JPH02224477A - Exposure controller - Google Patents

Abstract

PURPOSE:To switch the exposure control mode smoothly by holding the stopping state just before the switching in the case of applying the switching operation and correcting the held stopping as an initial value in the exposure control mode after the switching. CONSTITUTION:A holding circuit 14 holds the output voltage of a buffer amplifier 13 corresponding to the stopping value at the point of time when the switch is changed over to the manual exposure control mode and outputs the voltage to an adder 16. Moreover, a DC voltage variable circuit 30 varies a DC voltage supplied to the adder 16 in response to the operation of an UP switch 31 and a DOWN switch 32 and brings the stopping value to be adjusted manually based on the stopping value of an iris 2 holding by the holding circuit 14. The information of a stop information detector is operated just before the control is switched into the manual control and latched and the value is used as the initial value to apply the manual exposure control, then the stopping value before and after the changeover is not suddenly changed and smooth joint is attained.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an exposure control device for an imaging device, and is particularly suitable for use in a device capable of automatic and manual exposure operations.

(Background Art) In recent years, the development of video equipment such as video tape recorders (hereinafter abbreviated as VTR) has been remarkable, and automatic exposure adjustment devices have come to be equipped as standard, especially in camera-integrated VTRs. .

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

The amount of light incident from the optical system 1 is adjusted by an exposure adjustment mechanism (hereinafter referred to as iris) 2, and a subject image is formed 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.

The signal is separated into a luminance signal and a color signal, and converted by the camera encoder 5 into a standardized television video signal such as NTSC. An integrator 6 performs integration processing on the video luminance signal Y before gamma correction obtained from the camera signal processing circuit 4, and a calculator 7 generates a difference signal from a reference value 8. Using the difference signal as an exposure control signal, the driver 9 and actuator 10 control the iris 2 (diaphragm mechanism for adjusting exposure) so that the relationship between the output of the integrator 6 and a preset reference value 8 is constant. The opening amount is controlled.

(Problems to be Solved by the Invention) However, with conventional automatic exposure devices, the exposure for the subject intended by the photographer may not always be appropriate.

For example, when photographing a subject against a light source known as backlighting, or when only the subject is illuminated in a dark place,
Video cameras measure light averagely over a wide area that includes the background other than the subject, so in the former case the subject will be underexposed, and in the latter case the subject will be overexposed.

Therefore, if a video camera with an automatic exposure device determines that the exposure state that the photographer intended is not achieved, it is possible to switch from the automatic exposure operating state to the manual exposure operating state and set the exposure state that the photographer intended. Some have been proposed with manual exposure control means.

However, in these devices, when switching between automatic exposure operation and manual exposure operation, the aperture state operates discontinuously before and after the switching operation, resulting in an unnatural image.

(Means for Solving the Problems) The present invention was made for the purpose of solving the above problems, and is characterized by the ability to set a plurality of exposure control modes for controlling exposure conditions. The exposure control device includes a mode selection means for switching the exposure control mode, a holding means for storing exposure information, and when the exposure control mode is switched by the mode selection means, the holding means stores the exposure information immediately before switching. remember,
and means for supplying initial information of an exposure control mode after switching.

Further, the exposure control device is capable of setting an automatic exposure control mode for automatically controlling the exposure state and a manual exposure control mode for manually controlling the exposure state, and the exposure control device includes a switching means for switching each exposure control mode, and a switch for detecting exposure information. an aperture information detection means; a holding means for holding the output of the aperture value detection means immediately before switching when the switching means switches to the manual exposure control mode means; and an output of the holding means and the aperture information detection means. The exposure control device is equipped with a comparison means for comparing the output of the exposure control device with the output of the exposure control device and outputting exposure control information.

(Function) As a result, when switching between exposure control modes with different exposure control methods, it is possible to retain the exposure information before switching, so that the exposure state does not change discontinuously due to the switching operation. Control modes can be switched smoothly.

