JPS5991778A - Image pickup device and picture reproducer - Google Patents

Abstract

PURPOSE:To attain suitable exposure correction at all times by constituting exposure control information such as back light correction and AE lock so as to be superimposed on a video signal. CONSTITUTION:The light incident from a diaphragm 1 is converted into an electric signal at an image pickup device 2, scanned by a scanning control circuit 3 and outputted as a time series electric signal. This output is integrated by a prescribed period at an AE control circuit 4 and used for the feedback control of the diaphragm 1. On the other hand, an output of the device 2 is controlled to be a prescribed level by an AGC circuit 5 and converted into a signal suitable for the recording or transmission at a signal processing circuit 6. Further, a mode command circuit 7 applies a command signal to the circuit 4 to as to switch a reference level of the AE depending on the on/off of switches 8, 9. The output of the circuit 7 is applied to an ID signal forming circuit 10 to form an ID signal commanding the exposure state represented by on/off of the switches 8, 9 and to be superimposed on the output signal of the circuit 6.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an imaging device capable of special exposure, and an image reproducing device that can directly or indirectly reproduce an output signal of the imaging device as an image.

(Prior Art) In video cameras, the amount of incident light is automatically controlled using an auto iris or the like, but there are still problems with the responsiveness and mechanical responsiveness of the servo rug. Also, especially when a solid-state imaging device is used as an image sensor in a video camera.

Since the dynamic range is extremely narrow, the level of the video signal fluctuates greatly in response to exposure errors.

When shooting continuously, such as when shooting a movie, the rise time can be expected to be sufficient, so this problem is relatively small; however, when shooting only one frame, such as when shooting a methyl film, the rise time of the exposure control system is This is a big problem, and therefore the error cannot be ignored.

It is difficult to correct such a large error even with an AGC circuit generally provided in a camera.

Additionally, cameras sometimes compensate exposure for special effects (for example, backlight compensation) when taking images, but there are cases where there is an intentional exposure change like this and an unintentional change as mentioned above. The disadvantage is that the resulting video signal ends up being at the same level even when there is an exposure shift, and this cannot be determined on the side of an image reproducing device such as a printer or a video monitor. Therefore, the operator must manually adjust the level while monitoring the reproduced image, which is extremely inconvenient. In addition, since the player cannot distinguish between the two, there is a drawback that AGC cannot be simply applied.

(Objective) It is an object of the present invention to provide an imaging device and an image reproducing device that can eliminate the drawbacks of the prior art and that can always perform appropriate exposure correction.

(Example) The present invention will be described in detail below based on the drawings.

FIG. 1 is a diagram showing an example of the configuration of an imaging apparatus according to the present invention, and this embodiment is configured so that exposure control information such as backlight correction and AE clock is superimposed on a video signal.

Light incident through the aperture 1 is converted into an electrical signal in an imaging device 2 such as an image pickup tube or a solid-state imaging device, scanned by a scan control circuit 3, and output as a time-series electrical signal. The output from this device is A, E (A
It is integrated at a predetermined period by the autoexposure control circuit 4 and used for feedback control of the aperture sea. Thereby, automatic iris control is performed so that a constant amount of light is always incident on the device 2. On the other hand, the output of the device 2 is controlled to a constant level by the AGC circuit 5, and then converted by the signal processing circuit 6 into a signal suitable for recording or transmission.

Reference numeral 7 denotes a mode instruction circuit, which supplies an instruction signal to the AE control circuit 4 and the like to switch the reference level of AE in response to ON/OFF of switches 8 and 9.

The switch 8 is turned on, for example, during backlight correction.

of This is a switch to slightly raise the AEA reference level.

Also, 5 switch 9 is a switch to make the screen a little darker, for example at dusk or in a tunnel.
When N is selected, the AE reference level is set to slightly lower. These switches 8 and 9 constitute exposure state switching means of the present invention.

The output of the mode instruction circuit 7 serves as an instruction signal forming means.
D (Identif 1cation) is supplied to the signal circuit 10, forms an ID signal as an instruction signal for instructing the exposure state represented by ON' and OFF of the switches 8 and 9, and converts this into an output signal of the processing circuit 6. Superimpose.

As the ID signal, a method of superimposing a predetermined coded pulse within the vertical blanking period of the video signal, or a method of superimposing a low frequency pulse such as 4H (horizontal period) bit on the video signal. etc. are possible. 11
is an adding circuit as a superimposing means, and the output of 7 is connected to a recording device, a reproducing device, a transmitting device, etc.

