JPS60213918A - Picture recorder - Google Patents

Abstract

PURPOSE:To obtain a horizontally synchronized pulse in each scanning and to use primarily diffracted light for picture recording to record a picture corresponding to the whole scanning width of a laser beam by arranging a beam detecting means in an optical path for the 0-th order diffracted light of a modulated beam or a reflecting optical path. CONSTITUTION:A mirror 13 is arranged between a lens 7 forming an image on a distance proportional to an incident angle on an optical axis and a photosensitive drum 8 and a beam detector 14 is arranged on the photodetecting position of the reflected light of the 0-th order diffracted light by the mirror 13. In said constitution, laser beam light L0 diffracted by an acoustooptic modulator is reflected by the mirror 13 and made incident on the detector 14 and its beam is detected in each scanning to obtain a horizontally synchronized pulse. On the other hand, primary diffracted light is not irradiated on the mirror 13, but is directly projected to a photosensitive surface 8a of a drum 8 to form a latent image of the picture. Thus, the whole scanning width of the laser beam can be made to an effective picture area.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an image recording device that can widen the effective scanning width of a beam with a simple circuit configuration.

(b) Prior Art Recently, an image recording device using a laser beam, a so-called laser printer, has been developed and put into practical use. As an example of a laser printer, a laser beam is modulated based on an electrical signal containing image information (hereinafter referred to as "image signal"), and a recording medium such as a photoreceptor, film, or photographic paper is scanned, and image information is first recorded on the recording medium. There are systems in which a latent image is formed and then recorded as a visible image through electrophotographic processing or photographic development processing, and Figure 1 shows a typical optical scanning system. In the figure, ■ is the He that generates the laser beam.
- By exciting a gas laser such as a Ne laser, 2 a mirror, and 3 a piezoelectric element with a high-frequency signal, compression waves are generated within the crystal body, and the laser beam is passed through the compression waves to diffract the beam. is optically modulated by an acousto-optic modulator; 4 is a driver consisting of a high-frequency signal generator that drives the acousto-optic modulator 3; 5 is a beam expander that expands the beam diameter; 6 rotates at high speed to deflect the laser beam onto the photoreceptor. 7 is an fθ lens that forms an image at a distance proportional to the incident angle θ with respect to the optical axis (f is the focal length of the lens), 8 is a photosensitive material such as selenium. A photoreceptor drum 8 has a surface 8a, and a beam detector 9 is arranged near the axial end of the photoreceptor drum 8 on the path of the laser beam. The beam detector 9 is constituted by a photodiode, for example, and detects the passage of the laser beam for each scan and outputs a horizontal synchronizing pulse. When IO receives this horizontal synchronization pulse, it starts counting the dot clock CLK.
11 is a timing generation circuit that outputs a timing signal to start recording when the count value of the counter 10 reaches a predetermined value; 12 is an image information synthesis circuit that synthesizes the timing signal and the image signal S; and the driver 4 generates this synthesized image. A high frequency signal based on the signal is output and sent to the acousto-optic modulator 3.

In order to improve the accuracy of starting recording of one image in such a laser printer, for example, the Japanese Patent Publication No. 58-325
It has been proposed in issues such as No. 43.

However, in order to determine the writing timing of image information based on the horizontal synchronization pulse in this way, circuit elements and electric circuits such as oscillators, counters, and timers are required.
If an attempt is made to improve the accuracy of write timing, the circuit configuration becomes complicated, and the frequency of the reference block for time counting becomes high, making the process complicated. Furthermore, since a certain scanning length out of the entire scanning width of the laser beam is required to obtain the horizontal synchronization pulse, there is a problem in that the effective scanning length used for recording the image becomes shorter by that amount.

(c) Object and structure of the invention The present invention has been made in view of the above points, and provides an image recording device that diffracts and modulates a laser beam with an image signal and records an image by scanning the modulated beam. , the purpose is to improve the accuracy of image writing timing and widen the effective scanning width of the beam with a simple circuit configuration.
A beam detection means is provided in the optical path of the next diffracted light or the reflected optical path.

) Example The present invention will be explained below based on the drawings.

In a conventional laser printer, as shown in FIG. 2, among the diffracted lights obtained by modulating a laser beam with an acousto-optic modulator 3, the 0th-order diffracted light is blocked by a light-shielding plate 12, and only the 1st-order diffracted light L1 is blocked. is directed toward a rotating polygon mirror 6 and deflected to perform beam scanning.

In the present invention, among the diffracted lights obtained when a laser beam is modulated by an acousto-optic modulator 3, the 0th-order diffracted light is used for beam detection, and the 1st-order diffracted light is used for writing an image. As shown in FIG. 2, a mirror 13 is disposed between the fθ lens 7 and the photosensitive drum 8. This mirror 1
3, as shown in FIG. 4, is placed in the optical path of the 0th order diffracted light Lo, and a beam detector 14 is placed at a position to receive the reflected light of the 0th order diffracted light Lo by the mirror 13.

With such a configuration, the 0th order diffracted light of the laser beam diffracted by the acousto-optic modulator 3.

is reflected by the mirror 13 and enters the beam detector 14, so the beam is detected for each scan and a horizontal synchronizing pulse is obtained. Further, the first-order diffracted light L1 does not hit the Mi Q-13, but is directly projected onto the photosensitive surface 8a of the photosensitive drum 8, forming a latent image as in the conventional case. As a result, the entire scanning width of the laser beam becomes an effective image area, and by placing the beam detector 14 at a position that temporally coincides with the timing of the image writing tip of the first-order diffracted light, it is possible to determine the writing timing. A counter that creates a time delay (Counter 1 in Figure 1)
0) becomes unnecessary. For this,
The members that make up the optical system, such as lenses and polygons, in the width direction G
This can be made smaller, which is advantageous in terms of manufacturing and cost.

As described in detail, the present invention provides an image recording apparatus that diffracts and modulates a laser beam with an image signal, and records an image by scanning the modulated TF beam. Since the beam detection means is provided in the optical path or reflected optical path, a horizontal synchronizing pulse can be reliably obtained for each scan, and since monthly diffracted light is used for image recording, the entire scanning width of the laser beam can be used for image recording. The menu can be used effectively. Furthermore, by providing this beam detection means at a position that coincides temporally with the start point of image writing by the first-order diffracted light, delay elements and delay circuits such as counters and timers are no longer required, which simplifies the circuit configuration and improves image writing. Timing accuracy is improved and the optical system can be made more compact.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the schematic configuration of a conventional laser printer.
FIG. 2 is a diagram showing the paths and usage states of zero-order and first-order diffracted light in a conventional laser printer, and FIG. 3 is a plan view showing a schematic configuration of essential parts of a laser printer as an example of an image recording device according to the present invention. Figure 4 is a side +fti diagram of the main part shown in fiS3 diagram ζ. 1... Gas laser 3... Acousto-optic modulator 4...
Driver 6... Rotating polygon mirror 7... fθ lens 8
... Photoreceptor drum 9.14 ... Beam detector 10
...Counter 11...Timing generator 12...
・Picture "ti'r information synthesis circuit 13...Mirror patent applicant: Konishiroku Photo Industry Co., Ltd. Agent: Patent attorney: Hiroshi Suzuki (Figure 1) Figure 2 Figure 3 Figure 4

Claims (1)

[Claims] In an image recording device that diffracts and modulates a laser beam with an image signal and records an image by scanning the modulated beam, a beam detection means is provided in the optical path of the 0th order diffracted light or the reflected optical path of the modulated beam. An image recording device characterized by: