Abstract: An electronic endoscope system which captures an image of an object and displays the same on a display device is provided with a noise reduction system. The noise reduction system reduces noise included in a frame of an image signal for each color component. The noise-reduced color components are stored in a buffer, and then output as a video signal to be transmitted to a display where a color image of the object is displayed.

Abstract: A video-signal processing device is connectable to an electronic endoscope for feeding at least one kind of electric analog video signal from the electronic endoscope to a peripheral equipment. The video-signal processing device has a photo-coupler or a transformer coupler for making it possible to input the electric analog color video signal from the electronic endoscope to the video-signal processing device, whereby the electronic endoscope is electrically insulated from the peripheral equipment for an electrical security. Also, the video-signal processing device has an analog-to-digital converter for converting the electric analog video signal into a parallel electric digital video signal, a parallel-to-serial converter for converting the parallel electric digital video signal into a serial electric digital video signal, and an electrical-optical converter for converting the serial electric digital video signal into a serial optical digital video signal.

Abstract: A video-signal processing device connectable to an electronic endoscope capable of outputting a component-type electric analog color video signal. An analog-to-digital converter converts video-signal components of the component-type video signal into parallel digital color video-signal components. A color-conversion digital matrix circuit produces a parallel digital luminance signal-component, and two kinds of parallel digital color-difference signal-components based on the parallel digital color video-signal-components. A parallel-to-serial converter converts the luminance signal-component and digital color-difference signal-components into serial digital color video-signal-components. The electric analog video signal outputted from the electronic endoscope is fed outside the device as the serial electric digital video signal.

Abstract: A video-signal processing device is connectable to an electronic endoscope designed to output at least one kind of electric analog video signal, and comprises: an analog-to-digital converter for converting the electric analog video signal into a parallel electric digital video signal; and a parallel-to-serial converter for converting the parallel electric digital video signal into a serial electric digital video signal, whereby the electric analog video signal outputted from the electronic endoscope is fed outside from said device as the serial electric digital video signal.

Abstract: A video-signal processing device connectable to an electronic endoscope capable of outputting a component-type electric analog color video signal. An analog-to-digital converter converts video-signal components of the component-type video signal into parallel digital color video-signal components. A color-conversion digital matrix circuit produces a parallel digital luminance signal-component, and two kinds of parallel digital color-difference signal-components based on the parallel digital color video-signal-components. A parallel-to-serial converter converts the luminance signal-component and digital color-difference signal-components into serial digital color video-signal-components. The electric analog video signal outputted from the electronic endoscope is fed outside the device as the serial electric digital video signal.

Abstract: An electronic endoscope has an image sensor for converting an optical image into analog electric image-pixel signals, and an analog-to-digital converter for converting the analog electric image-pixel signals into digital electric image-pixel signals on the basis of a first series of clock pulses. A number of the converted digital electric image-pixel signals included in a one-horizontal-scanning-line being is based upon a frequency of the first series of clock pulses. The endoscope has a pixel-number converter for converting the number of the converted digital electric image-pixel signals into another number of digital image-pixel signals so as to enable the digital electric image-pixel signals to be externally outputted on the basis of a second series of clock pulses having a frequency different from that of the first clock pulses.

Abstract: A video-signal processing device is connectable to an electronic endoscope designed to output at least one kind of video signal, and comprises a character-information signal producer for producing a character-information signal on the basis of character-code data, and an adder for adding the character-information signal to the video signal outputted from the electronic endoscope, whereby the video signal carrying the character-information signal is fed outside from the device. When the endoscope further outputs a control signal in response to a turning-ON of a function switch thereof, the device comprises a memory for storing fixed character-code data; and a memory-reader for reading the fixed character-code data from the memory in response to the control signal outputted from the endoscope. The character-information signal producer produces a fixed character-information signal on the basis of the fixed character-code data read from the memory.

Abstract: A battery charger used to charge a battery has a voltage detector for detecting a voltage across a battery, a memory for storing detected voltage values, and a comparator for comparing a presently detected voltage with a previously stored voltage. If the detected voltage decreases below a certain value before a predetermined period of time elapses, it is determined that a battery that has been in storage for a long period of time is connected to the battery charger. The battery charger will then apply a constant current to the battery until a second predetermined period of time has elapsed.