JPS60120074A - Laser printer - Google Patents

Abstract

PURPOSE:To prevent a photosensitive body from being over-exposed to laser light, by a method wherein the condition in which the incidence of laser light modulated by an image signal on a photosenstive body is interrupted and the condition in which the incidence is permitted are switched from one to the other by a shutter means. CONSTITUTION:The laser light emitted from a semi-conductor laser 1 and polarized by a polygonal polarizer 3 is scanned on the photosensitive body 9 through a reflector 5. At this time, a shutter 19 for preventing black solid printing interrupts the light of a destaticizing lamp 6. When the irradiation of an image part with light is completed, the shutter 19 is turned so that the laser light is interrupted and the light from the lamp 6 is permitted to be incident on the photosensitive body 9. By previously setting the shutter 19 so as to interrupt the laser light when the photosensitive body 9 is stopped, the body 9 can be prevented from being over-irradiated with the laser light. The shutter 19 can be used both for preventing black solid printing and for interruption the laser light, and the lamp 6 functions also as a light source for a lamp for preventing black solid printing.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention involves scanning and irradiating a charged photoreceptor with a laser beam modulated by an image signal, and then performing a development and transfer process. There are some related to laser printers that record images on paper.

Problems with Conventional Structures In recent years, devices that record images by scanning a photoreceptor with laser light modulated by signals from a computer or a digital printer have been widely used as laser printers.

A conventional Shimiza printer will be explained with reference to FIG. Figure 1 is a schematic diagram of a conventional laser printer.
is a semiconductor laser, 2 is a collimator lens, 3 is a polygon deflector, 4 is an imaging lens, 5 is a reflection mirror, 6 is a static elimination lamp, 7 is a solid black protector, 11 is a transfer charger, 12 is plain paper, 13 14 is a cleaning device, and 14 is a fixing device.

The light beam of the semiconductor laser 1 modulated by the image signal is made into parallel light by the collimator lens 2, deflected by the polygon deflector 3, reflected by the reflection mirror 5, and then struck by the photoreceptor 9.
Scan above. The imaging lens 4 is a lens that focuses the scanning laser beam on the photoreceptor 9 to a required diameter of the slot 1. When the photoreceptor 9 charged by the charger 8 is irradiated with modulated laser light, an electrostatic latent image corresponding to the image is formed, which is visualized by the developer 10 and then transferred to the transfer charger 11. The image on the photoreceptor 9 is transferred to plain paper 12. The image on the plain paper 12 is fixed by a fixing device 14, and the remaining image on the photoreceptor 9 is removed by a cleaning device 13. The static elimination lamp 6 is a lamp for eliminating the electric charge on the photoreceptor 9. The solid black prevention lamp 7 is required in the case of a positive development method in which the portion of the photoreceptor 9 that has not been irradiated with the laser is developed black. This prevents non-image areas from developing black by irradiating and discharging them.

However, in the above-mentioned conventional configuration, since the laser light directly irradiates the photoreceptor 9, the photoreceptor 9 may be excessively exposed to the laser light. Especially when the laser beam path is being adjusted or when the photoconductor 9 is stopped, if the laser beam is applied to the photoconductor 9 excessively (OA7), the photoconductor 9 will temporarily suffer optical fatigue, causing more optical fatigue during recording. A memory phenomenon occurs in which parts of the image appear in the image.

Such optical fatigue of the photoreceptor 9 lasts for about several tens of minutes, so if the photoreceptor 9 is accidentally overexposed, there is a drawback that image recording cannot be performed during this period.

OBJECTS OF THE INVENTION The present invention solves the above-mentioned conventional drawbacks by preventing overexposure of the photoreceptor to laser light and preventing the laser light from directly igniting the photoreceptor, especially when adjusting the laser light while the photoreceptor is stopped. The purpose is to provide a laser printer that is designed to prevent

Structure of the Invention In order to achieve the above object, the laser printer of the present invention has the following features:
A light source that emits a 1F light modulated by an image signal, a scanning means for scanning a charged photoreceptor with a laser beam from the light source, and a shutter means disposed in a laser optical path near the photoreceptor. and a control means for driving the shutter means to switch between a state of blocking and a state of allowing irradiation of the laser beam onto the photoreceptor.

DESCRIPTION OF EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

FIG. 2 is a schematic diagram of the optical section of a laser printer according to an embodiment of the present invention, in which reference numeral 15 denotes a reflection mirror for synchronization detection;
16 is a synchronous detector, and 17 is a mechanical shutter. The rest of the structure is the same as the conventional example shown in FIG. Further, steps such as development and transfer are omitted from illustration.

