公开(公告)号：US5764378A

公开(公告)日：1998-06-09

申请号：US544703

申请日：1995-10-18

Applicant: Yasuhiro Oda ,  Kazuhiko Arai ,  Kazuhiro Iwaoka ,  Takayuki Yamashita ,  Masayo Higashimura ,  Masahiko Kubo

Inventor： Yasuhiro Oda ,  Kazuhiko Arai ,  Kazuhiro Iwaoka ,  Takayuki Yamashita ,  Masayo Higashimura ,  Masahiko Kubo

IPC: G03G15/01 ,  G06T1/20 ,  H04N1/405 ,  H04N1/48 ,  H04N1/21 ,  B41B15/00 ,  G06F15/00

CPC classification number: H04N1/4056

Abstract: The present invention provides an image forming apparatus including first image density signal converter having a first conversion property for converting a multi-valued image density input signal to an image density output signal at a timing synchronizing with an image density signal clock, second image density signal converter having a second conversion property different from the first conversion property for converting a part of the image density input signal corresponding to a low density portion to an image density output signal indicating a value within a range in which an image is not developed, selection signal generator for outputting a selection signal having a period longer than that of the image density signal clock to select the first or second image density signal converter in a predetermined order, a phase of the selection signal being shifted in turn per every one or more main scanning synchronizing signals, pattern signal generator means for generating a pattern signal having a period longer than that of the image density signal clock, controller for shifting the phase of the pattern signal generated by the pattern signal generator means per every one or more main scanning synchronizing signals to form a screen image having a predetermined screen angle, a pulse width modulator for outputting a pulse width modulation signal generated by modulating pulse width of the image density output signal output from the first and second image density signal converter utilizing the pattern signal. An image is formed in accordance with the pulse width modulation signal output from the pulse width modulator.

Abstract translation: 本发明提供一种图像形成装置，包括：第一图像浓度信号转换器，具有第一转换特性，用于在与图像浓度信号时钟同步的定时将多值图像浓度输入信号转换为图像浓度输出信号，第二图像浓度信号 转换器具有不同于第一转换特性的第二转换特性，用于将对应于低密度部分的图像浓度输入信号的一部分转换为指示图像未被显影的范围内的值的图像浓度输出信号，选择信号 发生器，用于输出具有比图像浓度信号时钟的周期长的周期的选择信号，以按预定顺序选择第一或第二图像浓度信号转换器，选择信号的相位依次按照每一个或多个主扫描 同步信号，用于产生模式信号的模式信号发生器装置 l具有比图像浓度信号时钟长的时间段的控制器，用于根据每个一个或多个主扫描同步信号移位由图案信号发生器装置产生的图形信号的相位，以形成具有预定屏幕角度的屏幕图像， 脉冲宽度调制器，用于输出通过利用图案信号调制从第一和第二图像浓度信号转换器输出的图像浓度输出信号的脉冲宽度产生的脉宽调制信号。 根据从脉宽调制器输出的脉宽调制信号形成图像。

公开(公告)号：US5587772A

公开(公告)日：1996-12-24

申请号：US543911

申请日：1995-10-17

Applicant: Kazuhiko Arai ,  Yasuhiro Oda ,  Masahiko Kubo ,  Masayo Higashimura ,  Kazuhiro Iwaoka ,  Takayuki Yamashita

Inventor： Kazuhiko Arai ,  Yasuhiro Oda ,  Masahiko Kubo ,  Masayo Higashimura ,  Kazuhiro Iwaoka ,  Takayuki Yamashita

IPC: B41J2/52 ,  H04N1/405 ,  H04N1/46 ,  G03G15/04

CPC classification number: H04N1/4056

Abstract: The present invention provides an image forming apparatus having image signal discrimination device for discriminating whether an image density signal belongs to a line image portion or a natural image portion including a halftone image and outputting a discrimination signal, first image density conversion device having a first conversion property for converting the image density signal to a conversion signal and outputting the conversion signal, second image density conversion device having a second conversion property which is different from the first conversion property for converting a range of the image density signal corresponding to a low density portion to a conversion signal indicating a value within a range in which an image is not developed and outputting the conversion signal, selection device for alternately selecting the first and second image density conversion device with a predetermined period, pulse width modulation device for modulating pulse widths of the conversion signals output from the first and second image density signal conversion device and outputting a pulse width modulation signal, pulse width modulation signal period changing device for changing a period of the pulse width modulation signal output from the pulse width modulation device and the period of selection carried out by the selection device in accordance with the discrimination signal output from the image density signal discriminating device, and image formation device for forming an image in accordance with the pulse width modulation signal output from the pulse width modulation device.

Abstract translation: 本发明提供一种具有图像信号识别装置的图像形成装置，用于鉴别图像浓度信号是属于行图像部分还是包括半色调图像的自然图像部分并输出鉴别信号，第一图像浓度转换装置具有第一转换 用于将图像浓度信号转换为转换信号并输出​​转换信号的第二图像浓度转换装置，具有与第一转换特性不同的第二转换特性，用于转换对应于低密度部分的图像浓度信号的范围 指示表示图像未被显影的范围内的值并输出转换信号的转换信号，用于以预定周期交替地选择第一和第二图像浓度转换装置的选择装置，用于调制脉冲宽度的脉宽调制装置 转换 从第一和第二图像浓度信号转换装置输出的信号并输出​​脉冲宽度调制信号，脉冲宽度调制信号周期改变装置，用于改变从脉宽调制装置输出的脉冲宽度调制信号的周期和携带的选择周期 根据从图像浓度信号识别装置输出的识别信号，通过选择装置输出图像形成装置，以及根据从脉宽调制装置输出的脉冲宽度调制信号形成图像的图像形成装置。