JPH05122595A - Video camera - Google Patents

Abstract

PURPOSE:To obtain a video camera which can selectively output image pickup signals in case of changing the quantity of light at an object. CONSTITUTION:A video camera part and a photo-camera part are integrally arranged in a cabinet. A level detection signal SIR for iris control and a level detection signal SAG for AGC control are supplied to a controller 27. When changing the level of the image pickup signal, the level of the signal SIR or SAG is changed as well. When the controller 27 detects the level changes of the signals SIR and SAG, video signals SCV in corresponding fields are read from a field memory 32 continuously for four fields and led through a changeover switch 31 to an output terminal 29. When a setting switch 33 is turned on, in a stroboscope fetching mode, only the video signal SCV corresponding to the object, for which the quantity of light is made sufficient by the stroboscopic light emission, can be selectively outputted through the memory 32 and only the high-quality signals can be recorded by a still picture recorder.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION This invention relates to video cameras.

[0002]

2. Description of the Related Art By using a video camera, it is possible to capture still images as well as moving images.

[0003]

In this case, for example, when the light amount of the subject is insufficient, if the image pickup signal corresponding to the subject having the sufficient light amount by the strobe emission can be selectively output, a high quality image pickup signal can be obtained. It is very convenient because only a still image recorder can record it.

Therefore, the present invention provides a video camera capable of selectively outputting an image pickup signal when the light amount of a subject changes.

[0005]

According to the present invention, a level detecting means for detecting the level of an image pickup signal output from an image pickup element, and a change in the signal level from the output signal of the level detecting means are larger than a predetermined level. And a memory control unit for controlling writing and reading of the memory based on an output signal of the level change detection unit. ..

[0006]

For example, when the amount of light of the subject is insufficient, the level of the image pickup signal of the subject for which the amount of light is sufficient due to the light emission of the strobe suddenly rises. Therefore, based on the output signal of the level change detection means, it becomes possible to selectively output, through the memory 32, only the image pickup signal of the subject whose light amount is sufficient.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. In this example, a video camera and a photo camera are integrally formed.

FIG. 1 is a perspective view showing the overall structure. In the figure, 1 is a cabinet. Although not shown, a video camera unit including an image pickup device, a signal processing circuit, and the like, and a photo camera unit including a film loading mechanism, a film driving mechanism, and the like are built in the cabinet 1.

Reference numeral 2 denotes an image pickup lens of the video camera section,
Reference numeral 3 is an imaging lens of the photo camera unit. That is, the optical system of the video camera unit and the optical system of the photo camera unit are configured separately. The imaging lens 2 has a focal length f of 7 mm to 42 m.
A 6x zoom lens of m is used. On the other hand, as the imaging lens 3, a fixed focus lens having a focal length f of 55 mm is used.

Further, in this example, an electronic viewfinder including a small CRT is provided in the cabinet 1.
A screen imaged by the video camera unit is displayed on the RT via the imaging lens 2. 4 is an eyecup. In addition,
No finder is provided to directly check the screen imaged by the photo camera unit via the imaging lens 3.

Further, 5T and 5W are zoom operation buttons for performing zoom operations in the TELE direction and the WIDE direction, respectively. Reference numeral 6 is a recording button for recording an image pickup video signal output from the video camera unit on the VTR, and 7 is a shutter button of the photo camera unit. Further, 8 is a film rewind operation button.

FIG. 2 shows the structure of the video camera section. Image light from a subject is supplied to a single-plate CCD solid-state image sensor 12 having a complementary color checker system color filter via an imaging lens 2 and an iris 11.

The zoom magnification of the image pickup lens 2 is adjusted by the zoom driver 41. FIG. 7 shows a specific configuration of the zoom driver 41. In the figure,
Reference numeral 411 denotes a lens that constitutes the imaging lens 2 and is for adjusting the zoom magnification. By moving the position of this lens 411 back and forth by rotational drive,
The zoom ratio is adjusted. For example, rotation to the T side adjusts in the TELE direction, while rotation to the W side adjusts in the WIDE direction.

The DC motor 412 drives the lens 411 to rotate. One end and the other end of the motor 412 are connected to the output terminals q1 and q2 of the zoom driver unit 413, respectively. The input terminals p1 and p2 of the zoom driver unit 413 are respectively connected to the zoom operation switch 4
2 is connected to the T-side and W-side fixed terminals.

