JP2938513B2 - Exposure equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to an electrostatic latent image by exposing and modulating a modulated light from a minute light-emitting segment array in pixel units onto a photoreceptor surface via an imaging optical system. The present invention relates to an exposure apparatus that forms an image.

2. Description of the Related Art Conventionally, in various electrophotographic recording apparatuses such as a digital copier, a facsimile, and a printer, an optical signal of a method of converting an information signal corresponding to an image to be recorded into optical information and writing the optical information on a photosensitive member. As a device, a self-scanning solid-state exposure device using a dot array fluorescent tube, an LED array, a liquid crystal array, or the like is often used.

For example, a dot array fluorescent tube is formed by arranging a large number of anode electrodes each having fine phosphor dots coated on the surface thereof in the main scanning direction to form light-emitting segments, and generating heat generated from a cathode such as a cathode filament. Electrons are guided to the phosphor dots on the anode electrode which are selectively energized in accordance with the information signal to emit light, and the information signal is suitably converted into optical information. Light emitted from the light-emitting segment in pixel units is incident on an imaging optical system configured by combining a lens array, an aperture plate, a roof mirror array, and the like, and a light shield for preventing flare from the imaging optical system. The surface of the photoreceptor is exposed through a slit formed in the photoreceptor to form an image.

However, the light quantity distribution from the minute light emitting segment array used in such a phosphor dot array tube or the like tends to vary due to various causes. If the variation in the amount of light from the minute light emitting segment array is large,
A large difference occurs in the exposed surface potential, which appears as uneven image density.

Conventionally, as an attempt to equalize the amount of light emitted from a minute light emitting segment array, for example, Japanese Patent Laid-Open No.
No. 8621, JP-A-62-184759, JP-A-62-1684
There is a device proposed in, for example, Japanese Patent Application Publication No. 63-63. In each of these devices, various measures have been taken to improve the structure and drive conditions of the phosphor dot array tube itself.

(Problems to be Solved by the Invention) However, it is practically very difficult to equalize the light amount distribution characteristics from the minute light emitting segment array only by changing the tube structure and the driving conditions, and it is expensive. I can't get it. For example, when the drive condition is electrically changed for each pixel to make the light amount level uniform, it is common to change the light emission time as the drive condition. However, this is technically difficult, and is difficult. There is a problem that the burden is large and the cost increases.

The device described in Japanese Utility Model Publication No. 1-2805 discloses an LED.
Although an attempt is made to equalize the amount of light emission by electrically correcting the variation in the amount of light in each LED of the array, the correction circuit is complicated, and the electric load is large and the cost is high.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an exposure apparatus which can make the amount of emitted light uniform with a simple configuration.

(Means for Solving the Problems) In order to achieve the above object, the invention described in claim 1 converts the light generated in units of pixels from a small light emitting segment array arranged on a certain straight line into image information. In accordance with an exposure apparatus configured to form an electrostatic latent image by exposing and scanning the modulated light on a photoconductor surface via an imaging optical system, the So that the light intensity distribution is uniform
The effective image height line of the imaging optical system is arranged so as to form a predetermined angle with respect to the direction of the linear arrangement of the minute light emitting segment array.

According to a second aspect of the present invention, light generated in pixel units from a small light emitting segment array arranged on a predetermined straight line is modulated in accordance with image information, and the modulated light is transmitted to an imaging optical system. An exposure apparatus that forms an electrostatic latent image by exposing and scanning the surface of the photosensitive member through the imaging optical system so that the light amount distribution from the minute light emitting segment array on the photosensitive member surface becomes uniform. The effective image height line is arranged so as to form a predetermined angle with respect to the direction in which the minute light emitting segment array is linearly arranged, and a voltage or a voltage for driving the minute light emitting segment array for correcting the light amount distribution of the minute light emitting segment array. It has a configuration including a control circuit for correcting current.

(Operation) In the configuration described in claim 1, even if the light amount of the light emitted from the minute light emitting segment array varies, the light utilization of the imaging element according to the luminance distribution of the minute light emitting segment array. Since the efficiency is changed to the opposite side, it is possible to adjust the amount of exposure light at the end of the image forming light on the photoconductor so as to match the amount of exposure light at the center. As a result, the amount of exposure light in the array direction is made uniform.