FIG. 2 is a diagram showing an example of the configuration of a playback device, in which a video signal including an ID signal input from an external input terminal or a playback head, etc. is separated into a video signal and a II) signal by an ID separation circuit 12 as separation means. The ID signal is input to the discrimination circuit 13. On the other hand, the video signal is level-adjusted via the AGC circuit 14, and then converted into a signal suitable for the video monitor 16 or a signal suitable for the printer 17 in the reproduced signal processing circuit 15. 18 is a changeover switch.

Further, the gain or level in the AGC circuit is controlled according to the output of the discrimination circuit 13.

With this configuration, when performing AB control, the exposure level is changed to achieve a special effect, and the original information is superimposed on the video signal as an ID signal and output. On the other hand, on the playback side as well, the level of the input video signal can be automatically adjusted based on this ID signal.

Figure 3 shows the mode instruction circuit 7 and ID signal circuit 1 in Figure 1.
2 is a diagram showing a specific example of the configuration of 0. FIG.

19 and 20 are resistors, 21 is an exclusive OR gate, 22 and 23 are AND gates, and 24 is a ring counter, and a horizontal synchronizing signal is input to the counter 24 as a clock. Also, its nth output and (n+1
)-th output Qn +1 is supplied to the above-mentioned gates )22 and 23, respectively. Further, this counter is reset by the vertical synchronizing signal and returns to 0, and can count the horizontal scanning line of one field. n(n+1) corresponds to two predetermined horizontal scanning line addresses within the vertical blanking period. It is desirable that this address be within a blanking period temporally preceding the video signal, for example after the special price pulse. Since it is configured as shown in the figure, it is studied during the 2H period at the predetermined timing of the vertical blanking period on the front side of the video signal of one field.

Qn+1 becomes rlj and 'IOJ, respectively, and then in the next IH period, Qn and Qn+1 become "0" and "1", respectively.
becomes. When Qn+1 is 1, the information on switch 8 is read, and when Qn+1 is 1, the information on switch 9 is read. And the ON/OFF information of each switch is 2
The bit ID signal is added to the video signal in adder 1. In addition, the gate 21 has switches 8 and 9 both ON.
This is to eliminate the situation where

FIG. 4 is a diagram showing an example of the configuration of the A'E control circuit 4. The output from the imaging device 2 is supplied to an integrating circuit 25 that performs integration at a predetermined period, and is used as photometric information.

Note that the photoelectric information input to the integrating circuit may be the output of a photometric sensor provided separately from the imaging device.

A frequency dividing circuit 26 divides the frequency of, for example, the vertical synchronizing pulse VD and supplies a reset signal output of the integrating circuit to the driver 27. It is also possible to switch and connect to the manual aperture value setting circuit 33 using the dry manual selector switch 32. 34 is a potentiometer that is linked to an aperture value setting dial (not shown).

Therefore, when the switch 32 is switched to the a side, automatic exposure control is performed based on the output of the integral circuit, and when switched to the b side, manual aperture control based on the aperture value setting dial is enabled.

On the other hand, in this embodiment, the β reference voltage of the differential amplifier is variable, and there are three types of voltages: a reference voltage Vl that is slightly higher than the reference voltage (■2) in the standard mode, and a slightly lower voltage (■). It is possible to switch.

28 is a constant voltage source, 29 to 31 are these voltages ■,
~V, respectively, are analog switches for selectively guiding them to the amplifier 26, and are controlled by gates 35-37, respectively. Each gate 35 to 37 has a switch 8,
The output of 9 is manually input, and when 8.9 is (0, 0), only gate 30 opens, when (]', O), only gate 29 opens, and when (0, 1), gate 3] A logic circuit is formed so that only one part opens. Because of this configuration, when the switch 8 is on, the diaphragm 1 is at the standard level υ
conversely, when the switch 9 is ON, the diaphragm 1 is closed more than the standard level.

Therefore, the level of the video signal will increase or decrease from the standard level depending on each case, but since this increase/decrease information is superimposed on the video signal as an ID signal, the level increase/decrease of this video information is not detected during playback. You can play it without canceling it.

FIG. 5 is a diagram showing an example of such a method of gain control on the reproduction side.

The same numbers as in FIG. 2 indicate the same elements. In the figure, numeral 38 denotes a ring counter having the same function as the ring counter 24 shown in the third diagram, which is reset by a vertical synchronization signal and counts horizontal synchronization signals. Then, at the same timing as the counter 24, that is, the nth and (n +
1) Extract the horizontal synchronization signal using gates 39 and 40.

