JPH0542717A - Exposing system and aligner - Google Patents

Abstract

PURPOSE:To provide exposing method and device wherein jaggedness can be undistinguishable. CONSTITUTION:In an image forming device for constituting 1 picture element by emission of an end face emissive EL element 10 for a plurality of times, an inclination angle 45 deg. of an outline of an image based on printing data with respect to the horizontal scanning direction is determined as a boundary. When this inclination angle is an inclination angle approximate to the horizontal scanning direction, the end face emissive EL element 10 is emitted selectively in accordance with image area at a picture element unit through which the outline passes. When the inclined angle is an inclined angle approximate to the vertical scanning direction, light intensity of the end face emissive EL element 10 is set in accordance with the rate of the image area at the picture element unit through which the outline passes.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exposure method and an exposure apparatus for forming an electrostatic latent image on a photosensitive member based on electrophotography.

[0002]

2. Description of the Related Art Recently, a line head composed of a large number of edge emitting EL (electroluminescence) elements arranged in the main scanning direction is arranged opposite to a photoconductor, and the outer peripheral surface of the photoconductor is charged, A line printer has been developed in which an electrostatic latent image is formed by irradiating a charged portion with light from each end surface emitting EL element of a line head, and the electrostatic latent image is developed and transferred to a sheet. The edge emitting EL device of this line head is a device in which a thin film active layer made of zinc sulfide or the like containing an active element is surrounded by a dielectric, and electrodes are formed on both surfaces of this dielectric. It has characteristics of extremely high emission intensity and fast response. FIG. 7 shows a part of an image based on the print data, where x is the size of one pixel in the main scanning direction and y is the size in the sub scanning direction, and the width of the edge emitting EL element in the main scanning direction is shown. Corresponds to x and the thickness is a fraction thereof. Therefore, an electrostatic latent image of one pixel is formed by causing one edge emitting EL element to emit light a plurality of times in the process of rotating the photoconductor.

As shown in FIG. 7, the outline L of the image is inclined with respect to the main scanning direction depending on the print data, but as long as the image is formed on a pixel-by-pixel basis, it is impossible to bring its outline close to a straight line. There is a problem that the outline of the line of the electrostatic latent image becomes jagged, which is called jaggies.

Therefore, since the edge-emitting EL element has a flat shape with a large width in the main scanning direction and a small thickness in the sub-scanning direction, the edge emitting EL element emits the edge surface according to the image area partitioned by each pixel into outlines. An exposure method has been considered in which a type EL element is caused to emit light selectively. That is, since one pixel is formed by a plurality of light emission, if an image formed by one light emission is a pixel component, one pixel is formed by a plurality of flat pixel components arranged in the sub-scanning direction. The degree of jaggies can be made inconspicuous by forming an image in units of one pixel component instead of in units of one pixel.

[0005]

As described above, since the edge emitting EL element has a flat shape with a small thickness in the sub-scanning direction, the method for forming an image in units of one pixel component is the main scanning. This is effective when the angle of the outline L with respect to the direction (horizontal direction) is small. However, as shown in FIG. 8, the angle of the outline L with respect to the main scanning direction is 4
If it exceeds 5 ° and is close to the sub-scanning direction (vertical direction),
Even if the number of times of light emission is set on a pixel-by-pixel basis, there are many image areas that extend outside the outline L, and there are many blank areas that are originally image areas inside the outline L, resulting in unevenness with respect to the outline L. It's impossible to make jaggies inconspicuous because of the increased number.

[0006]

SUMMARY OF THE INVENTION According to the present invention, a large number of flat edge emitting EL elements having a thickness smaller in the sub-scanning direction than the width in the main scanning direction are arranged in the main scanning direction so as to be opposed to a photoconductor. , The edge emitting EL in the process of rotating the photoconductor
In an image forming apparatus that forms an electrostatic latent image of one pixel by irradiating light from the element to the photoconductor a plurality of times, the inclination angle of the outline of the image based on the print data with respect to the main scanning direction is set to 45 °. The tilt angle close to the main scanning direction or the tilt angle close to the sub-scanning direction is determined separately. When the tilt angle is the tilt angle close to the main scanning direction, the outline passes through the pixel unit according to the image area. When the edge emitting EL element is selectively made to emit light and the tilt angle is a tilt angle close to the sub-scanning direction, the edge emitting EL element of the edge emitting EL element is adjusted according to the ratio of the image area in pixel units through which the outline passes. The light intensity was set.

[0007]

When the inclination angle of the outline of the image with respect to the main scanning direction is judged to be small at the boundary of 45 °,
By selectively emitting light from the edge-emitting EL element according to the image area in units of pixels through which the outline passes, an image area protruding outside the outline and an inner blank area are utilized by utilizing the flat shape of the edge-emitting EL element. And the jaggies can be made inconspicuous. When it is determined that the inclination angle of the outline of the image with respect to the main scanning direction is large at 45 °, the pixels through which the outline passes. It is possible to reduce the light intensity of the edge emitting EL element according to the ratio of the image area in units to reduce the light density of the image protruding outside the outline, thereby making jaggies less noticeable to the eyes. it can.

