Television – Camera – system and detail – Remote control
Reexamination Certificate
1996-08-05
2001-12-11
Garber, Wendy R. (Department: 2612)
Television
Camera, system and detail
Remote control
C348S211130
Reexamination Certificate
active
06330027
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a video input apparatus having separated camera unit and image processing unit connected with each other via a cable.
2. Related Background Art
A conventional video input apparatus having separated camera unit and image processing unit, can replace its camera unit depending upon user's needs. Expensive components such as signal processing circuits and frame memories are used in the image processing unit, and the camera unit can be supplied at low cost.
FIG. 9
is a block diagram showing the structure of a conventional video input apparatus of a camera unit separation type. In
FIG. 9
, reference numeral
100
represents a camera unit, and reference numeral
200
represents an image processing unit. The camera unit
100
and image processing unit
200
are connected by a cable
300
which is detachably connected to a connector
127
of the camera unit
100
and a connector
238
of the image processing unit
200
. Reference numeral
400
represents a host terminal which controls the camera unit
100
and image processing unit
200
and fetches a picked-up image.
In the camera unit
100
, reference numeral
124
represents a system control unit made of a one-chip microcomputer having a CPU (central processing unit), a ROM (read-only memory), a RAM (random access memory), and functions of, for example, a control board and a communication board. Reference numeral
120
represents a pickup lens, reference numeral
121
represents an image pickup element such as a CCD, reference numeral
123
represents an image pickup element driving circuit such as a TG (timing generator) which controls the accumulation operation, read operation, and reset operation of the image pickup element
121
in response to control signals from the system control unit
124
to thereby change the shutter speed. Reference numeral
122
represents an S/H AGC circuit for a sampling and holding operation to reduce noises of accumulated charges and for a gain adjustment operation of an image pickup signal in response to control signals from the system control unit to thereby change the gain of the image pickup signal
125
. The image pickup signal
125
is supplied via the cable
300
to a signal processing circuit
230
of the image processing unit
200
. Reference numeral
126
represents a data line which is connected between the system control unit
124
and the connector
127
, the data being transferred via the cable
300
to a system control unit
233
of the image processing unit
200
.
In the image processing unit
200
, reference numeral
233
represents the system control unit made of a one-chip microcomputer having a CPU, a ROM, a RAM, and functions of, for example, a control board and a communication board. The system control unit
233
performs a control of each device of the image processing unit
200
, a control of an auto-white balance, a communication to and from the camera unit
100
, and a communication to and from the host terminal
400
via a bus I/F circuit
235
. The image processing unit
200
can be detachably mounted on an expansion slot of a computer as a PC card or a signal processing board. For this mount, the bus I/F circuit
235
is used.
Reference numeral
230
represents the signal processing unit which converts an analog video signal on the image pickup signal line
236
transferred from the camera unit
100
via the cable
300
, into a standardized digital video signal. Reference numeral
231
represents an encoder circuit which converts the standardized digital video signal into a multiplexed composite signal which is output from a video signal output connector
234
. Reference numeral
232
represents a memory circuit which stores a digital video signal from the signal processing circuit
230
and host terminal
400
and controls an image memory read/write. The bus I/F circuit
235
is connected to a bus of the host terminal
400
. The bus I/F circuit
235
transfers the digital video signal and control data between the host terminal
400
and image processing unit
200
, and controls the memory circuit
232
in response to an instruction from the host terminal
400
. Reference numeral
237
represents a data/control line which is used for bidirectional data communications between the host terminal
400
and image processing unit
200
, and is connected to a control port of the system control unit
233
.
With the video input apparatus constructed as above, the operations of the camera unit
100
and image processing unit
200
can be controlled by the host terminal
400
via the bus I/F circuit
235
. For example, in order to change a shutter speed, a shutter speed control command is transferred from the host terminal
400
via the data line
237
of the bus I/F circuit
235
to the system control unit
233
of the image processing unit
200
. The system control unit
233
analyzes the received command, and if it is a shutter speed control command, this command is supplied via the data line
126
of the cable
300
to the system control unit
124
of the camera unit
100
. Upon reception of this command, the camera unit
100
controls the image pickup element driving circuit
123
to change the shutter speed.
The data transfer procedure of the system control units
233
and
124
of the image processing unit
200
and camera unit
100
is illustrated in FIG.
10
. Referring to
FIG. 10
, when the system control unit
124
of the camera unit
100
receives command data from the system control unit
233
of the image processing unit
200
(S
1001
), it is checked whether there is any error such as a check sum error, and if an error is detected, an abnormal reception notice is supplied to the system control unit
233
of the image processing unit
200
by using an ACK (acknowledge) frame (S
1001
). Upon reception of the abnormal reception notice, the system control unit
232
of the image processing unit
200
retransmits the command (S
1003
, S
1005
). If an error is not detected, a normal reception notice is supplied to the system control unit
233
of the image processing unit
200
by using the ACK frame (S
1006
). If an error is detected, an abnormal reception notice is supplied to the system control unit
233
of the image processing unit
200
by using an ACK frame (S
1002
, S
1004
).
As above, by detecting an error of data transmission and retransmitting a command when an error is detected, the host can control the camera unit
100
reliably.
The conventional apparatus described above is, however, associated with the following problem. In optimizing a video signal of the camera unit
100
with an AF (auto focus) control function and an AE (auto exposure) control function, it is necessary to read the frequency characteristics and luminance data of a subject necessary for optimization, from the signal processing circuit
230
of the image processing unit
200
and to transmit the read data to the camera unit
100
for the feedback control. This data is read from the signal processing circuit
200
synchronously with the V (vertical) sync signal of video synchronization, and is therefore called V sync data. Data transmission interval is short while this V sync data is transmitted from the image processing unit
200
to the camera unit
100
. Therefore, if the procedure of error detection and retransmission illustrated in
FIG. 10
is used, the timing of data transmission may be lost.
SUMMARY OF THE INVENTION
The invention has been made in consideration of the above problem. It is an object of the present invention to provide an image input apparatus capable of optimizing an error recovery process during data transmission between a camera unit and an image processing unit.
In order to achieve the above object, the present invention provides an image input apparatus having separated camera unit and image processing unit connected with each other by a cable, comprising data transmission/reception means for transferring data between the camera unit and image processing unit; first frame
Canon Kabushiki Kaisha
Garber Wendy R.
Moe Aung S.
Morgan & Finnegan , LLP
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