In this case, when a high level "H" signal is supplied to the terminal p1, current flows through the motor 412 in the direction from the terminal q1 to the terminal q2 (shown by the solid line), and the lens 411 rotates in the T direction. Driven. Conversely, when a high level “H” signal is supplied to the terminal p2, the terminal q2
A current flows from the terminal q1 to the motor 412 in the direction from the terminal q1 (shown by a broken line), and the lens 411 is rotationally driven in the W direction. When a high level “H” signal is not supplied to either of the terminals p1 and p2, no current flows in the motor 412, the lens 411 is not rotationally driven in either direction, and its position is maintained. To be done.

The movable terminal of the zoom operation switch 42 is connected to the power supply terminal. Operation button 5 of the cabinet 1 described above
When pressing T or 5W, the zoom operation switch 42 is connected to the T side and the W side, respectively. Zoom operation switch 4
When 2 is connected to the T side and the W side, a high level “H” signal is supplied to the terminals p1 and p2 of the zoom driver unit 413, and zoom adjustment is performed in the TELE direction and the WIDE direction.

FIG. 3 is a schematic diagram of color coding of the image pickup device 12. As shown in the figure, field reading is performed. In the A field, charges are mixed in pairs such as A1 and A2, and in the B field, charges are mixed in pairs such as B1 and B2. Then, from the horizontal shift register Hreg, A1, A2, ...
.. in the order of B, B1, B2, ...

Here, the order of charges a, b, ... Is (Cy +) in line A1 as shown in FIG.
G), (Ye + Mg), ..., (Cy + Mg), (Ye + G), ... on the A2 line, and (G + Cy), (Mg + Y) on the B1 line.
e), ..., and in the B2 line, (Mg +
Cy), (G + Ye), ...

Returning to FIG. 2, the electric charge output from the image pickup device 12 as described above is supplied to the CDS circuit (correlated double sampling circuit) 13 and taken out from the CDS circuit 13 as an image pickup signal. By using this CDS circuit 13, reset noise can be reduced as is well known.

Timing pulses necessary for the image pickup device 12 and the CDS circuit 13 are supplied from a timing generator 14. The timing generator 14 has 8
Reference clock CK0 of fsc (fsc is color subcarrier frequency)
And the horizontal and vertical sync signals HD and VD are supplied from the sync generator 16. On the other hand, the synchronization generator 1
6 is a clock CK of 4 fsc from the timing generator 14.
1 is supplied.

The image pickup signal output from the CDS circuit 13 is supplied to the level detection circuit 17, and the output signal of this detection circuit 17 is supplied to the iris driver 18. And
The iris driver 18 automatically controls the aperture of the iris 11.

Now, a process for obtaining the luminance signal Y and the chroma signal (color difference signal) from the image pickup signal output from the CDS circuit 13 will be described.

The luminance signal Y is obtained by adding the adjacent signals. In FIG. 4, a + b, b +
The addition signals of c, c + d, d + e, ... Are sequentially formed.

For example, the A1 line is approximated by the following equation. Here, Cy = B + G, Ye = R + G, Mg
= B + R.

Y = {(Cy + G) + (Ye + Mg))} × 1/2 = (2B + 3G + 2R) × 1/2 Further, the A2 line is approximated by the following equation.

Y = {(Cy + Mg) + (Ye + G))} × 1/2 = (2B + 3G + 2R) × 1/2 Other lines of the A field and lines of the B field are similarly approximated.

The chroma signal is obtained by subtracting adjacent signals.

For example, the A1 line is approximated by the following equation.

R−Y = (Ye + Mg) − (Cy + G) = (2R−G) Further, the A2 line is approximated by the following equation.

-(BY) = (Ye + G)-(Cy-Mg) =-(2B-G) The red difference signal R-Y and the red difference signal R-Y are similarly applied to the other lines of the A field and the line of the B field. The blue difference signal- (BY) is obtained line-sequentially and alternately.

Returning to FIG. 2, the image pickup signal output from the CDS circuit 13 is supplied to the AGC amplifier 19a. The output signal of the AGC amplifier 19a is the level detection circuit 19b.
The output signal of the detection circuit 19b is supplied to the AGC amplifier 19a as a control voltage via the buffer 19c. For example, the control voltage changes in the range of 2 to 4V, and the gain of the AGC amplifier 19a is correspondingly 10
˜29 dB (illustrated in FIG. 8). In this case, the control voltage is constant at 2V during the operation period of the iris 11.

