Abstract: A storage region for storing in advance information on contrast corresponding to an angle formed by an angle adjusting mechanism and a display screen is provided in advance. When adjustment of the information on contrast corresponding to one angle is made, a difference is determined between the information on contrast corresponding to the one angle and stored in advance in the storage region and adjusted information on contrast corresponding to the one angle, and the difference is added to the information on contrast corresponding to the remaining angles and stored in advance, thereby automatically adjusting the contrast corresponding to all the angles. Accordingly, as the user or the like only effects contrast adjustment for one angle, it becomes possible to automatically effect appropriate contrast adjustment and angle-of-visibility adjustment for all directions.

Abstract: A loudness control circuit having a sound volume adjusting variable resistor with a center tap is provided. The loudness control circuit has a buffer circuit of low output impedance having an input terminal to which a sound signal is applied through a high frequency coupling capacitor. The output terminal of the buffer circuit is connected through a series circuit of a low frequency blocking capacitor, a protective resistor and a shunt resistor to the center tap of the sound volume adjusting variable resistor. The connecting point of the protective resistor and the shunt resistor is grounded through an electronic switching element. The electronic switching element is turned on and off for the on-off control of loudness.

Abstract: An automatic ejection system includes a loading device. The automatic ejection system has a grille detector for detecting the removing of a grille from a car stereo and for producing a detachment signal, a tape detector for detecting existence of a tape in the car stereo and for producing a tape signal, and ejection controller responsive to the detachment signal and the tape signal for operating the loading device so as to automatically eject the tape from the car stereo.

Abstract: A cooling unit for cooling an acoustic device installed on the vehicle by using a cooling fan comprises a cooling fan drive circuit which outputs a DC voltage proportional to the input or output signal level of the acoustic device to control the speed of rotation of the cooling fan motor, whereby the noise of the cooling fan is suppressed in a sense of hearing when no signal is provided by the acoustic device.