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

(Embodiments) Hereinafter, embodiments of the exposure control device according to the present invention will be described in detail with reference to the respective figures.

FIG. 1 is a block diagram showing a first embodiment of an automatic exposure device according to the present invention. In addition, in the figure, the same reference numerals are given to the parts having the same configuration as those of the above-mentioned conventional example, and the explanation thereof will be omitted.

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

Furthermore, the luminance signal Y which has not undergone gamma conversion and is output from the camera signal processing circuit 4 is sent to an integrating circuit in order to generate a control signal for controlling the iris 2 to obtain proper exposure according to the luminance state of the screen. 6 and is integrated, the signal is input to an arithmetic unit 7, where it is compared with a reference value 8, and a difference signal corresponding to the difference is generated. This difference signal is sent to the switch 9 as an exposure control signal (iris control data).
The signal is supplied to the actuator 11 via the driver 10, and the iris 2 is controlled.

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

The output of the holding circuit 14 is added to the output of the variable DC voltage circuit 30 via the adder 16 and is supplied to the non-inverting input terminal of the differential amplifier 15. Further, the DC voltage variable circuit 30 varies the DC voltage level supplied to the adder 16 in accordance with the operation of the UP switch 31% and the DOWN switch 32, respectively. 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 varied, and the aperture value held in the holding circuit 14 can be arbitrarily changed. can be changed to The details will be described later.

In addition, by switching the switch 9 to the upper contact point 9A in the figure, the output of the computing unit 7 is connected to the driver 10, and the iris 2 is automatically controlled by the iris control data signal output from the computing unit for automatic exposure. It becomes control mode. When switch 9 is switched to contact 9B, the output of differential amplifier 15 is connected to driver IO, and iris 2 is controlled by the output voltage of the differential amplifier described above. In this state, as described above, the iris 2 can be controlled by varying the output of the differential amplifier by the summed output of the holding circuit 14 and the variable DC voltage circuit 30 that are input to the differential amplifier 15. That is, UP, DOWN switch 31.32
By operating the output voltage level of the variable DC voltage circuit 30, the iris 2 can be manually controlled.

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 for automatic exposure control mode, the switch 17A is switched to the contact 17A, and when the switch 9 is switched to the contact 9B for the manual exposure control mode, the switch 17 is switched to the contact 17A. 17B respectively. When the switch 17 is switched to the contact 17A, a predetermined high level control signal B is applied to the DC voltage variable circuit 30 and the holding circuit 14, respectively.
is supplied to override each operation. Further, when the switch 17 is switched to the contact 17B, a low level control signal is supplied to the variable DC voltage circuit 30 and the holding circuit 14, and thereby the holding circuit 14 switches the switch to manual exposure control mode. The output voltage of the buffer amplifier 13 corresponding to the current aperture value is held and output to the adder 16. In addition, the DC voltage variable circuit 30 includes an UP switch 31 and a DOWN switch 32.
The DC voltage supplied to the adder 16 is varied in accordance with the operation, and the aperture value can be manually adjusted based on the aperture value of the iris 2 held by the holding circuit 14.

In this way, the information from the aperture information detector, which was not used in automatic exposure control mode, is activated and held just before switching to manual control, and this value is used as the initial value for manual exposure control. The aperture value before and after switching does not change suddenly, making the connection smooth.

As mentioned above, in this state, the DC voltage variable circuit 30
By varying the voltage of , and shifting the voltage input to the non-inverting input of the differential amplifier 15 via the adder 16, the held aperture can be changed arbitrarily.

Here, the configuration diagram of the DC voltage variable circuit is shown in FIG.
When the P switch 31 or the DOWN switch 32 is pressed, a predetermined power supply voltage is input to the UP and DOWN counters 33, and if the UP switch side is pressed, the iris 2 is counted up and the iris 2 is driven to open, and the DOWN switch is If the side is pressed, a down count is performed and the iris 2 is driven in the closing direction. The output of the counter 33 is input to the D/A converter 34 and converted into an analog voltage.
It is supplied to an adder 16. Further, the reset signal generation circuit 35 generates a reset signal when the switch 17 is changed from automatic to manual, sets the output of the counter 33 to a preset reference value, and sets the output of the D/A converter 34 to 0.
This is to make sure that.