The image pickup signal output from the AGC amplifier 19a is supplied to the low-pass filter 20 which constitutes the brightness processing section. The low-pass filter 20 performs an addition process (averaging) of adjacent signals. Therefore, the luminance signal Y is output from the low-pass filter 20.

Further, the image pickup signal output from the AGC amplifier 19a is supplied to the sample hold circuits 21 and 22 constituting the chroma processing section. Sample and hold circuit 2
Sampling pulses SHP1 and SHP2 (illustrated by E and F in FIGS. 5 and 6) are supplied to timings 1 and 22 from the timing generator 14.

From the sample hold circuit 21, (Cy
A continuous signal S1 of + G) or (Cy + Mg) is output and supplied to the subtractor 23 (shown in FIGS. 5B and 6B). From the sample hold circuit 22, (Ye + M
g) or (Ye + G) continuous signal S2 is output and supplied to the subtractor 23 (shown in FIGS. 5C and 6C).

The subtractor 23 subtracts the signal S1 from the signal S2. Therefore, the subtractor 23 outputs the red color difference signal RY and the blue color difference signal-(BY) alternately line-sequentially (shown in FIGS. 5D and 6D).

The color difference signal output from the subtracter 23 is directly supplied to the fixed terminal on the b side of the changeover switch 24 and the fixed terminal on the a side of the changeover switch 25, and has a delay circuit having a delay time of one horizontal period. It is supplied to the fixed terminal on the a side of the changeover switch 24 and the fixed terminal on the b side of the changeover switch 25 via 26.

The changeover of the changeover switches 24 and 25 is controlled by the controller 27. That is, one horizontal period in which the red color difference signal RY is output from the subtractor 23 is b
It is connected to the side a, and on the other hand, it is connected to the side a during one horizontal period in which the blue color difference signal-(BY) is output. The controller 27 is supplied with the synchronization signals HD and VD from the synchronization generator 16 as reference synchronization signals and the clock CK1 from the timing generator 14.

Since the changeover switches 24 and 25 are changed over as described above, the changeover switch 24 outputs the red color difference signal RY in each horizontal period, and the changeover switch 25 outputs the blue color difference signal − (in each horizontal period. BY) is output.

The luminance signal Y output from the low-pass filter 20 and the color difference signals (RY) and-(BY) output from the changeover switches 24 and 25 are supplied to the encoder 28. The encoder 28 is supplied with the composite sync signal SYNC, the blanking signal BLK, the burst flag signal BF and the color subcarrier signal SC from the sync generator 16.

In the encoder 28, as is well known, the synchronizing signal SYNC is added to the luminance signal Y and the chrominance signal is quadrature two-phase modulated to form the carrier color signal C, and the color burst signal is added. .. And
The luminance signal Y and the carrier color signal C are added to form a color video signal SCV of the NTSC system, for example.

The color video signal SCV is supplied to the fixed terminal on the side a of the changeover switch 31. The color video signal SCV is supplied to the field memory 32 as a write signal, and its read signal is supplied to a fixed terminal on the b side of the changeover switch 31. Then, the output signal of the changeover switch 31 is led to the output terminal 29.

Further, the encoder 28 outputs a monochrome video signal SV (luminance signal Y to which the synchronizing signal SYNC is added), and the monochrome video signal SV is supplied to the electronic viewfinder 30 to display an image pickup screen on a small CRT. To be done.

The detection signals SIR and SAG from the level detection circuits 17 and 19b are supplied to the controller 27.
The controller 27 detects a level change of the image pickup signal when the strobe capture mode setting switch 33 (not shown in FIG. 1) is turned on to enter the strobe capture mode.

FIG. 9 shows the configuration of the level change detection section provided in the controller 27. In the figure, the detection signal SIR from the level detection circuit 17 is supplied to the inverting input terminal of the DC amplifier 51. The volume 52 is for adjusting the offset voltage, and the voltage obtained at the mover is supplied to the non-inverting input terminal of the DC amplifier 51.

