Fuji Xerox Co., Ltd.

Nobuhisa Kato

Fujio Moriguchi

Yuji Yatsuda

Shinichi Yasunaga

Mitsumasa Narahara

Kazumi Yamauchi

A coincidence circuit for detecting when n-bit binary input data coincides with the current value of an n-bit counter. A plurality of '1' detecting circuits determine, when a corresponding input bit is one, whether a corresponding counter bit is also one. A first-coincidence detecting circuit determines the first time that all the '1' input bits have corresponding '1' clock bits. Each '1' detecting circuit includes an inverter and a NOR gate. The first-coincidence detecting circuit includes an OR gate and a latch circuit.

Coincidence circuit

In an image recording apparatus capable of recording a halftone image, a gradation to bit-train converting table converts gradation data representing a gradation of tone at a picture element of an image into bit-train data whose bit pattern is based on the gradation data. For the gradation data representing a gradation in excess of a threshold gradation, the table converts the gradation data into such bit-train data that bits of the bit-train data corresponding to the gradation data are intermittently omitted after a train of bits corresponding to the threshold gradation is outputted. A bit-train to pulse-train converting section converts the bit-train derived from the gradiation to bit-train converting table into pulse-train signal of a pulse pattern analogous to that of the bit-train data. The pulse signal of such a discontinuous pulse pattern is applied to a heating element of a thermal head, which is provided corresponding to the picture element whose gradation data is under process. A heating temperature of the heating element is controlled below a predetermined temperature.

Halftone image gradation data converted to bit-train data with data

A thermal recording apparatus includes a resistance memory for storing resistance variation data associated with each of a plurality of resistive thermal recording elements. A picture element stores gradation data representing a plurality of picture elements to be recorded to reproduce a picture image. A gradation conversion mechanism receiving the stored gradation data and the stored resistance variation data associated with the recording elements to record the gradation data and corrects the values of the gradation data to compensate for the variations in the resistances of the recording elements from a predetermined value.

Thermal recording apparatus with resistance compensation

A printing device in which pulses corresponding in number to gradations to be visibly expressed are applied to the heat generating elements of a thermal had in such a manner that the heat generating elements are controlled in heat generation time. Image data storing means stores, as a recording unit of image data, image data of picture elements which can be recorded in one action. Gradation-to-bit-train conversion means receive the image data from the image data storing means in units of picture elements, and output bit trains representing the numbers of pulses according to the gradation to be expressed. Latch means latch the outputted bit trains thus outputted, selector means select bit for pulse application control from the latched bit trains, and count means cause the selector means to perform the selecting operation a predetermined number of times according to the gradation to be expressed, for all picture elements of each recording unit to control the number of pulses applied to each of the heat generating elements.

Thermal printing device

A thermal recording apparatus includes a comparator for comparing the black density of picture elements to be recorded by thermal recording elements to reference density levels, a counter accumulates a value representing the number of picture elements having density levels in certain ranges as a result of the comparison by the comparator. The counter value is used to adjust the pulse width of pulses used to energize the recording elements to compensate for fluctuations in the levels of the pulses due to the number of recording elements that are energized at one time and the durations of the energizations in order to record visible images of the picture elements with appropriate densities.

Thermal recording apparatus capable of gradation recording

A controller for an overlay printer in which an image is transferred in a plurality of superimposed layers to a recording medium removably secured on a rotatable drum subject to vibration on starting, comprising a first sensor for controlling the securing and release of the recording medium on the drum; and a second sensor for reducing vibrational influence from the start of rotatable motion of the drum and controlling printing of the image on the recording medium.

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Kanagawa, Japan

Nobuhisa Kato