[0008]

An embodiment of the present invention will be described with reference to the drawings. First, FIG. 1 shows the structure of an exposure apparatus. A host computer 1, a data judgment circuit block 2 which is a data judgment means, and a data conversion circuit 3 are connected in series. The print data transferred from the host computer 1 is print data based on a bit matte or outline font, but in any case, the data of the inclination angle of the outline of the image with respect to the main scanning direction is included in this print data. Therefore, in the data judgment circuit block 2, the inclination angle of the outline of the image in the main scanning direction is judged from the received print data by dividing the inclination angle close to the main scanning direction or the inclination angle close to the sub-scanning direction at the boundary of 45 °. The data judgment signal is output to the data conversion circuit 3 together with the print data. The data conversion circuit 3 determines a light emitting operation determining means for determining a light emitting operation of an edge emitting EL element, which will be described later, in accordance with an image area in pixel units through which the outline passes when the inclination angle is close to the main scanning direction. 4 and a light intensity setting means 5 for setting the light intensity of the edge emitting EL element according to the ratio of the image area in pixel units through which the outline passes when the inclination angle is close to the sub-scanning direction. Have. The head control circuit 6 outputs the drive signal set by the light emission operation determining means 5 and the drive signal set by the light intensity setting means 5 to a common driver 7 and a channel driver 8 which are drive units, respectively. Reference numeral 9 denotes a line head, which is formed by arranging a large number of edge emitting EL elements 10 on a substrate (not shown) in the main scanning direction. These edge-emitting EL elements 10 are obtained by enclosing a thin-film active layer made of zinc sulfide or the like containing an active element with a dielectric, and forming a common electrode 11 and a channel electrode 12 on both surfaces of this dielectric. The common electrode 11 is connected to the common driver 7, and the channel electrode 12 is connected to the channel driver 8.

As illustrated in FIG. 5, the channel electrode 12
When a positive / negative symmetrical low voltage pulse V ₁ is applied to the common electrode 11 and a positive / negative symmetrical high voltage pulse V ₂ close to the threshold voltage ± V _TH is applied to the common electrode 11, a difference V ₂ −V ₁ between these pulses is generated. It is applied to the light emitting type EL device 10. Therefore, by controlling the synchronization of these pulses V ₁ and V ₂ ,
A light emitting state as shown in FIG. 5A and a non-light emitting state as shown in FIG. 5B are obtained.

Therefore, as shown in FIG. 6, the edge emitting EL element 10 emits light when a positive and negative symmetrical pulse exceeding a threshold value is applied. The light intensity gradually increases, and afterglow is emitted when the applied pulse falls below the threshold value. Figure 6
(A) is an edge emission type EL in which a pulse continuously exceeding a threshold value
When applied to the element 10, the average light intensity exhibits a high value D because the cycle of the emission peak is short. 6 (b) is 3
Pulses that exceed the threshold value once per time are emitted from the edge emitting EL
When applied to the element 10, the average light intensity is lower than D (for example, B) because the emission peak cycle becomes longer.
Indicates. Therefore, this average light intensity is the ratio of the application frequency of the pulses exceeding the threshold value, for example, A (non-emission), B
It is controlled in four levels: (weak light), C (medium light), and D (strong light). This light intensity is naturally proportional to the density of the electrostatic latent image formed on the photoconductor.

Next, an actual exposure method will be described with reference to the flowchart of FIG. Based on the print data transferred from the host computer 1, the data judgment circuit block 2 has a tilt angle close to the main scanning direction or a tilt near the sub-scanning direction with the tilt angle of the outline of the image with respect to the main scanning direction being 45 °. Judgment is made according to the angle, and the result of the judgment (data judgment signal) is output to the data conversion circuit 3 together with the print data. In the data conversion circuit 3, when the inclination angle is close to the main scanning direction, the light emission operation determination unit 4 determines the light emission operation of the edge emitting EL element 10 according to the image area in pixel units through which the outline passes. However, when the tilt angle is close to the sub-scanning direction, the light intensity of the edge-emitting EL element 10 is set according to the ratio of the image area in units of pixels through which the outline passes.

FIG. 3 and FIG. 4 each show a part of an image based on the print data, and these images are examples in which an outline L inclined with respect to the main scanning direction is included. FIG. 3 is an example in which the outline L with respect to the main scanning direction is smaller than 45 ° and is close to the main scanning direction. At this time, the edge emitting EL element 10 is selectively driven on the basis of the light emission operation data set by the light emission operation determining means 4, so that in the pixel passing through the outline, the pixel component of the pixel component is changed according to the ratio of the image area. The number is reduced, and the area of the image protruding outside the outline L can be minimized. Therefore, the jaggy can be made inconspicuous.