With the above configuration, in normal imaging conditions, if the switches 9 and 17 are switched to the contacts 9A and 17A to set the automatic exposure control mode, the iris drive actuator 11 can be activated regardless of the LIP and DOWN switches. The iris 2 of the driver 10 is controlled by the iris control signal output from the arithmetic unit 7 so that the video signal level is constant.

Then switch 9.17 is connected to contact 9B.

When switching to 17B and entering manual exposure control mode, buffer amplifier 1 corresponding to the aperture value immediately before the switching operation is performed.
The output of 3 is held in the holding circuit 14, and at the same time tJP,
The DC voltage for iris control supplied to the adder 16 can be adjusted in accordance with the operation of the DOWN switch, and the iris control voltage supplied to the non-inverting input terminal of the differential amplifier 15 is held in the holding circuit 14. You can change the aperture value as the initial value. Then, the differential amplifier 15 drives the driver 10 so that the level of the non-inverting terminal and the DC voltage level supplied from the buffer amplifier 13 are equal. It can be adjusted to

In this way, when switching from automatic exposure control mode to manual exposure control mode, the aperture value immediately before switching is maintained.
Since manual aperture control can be performed from that aperture value, the aperture value does not become unstable and discontinuously move when switching to manual control (and a smooth and stable switching operation can be performed).

(Other Embodiments) Next, other embodiments of the present invention will be described with reference to FIGS. 3 and 4. This embodiment is an application of the present invention to a video camera with replaceable lenses, and includes the holding circuit 14, differential amplifier 15, adder 16, and DC voltage variable in the first embodiment shown in FIG. The functions of the circuit 30 are realized by a microcomputer on the camera side.

FIG. 3 is a block diagram showing the configuration of a video camera with interchangeable lenses to which the present invention is applied. Components that are the same as those in FIG.

In the figure, LS indicates a lens unit, and CM indicates a camera unit, which are connected by a mount portion MT. Further, a data communication path 27 for exchanging data between the camera and the lens is formed in this mount portion by means of electrical contacts (not shown). The communication between the camera unit CM and the lens unit LS is performed in synchronization with Vsync (vertical synchronization signal) because it is performed based on the processing of the television signal on the camera unit side.

In the camera unit 980M, the configurations of the image sensor 3, camera signal processing circuit 4, camera encoder 5, and integrator 6 are the same as those shown in FIG. In this 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 camera microcomputer) 20. A reference value 8 for iris control is also supplied to the camera microcomputer 20 via the A/D converter 26.

In addition, the switch 17 for switching between automatic and manual exposure control and the UP and DOWN switches 31 and 32 for adjusting exposure in manual exposure control mode in FIG. is supplied.

The luminance signal Y output from the camera signal processing circuit 4 is the first
As in the embodiment, a control signal for controlling the iris 2 to obtain appropriate exposure should be generated according to the brightness state of the screen (
, after being input to the integrating circuit 6 and integrated, the A/D converter 2
3, the image is taken into the camera microcomputer 20. 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 is subjected to a predetermined calculation to obtain iris control data corresponding to the difference, and then the result is communicated to the lens microcomputer 21 on the lens unit LS side via the data path 27. .

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

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 10 and actuator 11.

Therefore, in the automatic exposure control state, the 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 is calculated within the camera unit and sent to the lens unit as described above. By receiving the data and driving the iris on the lens unit side, the exposure state can be controlled so that the average level of the luminance signal always has a constant 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 using the automatic 1 manual changeover switch 17.

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

Next, upon receiving the manual exposure control mode command, the lens microcomputer 21 transmits a control value to the D/A converter 2 for stopping the iris 2 from its current state.
Output to 4. 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, and then sent to the A/D converter 2.
After being converted into a digital value by 5, the lens microcomputer 2
1. Further, the aperture value information taken into the lens microcomputer 21 is stored and held in a storage circuit within the lens microcomputer 21.

