JPH099136A - Image pickup device - Google Patents

Abstract

PURPOSE: To improve the performance of an automatic control function such as white balance control and exposure control. CONSTITUTION: An operating speed control section 19 controls the operating speed of an environment discrimination section 10 changing the control characteristic of a white balance control section 11 and an exposure control section 12 depending on image pickup environment, and the tracking performance is enhanced by increasing the operating speed just after application of power and when an image pickup environment changes considerably and the operation is made stable by slowing down the operating speed in other cases.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photographing device such as a video camera, a VTR integrated camera, an electronic still camera or the like having an automatic control function such as an automatic white balance control and an automatic exposure control. Regarding performance improvement of functions.

[0002]

2. Description of the Related Art In general photographing apparatuses, adjustments such as white balance adjustment and exposure adjustment are indispensable in order to obtain a good image. At present, many automatic control devices mounted on photographing devices such as home-use VTR integrated cameras are provided with automatic control functions such as automatic white balance control and automatic exposure control for automatically performing these adjustments.

However, it is known that in the automatic control by these automatic control devices, malfunctions (malfunctions) occur due to various factors. Regarding this problem, for example, the invention described in JP-A-5-308563 is
It is proposed to prevent malfunction of automatic control by determining the shooting environment of the shooting device to improve performance. This proposal determines the shooting environment, such as day and night, indoors and outdoors, based on the subject distance, lens aperture value, time information, etc., and based on the determination results, determines the control characteristics such as auto white balance control and automatic exposure control. By changing the value, malfunctions in automatic control are reduced.

[0004]

However, in the conventional apparatus as described above, it is difficult to execute the optimum automatic control according to the change of the photographing environment. For example,
If you set the automatic control characteristic that responds sensitively to the detected environmental change, there is a problem that the automatic control responds to a temporary or partial environmental change, resulting in an unstable shooting operation state. When the corresponding characteristics are set, the automatic control for changes in the subject (shooting environment) immediately after turning on the power or during panning becomes slow, and the time until the optimal shooting operation state is reached becomes longer, and the effect of automatic control is weakened. The problem occurs.

Therefore, an object of the present invention is to provide an automatic control means capable of always providing a preferable photographing operation state.

[0006] Specifically, the time from turning on the power of the apparatus to the time when stable shooting is possible is shortened, and the followability is improved with respect to changes in the shooting target such as during panning. In addition, it is to prevent an unstable shooting operation state due to a hypersensitive reaction.

[0007]

According to the present invention, there is provided an image pickup device for converting an optical image into an image pickup signal, signal processing means for processing the image pickup signal to generate a television signal, and determining a photographing environment, In an image pickup apparatus provided with an automatic control unit (white balance control, exposure control, image quality control unit, etc.) for controlling image pickup or signal processing characteristics based on a determination result,
The automatic control means is provided with an operation speed control means for controlling the speed of the control.

The operating speed control means controls the cycle of the environment judgment, or a time measuring unit for measuring the elapsed time from the power-on of the photographing apparatus, and a predetermined time elapses. Until then, a speed control unit for accelerating the control characteristic changing speed is provided, the time measuring unit is provided with a field counter, and the speed control unit changes the control characteristic changing speed with reference to the counting result of the field counter. It is characterized by

Further, the automatic control means is provided with an environment judging means, and the operation speed controlling means changes the control characteristic changing speed based on the environment information obtained from the environment judging means.

The automatic control means includes control means for controlling image quality control in the signal processing means, white balance control means for controlling gain of color signals, or exposure control means for controlling exposure amount of the image pickup device. It is characterized by that.

Further, the automatic control means is characterized in that the photographing environment is judged by using at least one or more of object distance information, lens zoom magnification information, exposure information and time information. The feature is that the shooting environment is determined using fuzzy inference.

Further, the photographing apparatus is characterized by further comprising recording means for recording the television signal and reproducing means for reproducing the recorded television signal.

[0013]

The operation speed control means increases the operation speed of the automatic control quickly until the predetermined time elapses after the power of the apparatus is turned on or when the change amount of the photographing environment exceeds the predetermined range. Automatically controlled to obtain a shooting operation state suitable for the shooting environment, and after the predetermined time has elapsed or when the amount of change in the shooting environment is within a predetermined range, the operation speed of the automatic control is slowed for stable shooting. Automatically control the operating state.

Therefore, the time from when the power of the apparatus is turned on to the time when stable photographing is possible is shortened, the followability with respect to the change of the photographing target at the time of panning, etc. is enhanced, and the reaction is hypersensitive. Therefore, it is possible to prevent an unstable shooting operation state.

