JPH0537866A - Video camera - Google Patents

Abstract

PURPOSE:To provide the video camera whose sensitivity is improved in an excellent way without causing saturation of the stored charge in the imaging device. CONSTITUTION:A video camera section and a photo camera section are arranged integrally in a cabinet. A photosensor 51 having a characteristic almost equal to a photosensor of each picture signal of an imaging device 12 is provided to the camera. An output of the photosensor 51 is integrated and its integration signal SIN is fed to a controller 27. The signal SIN corresponds to the stored charge of the imaging device 12. Every time a read pulse is fed to the imaging device 12, the signal SIN is reset. When the stored charge in the imaging device 12 reaches a proper amount and the signal SIN exceeds a prescribed value, a read pulse is fed from a timing generator 14 to the imaging device 12, from which an image pickup signal by one pattern is outputted. For example, when the light quantity of an object is insufficient, the storage time is extended to increase the sensitivity without causing the saturation of the stored charge of the imaging device 12.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a video camera suitable for use in taking still images.

[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, when the light quantity of the subject is insufficient, it is conceivable to increase the sensitivity by increasing the accumulation time so that the quantity of accumulated charges in the image pickup device is sufficient. Even if the accumulation time is lengthened, inconvenience such as image shift does not occur in still image capturing.

However, if the accumulation time is lengthened excessively,
Depending on the light quantity of the subject, inconvenience such as saturation of the accumulated charge of the image sensor may occur.

In view of this, the present invention provides a video camera which can favorably increase the sensitivity without causing the inconvenience such as the charge accumulated in the image sensor being saturated.

[0006]

SUMMARY OF THE INVENTION The present invention is directed to an optical sensor having substantially the same characteristics as the optical sensor of each pixel of an image sensor, an integrator for integrating an output signal of the optical sensor, and an output signal of the integrator. And a control means for supplying a read pulse to the image pickup device and resetting the output signal of the integrator when is larger than a predetermined value.

[0007]

The output signal of the integrator 52 corresponds to the amount of charge accumulated in the image pickup device 12. The predetermined value is set so that the output signal SIN of the integrator 52 exceeds the predetermined value when the accumulated charge amount of the image pickup device 12 becomes an appropriate amount. When the amount of accumulated charge of the image sensor 12 is appropriate, a read pulse is supplied to the image sensor 12, so that it is possible to increase the sensitivity by increasing the accumulation time without causing saturation of the accumulated charge.

[0008]

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 image pickup 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 for directly checking the screen imaged by the photo camera unit via the imaging lens 3.

Reference numerals 5T and 5W are zoom operation buttons for zooming 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 passes through the imaging lens 2 and the iris 11 and is a single-plate CCD solid-state imaging device (field storage type) 12 having a complementary color checkered color filter.
Is supplied to.

The zoom driver 41 adjusts the zoom magnification of the imaging lens 2. FIG. 7 shows a specific configuration of the zoom driver 41. In the figure,
Reference numeral 411 denotes a lens which 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,
Zoom magnification 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
Current flows from the terminal q1 to the motor 412 in the direction of 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 any 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, respectively, 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 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 the 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.

RY = (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 via the AGC circuit 19 to the low-pass filter 20 constituting the brightness processing section. The low-pass filter 20 performs addition processing (averaging) of signals next to each other.
Is performed. Therefore, the luminance signal Y is output from the low-pass filter 20.

Further, the image pickup signal output from the AGC circuit 19 is supplied to the sample hold circuits 21 and 22 constituting the chroma processing section. Sample and hold circuit 21,
Sampling pulses SHP1 and SHP2 (illustrated by E and F in FIGS. 5 and 6) are supplied to 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 and 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 difference signal RY is output from the subtractor 23 is b
It is connected to the side a while the horizontal difference signal − (B−Y) is output for one horizontal period. 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. Color video signal S output from the encoder 28
The CV is led to the output terminal 29.

Further, the encoder 28 outputs a monochrome video signal SV (luminance signal Y to which the synchronization 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.

Reference numeral 51 is an optical sensor having substantially the same characteristics as the optical sensor of each pixel of the image pickup device 12. The output signal of the optical sensor 51 is supplied to an integrator 52 including an operational amplifier 52a and a capacitor 52b.

Switch 5 connected in parallel with capacitor 52b
3 is connected, and on / off of the switch 53 is controlled by the controller 27. A sensitivity up mode setting switch 31 is connected to the controller 27, and the sensitivity up mode is set by turning on the setting switch 31. The switch 53 described above is turned on during the period until the end time t1 of the field where the setting switch 31 is turned on and after the end time t2 of the field where the setting switch 31 is turned off, and the capacitor 52b.
Is discharged. Further, the switch 53 is turned on at the timing when the read pulse is supplied to the image sensor 12 in the period from the time t1 to the time t2, and the capacitor 52 is turned on.
The discharge of b is performed. This discharge of the capacitor 52b resets the output signal SIN of the integrator 52 to Vb.

As described above, the optical sensor 51 has substantially the same characteristics as the optical sensor of each pixel of the image pickup device 12, and the capacitor 52b is discharged at the timing of the read pulse supplied to the image pickup device 12, so that the time t1 is reached. Output signal SIN of the integrator 52 in the period from to t2
Corresponds to the amount of charge accumulated in the image sensor 12.

