Television – Camera – system and detail
Reexamination Certificate
1997-05-27
2002-10-22
Moe, Aung S. (Department: 2612)
Television
Camera, system and detail
Reexamination Certificate
active
06469736
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a video camera which controls an image pickup action by serial communication.
2. Description of the Related Art
The control operation of every electronic apparatus has recently come to be carried out by using a microcomputer. In the case of a video camera, a control device of it includes a microcomputer. The control device is generally arranged to conduct serial communication with each applicable processing circuit for various purposes. For example, the constant of a signal processing circuit is changed. Data is taken into the control device from a white balance circuit, a light measuring circuit, an automatic focusing circuit, etc. An image pickup action is controlled according to such data.
FIG. 1
is a block diagram showing by way of example the arrangement of the conventional video camera. The video camera includes a focusing lens
1
which is arranged to be movable in the direction of an optical axis. An iris
2
is arranged in rear of the focusing lens
1
to adjust the quantity of incident light. An image sensor
3
is arranged in rear of the iris
2
to have an optical image of an object of shooting formed thereon and to photo-electrically convert the optical image into a video signal. The image sensor
3
is connected to a sample-and-hold (hereinafter referred to as CDS) circuit
4
which is arranged to sample and hold the video signal obtained from the image sensor
3
. To the CDS circuit
4
is connected an analog-to-digital (A/D) converter
5
which is arranged to convert the output of the CDS circuit
4
into a digital video signal. The A/D converter
5
is connected to a signal processing circuit
6
, a light measuring circuit
7
and an automatic focusing circuit
8
which are connected in parallel to each other. The signal processing circuit
6
is arranged to set a circuit gain and to convert the video signal into a TV signal by forming luminance and chrominance signals through various processes such as a gamma correction process, a blanking process, a synchronizing signal adding process, etc. The light measuring circuit
7
is arranged to detect the quantity of light obtained when an image is picked up. The automatic focusing circuit
8
is arranged to extract a focus signal, such as a high frequency component of the video signal.
The video camera has a microcomputer
12
arranged to perform overall control over an image pickup action. To the microcomputer
12
are connected a clock generator
25
which is arranged to output clock pulses, an iris driver
9
arranged to control the iris
2
, and a motor driver
10
. To the motor driver
10
is connected a motor
11
which is arranged to drive and move the focusing lens
1
. Further, the microcomputer
12
is provided with a switch
21
which is arranged to perform switching between terminals R and S. To a common terminal of the switch
21
is connected a common terminal of another switch
28
which is arranged to perform switching between terminals A and D. A switch
24
has its common terminal connected to the terminal D of the switch
28
and is arranged to perform switching between terminals R
1
and S
1
. The connecting relation between each of these switches and other parts of the video camera is as shown in FIG.
1
. The switching actions of the switches
21
,
28
and
24
are controlled by the microcomputer
12
.
The signal processing circuit
6
includes a control shift register
13
. The light measuring circuit
7
includes a control shift register
14
and a data shift register
15
. The automatic focusing circuit
8
includes a control shift register
16
and a data shift register
17
. The terminal R
1
of the switch
24
is connected to the data terminal of the data shift register
17
and that of the data shift register
15
. The terminal S
1
of the switch
24
is connected to the data terminal of the control shift register
16
, that of the control shift register
14
and that of the control shift register
13
.
The terminal A of the switch
28
is connected to one of the data terminals of an address shift register
20
. The output terminal of the clock generator
25
is connected to the control terminal of the address shift register
20
. To the address shift register
20
are connected the input terminals of a decoder
19
. The respective control terminals of the control shift register
13
, the control shift register
14
, the data shift register
15
, the control shift register
16
and the data shift register
17
are connected to the output terminals of the decoder
19
.
The conventional video camera which is arranged as described above operates as described below:
The microcomputer
12
transfers data to the signal processing circuit
6
in the following manner: In this case, the microcomputer
12
switches the connecting position of the switch
21
to the terminal S and that of the switch
28
to the terminal A. An address signal which indicates an address of the control shift register
13
is transferred from the microcomputer
12
to the address shift register
20
in accordance with the clock pulses applied from the clock generator
25
. The decoder
19
reads the address of the control shift register
13
by decoding the address signal outputted from the address shift register
20
and supplies a setting signal to the control shift register
13
in such a way as to set the control shift register
13
into a shiftable state.
Under this condition, the microcomputer
12
switches connecting position of the switch
28
to its terminal D and that of the switch
24
to its terminal S
1
. Then, in accordance with the clock pulses from the clock generator
25
, control data is transferred from the microcomputer
12
to the control shift register
13
which has been set into the shiftable state. Then, at the signal processing circuit
6
, a TV signal is prepared by setting the circuit gain at an optimum value on the basis of the control data transferred from the microcomputer
12
to the control shift register
13
. The TV signal thus obtained is outputted.
A data transferring action to be performed between the microcomputer
12
and the light measuring circuit
7
is next described as follows: The connecting position of the switch
21
is switched to the terminal S and that of the switch
28
is switched to the terminal A also in this instance. The microcomputer
12
then transfers an address signal which indicates an address of the control shift register
14
to the address shift register
20
, according to the clock pulses coming from the clock generator
25
. The decoder
19
decodes the address signal outputted from the address shift register
20
to read the address of the control shift register
14
. The decoder
19
then supplies a setting signal to the control shift register
14
to set the control shift register
14
into a shiftable state.
Under this condition, the connecting position of the switch
28
is switched to the terminal D and that of the switch
24
is switched to the terminal S
1
. Then, light-measuring-position data is transferred from the microcomputer
12
to the control shift register
14
which has been set in the shiftable state, in accordance with the clock pulses coming from the clock generator
25
. Upon receipt of the light-measuring-position data, the light measuring circuit
7
decides a light measuring position within an image plane on the basis of the light-measuring-position data transferred to the control shift register
14
from the microcomputer
12
. A digital video signal corresponding to the light measuring position thus decided is integrated. The result of the integration process is stored in the data shift register
15
as light measurement data.
Next, the connecting position of the switch
28
is switched to the terminal A while the connecting position of the switch
21
remains at the terminal S. The microcomputer
12
then transfers an address signal indicating an address of the data shift register
15
to the address shift register
20
in accordance with the cl
Canon Kabushiki Kaisha
Moe Aung S.
Robin Blecker & Daley
LandOfFree
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