[0015]

Embodiments of the present invention will be described below with reference to the drawings.

In FIG. 1, reference numeral 1 denotes a lens, which includes a focus lens and a zoom lens. Reference numeral 2 denotes a diaphragm for adjusting the amount of incident light, which is driven by a diaphragm driving circuit 17. An image pickup element 3 such as a CCD photoelectrically converts the subject image formed on the image pickup surface by the lens 1 into an image pickup signal. An AGC circuit (automatic gain control circuit) 4 amplifies an image pickup signal output from the image pickup device 3 to a predetermined signal level, and an A / D conversion circuit 5 converts an analog image pickup signal into a digital image pickup signal.

The signal processing circuit 6 generates a luminance signal and a color signal from the image pickup signal and performs known signal processing such as gamma correction. The encoder 7 converts the luminance signal and the chrominance signal output from the signal processing circuit 6 into a digital signal according to a standard television signal such as an NTSC system, and a D / A conversion circuit 8
Converts the digital signal into an analog standard television signal and outputs it.

A white balance control unit 11 controls the signal processing circuit 6 so that a white subject is reproduced in white regardless of the color temperature of the photographing environment. The white balance control unit 11 changes the control characteristic of white balance control every time the determination result is output from the environment determination unit 10.

An exposure control unit 12 controls the diaphragm 2 via the diaphragm drive circuit 17 so as to obtain an image signal of an appropriate level, and the image pickup via the image pickup device drive circuit 9. The exposure time of the element 3, that is, the shutter speed is controlled. The exposure control unit 12 changes the control characteristics of the diaphragm and the exposure time control each time the determination result is output from the environment determination unit 10.

Furthermore, the image pickup element drive circuit 9, the signal processing circuit 6, and the encoder 7 operate in accordance with the standard television system such as the NTSC system based on the synchronization signal output from the synchronization signal generator 20. .

The environment determination section 10 includes subject distance information output from the distance detection means 13, zoom magnification information output from the zoom value detection means 14, aperture value information output from the aperture detection means 15, and the time counter 16. Calculation of the illuminance of the subject, calculation of the background distance, and the like based on time information such as date / time output, gain information output from the AGC circuit 4, video signal information output from the signal processing circuit 6, and the like. The determination processing of the photographing environment is performed, and the automatic control for automatically changing the control characteristics of the white balance control unit 11 and the exposure control unit 12 is performed based on the determination result. It is effective to use fuzzy inference to judge the shooting environment. In addition, judgment of shooting environment and white balance control,
Regarding the exposure control, the method described in Japanese Patent Laid-Open No. 5-308563 is used, and the detailed description is omitted here.

In this embodiment, in order to realize the operation speed control of the automatic control, which is a feature of the present invention, the operation speed control means controls the operation speed of the environment determining section 10.

The operation speed control means in this embodiment is
A field counter 18 for clocking and an operation speed control unit 19 are provided. The field counter 18 outputs count value (elapsed time) information obtained by counting the vertical sync signal output from the sync signal generator 20, and the operation speed control unit 19 turns on the power of the photographing apparatus based on the count value information. The elapsed time from the time point is determined, and the operation speed control for changing the operation speed (determination operation cycle) of the environment control unit 10 is executed according to the elapsed time.

The control algorithm for this operation speed control will be described below with reference to the flow chart shown in FIG. Here, it is assumed that the flowchart shown in FIG. 2 is executed once per field in synchronization with the field frequency of the television system.

First, in step ST1, the number of fields after the power is turned on is counted. Next, in step ST2, a process of determining the elapsed time from the power-on time is performed based on the count number. As a result of this determination, while the elapsed time is less than the preset set time i seconds, the process proceeds to step ST3 to perform a series of processing for environment determination and white balance control and exposure control based on the determination result. However, in step ST2, when it is determined that the elapsed time from the power-on time is the set time i seconds or more, the process proceeds to step ST4 and the current field number is an integral multiple of a predetermined integer j, that is, It is determined whether or not jn (n is an integer) is equal. If it is equal, the process of step ST3 is performed, otherwise the process ends without performing step ST3. By these processes, the environment judgment and the white balance control and exposure control processing based on the judgment result are performed for each field for the period from the power-on time to the passage of i seconds. The environment determination and the white balance control and exposure control processing based on the determination result are performed every time. Here, if the field counter 18 is, for example, a 16-bit counter, the field counter 18 changes the number of fields from 0 to 6553.
After counting up to 6, it returns to 0 and repeats counting up to 65536 again. Also, set time i is 10 (seconds)
In the case of the NTSC method, it is possible to determine before and after the elapse of 10 seconds by determining whether the field count number is 600 or less. Furthermore, j
When 10 is set to 10 (field), after 10 seconds have passed from the time when the power was turned on, the environment judgment and the white balance control and the exposure control based on the judgment result are performed every 10 fields.