In this case, the output signal of the DC amplifier 51 changes in the range of 1.5 to 4 V, for example, in response to the change of the detection signal SIR. By adjusting the mover position of the volume 52, the input / output characteristics of the DC amplifier 51 can be changed as shown in FIG.

The output signal of the DC amplifier 51 is the comparator 53.
Is supplied to the inverting input terminal of and the delay circuit 55 having the delay time τ. Here, the delay time τ is set shorter than the time constant of the level detection circuit 17. In this example, the time constant of the level detection circuit 17 is one vertical period, and is set to τ = 1 msec, for example.

The output signal of the delay circuit 55 is supplied to the non-inverting input terminal of the comparator 53 via the -E voltage shift circuit 56, and the output signal of the comparator 53 is supplied to the OR gate 63. Here, E has a magnitude corresponding to the level difference with which the comparator 53 can stably determine the magnitude, and is set to 0.1 V in this example.

The detection signal SAG from the level detection circuit 19b is supplied to the inverting input terminal of the comparator 58 and the delay circuit 60 having the delay time τ. here,
The delay time τ is set shorter than the time constant of the level detection circuit 19b. In this example, the time constant of the level detection circuit 19b is one vertical period, and is set to τ = 1 msec, for example.

The output signal of the delay circuit 60 is supplied to the non-inverting input terminal of the comparator 58 via the -E voltage shift circuit 61, and the output signal of the comparator 58 is supplied to the OR gate 63. Here, E has a magnitude corresponding to a level difference with which the comparator 58 can stably determine the magnitude, and is set to 0.1 V in this example.

In the above configuration, the AGC amplifier 19a
Consider a case where the output image pickup signal changes as shown in FIG. 11B. FIG. 11A shows the vertical synchronizing signal VD.

During the iris operation period (the gain of the AGC amplifier 19a is constant at 10 dB), the output signal of the DC amplifier 51 changes as shown by the solid line a in FIG. 11C, and the output signal of the shift circuit 56 shows by the broken line b in FIG. It changes as shown in.

As a result, the time from the time t1 to τ when the level of the image pickup signal changes in the direction of increasing becomes larger than the signal supplied to the non-inverting input terminal of the comparator 53 than the signal supplied to its inverting input terminal. Therefore, a high level signal is output from the comparator 53 (illustrated in FIG. 11D).

The input / output characteristics of the DC amplifier 51 can be changed by adjusting the mover position of the volume 52 as described above. Therefore, the detection signal SIR
Can be saturated on the large level side or the small level side, the change in the imaging signal in that portion can be ignored, and the generation of the level change detection pulse PCD can be suppressed.

Further, during the AGC operation period (iris 11 is open), the detection signal SAG of the level detection circuit 19b is as shown in FIG.
1E changes as shown by the solid line a, and the shift circuit 6
The output signal of 1 changes as shown by the broken line b in the figure.

As a result, the time from time t2 to τ when the level of the image pickup signal changes in the direction of increasing becomes larger than the signal supplied to the non-inverting input terminal of the comparator 58 than the signal supplied to the inverting input terminal thereof. Therefore, a high level signal is output from the comparator 58 (illustrated in FIG. 11F).

Thus, the iris operation period and AGC
In each of the operation periods, when the level of the image pickup signal changes in the direction of increasing, a high level “H” signal is output from the comparators 53 and 58, and this is output from the OR gate 63 as the level change detection pulse PCD (FIG. 11G
(Illustrated in).

Returning to FIG. 2, writing and reading of the field memory 32 are controlled by the controller 27 via the memory controller 34, and switching of the changeover switch 31 is controlled by the controller 27. That is,
Until the field in which the level change detection pulse PCD of the high level "H" is detected, the field memory 32 is in the writing state and the changeover switch 31 is connected to the a side. And 4 fields from the following field
The memory 32 is in a read state, and the changeover switch 31 is connected to the b side. Further, from the subsequent field, the memory 32 is set to the writing state, and the changeover switch 31 is connected to the a side.

Here, FIG. 12A shows a vertical synchronizing signal VD, FIG. 12B shows a read pulse of the image pickup device 12, FIG. 12C shows accumulated charges in each field of the image pickup device 12, and FIG. 12E shows an image pickup signal of each field. I shall. As shown in FIG. 12D, when the strobe emits light corresponding to the nth field, the level of the image pickup signal corresponding to the nth field changes in the direction of increasing (illustrated in FIG. 12F).