After a predetermined period of time, the value of the iris 2 is periodically fetched into the lens microcomputer 21 via the encoder 12, buffer amplifier 13, and A/D converter 25 in the same manner as described above, and is stored in the lens microcomputer 21. When the control program described later outputs iris control data from the lens microcomputer 21 and switches the aperture value of the iris 2 to manual operation, it is compared with the value held in the memory circuit and these values are made equal. It is to be maintained in this state.

In addition, while the iris 2 is maintained in the above-mentioned manual exposure control mode, the values stored in the storage circuit from the camera unit side via the data communication path 27 are set to a specific range by the UP switch 31 and the DOWN switch 32. The aperture value of the iris 2 can be arbitrarily set by adding and subtracting.

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

First, the processing on the camera unit 0M side is shown in Figure 4 (
As shown in a), #C1: #C2: #C3: #C4: Check the input of a predetermined number of Vsync (vertical synchronization signal in the video signal) to set the communication timing to the lens unit LS side.

A predetermined number of Vsyncs have been generated. Set the chip select signal.

Parallel-serial conversion of iris data Sent from the camera side to the lens side.

Reset chip select signal Ru.

In the above-described operation, if a predetermined number of VsynC is not input at C1, the process moves to C5 to perform processing only on the camera unit 0M side without performing communication to the lens unit LS side.

#C5: #C6: #C7: #C8: #C9: #Cto: Exposure control operation automatic exposure control mode or in manual exposure control mode. Choose now.

Automatic exposure control mode is selected If so, the output from the A/D converter 23 output video signal level of integrator 6 is loaded into the camera microcomputer 20.

A/D conversion by the A/D converter 26 The level of the converted reference value 8 is set in the camera Load into icon 20.

Calculation (iris control data = video signal CI Return to and repeat the above flow.

Manual exposure control mode selected in C5 Manual exposure control mode if Determine whether it has just been set to Ru.

Immediately after manual exposure operation is set. If so, in the camera microcontroller 20 Set the stored value of the iris correction data to O. #C11: #C12: Reset to .

This correction data is used for manual exposure control in the lens microcomputer 21. When switching modes stored in Use the camera to manually change the aperture value. This is the correction value sent from the U side. Set by P, DOWN switch. It is something that can be done.

When operating in manual exposure control mode, Output setting button UP switch 31, D Determines whether the OWN switch 32 is pressed. If it is not pressed, the C1 star is pressed. Return to root.

UP to drive the iris to the open side If switch 31 is pressed, memory Add 1 to the iris correction data In addition, use this as new correction data. It is stored in the camera microcontroller and the C1 Return to root.

In other words, the odor inside the camera microcontroller # C13: to set the iris correction amount. Up/down counter 3 in Figure 2 Iris 2 on a counter like 3. The amount of correction toward the open side is set.

DO driven to the iris closing side If the WN switch 32 is pressed, Is it the stored iris correction data? Subtract 1 from the above and use this as new correction data. Stored in the camera microcontroller as C1 Return to the start.

Like C12, inside the camera microcontroller Correction amount to correct iris 2 to the closing side is set.

The above-mentioned control operation is repeated, and the iris control data corresponding to the automatic exposure control mode or manual exposure control mode is transmitted to the lens unit side each time the communication is made, and the iris 2 is controlled.

Next, processing on the lens side will be explained using the flowchart shown in FIG. 4(b).

#L1: #L2: #L3: #L4: #L5: Chip select signal from camera side Wait for communication while checking input. Ru.

Chip select signal is input If the data is transmitted by serial-to-parallel conversion, Import the iris control data that has been received. chip select must be entered. If the iris data is not updated, L Move to 4.

Receives communication from the camera side and automatically Exposure control mode is selected or manual exposure control mode is selected. Determine whether there are any.

