JPH0398066A - Partial exposure device - Google Patents

Abstract

PURPOSE:To prevent a switching part for an exposure beam from being exposed twice or not exposed at all by providing an exposure control means which performs switching control by decreasing the exposure energy of one of two exposure beams, to which the overlap exposed part of exposure ranges is exposed, and increasing the other at the same rate. CONSTITUTION:Exposure beam generating means 7a and 7b generate the exposure beams corresponding to the exposure ranges of a photosensitive body which is divided into the exposure ranges. Scanning means 8a and 8b generate the overlap exposed part which is exposed repeatedly at the exposure beam switching part of two adjacent partial exposure ranges with the exposure beams. An exposure control means 9 decreases the exposure energy of one of the two exposure beams, to which the overlap exposed part of the exposure ranges is exposed, and increases the other at the same rate to perform the switching control. Consequently, the part where the exposure beams are switched is neither double-exposed nor unexposed.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention relates to a divisional exposure device used in laser printers, etc., and more specifically, a relatively wide area of a photoconductor is divided into a plurality of parts and each part is exposed to a plurality of parts. The present invention relates to a divided exposure device that performs scanning exposure using a beam.

[Prior Art] An exposure device that scans and exposes a photoreceptor such as a photoreceptor drum with an exposure beam in a laser printer generally uses a semiconductor laser beam as a light source. If you try to expose a wide area of the photoreceptor with this exposure device, you will need large and expensive optical parts such as condensing lens system parts, and the exposure device will be very expensive. As an exposure apparatus for exposing a wide area, a divisional exposure apparatus is widely used, which is a combination of a plurality of small and inexpensive exposure apparatuses to expose a wide area in a divided manner.

Specific examples of the above-mentioned divided exposure apparatus are shown in FIGS. 4 and 5.
To explain with reference to the drawings, this is a drum-shaped photoreceptor 1 in which two first exposure devices 2a and a second exposure device 2b are arranged in parallel in the direction of its rotation axis. 1st
1. The second exposure devices 2a and 2b each include a semiconductor laser light source (not shown), an exposure beam generating means that generates a predetermined exposure beam from a laser beam, and a scanning system that irradiates and scans the photoreceptor l with the exposure beam. Built-in cheats, etc. The exposure beam 3a irradiated from the first exposure device 2a is applied to the photoreceptor I.
172 divided exposure ranges T1 of the predetermined wide exposure range T0
The exposure beam 3b irradiated from the second exposure device 2b scans and exposes the remaining 1/2 divided exposure range T, of the wide exposure range T0. 11th second exposure device 2a,
The exposure energy of the exposure beams 3a and 3b from the exposure beam 2b is constant, and by controlling the switching between the two exposure beams 3a and 3b, a wide exposure range is uniformly exposed.

[Problems to be Solved by the Invention] Since the individual exposure devices 2a and 2b in the above-described divided exposure device can be small and inexpensive, the entire device can be manufactured at low cost. There was a problem in that the exposure amount at the exposure beam joint varied greatly. That is, when the two exposure beams 3a and 3b are switched at the midpoint of the exposure range T0 without any positional deviation, (
As shown in the graph a), the exposure range T is wide. However, if the two exposure beams 3a and 3b overlap before and after the midpoint of the exposure range T0, then (b) in FIG.
As shown in the graph, the exposure range T.

The intermediate overlapping exposure portion T, is exposed with twice the intensity as the others. On the other hand, the previous exposure beam 3a and the subsequent exposure beam 3b
If there is a gap between the two, as shown in the graph (c) of FIG. 5, the exposure range T. An unexposed portion T, occurs in the middle of . Such double exposure or non-exposure in the middle of the exposure range T0 causes information recording errors due to exposure, so
In order to prevent double exposure or non-exposure, the connection between the scans of the two exposure beams 3a and 3b is adjusted accurately, but this adjustment is extremely delicate and difficult. At present, it is not possible to completely avoid the occurrence of exposure.

The present invention has been made in view of the above-mentioned points, and provides a split exposure device that does not require delicate adjustment of the connections between multiple exposure beams, and that eliminates the risk of double exposure or non-exposure occurring at the connections of exposure beams. is intended to provide.

[Means for Solving the Problems] In order to achieve the above object, the divided exposure apparatus of the present invention is divided into a plurality of exposure ranges and emits a plurality of exposure beams corresponding to each exposure range of a photoreceptor. a scanning means for generating an overlapping exposure portion that is exposed in an overlapping manner in an exposure beam switching portion of two adjacent divided exposure ranges using a plurality of exposure beams from the exposure beam generation means; Exposure control means is provided for switching and controlling the exposure energies of two exposure beams for overlappingly exposing the overlapping exposure portions by decreasing one and increasing the other at the same rate.

[Function] According to the divided exposure apparatus of the present invention having the above configuration,
The overlapping exposure area that is actively generated in the exposure range is double exposed with two exposure beams, but one of the two exposure beams is decreasing and the other is increasing, and the total exposure amount of both is This is an average value that is not significantly different from the exposure amount in other exposure ranges. This is the same even if there is a slight positional shift between the two exposure beams, and therefore, delicate adjustments in switching the exposure beams are no longer necessary.

[Example] Hereinafter, an example of the present invention will be described with reference to FIGS. I to 3.

