JP2834220B2 - Variable magnification recording optical printer - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical printer for forming an image on a photoreceptor by using a light emitting diode array light source. This is suitable for an optical printer of an image forming type.

[Conventional technology]

In this type of conventional apparatus, an image is formed by an optical system including a light emitting diode array light source LEDARY and a variable power lens CL as shown in FIG. By controlling the position of the variable power lens corresponding to the designation of the 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 photoconductor PC, and an image dot row of one line L is formed. You. By controlling the driving 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 performed on the photoconductor. You.

[Problems to be solved by the invention]

In the image formation using the variable power lens, as shown in FIG. 7, the incident angles θ of the respective light emitting dots D ₁ ,... D _n ,. As shown in (a) and (b), they differ depending on the magnification. Therefore, the illuminance of each of the imaging dots P ₁ ,..., P _n ,. In other words, the larger the angle of incidence θ away from the optical axis of the variable power lens, the lower the illuminance of the image surface becomes compared to the light emitting dot on the optical axis. Therefore, the light image of one line formed on the photoreceptor has an illuminance distribution having a high illuminance at the center in the form of a semi-cylindrical illumination.

As a result, the recorded image has density unevenness such that it is dark at the center of the screen and light at both ends.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an optical printer device capable of preventing a decrease in edge density due to a variable power lens and obtaining an image without density unevenness on a screen.

[Means for solving the problem]

In order to achieve the above object, a method is employed in which the light output of the light emitting diode array light source has a distribution so as to compensate for a decrease in the peripheral light amount of the variable power lens. The light emitting diode array light source is configured by arranging a large number of chips. Accordingly, by selecting and arranging chips having different light outputs, a light-emitting diode array light source capable of canceling a decrease in the peripheral light amount of the variable power lens is made possible.

[Action]

The light emitting diode array light source configured in this way is
When an image is formed on the photoreceptor through the variable power lens, the luminous output of the luminous dot having a large incident angle is large, so that the image plane illuminance is flattened at each point on the line.

〔Example〕

Hereinafter, the present invention will be described in detail with reference to the drawings. FIG. 1 shows an embodiment of the present invention. The light emitting diode array light source is indicated by LEDARY, and the light emitted from the light source is formed by the folding mirrors M ₁ , M ₂ , M ₃ and the variable power lens CL to form an optical path. When the magnification information is input, the number of pulses corresponding thereto is generated, and the variable power lens CL is moved to a position where the magnification can be obtained by a pulse motor (not shown). In this case the mirror M ₂ and M ₃ are having a mechanism for Tsuido in order to obtain a predetermined optical path length. Thereafter, the photoconductor PC is preliminarily charged on the photoconductor PC by the charger CH, and the light emitting diode array light source is driven based on the recording data. Generate a charge image. When the photoreceptor rotates in the direction of arrow RO and the charge image reaches the developing unit DV, the developing toner TR moves to the photoreceptor by electrostatic force and is visualized. Thereafter, the toner on the photoconductor is transferred to the paper by the transfer device TH.
It is transferred to PA and fixed to the paper by the fixing unit FX.

Light emitting diode array light source LEDARY in more detail second
Shown in the figure. The light-emitting diode array light source is composed of a large number of light-emitting diode array chips C having a plurality of light-emitting dots D arranged in a line, and a driver DR for energizing each light-emitting dot is integrated and arranged near the light-emitting diode array. Is done. The light emitting diode array and the driver group are mounted on a ceramic substrate KB to form a light emitting diode array light source, and are driven by an external input signal. In this embodiment, when an image is formed by a variable power lens, a chip having a high light emission output under the same driving current is arranged for a light emitting dot at an end of the light emitting diode array where the image plane illuminance is low. A light emitting diode array light source in which a chip having a low light emitting output is arranged at the light emitting dot located on the optical axis of the variable power lens. How these chips having different light output are arranged depends more particularly on the locus of movement of the variable power lens. In the case where recording is always performed at the center of the printer as shown in FIG. 7, the illuminance on the imaging surface of the photosensitive member is low at one end, is highest at the center, and is the same at the other end as the opposite end. Become a level. When this is plotted with respect to the light emitting dot, it becomes as shown in FIG. 3 (1). As it goes to both ends of the light emitting diode array light source, its image plane illuminance has a width depending on the magnification due to the difference in the incident angle. . Therefore,
When the chip arrangement of the light emitting diode array light source is performed according to the upper limit or the lower limit of the width, the image plane illuminance is flattened at one magnification, but the error increases at the other magnification.
Concentration unevenness is inevitable. In the present invention, in order to minimize the change in the illuminance of the image plane, various light emission output chips are shown in FIG. Were arranged in the same manner.

Further, in a printer in which the variable magnification lens is skewed as shown in FIG. 4 so that variable magnification recording can be performed by moving the variable magnification lens to one side of the photoconductor, the image surface illuminance of the light emitting dot on the photoconductor is set to the fifth. As shown in FIG. 1A, the distribution width also has a band shape. Also in this case, the light emitting diode array light source was constituted by selecting the chips to be arranged at the center value of the width. FIG. 5 (2) shows the light output state of the array chip. In the present embodiment, the light output of the light emitting diode array is selected and arranged so as to compensate for the decrease in the peripheral light amount of the variable power lens. Therefore, an illuminance distribution with small unevenness can be obtained at any magnification.

〔The invention's effect〕

As described above, according to the present invention, in variable magnification recording, a decrease in the amount of light at the periphery of the variable power lens is reduced, and the illuminance on the imaging surface on the photosensitive member is flattened, so that there is no density unevenness in the screen. There is an effect that an image can be obtained.

[Brief description of the drawings]

FIG. 1 is a block diagram of an optical printer showing one embodiment of the present invention, FIG. 2 is an explanatory view of a light emitting diode array light source of the embodiment of FIG. 1, and FIGS. 3 and 5 are light emitting diodes of FIG. FIG. 4 and FIG. 7 are views showing an optical path of a variable power lens that moves for setting a magnification, and FIG. 6 is a description generally showing a conventional variable power optical system. FIG. LEDARY ...... emitting diode array light source, C ...... emitting diode array _{multichip, D, D 1, D n} ...... emitting dots, P _1, P _n ...
… Imaging dot, CL …… magnifying lens.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-61-48982 (JP, A) JP-A-62-217677 (JP, A) JP-A-62-233270 (JP, A) (58) Field (Int.Cl. ⁶ , DB name) B41J 2/45 B41J 2/455

Claims (1)

(57) [Claims] A light emitting diode array light source, a variable power lens,
In an optical printer including a lens position control unit and a photoreceptor that positions the variable power lens according to a magnification specification,
A light emitting diode array light source is configured by arranging a large number of light emitting diode array chips having different light emitting outputs so as to compensate for nonuniform image plane illuminance on the photoreceptor surface caused by a decrease in peripheral light amount of the variable power lens. Variable magnification recording optical printer.