Ricoh Company, Ltd.

Masaaki Mori

Chiharu Okada

Toshio Kawakami

Masamitsu Haruna

Taizo Yoshida

Jiro Koyama

A system for driving a thermal print head including a plurality of heat-producing elements which are activated selectively in accordance with digital image data obtained from an analog image signal is provided. In one aspect, the driving system is so structured to insert additional data between any two adjacent image data whenever the space between the two exceeds a predetermined level thereby allowing to maintain the dot density at constant when printed. In another aspect, the driving system controls the time period of activation of each of the heat-producing elements in accordance with preheat control data obtained by carrying out AND processing between each of the digital image data of one print line and the corresponding each of the digital image data of the next following print line. In a further aspect, the present driving system has a structure such that a reference point in a print line may be set at a desired location along the print line.

System for driving a thermal print head for constant dot density

A pattern memory for use in a thermal printer system stores a temperature-compensated pattern of a character to be printed on recording paper using a thermal print head having a plurality of heat-producing elements arranged in a single array is provided. The pattern is defined in the form of a dot matrix, each dot containing two or more binary data, each of which, if having a predetermined one of the two possible states, is associated with a predetermined activation time period for activating one of the heat-producing elements. The binary state of each of the two or more data in each dot is determined such that a level of heat produced by any of the heat-producing elements may be maintained at constant. In one embodiment having two binary data in each dot, the pattern is determined such that the one of the two data of a dot has '0' and the other has '1' if this dot is to be printed for a second time or more by the same heat-producing element in succession.

Pattern memory for use in thermal recording

System for driving a thermal print head

A thermal print head driving system supplies a predetermined number of driving pulses to each of a plurality of heat-producing elements arranged in a line to record a single dot of desired tone. The pulse width of driving pulse is controlled in accordance with the temperature at or in the vicinity of the heat-producing elements thereby allowing to maintain the density level of desired tone at constant. In another aspect of the present invention, it is so structured that driving pulses may be applied to the heat-producing elements in a continuous manner without producing a cooling period during switching between tone levels. In a further aspect of the present invention, it is so structured that a predetermined number of driving pulses for each of predetermined number of tone levels is altered in consideration of the data in at least one of preceding recording lines, thereby allowing to carry out a high speed recording operation without causing fluctuations in predetermined tone density level.

Thermal print head driving system

A thermal recording system includes a thermal print head provided with a plurality of electrical resistors arranged in the form of a single row and selectively activated when an activation pulse is supplied, a brute supply for supplying a power supply voltage to the resistors and a pulse generator for controlling the duration of the activation pulse in accordance with the level of the power supply voltage actually applied to the resistors. The pulse generator controls the pulse width of the activation pulse so as to maintain substantially constant the activation energy defined as a product of (power supply voltage actually applied).sup.2 and (pulse width of activation pulse).

Thermal recording system using unregulated power supply

An optical switching device for switching the transmission of light waves is provided. The main feature of the present invention is the usage of a light-transmitting, crystalline material having a temperature dependent index of refraction. That is, the light transmission condition is altered by controlling the temperature of such a material. In one form of the present invention, a main waveguide and a branched waveguide are provided and light waves are switched between the main and branched waveguides by controlling the temperature of a particlar portion of the intersection region. In another form of the present invention, a pair of waveguides is oppositely arranged in an end-to-end relation with a gap therebetween, and a switching region is defined in the gap. When the switching region is heated, the waveguides are optically connected; whereas, they are optically disconnected at normal temperature condition.

Optical switching device

The simultaneous multi-beam optical modulation system comprises the steps of producing a dummy signal in such a manner that the sum of a plurality of signals and the dummy signal is kept constant, modulating the amplitudes of assigned carriers by the dummy signal and the plurality of the signals so as to produce a modulated output and applying the modulated output to an acoustic optical element.

Simultaneous multi-beam optical modulation system

The simultaneous multi-beam optical modulation process comprises the steps of obtaining a plurality of modulated signals with the amplitude of carriers having different frequencies modulated by a plurality of signals, and driving an acoustic optical element by the modulated signals so that a light modulation is performed by the acoustic optical element. In this system, a dummy signal is produced by squaring a plurality of the signals and adding and then inverting the squared signals and a setting voltage for setting an overall deflection efficiency of the acoustic optical element, or by adding and then inverting a plurality of the signals and the setting voltage and then squaring the sum. The amplitude of an assigned carrier is modulated by the dummy signal and a modulated output is obtained. The modulated output and the modulated signals are summed up into a summed-up signal, which is then applied to the acoustic optical system. An apparatus for carrying out the process is also described.

The simultaneous multi-beam optical modulation process comprises the steps of producing a dummy signal in such a manner that the sum of a plurality of signals and the dummy signal is kept constant, modulating the amplitudes of assigned carriers by the dummy signal and the plurality of the signals so as to produce a modulated output and applying the modulated output to an acoustic optical element. An apparatus for carrying out the process is also disclosed.

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Kawasaki, Japan

Masaaki Mori