Abstract: A sensitivity setting device and an electrocardiograph which includes the sensitivity setting device include a differential amplifier whose amplification factor is changed by a CPU and a CR differentiator connected to the differential amplifier for providing an appropriate electrocardiogram waveform. The CR differentiator includes capacitor and two parallel resistors connected with the capacitor with one of the resistors being connected to an analog switch which is switched on/off by the CPU. If there is an input electrocardiogram waveform from a pair of electrodes attached to a patient's body directly after the measurement of the electrocardiogram waveform, the electrocardiogram waveform is amplified with an initial set amplification factor by the differential amplifier and the resulting signal is inputted to the CR differentiator.

Abstract: An image display circuit supplies gray scale data according to a video signal to a liquid crystal panel to present a gray-scaled display and scans the liquid crystal panel N times during one field period of a video signal. The image display circuit includes a table ROM comparing a current video signal with a previous video signal of one frame before, and generates gray scale data for N times in accordance with the comparison result. Gray scale data greater than the gray scale of the current video signal is generated when the comparison result indicates that the gray scale of the current video signal is greater than that of the previous video signal, and gray scale data smaller than the gray scale of the current video signal is generated when the gray scale of the current video signal is found to be smaller than that of the previous video signal. Based on the generated gray scale data, the liquid crystal panel is driven with the proper gray scales.

Abstract: In a portable electrocardiograph, a first measuring electrode that is to be held by a hand during measurement and comes into contact with the palm is provided on a body case. A second measuring electrode that to be pressed against the chest is provided on an arm member provided on the body case in foldable manner. The arm member is placed on the surface facing the body case when the arm member is folded onto the body case. Therefore, to measure electrocardiographic waves with this electrocardiograph, the user has only to slide the arm member into the opening between buttons on the front of his or her clothes or the opening in the shirt at the armpit, and then contacts the second measuring electrode with his chest for measurement. Therefore, it is not necessary to apply the apparatus perpendicularly to the chest. The user has only to place the apparatus almost in parallel to the chest and press the second measuring electrode against the left side of the heart in the chest.

Abstract: In a liquid crystal display device, to improve the contrast, the frame frequency is raised by scanning the scanning electrodes of the liquid crystal display panel a plurality of times during one field interval of the video signal. The scanning electrodes are divided into two groups, which are scanned alternately. An image memory is provided to store video signals. In scanning the liquid crystal display panel, the video signal from the video signal supplying source and the video signal read from the image memory are alternately supplied to the liquid crystal display panel. The image memory stores only part of the video signal such as the video signal for every other horizontal scanning period or the signal consisting of the most significant bit only, not the entire video signal.