The environment determination unit 10, the field counter 18, and the operation speed control unit 19 shown in FIG. 1 can be configured by using a microcomputer and its control program, but other hardware that operates in the same manner is used. It may be configured by using. In addition, step S shown in FIG.
The determination processing of T2 and step ST4 is performed using the count number information of one field counter 18, but another field counter may be provided for the determination processing of step ST4. In this case, a separately provided field counter may be configured to reset after counting up to j fields. Further, the field counter 18 may be replaced with a general timer for implementation.

As described above, according to this embodiment, immediately after the power is turned on, it is desired to automatically control the photographing operation state so that the photographing operation state immediately matches the photographing environment. The control execution interval is shortened to increase the control operation speed, and during normal shooting after which a stable operation state is required, the environment operation and the characteristic control execution interval based on the result of the judgment are extended to increase the control operation speed. Slow down. As a result, it becomes possible to perform a control operation according to the state of the apparatus, and as a result, it becomes possible to further improve the white balance control and the exposure control.

Next, another embodiment of the present invention will be described with reference to FIGS.
This will be described with reference to FIG. This embodiment has substantially the same configuration as the embodiment shown in FIG. 1, but the operation speed control unit 19 controls the operation speed of the environment determination unit 10 based on the environment information obtained from the environment determination unit 10. Are different. In addition,
In FIG. 3, the same components as those in FIG. 1 are designated by the same reference numerals, and overlapping description will be omitted.

The control algorithm for operating speed control in this embodiment will be described below with reference to the flow chart shown in FIG. Here, it is assumed that the flowchart shown in FIG. 4 is executed once per field in synchronization with the field frequency of the television system.

First, in ST21, as in the embodiment shown in FIG. 1, the number of fields after the power is turned on is counted. Next, in step ST22, the illuminance of the subject is calculated. The calculation of the illuminance of the subject is necessary for the environment determination and is performed by the environment determination unit 10. This illuminance calculation uses the calculation method described in Japanese Unexamined Patent Publication No. 5-308563 and will not be described in detail here. After the subject illuminance is calculated, the average value of the subject illuminance in an arbitrary period is obtained in step ST23. Next, step ST2
In step 4, the average value obtained in step ST23 and the magnitude of the change amount of the current subject illuminance are determined. If the change amount is greater than a predetermined change amount, the process proceeds to step ST25 and the environment determination and white based on the determination result are performed. Performs balance control and exposure control. If the amount of change is smaller than the predetermined value, the process proceeds to step ST26 and the process of step ST25 is performed for each j field.

Here, an example of changes in the illuminance of the subject during photographing will be described with reference to FIG. A period A in FIG. 5 is a period during which outdoor shooting is performed. During this period, the illuminance of the subject changes depending on conditions such as the reflectance of the subject and the sun / shadow, but the amount of change is within a limited range. On the other hand, the period B indicates a period in which the indoors are panned indoors. In this period B, the illuminance of the subject changes greatly.
Next, the period C is a period during which indoor photography is performed, and like the period A, the amount of change is within a certain range.
Since the subject illuminance during outdoor shooting is approximately 10,000 lux or more and the subject illuminance during indoor shooting is approximately 1000 lux or less, the illuminance change determination value in step ST24 in the flowchart shown in FIG. 4 is, for example, ± 20 dB.
If set to (10 times or 1/10), in period B in FIG. 5, the environment determination operation interval is shortened to speed up the control operation, and in periods A and C, the environment determination operation interval is increased to control operation speed. Can be slowed down.

As described above, according to the present embodiment, the operation speed of the environment determination operation is increased when the shooting state changes abruptly, such as panning from the outdoors to the indoors, and otherwise the environment determination operation is performed. Decrease the operation speed. As a result, it becomes possible to perform the environment determination operation according to the shooting state, and it is possible to further improve the white balance control and the exposure control based on the environment determination operation.

In this embodiment, the operation speed of the environment determination operation is changed according to the change amount of the illuminance of the subject, but the operation of the environment determination operation is performed according to the change amount of the subject distance or the change amount of the subject color temperature. It can also be configured to change the speed.