In the configuration described in claim 1, in addition to the above configuration, correction of the transmitted light amount and correction of the electrical absolute light amount are performed, so that the correction of the transmitted light amount by the imaging optical system is not sufficient. In such a case, fine adjustment is performed with high accuracy by performing voltage or current correction for driving the minute light emitting segment array, and the exposure light amount is highly uniform.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

First, as shown in FIG. 4, the exposure apparatus 1 according to the present invention is arranged so as to be close to the surface of the photosensitive drum 2 and includes a minute light emitting segment array 11 and an imaging element 12. I have. Around the photosensitive drum 2, a charging charger 3, a developing device 4, a transfer charger 5, a separation charger 6, a cleaning device 7, a neutralization lamp 8, and the like are arranged in a ring shape.

In the exposure apparatus 1, light generated from the minute light-emitting segment array 101 on a pixel-by-pixel basis is modulated according to image information and then exposed and scanned on the surface of the photosensitive drum 2 via the imaging element 102, whereby A predetermined electrostatic latent image is formed. This electrostatic latent image is visualized by the developing device 4, and a toner visible image is obtained on the photosensitive drum 2. A negative-positive recording method is employed as the recording method of the present embodiment. A portion corresponding to an image portion is exposed on the surface of the uniformly charged photosensitive drum 2 and is reduced by this exposure. The toner is adhered to the portion where the surface potential of the photosensitive drum 2 is lowered, and development is performed.

The toner visible image obtained on the photosensitive drum 2 is copied on the transfer paper 10 fed at a predetermined timing by the action of the transfer charger 5 and further transferred to the transfer paper 10.
Is passed through the fixing device 11 to fix the toner visible image.

As the minute light emitting segment array 101, an LED array, an LSC array, a fluorescent tube dot array, or the like is used. As the imaging element 102, a selfoc lens array, a roof mirror lens array, or the like is used. In the exposure apparatus 1 shown, a minute light-emitting segment array 10
A fluorescent tube dot array (FLDA) is employed as 1 and a roof mirror lens array (RAMLA) is employed as the imaging element 102.

That is, as shown in FIG. 3, a glass substrate 101a of a fluorescent tube dot array 101 is provided on a rigid base 103 of the exposure apparatus 1 via an elastic plate 104, and the glass substrate The bottom plate of the housing 105 is attached so as to cover 101a. Above rigid base 103
Has a predetermined rigidity so as to force the glass substrate 101a to warp, and the glass substrate 101a is bonded to the rigid base 103 or the housing 105
And the rigid base 103.

On the glass substrate 101a, anode electrodes are arranged at predetermined intervals in a staggered manner from the side end toward the center, and the tip of the anode electrode has phosphor dots on its surface.
101b is applied to form a light emitting segment. These phosphor dots 101b are arranged in an array so as to be arranged in a dot shape in the main scanning direction.

A mesh-like grid having a honeycomb structure with a constant thickness is adhered to the base end surface of the anode electrode via an insulating layer. This grid is connected to the glass substrate 10
It extends along both sides in the main scanning direction, which is the longitudinal direction of 1a, and these two grids are arranged so as to sandwich each phosphor dot 101b with a fixed interval width.

A face glass 101c having a U-shaped cross section is placed on the glass substrate 101a including the grid, and the internal space thereof is kept at a vacuum. In this internal space, a pair of cathode filaments as a cathode is stretched along the longitudinal direction of the glass substrate 101a. On the other hand, the thermoelectrons generated and emitted from the cathode filament cause the phosphor dots 101b to stimulate and emit light. That is, if a constant voltage is applied to the grid and a constant alternating current is applied to the cathode filament, the cathode filament is heated by Joule heat, and thermoelectrons are generated at this time. When the anode electrode is set to a positive potential state with respect to the cathode center potential, the thermoelectrons are accelerated and controlled when passing through the grid, and thereafter are attracted to the anode electrode to excite the energy of the fluorescent substance. The excited electrons flow to the base of the fluorescent substance, and at this time, the fluorescent dots 101b emit light with a predetermined luminance, and the emission energy is converted into a roof mirror lens array 102 as an image forming element.
Through the photosensitive drum 2 as an electrostatic latent image.

Further, a hole 105a is formed in the housing 105, and light emitted from a phosphor dot 101b as a light emitting point and transmitted through a face glass 101c passes through the hole 105a and is located above a bottom plate of the housing 105. It is to be emitted to. The holes 105a also serve to prevent stray light.

A groove is provided on the upper side of the bottom plate of the housing 105, and a roof mirror lens array 102 as an imaging element is attached to the groove so as to extend in the main scanning direction. This roof mirror lens array
The reflecting plate 102a of 102 is installed so as to make an angle of about 45 ° with the optical axis of the light beam, and furthermore, the reflecting plate 102a
A transparent body 102b is attached to the lower edge portion of the lower side so as to extend in the same direction as the reflection plate 102a. This transparent body 10
The lower edge of 2b is engaged with the upper surface of the bottom plate 105 so as to abut in an oblique direction.

