Ricoh Company, Ltd.

Subaru Corporation

Tomoatsu Imamura

Toshitaka Senma

Kazuyuki Shimada

Nobuo Iwata

Hiroyuki Suzuki

Masumi Sato

Tomonori Tanaka

Shigeyuki Araki

Takamasa Hayashi

Toshiya Tateishi

Yukihito Inaba

Takeki Nemoto

Masahiro Yoshimi

An onboard device includes a first cover member having a first abutment surface, a second cover member having a second abutment surface abutting on the first abutment surface and an internal space for housing an electrical apparatus with the first cover member, a transmission portion that is formed in one or both of the first and second cover members, extends, from the first and second abutment surfaces, outward in an abutment direction in which the first and second abutment surfaces abut against each other and transmits sound more easily from the internal space to outside of the first and second cover members than adjacent regions in the first and second cover members, and a soundproof cover that has a through-hole penetrating in the abutment direction. The first abutment surface, the second abutment surface, and the transmission portion are located inside the through-hole.

Onboard device

An image forming apparatus capable of changing the diameter of a dot in the main and subscanning directions to form various kinds of dots and thereby high resolution images with tones. A data converting circuit separates input image data into pulse width modulation data and power modulation data and distributes them to a pulse width modulating circuit and a power modulating circuit. The pulse width modulating circuit changes the duration of a laser beam issuing from a laser diode to change the diameter of a dot in the main scanning direction. The power modulating circuit changes the exposing energy of the laser beam per unit area and unit time in order to change the dot diameter in the subscanning direction. The modulating circuits control an image writing device in cooperation so as to produce a high resolution image with tones.

Image forming apparatus capable of forming an image by dots having

A semiconductor laser unit includes a casing, a printed circuit board fastened to the casing, and a laser diode unit which includes a laser diode and a photodiode for monitoring a laser beam emitted from the laser diode. The laser diode unit is accommodated in the casing. The semiconductor laser unit also includes a monitor output amplifier for amplifying an output signal of the photodiode, and a reference voltage generator for generating a reference voltage signal which is to be compared with an output voltage signal of the monitor output amplifying means in order to set a light intensity of the laser beam to a predetermined value.

Semiconductor laser unit

A semiconductor laser control apparatus for controlling an intensity of light emitted from a semiconductor laser by controlling a drive current to by supplied to the semiconductor laser, includes a first circuit which roughly determines a first value of the drive current so as to obtain a intensity of light near a desired intensity of light emitted from the laser diode, a second circuit which precisely determines a second value of the drive current so as to obtain the desired intensity of light, after determining the first value of the drive current by the first circuit, and an adder which adds the first value of the drive current determined by the first circuit and the second value of the drive current determined by the second circuit. The drive current having an added value is supplied to the semiconductor laser.

Semiconductor laser control apparatus

A photoelectric transducer (14) produces first and second periodic signals (A), (B) which are 90.degree. out of phase with each other in response to rotation of a servo motor shaft (12a). The first and second signals (A), (B) are differentiated, directly full wave rectified and summed to produce a velocity signal (Vw-) having a magnitude proportional to the rotational velocity of the shaft (12a). The peaks of the first and second signals (A), (B) are detected to produce a reference signal (Vr) having a magnitude corresponding thereto. The magnitude of the reference signal (Vr) is reduced in accordance with the difference between the present position of the shaft (12a) and a command position to produce a velocity command signal (Vc+). The velocity signal (Vw-) is compared with the velocity command signal (Vc+), to produce a drive signal corresponding to the difference therebetween which is applied to the motor (12). Fluctuations in the amplitude, D. C. component and phase of the first and second signals (A), (B) affect the reference signal (Vr) and the velocity signal (Vw-) equally and are thereby cancelled out. The reference signal Vr is also applied to compensate the signals (A) and (B) for variations in phase and the like to produce accurate position pulses. A drive means (27) for the motor (12) includes a hybrid chopper and dropper amplifier and means for eliminating audible chopper sound.

Stabilized servo motor positioning apparatus

A photoelectric transducer (14) produces first and second periodic signals (A), (B) which are 90.degree. out of phase with each other in response to rotation of a servo motor shaft (12a). The first and second signals (A), (B) are differentiated, directly full wave rectified and summed to produce a velocity signal (Vw+), (Vw-) having a magnitude proportional to the rotational velocity of the shaft (12a). The peaks of the first and second signals (A), (B) are detected to produce a reference signal (Vr) having a magnitude corresponding thereto. The magnitude of the reference signal (Vr) is reduced in accordance with the difference between the present position of the shaft (12a) and a command position to produce a velocity command signal (Vc+), (Vc-). The velocity signal (Vw+), (Vw-) is compared with the velocity command signal (Vc+), (Vc-) to produce a drive signal corresponding to the difference therebetween which is applied to the motor (12). Fluctations in the amplitude, D.C. component and phase of the first and second signals (A), (B) affect the reference signal (Vr) and the velocity signal (Vw+), (Vw-) equally and are thereby cancelled out.

A monolithic photosensor array comprises first, second and third identical photodiodes. A light emitting diode illuminates the third photodiode continuously. An occluder disc is rotatably driven from the shaft of a servo motor between the light emitting diode and the first and second photodiodes. The disc is formed with a plurality of circumferentially spaced apertures which alternately cover and uncover the photodiodes which produce quasisinosoidal position signals in response thereto, the position signals of the first and second photodiodes being relatively 90.degree. out of phase. A computing circuit produces a motor shaft velocity command signal corresponding to the number of steps the shaft must rotate from the initial position to the new desired position and progressively reduces the magnitude of the velocity signal in response to the position signals. A differentiating circuit differentiates the position signals and their inversions and a commutator produces an actual velocity signal by sampling the peak values of the differentiated position signals. A comparator compares the velocity signal with the velocity command signal and produces an error signal corresponding to the difference therebetween which is fed to the motor as a drive signal. A sensor senses the output voltage of the third photodiode and an intensity control circuit adjusts the current flow through the light emitting diode until said output voltage has a predetermined value, thereby compensating for ambient temperature and other variations of all three photodiodes. A stable reference voltage for the apparatus is derived from the sensor.

Servo control apparatus

A sensor array produces two sinusoidal position signals which vary in phase by 90.degree. in response to rotation of a servo motor shaft. These position signals are inverted and the position signals and their inversions are commutated to produce a velocity signal. A position error signal is generated which indicates the difference between the actual motor shaft position and the command position. A reference signal is voltage divided in accordance with the position error signal to produce a velocity command signal which is compared with the velocity signal to produce a motor drive signal. The position signals and their inversions are half wave rectified, integrated and summed to produce the reference signal as a varying D. C. signal, the magnitude of which corresponds to the amplitude of the position signals and compensates for variations in said amplitude caused by high frequency attenuation in the sensor array and like phenomenon.

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Tokyo, Japan

Tomoatsu Imamura