A half-tone image recorder in which input digital data is represented by a plurality of bit data for each pixel. A data conversion device outputs digital data indicative of a recording-start position and a recording-end position, based on the input digital data. A recording device such as a laser printer records an image in accordance with the output digital data from the data conversion device. The data conversion device controls a first value of the digital data indicative of the recording-start position and a second value of the digital data indicative of the recording-end position so as to change a black-area growing direction within one pixel in the recorded image. This results in the recordation of a high-quality half-tone image without conspicuous vertical stripes and without conspicuous white stripes in the main-scanning direction of the recording device due to pitch irregularity.

Halftone image recording apparatus and method based on first and second timing signals chosen from a plurality of synchronized clocks

In a control system for an information recording laser beam, an intensity of a laser beam is varied in a predetermined variation pattern during each of sequential one-pixel periods. The laser beam is periodically activated and deactivated in synchronism with a change of the one-pixel periods. A duration of the activating the laser beam within each of the one-pixel periods is controlled in accordance with a density of each of pixels of an image to be recorded.

Control system for information recording laser beam

A pulse-width modulation device for controlling shapes of dots printed out by a printer by regulating shapes of pulses of pulse-width modulation signals, which respectively represent gray levels of pixels of input image, according to code signals respectively indicating shapes of pulses of pulse-width modulation signals, each of which has a duration composed of time slots respectively corresponding to bits of image data representing a gray level of a pixel. The pulse-width modulation device is provided with a code converter for converting image data corresponding to each pixel of an input image into a predetermined code indicating a shape of a pulse of a corresponding pulse-width modulation signal and for outputting a code signal representing the predetermined code. The indicated shape of the pulse is formed by making the corresponding pulse modulation signal have a high level at a predetermined number of time slots thereof, which are serially counted from the time slot corresponding to the most significant bit of the image data or from the time slot corresponding to the least significant bit of the image data according to a gray level of each pixel. The pulse-width modulation device is further provided with a pulse generating circuit for receiving the code signal and for generating the pulse of the predetermined pulse-width modulation signal according to the code in response to a predetermined clock signal.

A pulse-width modulation device

PURPOSE:To enable gradational representation and to increase the degree of freedom of the setting of write gradations corresponding to image data by modulating a semiconductor laser with the image data which is converted by a data converting means CONSTITUTION:A temperature detecting element 46 consisting of a thermistor is arranged nearby a laser diode 22 to detect its temperature and the output Vt obtained by dividing a source voltage by the temperature detecting element 46 and a resistance 56 is converted by an analog/digital converter 47 from analog to digital and supplied as a select signal SEL to a ROM 43 As the temperature increases, the thermistor 46 decreases in resistance value, so the output Vt increases and the signal SEL increases When the temperature is lowered, on the other hand, the signal SEL decreases Thus, a modulating means modulates the semiconductor laser with the image data converted by the data converting means Consequently, the superior gradational representation is enabled and the degree of freedom of the setting of write gradations corresponding to the image data is increased

Semiconductor laser modulating device

PURPOSE:To obtain required picture quality by selecting optimum pulse width responding to requirement and outputting a final picture element signal to a modulating means CONSTITUTION:A scanning type picture recording part 100 and a picture element information generating part 10 are connected by signal transmission pathes 1a-1d A picture element signal 300 from a picture element information forming part 12 and a clock signal 305 from a clock generating part 11 are inputted into a flip-flop 200, and a shaping picture element signal 301 is outputted A laser beam from a laser oscillator 110 is modulated in intensity by a beam modulating device 120 and made into a laser beam 303 by being holozontally swept by a poly hedron rotary mirror 130 Then an image is formed on a photo sensitive drum 170 by an image forming lens 150 A beam detector 160 detects the position of the beam 303, outputs the start timing signal 320 of an input signal to modulator 120 to give desirable beam information on the drum 170 through a scanning start timing signal 320, and inputs it into the generating part 10 The signal 301 selects reduction or magnification as the final picture element signal 302 at a fine adjusting part 210 Thus, required picture quality can be obtained

Scanning type picture recorder

PURPOSE: To generate a natural intermediate tone picture whose center of recording dots is coincident by providing a pulse generating means comparing a code signal converted by a code conversion means with a code signal commanding a pulse width of a modulation signal and generating a pulse width modulation signal having a prescribed pulse width in a laser beam printer. CONSTITUTION: A comparison result signal HH of a comparator 22 is outputted to a glitch elimination circuit 24. A pulse signal II is outputted from the glitch elimination circuit 24. A code converter 1 converts counts C(0∼7) outputted from a counter 23 into code signals B(6,4,2,0,1,3,5,7). Thus, while the timewise center phase of the width of the pulse width modulation signal II is kept nearly constant, the output data A is changed with respect to the input data D(O-7). The center of phase is deviated slightly in comparison with an ideal pulse width, but when the input data D is a 6-bit signal to express, e.g., 64-gradation, the center of the pulse width modulation signal II approaches limitlessly the ideal form. COPYRIGHT: (C)1987,JPO&Japio

Junichi Kimizuka

Papers

Pulse width modulator