Video camera apparatus capable of simply extracting...

Television – Camera – system and detail – Optics

Reexamination Certificate

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Details

C348S223100, C348S229100, C348S280000

Reexamination Certificate

active

06747704

ABSTRACT:

BACKGROUND OF THE INVENTION
The present invention is generally related to a video camera apparatus with using an image sensor, e.g., a CCD. More specifically, the present invention is directed to a video camera apparatus capable of simply extracting brightness information used in an auto-iris control.
In general, video camera apparatuses with employing CCDs (charge-coupled devices) as solid-state image pick-up devices are widely marketed. These video camera apparatuses are equipped with various functions, for instance, auto-iris control (automatic diaphragm control), auto-focus control, auto-white balance control, and the like. These functions are automatically controlled by employing the feedback loops.
A typical automatic function controlling arrangement of the conventional video camera apparatus is represented in FIG.
1
and FIG.
2
.
In the first circuit arrangement of
FIG. 1
, in response to imaging light entered via a lens system
21
into a CCD
22
, for example, the respective pixel signals R (red), G (green), and B (blue) are outputted from this CCD
22
.
The gains of these R, G, B pixel signals are controlled by an AGC (auto-gain control) circuit
23
, and thereafter the gain-controlled R, G, B pixel signals are converted into digital pixel data by an A/D converter
24
. Then, after the digital clamping process is performed to these digital pixel data by a clamp circuit
25
, preselected gains are applied to the respective R, G, B pixel data by a white balance amplifier
26
in order to perform the white balance.
After the gain control for the white balance control is carried out, each of the resulting pixel data is supplied to a luminance signal (Y-signal) processing circuit
27
and a chrominance signal processing circuit
28
.
In this luminance signal processing circuit
27
, the camera process operations such as the &ggr; (gamma)-correction and the white clipping are carried out with respect to the R, G, B pixel data supplied to this luminance signal processing circuit
27
, and further a luminance signal (Y-signal) is produced by executing the matrix calculation process with using the R, G, B pixel data. Thus, this luminance signal functioning as the imaging data is supplied from this luminance signal processing circuit
27
to the post-stage circuits.
Also, the chrominance signal processing circuit
28
produces color difference signals “R−Y” and “B−Y” by performing the matrix calculation process with employment of the camera-processed R, G, B pixel data, and thereafter outputs these color difference signals “R−Y” and “B−Y” to the post-staged circuits.
The gains which are applied to the respective color pixel data by the white balance amplifier
26
are controlled by the feedback loop. To execute this feedback control, it is required to detect the levels as these color signals, i.e., R (red) signal, G (green) signal, and B (blue) signal. To this end, the R signal, the G signal, and the B signal are extracted from the chrominance signal processing circuit
28
, and signal levels thereof are detected by an auto-white balance detecting unit
31
. The level information D
AWB
of the respective color pixel data are supplied to a controller
32
constituted by a microcomputer (not shown in detail), and the gains of the respective colors used in the white balance are calculated. For example, the gains with respect to the R signal and the B signal are calculated in order that both the R signal and the B signal own the same signal levels with regard to the level of the G signal under such a condition that the reference imaging object is imaged by the video camera apparatus. Then, the white-balance gain control information S
AWB
is supplied to the white balance amplifier
26
so as to control, for example, the gain of the R signal and the gain of the B signal.
On the other hand, the luminance information of the image signals are used in the auto-iris operation and the auto-focus operation. That is, the luminance signal produced in the luminance signal processing circuit
27
is extracted to be supplied to the auto-iris detecting unit
29
and the auto-focus detecting unit
30
.
In the auto-iris detecting unit
29
and the auto-focus detecting unit
30
, the diaphragm controlling information D
AE
and the focus controlling information D
AF
are extracted, and then are supplied to the controller
32
.
In response to the diaphragm (iris) controlling information D
AE
, namely the brightness information, the controller
32
supplies an iris control signal S
AE
to a timing generator
34
and an AGC circuit
23
in order to control the CCD exposure time and the gains, so that the iris control can be performed.
Also, in response to the focus controlling information D
AF
, namely, such information corresponding to the focusing condition of the lens system
21
, the controller
32
supplies a focus control signal S
AF
to a focus motor
33
so as to move a focus lens employed in the lens system
21
, so that proper focusing conditions can be realized.
FIG. 2
schematically shows another structural example of the conventional camera apparatus. It should be noted that the same reference numerals shown in
FIG. 1
will be employed as those for denoting the same, or similar circuit portions, and therefore, descriptions thereof are omitted.
In this conventional video camera apparatus, a luminance signal producing unit
35
is provided independent from the luminance signal processing circuit
27
in order to acquire brightness information and the like in the auto-iris detecting unit
29
and the auto-focus detecting unit
30
. In other words, the respective R, G, B pixel data outputted from the white balance amplifier
26
are supplied to the luminance signal producing unit
35
to thereby produce such a luminance signal used in the auto-iris detecting operation and also the auto-focus detecting operation.
The above-described conventional circuit arrangements own the below-mentioned problems.
In the case of the circuit arrangement shown in
FIG. 1
, the luminance signal used in the auto-iris detecting operation and in the auto-focus detecting operation is derived from the luminance signal processing circuit
27
. This luminance signal corresponds to such a signal produced by executing a large number of process operations to the original pixel signal in the luminance signal processing circuit
27
. As to the auto-iris operation, this auto-iris operation is preferably controlled based on the signal which is substantially equal to the original pixel signals directly outputted from the CCD
22
. However, in this conventional video camera apparatus, the luminance signal produced by executing these various process operations to the original pixel signals within the luminance signal processing circuit
27
must be employed.
On the other hand, in another conventional video camera apparatus with separately employing the luminance signal producing unit
35
as shown in
FIG. 2
, since this luminance signal producing unit
35
merely produces such a luminance signal exclusively directed to the auto-iris/auto-focus detecting purposes, the unnecessary process operations for these detecting operations can be omitted. However, in principle, this conventional video camera apparatus necessarily requires the circuit for performing the luminance signal producing calculations similar to the calculations executed in the luminance signal producing circuit
27
. In other words, since two sets of the similar circuit arrangements are required in this video camera apparatus, there is a useless circuit arrangement.
Also, in any cases of FIG.
1
and
FIG. 2
, the auto-white balance control loop is mixed with the auto-iris control loop.
In particular, it is desirable to execute the white balance control at the pre-stage circuit, rather than at the luminance/chrominance signal process operations. Accordingly, there is no way except that the luminance signal used in the iris control operation is derived at the post-stage circuit of the white balance amplifier
26
.
On the other hand, in p

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