JP2003114393A - Optical scanner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical scanner which enables a user to accurately grasp a printing start position even an electrophotographic printer uses a plurality of scanning light beams by outputting a horizontal synchronizing signals for the respective scanning light beams. SOLUTION: The printer which uses an electrophotographic system using an optical scanner for scanning a photosensitive body using a plurality of lines of laser light beams, has a laser detection member which detects the plurality of laser light beams and a reflecting mirror for irradiating a radiation detector mounted on the member. The optical scanner achieves the purpose by making the scanning-directional width of the reflecting mirror narrower than the intervals of the respective laser light beams.

Description

Description: BACKGROUND OF THE INVENTION [0001] 1. Field of the Invention [0002] The present invention relates to an optical scanning device that scans a photoconductor using a plurality of laser beams. FIG. 1 is a conceptual view of an optical scanning device showing an embodiment of an optical scanning device. The laser light emitted from the light source 101 is applied to the rotating polyhedron 103 through the lens 102, and the aspheric lens 1 is rotated by the rotation of the rotating polyhedron 103.
The laser beam passes through the mirror 104 and is scanned by the reflection mirror 105 and the photoconductor 106. The laser beam scanned by the reflection mirror 105 is scanned by a radiation detector (not shown) mounted on the laser beam detecting member 107. Laser light detecting member 10
The role of 7 is to generate a horizontal synchronizing signal, that is, to determine from which position to scan the print data when scanning the laser beam on the photoconductor. FIG. 4 shows a general detecting means used to achieve the above function. When the scanning light 111 is irradiated on the radiation detector 201 mounted on the laser light detecting member 107, the photoelectric current 202 is generated by the photoelectric effect of the radiation detector.
Occurs. The photocurrent 202 is converted into a voltage by the resistor 203 and is amplified by the amplifier 204 to obtain a waveform as shown in FIG. This waveform is configured such that the waveform is shaped by a waveform shaping circuit 205 at the subsequent stage and then output to the print control device as the above-described horizontal synchronization signal through the buffer circuit 206. [0004] On the other hand, as the demand for high resolution increases, the number of scanning light beams scanned at one time often increases as the printing speed increases. The fact that a plurality of scanning light beams is generated depends on whether the laser
07 is a plurality of scanning lights, and it is necessary to output a horizontal synchronization signal for each scanning light. However, as shown in FIG. 6, when a plurality of scanning lights are applied to the radiation detector 201 in time series and simultaneously, for example, when the number of scanning lights is two, the amplifier 204 shown in FIG.
However, in the conventional circuit shown in FIG. 4, since the threshold value in the waveform shaping circuit 205 is fixed to a preset value, each of the scanning lights 111 and 11 can be obtained.
2, a horizontal synchronization signal cannot be output, and a problem arises in that the printing start position cannot be synchronized between the scanning lights. An object of the present invention is to provide an optical scanning device capable of outputting a horizontal synchronizing signal for each scanning light even if there are a plurality of scanning lights, and accurately ascertaining a printing start position for each scanning light. To provide. SUMMARY OF THE INVENTION An object of the present invention is to provide an optical scanning apparatus for scanning a photosensitive member using a plurality of laser beams.
This is achieved by having a reflecting mirror in which the width of the reflecting mirror in the scanning direction is smaller than the interval between the plurality of laser beams in the scanning direction. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention is shown in FIGS.
This will be described with reference to FIG. FIG. 1 is a conceptual diagram of an optical scanning device according to the present invention, FIG. 2 is a block diagram of an operation circuit showing one embodiment of a laser light detecting member, and FIG. 3 shows an output waveform of an amplifier 204 obtained by the present embodiment. In the present embodiment, a description will be given of a case where a photodiode is used as the radiation detector 201 and control is performed in the case where two scanning lights 111 and 112 are irradiated. First, when the photodiode 201 is irradiated with the first scanning light 111, a photoelectric current 202 is generated by the photoelectric effect of the photodiode 201. This photocurrent 2
02 is converted into a voltage by the current-voltage conversion resistor 203. The converted voltage is amplified by the amplifier 204 and output to the buffer circuit 206 through the waveform shaping circuit 205. The first scanning light 111 is reflected by the reflection mirror 10.
Irradiation is performed only for the time required to scan No. 5, and the irradiation to the photodiode 201 is eventually completed. At this time, the second scanning light 1
In No. 12, since the width of the reflecting mirror 105 is smaller than the interval between the scanning light 111 and the scanning light 112, the reflecting mirror 105 is not yet irradiated to the reflecting mirror 105 and the photodiode 201 is not irradiated. Therefore, the second scanning light 1 is applied to the photodiode 201.
Since the output voltage of the amplifier 204 can return to the initial state as shown in FIG. 3 before the irradiation of the light source 12, the output voltage of the amplifier 204 does not accumulate as shown in FIG. As a result, a horizontal synchronization signal for the first scanning light 111 can be obtained. Next, when the second scanning light 112 is irradiated, a horizontal synchronization signal for the scanning light 112 can be obtained in the same manner as in the case of the first scanning light 111. Therefore, even if there are a plurality of scanning lights, it is possible to output a horizontal synchronizing signal for each scanning light. In this embodiment, two scanning beams are used. However, it is needless to say that a print start position signal can be generated in the same manner even if the scanning beam is further increased. As described above, according to the present invention, a horizontal synchronizing signal is output for each scanning light even if there are a plurality of scanning lights, and the printing start position for each scanning light can be accurately determined. An optical scanning device that can be grasped can be provided.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a conceptual diagram of an optical scanning device showing one embodiment of the present invention. FIG. 2 is a block diagram of a laser light detection circuit showing one embodiment of the present invention. FIG. 3 is an output waveform diagram of the amplifier in FIG. 2; FIG. 4 is a block diagram of a conventional laser light detection circuit. 5 is an output waveform diagram of the amplifier in FIG. FIG. 6 is an explanatory diagram of a case where a plurality of scanning lights are applied to a radiation detector using a conventional optical scanning device for single scanning light. FIG. 7 is an output waveform diagram of an amplifier when a radiation detector is irradiated with a plurality of scanning lights by using a conventional optical scanning device for single scanning light. [Description of Signs] 105 is a reflection mirror, 107 is a laser beam detecting member, 11
Reference numeral 1 denotes a first scan, and 112 denotes a second scan light.

Claims (1)

Claims: 1. An electrophotographic printing apparatus using an optical scanning device that scans a photosensitive member using a plurality of laser beams, wherein each of the plurality of laser beams is detected. A laser light detection member, and a reflection mirror for irradiating a radiation detector mounted on the member, wherein a width of the reflection mirror in a scanning direction is smaller than an interval between the plurality of laser beams. Optical scanning device characterized by the following.