Automatic exposure control mode is selected When the iris control data is converter 24 and iris 2. Control.

Manual exposure control mode is selected When the manual control mode is #L6: #L7: #L8: #L9: It is determined whether or not it has just occurred.

and set to manual exposure control mode. If it is immediately after, use the following L6, L Perform step 7.

Iris 2 drive is stopped. Ru.

for detecting the iris aperture value. Encoder (e.g. Hall element) 1 Import the current aperture value data of 2, The value is retained in the lens microcomputer 21. do.

Set to manual exposure control mode If so, the aperture value in the lens microcontroller The transmitted correction data is included in the retained data. Add the data and use the result as a new Store as retained data.

Current encoders e.g. Hall element The aperture value data of child 12 is sent to the A/D converter. The A/D converted value in 25 is converted into a lens mask. Import into icon 21.

#LLO: #L11: ＃　L　12　: #L13: #L14: Aperture value data c of encoder 12 element data) and retention data are equal. judge whether it is appropriate.

Encoder (Hall element) 12 aperture From the value data, the lens microcontroller Determine the size relationship of retained data.

In LIO, [Encoder (Hall element) ) data] = [retained data], then Stop driving the iris and return to Ll. Ru.

In Lll, [encoder (Hall element) ) data] < [retained data], then Drive iris 2 to open side and move to Ll and return.

In Lll, [encoder (Hall element) ) data]> [retained data], then Drive to the closing side of the iris to Ll and return.

The above control flow is repeated, and each time communication from the camera unit 0M is received, the control information is updated and the iris 2 is controlled.

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

In the flowchart in this case, steps C1-C4 in FIG. 4(a) and steps L1-L2 in FIG. 4(b) may be omitted.

In addition, according to the above-mentioned embodiment, the configuration was explained using as an example the configuration in which the aperture value is held when switching from automatic exposure control mode to manual exposure control mode, but it may also be applied to the reverse switching (, The present invention is not limited to any type, and 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, switching from automatic exposure control mode to manual exposure control mode, or between a plurality of exposure control modes with different methods, such as boat fishing, is possible. When an aperture operation is performed, the aperture state immediately before the change is maintained, and in the exposure control mode after the change, the retained aperture is used as the initial value and corrected, so the exposure control mode can be changed smoothly. This facilitates exposure correction and prevents the occurrence of unsightly and unnatural images due to discontinuity or sudden changes in the exposure state, especially before and after switching the exposure control mode.

[Brief explanation of the drawing]

FIG. 1 is an overall block diagram showing a first embodiment of the present invention. FIG. 2 is a block diagram of essential parts for explaining the configuration and operation for manually correcting the aperture value in the present invention. 3 is an overall block diagram showing the second embodiment of the present invention, FIG. 4 is a flowchart for explaining the iris control operation of the second embodiment, and FIG. 5 is an example of a conventional device before the present invention. FIG. Canon Co., Ltd. Sai 2 Figure Lens side Figure 4 (!0) I3 Do OP: Non-linear Ishi7bi 1qJ Figure 4 (cL) Camera side

Claims (3)

[Claims] (1) An exposure control device capable of setting a plurality of exposure control modes for controlling an exposure state, which comprises a mode selection means for switching the exposure control mode, a holding means for storing exposure information, and a mode selection means for storing exposure information. and when the exposure control mode is switched, the holding means stores the exposure information immediately before the switching, and supplies the information as initial information of the exposure control mode after the switching. . (2) An exposure control device capable of setting an automatic exposure control mode for automatically controlling the exposure state and a manual exposure control mode for manually controlling the exposure state, comprising a switching means for switching each exposure control mode, and a means for detecting exposure information. aperture information detection means; a holding means for holding the output of the aperture value detection means immediately before switching when the switching means switches to the manual exposure control mode means; and an output of the holding means and the aperture information. An exposure control device comprising: comparison means for comparing the output of the detection means and outputting exposure control information. (3) The exposure control device according to claim (2), further comprising a correction means for varying the value held by the holding means.