FIG. 4 shows an example in which the outline L with respect to the main scanning direction is larger than 45 ° and is close to the sub scanning direction. At this time, the light intensity A set by the light intensity setting means 5
By setting the frequency at which the pulse is applied to the edge emitting EL element 10 exceeding the threshold value based on B, C, and D, the light density of the image protruding outside the outline L can be reduced, and therefore, Visually make jaggies inconspicuous. In FIG. 4, the density of the shaded lines is shown corresponding to the light intensities A, B, C, and D, but the density of the shaded lines and the light density are proportional.

[0014]

According to the present invention, a large number of flat edge emitting EL elements having a thickness smaller in the sub-scanning direction than the width in the main scanning direction are arranged in the main scanning direction so as to face the photoconductor. In an image forming apparatus that forms an electrostatic latent image of one pixel by irradiating the photosensitive member with light a plurality of times from the edge-emitting EL element in the process of rotating the image, main scanning of an outline of an image based on print data. The inclination angle with respect to the direction is determined by dividing it into an inclination angle close to the main scanning direction or an inclination angle close to the sub-scanning direction with a boundary of 45 °. When the inclination angle is close to the main scanning direction, the outline is determined. When the inclination angle is an inclination angle close to the sub-scanning direction, the edge surface emission type EL element is selectively caused to emit light in a pixel unit in which the outline passes, and an image area is passed in a pixel unit in which the outline passes. Said end emission type EL according to the ratio of
Since the light intensity of the element is set, when it is determined that the inclination angle of the outline of the image with respect to the main scanning direction is smaller than 45 °, the edge emission according to the image area is performed in pixel units through which the outline passes. By selectively causing the type EL element to emit light, the flat shape of the edge-emitting type EL element can be utilized to minimize the image area protruding to the outside of the outline and the blank area on the inside. When it is determined that the inclination angle of the outline of the image with respect to the main scanning direction is large at a boundary of 45 °, the edge-emitting type according to the ratio of the image area in units of pixels through which the outline passes. EL
The light intensity of the element can be reduced to reduce the light density of the image protruding outside the outline, which has the effect of making jaggies less visible.

[Brief description of drawings]

FIG. 1 is an electronic circuit diagram showing an embodiment of the present invention.

FIG. 2 is a flowchart thereof.

FIG. 3 is an explanatory diagram showing a part of an image converted from the print data.

FIG. 4 is an explanatory diagram showing a part of an image converted from the print data.

FIG. 5 is a timing chart of voltage pulses applied to the common electrode and the channel electrode.

FIG. 6 is a timing chart showing the relationship between the pulse applied to the edge emitting EL device and the light intensity.

FIG. 7 is an explanatory diagram showing a part of an image based on conventional print data.

FIG. 8 is an explanatory diagram showing a part of an image converted from conventional print data.

[Explanation of symbols]

 2 data determination means 4 light emission operation determination means 5 light intensity setting means 7, 8 drive section 10 edge emitting EL element

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification number Internal reference number FI Technical display location B41J 2/485 G03G 15/04 116 9122-2H G09G 5/28 9061-5G H04N 1/04 Z 7251 -5C // G09G 3/12 301 K 9176-5G

Claims (2)

[Claims] 1. A process in which a large number of flat edge emitting EL elements having a thickness smaller in a sub-scanning direction than a width in a main scanning direction are arranged in the main scanning direction so as to face a photoconductor and the photoconductor is rotated. In an image forming apparatus that forms an electrostatic latent image of one pixel by irradiating the photosensitive member with light from the edge emitting EL element a plurality of times, the inclination angle of the outline of the image based on the print data with respect to the main scanning direction. 45 °
Is determined as an inclination angle close to the main scanning direction or an inclination angle close to the sub-scanning direction. If the inclination angle is an inclination angle close to the main scanning direction, the image area is defined in pixel units through which the outline passes. When the tilt angle is close to the sub-scanning direction, the edge-emitting EL element is selectively made to emit light according to the edge-emitting type EL element, and the edge-emitting type EL element is selected according to the ratio of the image area in pixel units through which the outline passes. An exposure method, wherein the light intensity of the EL element is set. 2. A process in which a large number of flat end-face emitting EL elements having a thickness smaller in the sub-scanning direction than in the main scanning direction are arranged in the main scanning direction so as to face the photoconductor and the photoconductor is rotated. In an image forming apparatus that forms an electrostatic latent image of one pixel by irradiating the photosensitive member with light from the edge emitting EL element a plurality of times, the inclination angle of the outline of the image based on the print data with respect to the main scanning direction. 45 °
With a boundary as a boundary, the data judgment means for judging whether the tilt angle is close to the main scanning direction or the tilt angle close to the sub-scanning direction, and a pixel unit through which the outline passes when the tilt angle is close to the main scanning direction. The light emitting operation determining means for determining the light emitting operation of the edge emitting EL element according to the image area, and the ratio of the image area in pixel units through which the outline passes when the inclination angle is an inclination angle close to the sub-scanning direction. Light intensity setting means for setting the light intensity of the edge emitting EL element in accordance with the above, and each of the edge emitting EL element is connected to the light emission operation determining means and the drive section connected to the light intensity setting means. An exposure apparatus characterized by being connected.