Therefore, the level change detection section of the controller 27 outputs the level change detection pulse PCD corresponding to the image pickup signal of the nth field (shown in FIG. 12G). Therefore, the memory 32 up to the signal of the nth field
The signal of the nth field is repeatedly read from the memory 32 in the subsequent 4 fields, and is sequentially updated and written again in the memory 32 from the signal of the (n + 5) th field (shown in FIG. 12H).

Further, the change-over switch 31 is connected to the b side only during the period of 4 fields in which the memory 32 is in the read state, and is connected to the a side during the other periods (shown in FIG. 12I). Therefore, the changeover switch 31 outputs signals in the order shown in FIG. 12J. That is, the signal of the nth field corresponding to the stroboscopic light emission is continuously output for four fields.

Although not shown, a VTR or a still picture recorder is connected to the output terminal 29 for recording. When recording with a still image recorder, a high-quality signal from a subject with a sufficient amount of light can be recorded by capturing a signal corresponding to the above-mentioned four-field period.

As described above, according to this embodiment, for example, when the light amount of the subject is insufficient, the video signal SC for one field of the subject for which the light amount is sufficient due to the light emission of the strobe light.
V is continuously output from the memory 32 for four fields, and this is selectively led to the output terminal 29. Therefore,
For example, a still image recorder can record only a high-quality video signal SCV from a subject having a sufficient amount of light.
Here, the stroboscopic light emission is not limited to that of the self, but the stroboscopic light emission of another person can be used.

In the above embodiment, the continuous period of the video signal SCV corresponding to strobe light emission is set to 4 fields, but the invention is not limited to this.
It can be made longer.

Further, in the above-described embodiment, it is detected that the level of the image pickup signal is changed in the direction of increasing, and thereby the corresponding video signal SCV is selectively output. On the contrary, the level of the image pickup signal is reversed. The same operation can be performed by detecting a change in the small direction. Accordingly, when the state of the subject changes and the level of the image pickup signal changes, the corresponding video signal SCV can be selectively output, which is also suitable as a surveillance video camera.

[0065]

According to the present invention, when the state of the subject changes and the level of the image pickup signal changes, it is possible to selectively output the corresponding image pickup signal. As a result, only the image pickup signal corresponding to the change in the state of the subject can be recorded by the still image recorder, which is suitable as a surveillance video camera. In addition, only the image pickup signal of the subject whose light quantity is sufficient due to the strobe emission can be selectively output through the memory, and only the high quality image pickup signal can be recorded by the still image recorder.

[Brief description of drawings]

FIG. 1 is a perspective view showing an appearance of an embodiment.

FIG. 2 is a diagram showing a configuration of a video camera unit.

FIG. 3 is a schematic diagram of color coding.

FIG. 4 is a diagram showing an output of a horizontal output register.

FIG. 5 is a diagram for explaining color signal processing.

FIG. 6 is a diagram for explaining color signal processing.

FIG. 7 is a diagram showing a configuration of a zoom driver.

FIG. 8 is a diagram showing a gain control characteristic of an AGC amplifier.

FIG. 9 is a diagram showing a configuration of a level change detection unit.

FIG. 10 is a diagram showing input / output characteristics of a DC amplifier.

FIG. 11 is a diagram showing a level change detection operation.

FIG. 12 is a diagram for explaining an output signal.

[Explanation of symbols]

 1 Cabinet 2, 3 Imaging Lens 4 Eye Cup 5T, 5W Zoom Operation Button 6 Recording Button 7 Shutter Button 12 CCD Solid State Imaging Device 14 Timing Generator 16 Synchronization Generator 20 Low Pass Filter 21 and 22 Sample Hold Circuit 23 Subtractor 24, 25 , 31 Changeover switch 26 Delay circuit 27 Controller 28 Encoder 29 Output terminal 30 Electronic viewfinder 32 Field memory 33 Strobe capture mode setting switch 34 Memory controller

Claims (1)

[Claims] 1. A level detecting means for detecting a level of an image pickup signal outputted from an image pickup element, and a level change detecting means for detecting that a change in signal level is larger than a predetermined level from an output signal of the level detecting means. A video camera comprising: a memory for storing at least one screen of the image pickup signal; and memory control means for controlling writing and reading of the memory based on an output signal of the level change detection means.