The above-mentioned two embodiments are each configured to control the operation speed of the environment judgment according to the elapsed time after the power of the apparatus is turned on or the photographing condition. It is also possible to combine the examples. Further, although the two embodiments are configured to change the control characteristics of the white balance control and the exposure control based on the result of the environment determination, the image quality control disclosed in Japanese Patent Laid-Open No. 5-308563, etc. It is also possible to use it by changing the control characteristics of other automatic control functions such as the above, and to arbitrarily configure these automatic control functions.

The speed control of the control operation can also be realized by keeping the interval of the control operation constant and changing the control amount per time.

FIG. 6 shows an example of a VTR-integrated camera constructed by using a photographing device having the above-mentioned automatic control means. In the figure, reference numeral 21 is a photographing device as in the above-described two embodiments, and 22 is the photographing device 21.
A recording unit for recording the video signal output from the magnetic tape or the like, and a reproducing unit 23 for reproducing a television signal from the video signal recorded in the recording unit 22.

In the VTR-integrated camera constructed as described above, the automatic control functions such as white balance control, exposure control, image quality control, etc. are improved in performance as described above.
A good image can be obtained.

[0038]

As described above, according to the present invention, the speed of the control operation based on the environment judgment is changed by the operation speed control means according to the state of the apparatus and the photographing state, so that the white balance control and the exposure control are performed. It is possible to improve the performance of the automatic control functions such as the above, and always obtain a preferable shooting operation state. In particular, it shortens the time from turning on the power of the device until stable shooting is possible, improves the followability to changes in the shooting target such as panning, and is unstable due to a sensitive reaction. It is possible to prevent such a situation that a different shooting operation is performed.

[Brief description of drawings]

FIG. 1 is a block diagram of an image pickup apparatus showing an embodiment of the present invention.

FIG. 2 is a flowchart for explaining operating speed control in the image capturing apparatus shown in FIG.

FIG. 3 is a block diagram of an image pickup apparatus showing another embodiment of the present invention.

FIG. 4 is a flowchart for explaining the operation of the operation speed control in the image capturing apparatus shown in FIG.

FIG. 5 is a characteristic diagram for explaining an example of changes in subject illuminance during shooting.

FIG. 6 is a block diagram showing an example of a VTR-integrated camera using the image pickup apparatus according to the present invention.

[Explanation of symbols]

1 ... Lens, 2 ... Aperture, 3 ... Image sensor, 4 ... AGC circuit, 6 ... Signal processing circuit, 10 ... Environment determination unit, 11 ... White balance control unit, 12 ... Exposure control unit, 18 ... Field counter, 19 ... Operation speed control unit.

Claims (11)

[Claims] 1. An image pickup device for converting an optical image into an image pickup signal,
An image pickup apparatus comprising: a signal processing unit that processes the image pickup signal to generate a television signal; and an automatic control unit that determines a shooting environment and controls image pickup or signal processing characteristics based on the determination result. The automatic control means is provided with an operation speed control means for controlling the speed of the control, and a photographing apparatus. 2. The photographing apparatus according to claim 1, wherein the operation speed control means controls a cycle of the environment determination. 3. The operating speed control means according to claim 1 or 2, wherein the operation speed control means controls a speed of control characteristic change until a predetermined time elapses, and a time measuring unit for measuring an elapsed time after the power of the photographing apparatus is turned on. An imaging device comprising a speed control unit for speeding up. 4. The photographing apparatus according to claim 3, wherein the time counting unit includes a field counter, and the speed control unit changes the control characteristic changing speed with reference to the counting result of the field counter. 5. The automatic control means according to claim 1 or 2, wherein the automatic control means comprises an environment determination means, and the operating speed control means comprises:
An image pickup apparatus, characterized in that a control characteristic changing speed is changed based on environment information obtained from the environment determining means. 6. The photographing apparatus according to claim 1, wherein the automatic control means includes control means for controlling image quality control in the signal processing means. 7. The photographing apparatus according to claim 1, wherein the automatic control means includes a white balance control means for controlling a gain of a color signal. 8. The photographing apparatus according to claim 1, wherein the automatic control means includes an exposure control means for controlling an exposure amount of the image pickup device. 9. The automatic control means according to claim 1, wherein the automatic control means uses at least one or more of object distance information, lens zoom magnification information, exposure information, and time information to determine a photographing environment. An imaging device characterized by making a determination. 10. The photographing apparatus according to claim 1, wherein the automatic control means determines the photographing environment using fuzzy inference. 11. The photographing apparatus according to claim 1, further comprising a recording means for recording the television signal and a reproducing means for reproducing the recorded television signal. Shooting device.