41.42 is an R-S flip-flop (R-8FF) set by the 71-element output of gate 39.40.
It is reset by the vertical synchronization signal. FF4], 42
The Q output of is determined by the gates 43 to 45, and the three potential levels V, , V formed by the constant voltage source 46 are determined by the gates 43 to 45.
, , V, , (V, <V, <Yx) by controlling analog switches 47 to 49.

50 is a transistor such as a FET whose gate is controlled by this voltage, and its impedance changes depending on the voltage level of the gate. Note that the transistor 55 is also a transistor such as an FET having the same variable impedance function as the transistor 50.

5], 52 are voltage dividing resistors, and these resistors 51.5
2. and transistor 50. '55 allows human-level control.

53 is an amplifier, the output of which is passed through a low-pass filter 54
The gate of the transistor 55 is controlled by negative feedback. Therefore, the circuits 51 to 55 form an AGC circuit.

In this embodiment, a transistor 50 as a variable impedance means 2 is further provided to control the level of human power applied to the AGC circuit. Incidentally, the output of the amplifier 53 is led to the above-mentioned reproduction processing circuit 15. With this configuration, when fC is used to perform AE control at the normal reference level during imaging, that is, when the outputs of the gates 39 and 40 are ro', 4o, and +, respectively, the transistor 50 A voltage (2) is applied to the gate, resulting in a predetermined impedance (Z,).

In addition, when the AE level is increased for backlight correction etc. during imaging, that is, when the gates 39 and 40 are respectively "1" and "0", a voltage V lower than the voltage V2 is applied to the gate of the transistor 50. is applied, the impedance Z of the transistor 50 becomes higher than Z, and the level of the signal input to the amplifier 53 increases slightly. Therefore, the reproduced image becomes brighter.

Conversely, when the reference level of AE is lowered during imaging, that is, when the gates 39 and 40 are rOJ and rlj, respectively, the voltage V is applied to the gate of the transistor 50.

A higher voltage (2) is applied, the impedance Z of the transistor 50 becomes lower than Z2, and the input signal level of the amplifier 53 decreases slightly. Therefore, the reproduced image becomes dark.

Incidentally, in the embodiment, the reference level of AE during imaging and AGC on the reproduction side can be switched in three levels.

Of course, the switching may be performed in many stages, or may be performed continuously.

Further, in the embodiment, on the playback side, for example, three different A
I am trying to select the GC level.

When the image is captured at the full AE level on the imaging side, the image is set to A on the playback side.
Activate the GC and set the AE level to the standard level on the imaging side.
- If the signal goes up or down, the AGC on the playback side may be disabled.

In addition, in the embodiment, the reference voltage of the differential amplifier on the imaging side is changed, but any type may be used as long as the signal level for controlling the aperture is changed. .

Further, as described above, the ID signal may be superimposed on the video signal in any loose form.

Furthermore, in this embodiment, the level control of the video signal is performed in relation to the AG circuit on the playback side.

The I
Gain adjustment or signal attenuation rate may be controlled according to the D signal.

Next, FIG. 6 is a diagram showing another embodiment of the present invention.

In this embodiment, the AE rotary switch 56 is turned on.

OFF is superimposed on the video signal as an ID signal, whereby the aperture is fixed and the level fluctuation of the video signal during that time is reproduced as is.

That is, as shown in FIG. 7, in the reproducing machine, the output of the ID separation circuit 12 is discriminated by a discrimination circuit, and when the AE lock is applied, the gain of the amplifier 57 in the feedback loop of the AGC circuit is attenuated or zeroed. I have to. As a result, when the AE lock occurs, the intended shooting effect on the imaging side, where AGC on the playback side works little or not at all, is canceled, and if the amount of feedback is attenuated, minute level fluctuations are suppressed. .

In the example shown in FIG. 5, since the entire input level to the AGC circuit was changed, there was a risk that intentional fluctuations in the human power level would be corrected by the AGC circuit, but as shown in FIG. If this is done, the problem of the configuration shown in FIG. 5 will not occur because the only change is the way the AGC operates.

FIG. 8 is a diagram illustrating another embodiment of the present invention, which is an effective configuration when there is unevenness in the responsiveness or accuracy of the aperture control.

