JPH03120058A - Variable magnification recording optical printer - Google Patents

Abstract

PURPOSE:To prevent the deterioration of density at the periphery due to a variable magnification lens for obtaining an image without density irregularity in a frame by a method wherein tips having different optical output are selected and arranged. CONSTITUTION:Tips having a higher illuminant output at the same driving current are arranged for illuminant dots at ends of light emitting diode alley C where image illuminance decreases when an image is in focus through a variable magnification lens CL, and the tips having a lower illuminant output are arranged for illuminant dots located on the optical axis of the variable magnification lens in order to constitute a light emitting diode alley light source LEDARY. That is, the tips having a variety of illuminant output are arranged so as to compensate the decrease in the image illuminance according to the central value of the image illuminance distribution range, so that the variation in the image illuminance is diminished as much as possible. Thereby, the decrease in the image illuminance at the periphery of the variable magnification lens is diminished, and the illuminance on the image formation surface of a photo-sensitive plate is made even, so that an image without irregular density within a frame can be obtained.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an optical printer that forms an image on a photoreceptor using a light emitting diode array light source. This is suitable for optical printers that form images.

[Conventional technology]

In this type of conventional apparatus, as shown in FIG. 6, image formation is performed by an optical system comprising a light emitting diode array light source LEDARY and a variable magnification lens CL. By controlling the position of the variable magnification lens in response to the specified magnification, each light emitting dot D of the light emitting diode array becomes a reduced dot image or an enlarged dot image on the surface of the photoreceptor PC, and an imaged dot row of - line L is formed. Ru. Then, by controlling the drive cycle of the light emitting diode array light source in relation to the magnification of the variable magnification lens and forming lines one after another based on the recording data, variable magnification recording of characters and images is achieved on the photoreceptor. Ru.

[Problem to be solved by the invention]

In image formation using a variable magnification lens, as shown in FIG. 7, each light emitting dot D! , . . .Dn, . Therefore, each image forming drum h P 1. formed on the photoreceptor through the variable magnification lens. , . . . P4° . That is,
The farther a dot is from the optical axis of the variable magnification lens and the larger the incident angle O, the lower the image plane illuminance is compared to the light emitting dot on the optical axis. Therefore, one line of optical image formed on the photoreceptor is
A semicylindrical illuminance distribution with high illuminance in the center.

The resulting recorded image has density unevenness in that it is dark at the center of the screen and light at both ends.

SUMMARY OF THE INVENTION An object of the present invention is to provide an optical printer device that prevents a reduction in edge density caused by a variable magnification lens and that can produce an image with uniform density on the screen.

[Means to solve the problem]

In order to achieve the above object, a method was adopted in which the light output of the light emitting diode array light source was distributed so as to compensate for the decrease in peripheral light intensity of the variable magnification lens. A light emitting diode array light source is constructed by arranging a large number of chips. Therefore, by selecting and arranging chips with different light outputs, it is possible to create a light emitting diode array light source that cancels out the reduction in peripheral light intensity of the variable magnification lens.

[Effect]

When the light emitting diode array light source configured in this way forms an image on the photoreceptor through the variable magnification lens, the light emitting dots with a large incident angle have a large light emitting output, so the image surface illuminance is flat at each point on the line. be converted into

〔Example〕

The present invention will be described in detail below using the drawings. FIG. 1 shows an embodiment of the present invention. Light emitting diode door 1
The noise light source is indicated by LEDARv, and the light emitted from it is reflected by folding mirrors Ml, M2 . An optical path is formed by M3 and variable magnification lens CL. When magnification information is input, a corresponding number of pulses is generated, and a pulse motor (not shown) moves the variable magnification lens CL to a position where the magnification can be obtained. At this time, mirrors M2 and M3 have a tracking mechanism to obtain a predetermined optical path length. Thereafter, the photoconductor PC is uniformly charged in advance by the charger CH, and when the light emitting diode array light source is driven based on the recorded data, the imaged dot light on the photoconductor disappears the charged charge and forms a charge image. generate. When the photoreceptor rotates in the direction of arrow RO and the charge image reaches the developer DV, the developing toner TR is moved to the photoreceptor by electrostatic force and becomes a visible image. After that, the toner on the photoreceptor is transferred to the paper PA by the transfer device TH,
It is fixed to the paper by the fixing device FX.

