JPS60154267A - Image recording method - Google Patents

Abstract

PURPOSE:To obtain an image with good resolution by specifying light beam condition and light beam scanning condition so that picture element diameters of each picture element to be recorded in a main and a subscanning direction are equalized to each other. CONSTITUTION:Emitted light from a fine light emitting segment of a picture elememt unit is modulated with binary image information and its modulated light is exposed to and scanned on the surface of a photosensitive body 4 through an optical image formation system 2 to record a visual image. Then the pulse width of image information is so varied that 0.6<=rhoy/rhox<=1.0 and 0.5<=rho.Tp <=1.5, where rhox and rhoy are the ratio of the beam diameter in the main scanning direction to the picture element pitch in the main scanning direction and the ratio of the beam diameter to the picture element pitch in the subscanning direction and Tp is the ratio of exposure time to one-picture-element scanning time at the boundary between an image part and a no-image part.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an image recording method in an optical scanning electrophotographic recording apparatus using a minute light emitting segment as a light source.

k Tohaku 1 Conventionally, laser printers that scan laser beams to create records have complicated optical systems, etc.
In order to simplify the light source and optical system, a fluorescent dot array tube in which fluorescent substances are arranged in pixel units in an array in the main scanning direction is used as a light source.V) The generated light is modulated according to binary image information. An optical scanning type that forms an electrostatic latent image by exposing the surface of a photoreceptor that is sent in sub-scanning direction through an imaging optical system, and records the image information according to the image information by visualizing the latent image. An electrophotographic recording device has been developed (see Japanese Patent Laid-Open No. 108864/1983).

However, such conventional optical scanning electrophotographic recording devices use a fluorescent dot array tube in which faintly luminescent phosphors are arranged in an array in the main scanning direction in pixel units as the light beam, which makes it difficult to record images. This is disadvantageous in terms of image resolution.

In other words, in the main scanning direction, the influence of the emission intensity distribution from the regularly arranged light emitters is quite large.
In addition, in the sub-scanning direction, since the light emitter emits light at a predetermined timing according to the sub-scanning feed of the photoreceptor, the diameter of the visualized pixel varies due to the difference in characteristics in both scanning directions. The resolution of the recorded image will be poor depending on the main and sub-scanning directions.

The present invention has been made in consideration of the above points, and is a method for recording high-resolution images having the same pixel diameter in each of the main and sub-scanning directions when recording images in an optical scanning type electrophotographic recording device. An object of the present invention is to provide an image recording method that enables the following.

1 litter An embodiment of the present invention will be described in detail below.

In the image recording method according to the present invention, for example, an optical scanning type electrophotographic recording using a fluorescent dot array tube 1 in which fluorescent substances are arranged in an array in the main scanning direction in pixel units as shown in FIG. 1 is used as a light source. In the apparatus, a light beam modulated according to the binary image information BS emitted from the fluorescent dot array tube 1 is exposed to the 4 surfaces of the drum-shaped photoreceptor that is sent in the sub-scanning direction through the imaging optical system 2. The main pixel in the image that is visualized when forming an electrostatic latent image.

The purpose is to provide eight light beam conditions and scanning conditions for the light beam such that the pixel diameter in each sub-scanning direction is the same.

In the optical scanning type electrophotographic recording device shown in FIG. 1, the ON of each phosphor arranged in a line in the main scanning direction is determined for each pixel in the fluorescent dot array tube l according to the binary image information BS. , a minute emitted beam directly modulated by turning off the light is sent in a sub-scanning direction through the imaging optical system 2, and is irradiated onto the surface of the drum-shaped photoreceptor 4, which is uniformly charged by the charger 3.

The electrostatic latent image formed by the exposure is made into a visible image by a developing device 5, and then transferred to a recording paper 7 by a transfer device 6. 8 in the figure indicates a cleaner that cleans the toner remaining on the surface of the photoconductor 4 after transfer. In FIG. , and drive ICI 3
shows a specific example of the structure of the fluorescent dot array tube 1 which is integrated with the terminal 14 on the same substrate 15. Furthermore, instead of the fluorescent dot array tube 1, an array of LEDs arranged in pixel units may be used as the light source.