That is, prior to the main imaging, the brightness of the image is detected in advance by a photometric element, and the aperture value is determined by the photometric circuit 59. The aperture υ is controlled based on this aperture value or the aperture value of the manual aperture setting means 33.

60 is a switch for switching between the two. However, the response of the aperture is extremely low compared to the imaging time, so the setting value in the manual setting circuit or photometry circuit 59 (,
The actual aperture condition at the time of image capture may include some errors.

When reading out the signal of the captured image, the measurement circuit 61 measures the average level or integral level of this signal to detect the actual exposure level, and this level and the settings made manually or by AE before capturing the image. An error signal is formed by comparing the level with the comparator 62, and this error signal is sent to the ID signal forming circuit 10.
By converting the signal into a D signal and superimposing it on the video signal obtained via the process circuit 6, it is also possible to correct the aperture error on the reproduction side. In this case, although the circuit configuration on the playback side is not particularly shown, the AGC
The gain of the circuit, the input signal level, the amount of feedback, etc. may be adjusted.

FIG. 9 is a simplified version of the configuration of the embodiment shown in FIG. I decided to let them do it.

That is, when setting the still mode and movie mode for image capture, the switch 63 is changed and the stealth mode is set.
The output of the D signal generator 64 or the movie ID generator 65 is selectively superimposed on the video signal.

On the reproduction side, this ID signal is determined and if it is a still ID signal, the gain of the amplifier 66 provided in front of the AGC circuit 14 is increased or decreased by a predetermined amount.

This method is based on the premise that the aperture is fully closed or fully open in its initial state before photographing.

For example, when starting from a fully closed position, the aperture error at the time of image capture of the device 2 is averaged for all apertures, the gain of the amplifier 66 is increased by an amount corresponding to this average aperture error, and the initial state is Conversely, when the aperture is fully open, the average aperture error can be calculated, so even if the aperture value data or the error data at that aperture value is superimposed on the video signal as a signal. good. If 7c is used, the aperture error can be corrected more accurately.

(Effects) As explained above, according to one aspect of the present invention, even when the exposure level is raised or lowered from the standard level to achieve a special effect during imaging, the AGC circuit on the playback side allows ? The effect of L can be reproduced without being canceled.

Also, when the exposure is fixed such as with AE lock, the A on the playback side
Since the function of the GC circuit is reduced or cut, changes in the video level at the time of imaging can be reproduced as is. Further, according to the embodiment, the actual aperture state and the set aperture are compared, an ID signal corresponding to the error is superimposed, and the error is corrected based on this ID signal during playback. Regardless of the responsiveness of the aperture, a screen with the desired brightness can always be obtained. Furthermore, the AG (7) on the imaging side can be simplified and the device can be made smaller.

Further, according to the embodiment, in the case of stealth imaging, the gain on the reproduction side is increased or decreased by a predetermined amount.5. Since the instruction is given by an ID signal, the ID signal forming circuit on the imaging side and the gain adjustment circuit on the reproduction side are simplified.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing a first configuration example of an imaging device of the present invention, FIG. 2 is a diagram showing a first configuration example of an image reproducing device, and FIG. 3 is a diagram showing a mode instruction circuit and a mode instruction circuit in FIG. FIG. 4 is a diagram showing an example of the configuration of an ID signal forming circuit; FIG. 4 is a diagram showing an example of the configuration of the AE control circuit in FIG. 1; Figure 5 shows the ID separation circuit, discrimination circuit, and A in Figure 2.
FIG. 6 is a diagram illustrating a second configuration example of the imaging device of the present invention, and FIG. 7 is a diagram illustrating a second configuration example of the image reproducing device of the present invention. Fig. 8 is a diagram showing a third embodiment of the imaging device of the present invention, and Fig. 9 is a diagram showing another embodiment of the imaging device and image reproducing device of the invention.1... Aperture; 2: Imaging device, 7: Mode instruction circuit, 8: Switch for increasing exposure, 9: Switch for decreasing exposure, 1o: ID signal forming circuit. Patent applicant: Canon Co., Ltd. company

Claims (2)

[Claims] (1) Exposure state switching means for exposing a virtual image device to a different level from a preset fc exposure level, and instruction signal formation for forming an instruction signal for instructing the selection state of the switching means. and a superimposing means for superimposing the output of the forming means on a video signal formed from the output of an imaging device. (2) An image having a separation means for separating an instruction signal from a video signal including an instruction signal regarding an exposure state, and a level control means for controlling the level of the video signal in accordance with the instruction signal separated by the separation means. playback device.