Next, the operation will be explained. The light beam of the semiconductor laser 1 collimated by the collimator lens 2 is passed through the polygon deflector 3
The beam is deflected by the beam and scanned on the photoreceptor 9. A part of the scanned laser beam is guided to a synchronization detector 16 by a reflection mirror 15 for synchronization detection. The synchronous detector 16 determines the position of the scanning laser beam and is φ. When adjusting the optical path of the laser beam and adjusting the reflection mirror 15 for synchronization detection so that the laser beam hits the IWJ detector 16, the photoconductor 9 is normally stopped, but in this case, the photoconductor A mechanical shutter 17 near the photoreceptor 9 operates to continuously cut off the laser beam and prevent the C-Lury light from being irradiated onto the photoreceptor 9. Mechanical Shitotsuta 17
is located in the laser optical path closer to the photoreceptor 9 at the rear stage than the reflection mirror 15 for synchronization detection, so even if the mechanical shutter 17 is cut off, the optical path of the synchronization detector 16 can be adjusted. Reference numeral 18 denotes a control circuit for the mechanical shutter 17, which drives the mechanical shutter 17 to continuously cover the optical path when a stop signal for the photoreceptor 9 and a laser drive signal are output at the same time.

As described above, according to this embodiment, it is possible to block the laser light by the mechanical burr/vine 17 and prevent the photoreceptor 9 from being excessively irradiated with the laser light.

Next, another embodiment of the present invention will be described with reference to FIG. In FIG. 3, numeral 19 denotes a shutter for preventing solid black, and this shutter 19 for preventing solid black also serves as a shutter for the laser beam "aIi".

The configuration of the bar is similar to the conventional example shown in FIG.

Next, the operation will be explained. The laser beam of the semiconductor laser 1 deflected by the polygon deflector 3 is reflected by the reflection mirror 5 and scanned on the photoreceptor 9.

Here, the shutter 19 for preventing solid black blocks the light from the static elimination lamp 6 during image irradiation. As soon as the irradiation of the image area with the laser beam is completed, the shutter 11 and ivy 19 rotate to block the laser beam so that the light from the static elimination lamp 6 hits the photoreceptor 9. If the photoreceptor 9 is stopped, the shutter 1
9 is set to block the laser beam. In this way, excessive irradiation of the photoreceptor 9 with laser light can be prevented.

Here, since the shutter 19 serves both as a solid black prevention shutter and a laser beam blocking shutter, costs can be reduced. Further, the static eliminating lamp 6 also serves as a light source for a lamp for preventing solid black. In this embodiment as well, the operation of the shutter 19 is controlled by a control circuit similar to that shown in FIG.

In this way, the laser beam can be cut off at low cost by using the shutter 19 also as the shutter for preventing solid black.

DETAILED DESCRIPTION OF THE INVENTION According to the present invention, a shutter means for blocking laser light is provided near the photoreceptor to prevent the photoreceptor from being overexposed to the laser light. ,
Images with strong memory effects can be recorded.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of a conventional laser printer, FIG. 2 is a schematic diagram of a laser printer according to an embodiment of the present invention, and FIG. 3 is a schematic diagram of a laser printer according to another embodiment of the present invention. It is a diagram. 1... Semiconductor laser, 3... Polygon deflector, 6...
・Static elimination lamp, 7 ・ Lamp for preventing solid black, 9 ・・
・Photoreceptor, 17.19...Shutter, 18...Control circuit agent Hiroshi Morimoto Figure 1 Figure 2 Figure 3

Claims (1)

[Scope of Claims] 1. A light source that emits a laser beam modulated by an image signal, a scanning means that scans a charged photoconductor with a laser beam from this light source, and a laser near the photoconductor. A laser printer comprising a shutter means disposed in an optical path, and a control means for driving the shutter means to switch between a state of blocking and a state of allowing the irradiation of laser light onto a photoreceptor. 2. The control means is According to claim 1, the shutter means blocks the laser light to prevent the laser light from hitting the photoreceptor when the laser light is emitted while the photoreceptor is stopped. 3. When the shutter means does not block the laser light and the light from the solid black stop lamp hits the photoreceptor,
2. A laser printer according to claim 1, wherein the laser printer is configured so that the photoreceptor is irradiated with light from a lamp for preventing solid black.