Now, when the light beam conditions and light beam scanning conditions are variously changed, the relative potential V and the relative potential V and each relative distance X and Y in the main and sub-scanning directions in the exposure pattern of one line in both the main and sub-scanning directions are shown. Examples of the characteristics of the relative exposure energy Q are shown in FIGS. 3 to 5, respectively. Note that the relative distances X and Y are the ratio of the distance to each pixel pitch in the main scanning direction and the sub-scanning direction, and the relative potential V
is the ratio of the surface potential (uniformly charged potential) of the photoreceptor when exposed to light when the exposure energy is zero (relative exposure energy Q is the maximum exposure energy), and the actual exposure energy to I/g. Each ratio is hailed. Here, for the sake of explanation, the same data is used in each of FIGS. 3 to 5 (a).

Figure 3 shows the characteristics when the ratio ρ of the beam diameter in the sub-scanning direction to the pixel pitch in the sub-scanning direction is set to approximately 0.94, and (a) of the same figure shows the ratio of the beam diameter in the main scanning direction to the pixel pitch in the main scanning direction. The ratio ρ is changed, and FIG. 10B shows a change in the ratio Tp of the exposure time of the light beam to the scanning time of one pixel. The characteristics indicated by thick lines in the figure are potential distributions that are similar to each other in the main and sub-scanning directions, and in this case, ρ, aO, 94, ρ-1°1
8, TP=0.6 is obtained, and therefore, the light beam condition in this case is ρ, /ρ, = 0.7979, and the light beam scanning condition is ρ, ・Tp”0.564. What is beam diameter?

It is defined by the cross-sectional shape at the position e-1 (approximately 13.5%) of the peak of the beam intensity distribution having a Gaussian distribution.

Figure 4 shows the characteristics when the ratio ρ of the beam diameter in the sub-scanning direction to the pixel pitch in the sub-scanning direction is set to approximately 1.18.
The figure (a) shows the ratio ρ8 of the beam diameter in the main scanning direction to the pixel pitch in the main scanning direction, and the figure (b)
is the ratio Tp of the exposure time of the light beam to the scanning time of one pixel
It is a change of . The characteristics indicated by thick lines in the figure are those in which the potential distribution is similar to each other in the main and sub-scanning directions, and in this case, ρ,! =1.18. ρ, gourd 1.42. Tp! 0.7 is obtained, and therefore, the light beam condition in this case is ρY/ρ work=0.831°, and the light beam scanning condition is ρ,·Tp=0.826.

Figure 5 shows the characteristics when the ratio ρ of the beam diameter in the sub-scanning direction to the pixel pitch in the sub-scanning direction is set to approximately 1.42. The ratio ρ8 is changed, and the figure (b) is the result where the ratio Tp of the exposure time of the light beam to the scanning time of one pixel is changed. The characteristics indicated by thick lines in the figure are potential distribution states that are similar to each other in the main and sub-scanning directions, and in this case, ρY=1.42. ρ4-1.
65. 'rp=o, a are obtained, and therefore, the light beam conditions in this case are ρY/ρ,=0.861°, and the light beam scanning conditions are ρ,·Tp=1.136, respectively.

Furthermore, by appropriately changing the value of ρ, each parameter ρX I
If T P is set to various values, similar potential distribution states can be obtained in the main and sub-scanning directions, as described above.

However, from the above considerations, empirically, ρ is 0.6.

/ρ, 1.0 and 0.5〈ρ,・TP〈1.5, it can be seen that practically similar potential distribution states can be obtained in the main and sub-scanning directions. .

If we take an example of the conditions obtained so far and look at the two-dimensional distribution state, it will be as shown in FIGS. 6 and 7.

FIG. 6 shows ρYkl', 18. ρ = 11.42. T
This shows the distribution of exposure energy Q when a 7- grid pattern is drawn for each pixel under the condition of P=0.7, and Figure 7 shows the distribution of surface potential on the photoreceptor at that time. . The graph shown here is based on a computer simulation, but if an electrostatic latent image is actually formed on the surface of the photoreceptor and visualized under these conditions,

The result is that the line widths of the gratings are almost the same in the sub-scanning direction.