The light emitting diode array light source LEDARY is shown in more detail in FIG. The light emitting diode array light source is made up of a large number of light emitting diode array chips C each having a plurality of light emitting dots D arranged in a row, and a driver DR for energizing each light emitting dot is integrated and arranged near the light emitting diode array. be done.

These light emitting diode arrays and driver groups are mounted on the ceramic substrate KB to form a light emitting diode array light source, and are driven by external input signals. In this example, for the light-emitting dots at the ends of the light-emitting diode array, where the image plane illuminance is low when imaged by the variable magnification lens,
Arranging chips with high light output under the same drive current,
A light emitting diode array light source was constructed in which a chip with a low light emitting output was placed at a light emitting dot located on the optical axis of the variable magnification lens. How these chips with different light emitting outputs are arranged depends in detail on the locus of movement of the variable magnification lens. When recording is always performed at the center of the printer as shown in Figure 7, the illuminance of the image forming surface of the photoreceptor is low at one end, highest at the center, and the same at the other end as at the opposite end. become the level.

When this is plotted against the luminescent dots, Figure 3 (1
), the image plane illuminance has a width depending on the magnification due to the difference in the incident angle as it approaches both ends of the single light emitting diode array light source. Therefore, if the chips of the light emitting diode array light source are arranged according to the upper or lower limit of the width, the image plane illuminance will be flattened at one magnification, but the error will become large at the other magnification, and it will be uneven by 1 degree. I can't escape it.

In the present invention, in order to minimize changes in image plane illuminance,
Chips with various light emitting outputs were arranged as shown in FIG. 3 (2) so as to compensate for the decrease in illuminance in terms of the median value of the image plane illuminance distribution width.

In addition, in a printer in which the variable magnification lens is moved obliquely as shown in Fig. 4 so that variable magnification recording can be performed by moving it to one side of the photoreceptor, the image plane illuminance of the light emitting dot on the photoreceptor is
As shown in Figure (1), this also has a band-like distribution width. In this case as well, a light emitting diode array light source was constructed by selecting chips arranged with the median width. FIG. 5(2) shows the optical output state of the array chip. In this embodiment, the light output of the light emitting diode array is selected and arranged so as to compensate for the decrease in peripheral light intensity of the variable magnification lens, so that an illuminance distribution with small irregularities can be obtained at any magnification.

〔Effect of the invention〕

As explained above, according to the present invention, in variable magnification recording, the decrease in peripheral light intensity of the variable magnification lens is reduced, and the illuminance of the imaging surface on the photoreceptor is flattened, so that there is no density unevenness within the screen. This has the effect that an image can be obtained.

[Brief explanation of drawings]

Fig. 1 is a configuration diagram of an optical printer showing an embodiment of the present invention, Fig. 2 is an explanatory diagram of a light emitting diode array light source of the embodiment of Fig. 1, and Figs. 3 and 5 are diagrams of the light emitting diode array of Fig. 2. An explanatory diagram showing an example of the configuration of an array light source, FIGS. 4 and 7 are diagrams showing the optical path of a variable magnification lens that moves to set the magnification, and FIG. 6 is an explanation generally showing a conventional variable magnification optical system. It is a diagram. LEDARY...Light emitting diode array light source, C...
・Light-emitting diode array chip, D, Dl, D...Light-emitting driver Fig. 1 Fig. 3 Fig. 2 7° 4 standing i □ Fig. 4 F'C LEDAF, γ Cause C Fig. 5 Inauguration 7゛Io Fighting Y Raidt No. (1) ÷・/7° Communication! (2) Fig. 7 (Ku) etc. 4 Grind (b) 4x

Claims (1)

[Claims] 1. In an optical printer equipped with a light emitting diode array light source, a variable magnification lens, a lens position control means for positioning the variable magnification lens according to a specified magnification, and a photoconductor, the light on the surface of the photoconductor that occurs due to a decrease in the amount of peripheral light of the variable magnification lens A variable magnification recording optical printer characterized in that a light emitting diode array light source is constructed by arranging a large number of light emitting diode array chips having different light emitting outputs so as to compensate for non-uniform illuminance on an image plane.