FIG. 1 shows the predetermined exposure range T of the photoreceptor I. This shows a divisional exposure device that performs divisional exposure using two first exposure devices 4a and a 21s optical device iZ4b. The first exposure device 4a includes a light source such as a semiconductor laser 5a, an exposure beam generating means 7a of an optical system that generates an exposure beam 6a necessary for exposure from the laser light irradiated from the semiconductor laser 5a, and an exposure beam generating means 7a that generates an exposure beam 6a. Exposure of body 1 and encirclement T. It is composed of a scanning means (polygon mirror polarizer) 8a that scans with Similarly to the first exposure device 4a, the second i1K optical device 4b also includes a semiconductor laser 5b, a thousand stages 7b for generating the exposure beam 6b, and a scanning means (polygon mirror polarizer) 8b1.
It is composed of an f-0 lens 8b'. The exposure of each of the exposure devices 4a and 4b is controlled by an exposure control means 9.

In the above embodiment, as shown in the graphs (a), (b), and (c) of FIG.
A shows the wide exposure range T of the photoreceptor I. The second exposure device 4b exposes an area Ts slightly wider than 1/2 of the exposure area Ts.
. By dividing and exposing an area T8 slightly wider than the remaining 1/2 of
The end and beginning portions of the two divided exposure ranges T, T8 are overlapped, and the exposure energies of the two exposure beams 6a and 6b in this overlapping exposure portion T7 are decreased and increased at the same rate. Features. To explain in detail, the width of the overlapping exposure portion T7 where the two exposure beams 6a and 6b overlap is adjusted by the scanning means 8a and 8b,
A first exposure device 4a that scans and exposes this overlapping exposure portion T7.
The exposure beam 6a undergoes modulation in which the intensity linearly decreases from a predetermined value to zero by the exposure control means 9, and the overlapping exposure portion T
, the exposure beam 6b of the second exposure device 4b is modulated by the exposure control means 9 so that the intensity increases linearly from O to a predetermined value P0.

Therefore, if the scanning range of the exposure beams 6a, 6b of the first and second exposure devices 4a, 4b on the photoreceptor l is adjusted to an appropriate position, as shown in the graph (c) of FIG. , the exposure beam is switched when the exposure beam 6a starts decreasing and the exposure beam 6b increases, and the exposure amount at the overlapping exposure portion T7 at this time is:
A predetermined value P that is obtained by adding the exposure amount of the exposure beam 6a that decreases at a predetermined rate and the exposure amount of the exposure beam 6b that increases at the same rate.

The wide exposure range T0 is exposed with a uniform exposure amount P0 throughout. The graph (2) in FIG. 2 shows the divided exposure ranges T, , T. shows a case in which the overlapping exposure portions T8 are separated from each other from the proper position, and in this case, the overlapping exposure portion T8 becomes a little narrower and the exposure amount decreases a little, but there is no risk of non-exposure. The graph (E) in FIG. 2 shows the divided exposure range T by the two exposure beams 6a and 6b.
, , T6 approach each other from the proper position. In this case, the overlapping exposure portion T, spreads out a little and its exposure amount increases a little, but it does not receive twice the exposure.

The above two exposure beams 6a and 6b are obtained from different semiconductor lasers 5a and 5b, respectively, but this is not limited to this example. For example, light from one semiconductor laser light source may be split into two beams using a half mirror. It may be divided to obtain two desired exposure beams. Further, the light amount of the exposure beam in the overlapping exposure portion may be modulated by high-speed pulse modulation.

Figure 3 shows two semiconductor lasers s of the divisional exposure device in Figure 1.
The modulation means 10 which modulates the light intensity of lights a and sb based on light intensity information inputted from the outside is connected to the exposure control means 9.
The modulation means 10 is integrated into the two exposure beams 6.
Perform modulation of a and 6b.

The operating principle of divided exposure in this case is the same as that of the tip embodiment.

[Effects of the Invention] As is clear from the above detailed explanation, when a wide area is dividedly exposed with a plurality of exposure beams, the divided exposure apparatus of the present invention actively uses the portion corresponding to the switching portion of the exposure beam. By overlapping the two exposure beams and increasing the intensity of the two exposure beams in this overlapping exposure area, one is decreased and the other is increased, and the amount of addition of both is averaged. There is no need to worry about double exposure or non-exposure, and it is possible to accurately divide and expose a wide range without making delicate exposure beam switching adjustments.

Further, as described in claim 2, the light intensity of the light source is modulated based on light intensity information from the outside to perform intensity modulation of the exposure beam in the exposure range, thereby exposing the photoreceptor to the light intensity information from the outside. It is possible to do so.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing one embodiment of the present invention, and (A) to (E) in FIG. 2 are for explaining various relationships between the exposure range of the photoreceptor and its exposure amount in the apparatus of FIG. 1, respectively. This is a graph of FIG. 3 is a block diagram showing another embodiment of the present invention. FIG. 4 is a block diagram of a conventional divided exposure device, and FIG. be. 4a, 4b... Exposure device, 5a, 5b... Semiconductor laser (light source), 7a, 7b... Exposure beam generating means, 8a, 8b... Scanning means, 9... Exposure control means,
lO...Modulation means.

Claims (1)

[Scope of Claims] 1. Exposure beam generation means that is divided into a plurality of exposure ranges and generates a plurality of exposure beams corresponding to each exposure range of the photoreceptor; and a plurality of exposure beams from the exposure beam generation means. scanning means for producing an overlapping exposure portion that is overlapped with the exposure beam switching portion of two adjacent divided exposure ranges; and exposure energy of the two exposure beams that overlappingly exposes the overlapping exposure portion of the exposure range. 1. An exposure control device for controlling switching by decreasing one and increasing the other at the same rate. 2. The divided exposure apparatus according to claim 1, further comprising modulation means for modulating the light intensity of each of the plurality of exposure beams based on light intensity information inputted from the outside.