As described above, in the image recording method according to the present invention, the light beam conditions and the light beam scanning conditions are set so that electric potential distribution states similar to each other can be obtained particularly in the main and sub-scanning directions when recording an image in an optical scanning electrophotographic recording device. By forming an electrostatic latent image on the photoreceptor surface in accordance with binary image information, it is possible to always record a high-resolution image with the same pixel diameter in each main and sub-scanning direction. become. Basically, at the stage of forming an electrostatic latent image on the photoreceptor surface, ρ8. By defining ρy #TP, it becomes possible to control the pixel diameter in each of the main and sub-scanning directions. In addition, in the present invention, in order to obtain potential distribution states similar to each other in the main and sub-8 scanning directions, positive-positive recording is performed to visualize non-exposed areas, and positive-positive recording is performed to visualize exposed areas. It is effective for both negative and positive records.

Although the present invention has been described with attention to light beam conditions and light beam scanning conditions, the quality of recorded images is determined by many other factors such as scanning speed, beam power, visualization level, etc. , In order to obtain an even higher quality image, ρ, /ρi, ρ,
- It is desirable to determine each value of Tp.

Further, as a specific means for controlling the value of Tp,
This can be easily implemented by changing the pulse width of the binary image information at the boundary between the image area and the non-image area.

shame The above describes the image recording method according to the present invention.

In particular, the main character of each pixel recorded in an optical scanning electrophotographic recording device that uses a minute light emitting segment as a light source.

The light beam conditions and light beam scanning conditions are specified in order to make the pixel diameter in the sub-number scanning direction the same, and this has the excellent advantage of being able to record images with good resolution. are doing.

[Brief explanation of drawings]

Fig. 1 is a simplified configuration diagram showing an optical scanning electrophotographic recording device using a fluorescent dot array tube as a light source, Fig. 2 is a perspective view showing an example of the configuration of a fluorescent dot array tube, and Figs. 3 (a) and (b).
)/)Characteristics of each relative potential with respect to the relative distance in the main scanning direction and the relative distance in the sub-scanning direction when y is set to approximately 0.94, Figures 4(a) and (b) show that ρ is approximately 1 Characteristic diagrams of each relative potential with respect to the relative distance in the main scanning direction and the relative distance in the sub-scanning direction when set to .18, Figures 5 (a) and (b)
) is a characteristic diagram of each relative potential with respect to the relative distance in the main scanning direction and the relative distance in the sub-scanning direction when ρ is set to approximately 1.42. Figure 6 shows the characteristics of each relative potential when a grid pattern is drawn for each pixel. A two-dimensional distribution diagram of exposure energy, and FIG. 7 is a distribution diagram of surface potential on the photoreceptor at that time. ■... Fluorescent dot array tube 2... Imaging optical system 3
...Charger 4...Photoreceptor 5...Developer 6.
...Transfer device 7... Recording paper 8... Cleaner applicant's agent Kiyoshi Torii (111 = 12- Figure 3 (a) (b) Figure 4 (a) (b) Sub 1yj: γrW) 8 %L at t5 YFigure 5 (a) (b) 1! 'ILtWfila%fPE Difficulty Figure 6: 11 pairs of sub-rikusakata shunsaro and figure 7: Bevel (2r square rabbit vs. distance)

Claims (1)

[Claims] The light generated by the minute light emitting segment in each pixel is modulated by binary image information, and the modulated light is exposed and scanned on the photoreceptor surface via an imaging optical system to form an electrostatic latent image, and the latent image is visualized. In an optical scanning electrophotographic recording device that performs recording according to image information by imaging, the ratio ρ of the beam diameter in the main scanning direction to the pixel pitch in the main scanning direction, and the ratio ρ in the sub scanning direction to the pixel pitch in the sub scanning direction Beam diameter ratio ρY
The value of ρ7/ according to is 0.6 and ρY/~1.0
and the product of the ratio of exposure time to one pixel scanning time Tp and ρ at the boundary between the image area and the non-image area satisfies the condition that 0.5 and ρ, and Tp and 1.5. An image recording method in which the pulse width of image information is changed so that the pulse width of the image information is changed.