Electronic endoscope apparatus which superimposes signals on power supply
View Patent ↗An electronic endoscope apparatus has a single coaxial cable installed between a scope A and a processor unit B. Waveform superimposing circuits superimpose a video signal on power transmitted through the coaxial cable and sequentially superimpose scope-side reference pulses and processor-side reference pulses alternately on horizontal scanning blanking periods in one field of the video signal. At the same time, the scope A and processor unit B generate reference signals and various timing signals synchronized with the reference pulses of the counterpart and perform video processing based on them. This enables accurate sampling even when scopes with different pixel counts are used. Also, a scope information signal and electronic shutter control signal may be superimposed on a predetermined blanking period in the video signal. Alternatively, an electromagnetic coupler may be installed instead of the coaxial cable and the video signal and reference pulses may be superimposed on AC power supplied electromagnetically.
1. An electronic endoscope apparatus comprising:
an electronic endoscope equipped with an image pickup device;
a main unit which is connected with the electronic endoscope and includes a processor unit;
a sample/hold circuit which samples and holds a video signal obtained by the image pickup device;
a common power/signal line which connects the electronic endoscope with the main unit;
a power supply circuit which is installed in the main unit and supplies power to the electronic endoscope via the common power/signal line;
a scope-side waveform superimposing circuit which superimposes a video signal obtained by the image pickup device on the power transmitted through the common power/signal line and superimposes scope-side reference pulses on a plurality of horizontal scanning blanking periods in a field or frame of the video signal;
a processor-side waveform superimposing circuit which superimposes processor-side reference pulses on a plurality of horizontal scanning blanking periods that exist in a field or frame of the video signal supplied via the common power/signal line and that are not superimposed with the scope-side reference pulses;
a processor-side separating circuit which separates the video signal and scope-side reference pulses superimposed on the common power/signal line;
a processor-side synchronizing signal generator which forms a signal synchronized with the scope-side reference pulses outputted from the processor-side separating circuit;
a scope-side separating circuit which separates the processor-side reference pulses superimposed on the common power/signal line; and
a scope-side timing generator which forms a signal synchronized with the processor-side reference pulses outputted from the scope-side separating circuit.
2. The electronic endoscope apparatus according to claim 1 , wherein oscillation frequency of an oscillator installed in the processor-side synchronizing signal generator differs from oscillation frequency of an oscillator installed in the scope-side timing generator.
3. The electronic endoscope apparatus according to claim 2 , wherein a crystal oscillator is installed in one of the processor-side synchronizing signal generator and the scope-side timing generator and an LCR oscillator is installed in the other of them.
4. The electronic endoscope apparatus according to claim 1 , comprising:
an electromagnetic coupler which is installed instead of the common power/signal line and connects the electronic endoscope and the main unit electromagnetically; and
a power supply circuit which is installed in the main unit and supplies AC power to the electronic endoscope via the electromagnetic coupler,
wherein the video signal, scope-side reference pulses, and processor-side reference pulses are superimposed on the AC power.