The output signal SIN of the integrator 52 is supplied to the controller 27. At the controller 27, time t
In the period from 1 to t2, it is determined whether the level of the output signal SIN exceeds the predetermined value VTH. The predetermined value VTH is set to be equal to the level of the signal SIN when the accumulated charge amount of the image pickup device 12 becomes an appropriate amount.

When the level of the signal SIN exceeds the predetermined value VTH, the controller 27 supplies the read pulse generation data DSG to the timing generator 14, and the timing generator 14 synchronizes with the next vertical synchronizing signal VD. A read pulse is supplied to 12. Note that, except for the period from time t1 to time t2, the timing generator 14 supplies the read pulse to the image sensor 12 in synchronization with each vertical synchronization signal VD.

Further, in the period from time t1 to time t2, the controller 27 outputs the fetch pulse PTI in synchronization with the read pulse supplied from the timing generator 14 to the image pickup device 12. This capture pulse PTI is output from the output terminal 2 for example.
It is used to take in one screen of data to a still picture recorder (not shown) connected to 9.

In the above structure, the setting switch 31 is turned on and off as shown in FIG. 8B. Figure 8A
Indicates the vertical synchronizing signal VD. A period until the end time t1 of the field in which the setting switch 31 is turned on,
In the period after the end time t2 of the field in which the setting switch 31 is turned off, the read pulse is supplied from the timing generator 14 to the image pickup device 12 in synchronization with each vertical synchronization signal VD (shown in FIG. 8C).

As shown in FIG. 8D, the switch 5 is turned on at time t1.
When 3 is turned off, the output signal SIN of the integrator 52 gradually increases as shown in FIG. 8E. When the amount of accumulated charge of the image pickup device 12 becomes appropriate and the level of the signal SIN exceeds a predetermined value VTH, a read pulse is supplied from the timing generator 14 to the image pickup device 12 in synchronization with the next vertical synchronization signal VD ( (See Figure 8C). Then, the switch 53 is turned on at the timing of this read pulse to reset the output signal SIN of the integrator 52, and then the signal SIN gradually increases again. Thereafter, the same operation as described above is performed until the time point t2, and the read pulse is supplied from the timing generator 14 to the image pickup device 12 every time the accumulated charge amount of the image pickup device 12 becomes an appropriate amount.

Therefore, the accumulated charge in the image pickup device 12 is as shown in FIG. 8F, and the image pickup signal output from the image pickup device 12 is as shown in FIG. 8G. That is, every time the accumulated charge amount of the image pickup device 12 becomes appropriate during the period from the time t1 to the time t2, the image pickup device 12 outputs an image pickup signal for one screen in the next field, thereby forming the video signal SCV. It is led to the output terminal 29.

When the read pulse is supplied to the image sensor 12 outside the period from the time t1 to the time t2, the image pickup signal for one screen is picked up by the image sensor 12 in the next field regardless of the accumulated charge amount of the image sensor 12. Is output.

Further, the capture pulse PTI is output from the controller 27 at the timing when the read pulse is supplied to the image sensor 12 during the period from time t1 to time t2 (shown in FIG. 8H). Therefore, by using this capture pulse PTI, for example, in a still image recorder connected to the output terminal 29,
The amount of accumulated charge of the image sensor 12 is output as an appropriate amount 1
Image signals for the screen can be captured (illustrated in FIG. 8I).

As described above, in this example, the setting switch 31 is turned on to enter the sensitivity up mode,
Each time the amount of accumulated charge of the image sensor 12 becomes appropriate, an image signal for one screen is output from the image sensor 12 in the next field. Therefore, for example, when the amount of light of the subject is insufficient, it is possible to increase the accumulation time and increase the sensitivity without inducing saturation of the accumulated charges, and it is possible to favorably capture the still image.

Although the image pickup device 12 in the above-described embodiment is of the field storage type, it is needless to say that the same can be applied to the frame storage type.

Further, in the above-mentioned embodiment, the video camera and the photo camera are integrated, but the same applies to a type in which a separate photo camera is fixed to the video camera for use. be able to.

[0056]

According to the present invention, since the read pulse is supplied to the image pickup device each time the amount of accumulated charge of the image pickup device reaches an appropriate amount, the accumulation time is lengthened without causing saturation of the accumulated charge and the sensitivity is increased. You can improve. In particular, it is effective when a still image of a subject with insufficient light quantity is captured.

[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 an operation in a sensitivity up mode.

[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 Changeover switch 26 Delay circuit 27 Controller 28 Encoder 29 Output terminal 30 Electronic viewfinder 31 Sensitivity up mode setting switch 51 Optical sensor 52 Integrator

Claims (1)

Claim: What is claimed is: 1. An optical sensor having substantially the same characteristics as an optical sensor of each pixel of an image sensor, an integrator for integrating an output signal of the optical sensor, and an output signal of the integrator being a predetermined value. And a control means for supplying a read pulse to the image pickup device and resetting the output signal of the integrator when the value exceeds the value.