Television – Camera – system and detail – Combined image signal generator and general image signal...
Reexamination Certificate
1997-09-02
2003-04-08
Vu, Ngoc-Yen (Department: 2612)
Television
Camera, system and detail
Combined image signal generator and general image signal...
C348S231900, C382S236000, C386S349000, C714S708000
Reexamination Certificate
active
06545709
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a wireless receiving apparatus and a method therefor, and more particularly to a technology for recording wireless transmitted image information on a recording medium.
2. Related Background Art
There is recently proposed a configuration of the video camera which is divided into a camera unit for generating image information from the optical image of the object and a recording unit for recording the image information generated by the camera unit and in which the image information of the camera unit is wireless transmitted to the recording unit.
FIG. 1
is a block diagram showing the configuration of an image pickup device
100
having the above-mentioned camera unit, and
FIG. 2
is a block diagram showing the configuration of a recording device
200
having the above-mentioned recording unit.
Referring to
FIG. 1
, there are provided a camera unit
102
for converting the optical image of the object into an electrical signal thereby generating image signal; a control unit
104
for controlling the entire image pickup device
100
, including for example focus control and exposure control; a wireless transmission circuit
106
for wireless transmission of the image signal generated in the camera unit
102
and the control signal generated in the control unit
104
to an external recording device; a wireless reception circuit
108
for demodulating the wireless signal transmitted from an external device thereby restoring the signal before transmission; an antenna
110
; a switch
112
for either (a) sending the output of the wireless transmission circuit
106
to the antenna
110
, or (b) sending the output of the antenna
110
to the wireless reception circuit
108
under the control of the control unit
104
; and a power supply unit
114
for electric power supply to the entire image pickup device
100
.
Referring to
FIG. 2
, there are provided an antenna
202
; a switch
204
for either (a) sending the output of a wireless transmission circuit
208
to the antenna
202
, or (b) sending the output of the antenna
202
to the wireless reception circuit
205
; a wireless reception circuit
206
for demodulating the wireless signal transmitted from the external image pickup device thereby restoring the signal before transmission; a wireless transmission circuit
208
for effecting a modulation process for wireless transmission of the control signal, released from a control unit
212
, to an external device; a recording unit
210
for recording the image information transmitted from the external device on a recording medium such as a magnetic tape and reproducing such recorded information; a control unit
212
for controlling the entire recording device
200
, capable of controlling the recording and reproducing operations of the recording unit by unrepresented operation keys; and a power supply unit
214
for electric power supply to the entire recording device
200
.
The above-explained configuration allows the recording device
200
to record the image information, sent by wireless transmission from the image pickup device
100
, on the magnetic tape or the like by controlling the recording unit
210
.
Also in recent years, the transmission of the image information by the spread spectrum communication methods is attracting attention for the wireless communication in such wireless system as mentioned above.
In the following there will be given a brief explanation of the direct sequence modulation, which is one of the modulation methods employed in the spread spectrum communication.
In the direct sequence modulation, the transmitting device effects diffusion modulation of the information signal to be transmitted (base band signal) by means of a series of diffusion codes such as pseudo noise (PN) codes, so as to obtain a signal of a band width which is extremely wider than that of the base band signal. The diffusion modulated signal, after the direct sequence modulation, is further modulated, for example by PSK (phase shift keying) or FSK (frequency shift keying), into a signal of a wireless frequency and is wireless transmitted.
The receiving device converts the received signal of the wireless frequency by a demodulation process, corresponding to the modulation process in the transmitting device, into the diffusion modulated signal. The receiving device further executes an inverse diffusion modulation on such diffusion modulated signal, utilizing a series of diffusion codes, same as that employed in the diffusion modulation of the transmitting device, thereby restoring the base band signal prior to the transmission.
In such spread spectrum communication utilizing the direct sequence modulation, the information signal is transmitted with a transmission band much wider than that of the original information signal. For this reason, if the transmission band width is given, the transfer rate is significantly lower than that in the ordinary wireless transmission without the diffused modulation. Consequently, the above-explained direct sequence modulation is not suitable for the high-speed transmission of a large amount of data such as image information.
The wireless communication system explained above has been associated with the following drawbacks. Because the image pickup device
100
and the recording device
200
are mutually separated, each device has to be equipped with a battery. Consequently, in the course of wireless communication of the image information between the image pickup device
100
and the recording device
200
, in a case where the image pickup device
100
develops an abnormality (for example the transmission of the image information is disabled for example by a low battery capacity of the power supply unit
114
or by cutting off of the power supply in the image pickup device
100
), the wireless reception circuit
206
and the recording unit
210
in the recording device
200
continue the process, thereby continuing the recording of the abnormal reception signal and wasting the electric power of the recording device
200
.
A similar situation arises also in a case where the image information cannot be properly received for a prolonged period by a large distance between the image pickup device
100
and the recording device
200
or by the presence of an obstacle therebetween.
SUMMARY OF THE INVENTION
An object of the present invention is to solve the above-described drawbacks.
Another object of the present invention is to provide a wireless receiving device capable of controlling the recording operation in the wireless reception device according the status of reception of the signal, thereby suppressing the wasted use of the recording medium and the wasted electric power consumption.
The above-mentioned objects can be attained, according a preferred embodiment of the present invention, by a wireless receiving apparatus for receiving a wireless transmitted information signal and recording the information signal on a recording medium through a recording unit, comprising:
a) detection means for detecting the reception status of the information signal;
b) timer means for counting time of continuation of a predetermined inferior reception status, according to the result of detection by the detection means; and
c) control means for terminating the recording operation of the recording unit in a case where the time of continuation counted by the timer means becomes at least equal to a predetermined time.
According to another embodiment, there is also provided a wireless receiving apparatus for receiving a wireless transmitted information signal and recording the information signal on a recording medium through a recording unit, comprising:
a) detection means for detecting the reception status of the information signal; and
b) control means for controlling the recording operation of the recording unit according to the result of detection by the detection means and causing information signal, received prior to the first-mentioned information signal, to be recorded on the recording m
Maeda Masamine
Takei Hirofumi
Canon Kabushiki Kaisha
Fitzpatrick ,Cella, Harper & Scinto
Vu Ngoc-Yen
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