Dainippon Screen Mfg. Co., Ltd.

Takahide Hirawa

Eiichi Tamaki

Hiroshi Sano

Yoshikazu Kataoka

Junichi Shiomi

Hiroshi Nomoto

Yasunori Nakamura

Yoshikazu Kago

Yoshiki Mizuno

Hitoshi Matsuda

Akira Hikita

In an image recording apparatus, a shift amount for shifting a transition position of an output light amount from a light modulator element is obtained with respect to each pixel value-change point in a pixel line in order to correct displacement of writing. In a case where the shift amount excesses a width corresponding to one pixel on a substrate, a pixel value in the pixel line is altered so that the pixel value-change point moves by the number of pixels of an integer part of a value obtained by dividing the shift amount by the width, and the shift amount corresponding to the pixel value-change point is modified to a value equivalent to a decimal part. It is therefore possible to shift the transition position of the output light amount in excess of the distance corresponding to one pixel in recording an image, to record the image with accuracy.

Image recording apparatus and image recording method

In an image recording apparatus for recording an image by guiding zeroth order diffracted light beams from a plurality of diffraction grating type light modulator elements as signal beams to a recording medium, a transition of each of light modulator elements from an OFF state to an ON state is detected and when this transition is detected, the light modulator element is temporarily supplied with an auxiliary driving voltage (V) between a driving voltage (V) for bringing the light modulator element into the ON state and a driving voltage (V) for bringing the light modulator element into the OFF state. This suppresses an overshoot due to a sharp change of the light modulator element to the ON state and achieves beam writing with appropriate line space ratio.

Image recording apparatus and image recording method using diffraction grating type light modulator

An illumination lens applies a laser beam emitted from a laser light source onto a light valve. The laser beam divided into a number of beams and modulated in the light valve is reflected by a total internal reflection prism so that the optical path thereof is bent, and thereafter passes through a zoom lens to be focused on a recording medium mounted on the surface of a drum. At this time, an image of a single pixel is recorded with a plurality of adjacent laser beams in a subscanning direction (direction of arrangement of the laser beams). The image can be recorded on the recording medium with sufficient power density.

Image recorder

In an image recording apparatuswhich records an image on a recording mediumby moving an optical headwhile rotating the recording mediumheld by a holding drum, a photodetectorhaving a plurality of photodetector elementsis provided in a range of movement of the optical head. In correcting beam intensity, the optical headis positioned so precisely that the photodetectorcan receive the signal light beams. This constitution makes it possible to detect signal light beams from the light modulator with high S/N ratio as compared with a conventional case where one photodetector element sequentially receives the signal light beams, and therefore possible to correct the beam intensities with high accuracy.

Method for correcting the beam intensity in an image recording apparatus using a multi-channel light modulator

In an image recording apparatus for recording an image by guiding zeroth order diffracted light beams from a plurality of diffraction grating type light modulator elements as signal beams to a recording medium, a transition of each of light modulator elements from an OFF state to an ON state is detected and when this transition is detected, the light modulator element is temporarily supplied with an auxiliary driving voltage (V ) between a driving voltage (V ) for bringing the light modulator element into the ON state and a driving voltage (V ) for bringing the light modulator element into the OFF state. This suppresses an overshoot due to a sharp change of the light modulator element to the ON state and achieves beam writing with appropriate line space ratio.

A driving element ( ) for driving light modulator elements ( ) is provided with a register ( ) for storing driving voltage data ( ) and clock selection data ( ), a clock selection part ( ) for selecting an update clock ( ) out of a group of control clocks ( ) on the basis of the clock selection data ( ), and a D/A converter ( ), a current source ( ) and a resistance ( ) for converting the driving voltage data ( ) into a driving voltage. The timing of the update clock ( ) is shifted by the clock selection data ( ), to thereby control a driving timing of each light modulator element ( ). This makes it possible to achieve an appropriate writing while suppressing effects of driving characteristics of the light modulator elements ( ), the widths of irradiation areas irradiated by the light modulator elements ( ) in a scan direction, photosensitive characteristics of a recording medium and the like.

An image recorder performs a first distortion correction at the resolution of an input image and a second distortion correction at the resolution of a recording head. The first distortion correction is performed by setting an angle difference between a write angle and a read angle to and from address space in a buffer memory (BM) to be equal to an inclination angle of scanning lines with respect to a main scanning direction. The second distortion correction is performed by shifting image data obtained by the first distortion correction in a sub-scanning direction by an amount responsive to the inclination angle. The smallest unit of the amount is one pixel unit (P). More specifically, image data is shifted by the width of one pixel (D) in blocks for memory access, and then for output of a gradient value for each pixel (D), it is further shifted by the width of one pixel unit (P) in sub-blocks which are obtained by dividing each block.

An image quality on a recording material is influenced by, for example, the sensitivity of a developer for use in developing the recording material. Compensating for the lowering of the sensitivity of the developer requires increasing the amount of emission of a laser beam. However, there is a difference in the amount of change between dimensions, in a main scanning direction and in a sub-scanning direction, of a dot blackened depending on the increase in the amount of emission of the laser beam. Increasing or decreasing the time duration of emission of the laser beam by a predetermined amount achieves adjustment of the dimension of the dot in the main scanning direction. Specifically, there is provided a memory for storing therein the sensitivity of the developer, the amount of emission of the laser beam and the time duration of emission of the laser beam in corresponding relation to each other, and the emission from a laser light source is adjusted by reading the amount and time duration of emission corresponding to the sensitivity of the developer from the memory.

Image recorder and method of recording image

Each recording pixel is divided into M small divisions where M is an integer of not less than 2. A threshold pattern is provided for the small divisions where a threshold value is assigned to each of the M small divisions corresponding to each recording pixel. The threshold values assigned to the M small divisions are compared with a multi-tone image signal to produce M pieces of binary comparison results. An image recording signal is generated as a function of a sum n of the M pieces of binary comparison results.

Method and apparatus for recording halftone image utilizing tone reproduction at each pixel

The present invention generates a first threshold value constituting a first threshold pattern and a second threshold value constituting a second threshold pattern. The first threshold pattern is to reproduce a relatively large number of tones and is relatively small in size, while the second threshold pattern has a relatively small number of tones and is relatively large in size. An arithmetic operation is carried out on the first threshold value and the second threshold value so as to generate a third threshold value. The third threshold value is compared with an image signal to generate a dot signal representing a halftone dot.

Method and apparatus for generating halftone dots

A plurality of correction look-up tables are prepared corresponding to offsets of halftone dot areas. An offset of a halftone dot area including the subject pixel is calculated, and a correction look-up table specified by the offset is selected in order to correct an input density value. Threshold values read out from an SPM (screen pattern memory) 130 may be corrected instead. Alternatively, a plurality of SPMs are prepared, each of which stores corrected threshold values corresponding to each offset, and an appropriate SPM is selected according to the offset. Accordingly, halftone dots are generated to faithfully reproduce a desired tone specified by multi-tone image data.

Method and apparatus for generating halftone image with halftone dot

A priority grade is provided to each of several graphic figures. Respective contour lines of the graphic figures are classified into two groups according to respective locations. Respective contour lines in the two groups are serially selected in a descending order of main scanning coordinate values, and are compared with each other to specify a cross point having the largest coordinate value within a selected pair of cross points. A component of the raster data is generated on the basis of the selected cross point when a priority grade of the selected cross point satisfies a predetermined condition in connection with respective priority grades of the other cross points.

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Kyoto, Japan

Takahide Hirawa