processing only on the camera unit CM side.

# C5: Select whether to perform the exposure control operation in the automatic exposure control mode or in the manual exposure control mode.

# C6: If automatic exposure control mode is selected,
The output video signal level of the integrator 6 output from the A / D converter 23 is read into the camera microcomputer 20.

# C7: The level of the reference value 8 A / D converted by the A / D converter 26 is read into the camera microcomputer 20.

# C8: Calculation (iris control data = video signal level-
(Reference level), return to C1, and repeat the above flow.

# C9: When the manual exposure control mode is selected in C5, it is determined whether or not the manual exposure control mode has just been set.

# C10: If it is just after setting to manual exposure operation,
The stored value of the iris correction data in the camera microcomputer 20 is reset to zero.

This correction data is a correction value transmitted from the camera to manually change the aperture value at the time of mode switching stored in the lens microcomputer 21 in the manual exposure control mode, and is used by the UP and DOWN switches. Is set.

# C11: In the manual exposure control mode operation, it is determined whether the exposure setting buttons UP switch 31 and DONW switch 32 have been pressed, and if not, the process returns to the start of C1.

# C12: If the UP switch 31 that drives the iris to the open side is pressed, 1 is added to the stored iris correction data, and this is stored as new correction data in the camera microcomputer, and the process proceeds to the start of C1. Return.

That is, the up / down counter of FIG. 2 for setting the iris correction amount in the camera microcomputer.
The amount of correction of the iris 2 toward the open side is set in a counter such as 33.

# C13: DOWN switch 32 that drives the iris to the closing side
If is pressed, 1 is subtracted from the stored iris correction data, this is stored as new correction data in the camera microcomputer, and the process returns to the start of C1.

Similarly to C12, a correction amount for correcting the iris 2 to the closing side is set in the camera microcomputer.

By repeating the above control operation, the iris 2 is controlled by transmitting iris control data corresponding to the automatic exposure control mode and the manual exposure control mode to the lens unit every time transmission is performed.

Next, the processing on the lens side will be described with reference to the flowchart shown in FIG.

# L1: Wait for communication while confirming the input of the chip select signal from the camera.

# L2: When the chip select signal is input, the transmitted iris control data is captured by serial-parallel conversion. If the chip select is not input, the iris data is not updated, and the flow shifts to L4.

# L3: Receives communication from the camera and determines whether the automatic exposure control mode or manual exposure control mode is selected.

# L4: When the automatic exposure control mode is selected, iris control data is supplied to the D / A converter 24 to control the iris 2.

# L5: When manual exposure control mode is selected,
It is determined whether or not the manual control mode has just been set. If it is immediately after the manual exposure control mode is set, the following operations L6 and L7 are performed.

# L6: The drive of the iris 2 is stopped.

# L7: The current aperture value data of an encoder (for example, a hall element) 12 for detecting the aperture value of the iris is taken in, and the value is held in the lens microcomputer 21.

# L8: If set to manual exposure control mode,
The transmitted correction data is added to the aperture value holding data in the lens microcomputer, and the calculation result is stored as new holding data.

# L9: A value obtained by A / D conversion of the current encoder, for example, the aperture value data of the Hall element 12 by the A / D converter 25, is taken into the lens microcomputer 21.

# L10: It is determined whether the aperture value data (Hall element data) of the encoder 12 is equal to the held data.

# L11: The magnitude relationship between the data held in the lens microcomputer is determined from the aperture value data of the encoder (Hall element) 12.

# L12: L10, [Encoder (Hall element) data]
= [Hold data], stop driving the iris and
Return to.

# L13: In L11, [Encoder (Hall element) data]
If [<holding data], drive the iris 2 to the open side and return to L1.

# L14: In L11, [Encoder (Hall element) data]
If> [held data], drive to the closing side of the iris and return to L1.

Repeat the above control flow to get the camera unit
Each time a communication from the CM is received, the control information is updated and the iris 2 is controlled.

Further, although the above-described embodiment is a configuration of the VTR integrated camera of the interchangeable lens system, communication between the camera and the lens is not performed as in the present embodiment, and the present invention can be similarly applied to an integrated VTR of a type that cannot exchange lenses. Needless to say, it is a technology.

In this case, the flow chart may simply omit the steps C1 to C4 in FIG. 4A and the steps L1 to L2 in FIG. 4B.

According to the above-described embodiment, the configuration in which the aperture value is held when switching from the automatic exposure control mode to the manual exposure control mode has been described as an example. However, the configuration may be applied to the reverse switching. However, the present invention can be widely and generally applied to switching between different types of exposure control modes.

(Effects of the Invention) As described above, according to the automatic exposure control device of the present invention, the switching operation from the automatic exposure control mode to the manual exposure control mode or between a plurality of exposure control modes generally using different methods is performed. When the exposure control mode is performed, the aperture state immediately before the switching is held, and in the exposure control mode after the switching, the held aperture position is corrected as an initial value, so that the exposure control mode can be switched smoothly, and Correction can be facilitated, and the occurrence of an unsightly and unnatural screen due to discontinuity or sudden change of the exposure state, particularly before and after switching of the exposure control mode, can be prevented.

[Brief description of the drawings]

FIG. 1 is an overall block diagram showing a first embodiment of the present invention. FIG. 2 is a block diagram of a main part for explaining the structure and operation for manually correcting the aperture value in the present invention. FIG. 3 is an overall block diagram showing a second embodiment of the present invention, FIG. 4 is a flowchart for explaining an iris control operation of the second embodiment, and FIG. 5 is an example of a conventional device before the present invention. FIG.

Claims (4)

(57) [Claims] 1. A mode switching means for switching between an automatic exposure control mode for automatically controlling an iris and a manual exposure control mode for manually controlling an iris. The mode switching means switches the automatic exposure control mode from the manual exposure control mode. When the mode is switched to, the exposure control value immediately before the switching is held and set as an initial value in the manual exposure control mode. When the mode is switched from the manual exposure control mode to the automatic exposure control mode, the manual control immediately before the switching is performed. And control means for shifting to an automatic exposure control mode using an aperture value in the mode as an initial value. 2. A camera system comprising a lens unit and a camera to which the lens unit can be attached and detached, wherein an automatic exposure control mode for automatically controlling an aperture, and a manual exposure for manually controlling the aperture are provided on the camera side. A mode switching unit for switching between control modes, an arithmetic unit for calculating exposure control information based on a video signal level in the automatic exposure control mode, and an operation unit for manually operating the aperture in the manual exposure control mode, The information of the exposure control mode selected by the mode switching means, the exposure control information calculated by the calculating means in the automatic exposure control mode, the operation information of the operation unit in the manual exposure control mode, Camera-side control means for transmitting to each of the lens units. Receiving the control information transmitted from the camera-side transmitting means, and when the mode switching means switches from the automatic exposure control mode to the manual exposure control mode, the exposure control value immediately before the switching is performed. Is held as the initial value in the manual exposure control mode, and when the mode is switched from the manual exposure control mode to the automatic exposure control mode, the aperture value in the manual control mode immediately before the switching is set as the initial value, and the automatic exposure control is performed. A camera system comprising: lens-side control means for shifting to a mode. 3. The lens unit according to claim 2, wherein the lens unit is used in the camera system. 4. The camera according to claim 2, wherein the camera is used in the camera system.