Then, the light reflected by the reflection plate 102a passes through an imaging optical system formed by combining the lens array 102c and the roof mirror array 102d, so that the photosensitive drum 2 is illuminated. I have. The lens array 102c is
A roof mirror array in which a number of imaging lenses are continuously arranged at a constant pitch in the main scanning direction.
Reference numeral 102d denotes a structure in which a roof-shaped reflecting surface is continuously formed, and a light beam incident from the lens array 102d is reflected by the roof mirror array 102d and converges on the surface of the photosensitive drum 2. Irradiation and exposure are performed as described above. The lens array 102c and the roof mirror array 102d are pressed and held at fixed positions by a leaf spring 102e.

The image forming light beam to the photosensitive drum 2 is irradiated to the photosensitive drum 2 through a slit for preventing flare. The slit is formed on a light-shielding dust-proof cover 106 that is provided so as to cover an image forming light beam on the photosensitive drum 2. The light shielding dust cover 106 is
One end edge of the bottom plate of the housing 105 is slidably mounted on the front surface of the bottom plate of the housing 105. Alligator screwed. Fixing screw 105b
The housing 105 is screwed into an alligator through an elongated hole formed at an edge portion of the light-shielding dust-proof cover 106. When the fixing screw 105b is loosened, the light-shielding dust-proof cover 106 can be moved and adjusted with respect to the photosensitive drum 2 so as to move forward and backward.
Thus, the position of the slit can be adjusted so that the slit also advances and retreats with respect to the photosensitive drum 2.

Here, as shown in FIGS. 1 and 2, the effective image height line of the roof mirror lens array 102c as an imaging element is slightly smaller than a straight line in the array of the phosphor dots 101b. The angle is set at an angle θ. As a result, the image height position of the imaging element is continuously changed depending on the arrangement direction, and the amount of light taken in is adjusted to make the distribution of the amount of exposure light on the photosensitive drum 2 uniform.

For example, as shown in FIG.
In the case where the light quantity distribution of 1b has a large luminance at both ends and a small luminance at the center, and the light quantity distribution characteristic of the roof mirror lens array 102d as the imaging element is in the state shown in FIG. Normally, the position of the image height position h at the peak of the light amount distribution is used, but in this embodiment, the position of the image height position h 'is used, and therefore, as shown in FIG. Light utilization efficiency having various distribution characteristics is set. In other words, the emission line of the phosphor dots 101b having the emission distribution shown in FIG. 5 is set on the line at the image height position h ', and the light intensity and brightness at both end portions of the phosphor dots 101b are determined. For a high place, a place where the light use efficiency of the image forming light of the image forming element 102 is low is used, and for a place where the light intensity is low in the central part of the phosphor dot 101b, the image forming element 102 is used. An image height position where the light use efficiency of the image light is high is used.

In such a configuration, even if the light amount of the light emitted from the phosphor dot 101b is different between the central portion and the end portion, the imaging element is formed in accordance with the luminance distribution of the phosphor dot 101b. Since the light use efficiency of 102 has been changed to the opposite side, it is possible to adjust the amount of exposure light at the end of the imaging light on the photosensitive drum 2 so as to match the amount of exposure at the center. As a result, as shown in FIG. 8, the exposure light amount in the array direction is made uniform.

Further, in addition to the above-described embodiment, if the correction of the transmitted light amount and the correction of the electric absolute light amount are performed, it is possible to form an image with higher accuracy and higher quality. That is, the light amount distribution (FIG. 9 (a)) causing the variation is made uniform to some extent by first tilting the image height direction of the optical system as in the above-described embodiment, and the transmitted light amount by this imaging optical system is used. If the correction is not sufficient, fine adjustment is accurately performed by performing voltage or current correction for driving the light emitting segment array, and the exposure light amount is highly uniform (FIG. 9 (b)). )).

(Effect of the Invention) As described above, according to the first aspect of the present invention, the amount of transmitted light is arrayed by changing the image height position of the imaging element so as to make the variation in the amount of light of the light emitting segment array uniform. Since the adjustment is made for each location in the direction, the light quantity distribution on the photoreceptor can be reliably made uniform with a simple configuration, and the density unevenness of the output image can be satisfactorily eliminated.

Further, the invention described in claim 2 is the same as that in claim 1 above.
In addition to the correction of the transmitted light amount according to the invention described in (1), the correction of the absolute light amount is performed electrically, so that an even more accurate fine adjustment can be performed with high accuracy while avoiding an increase in the electric load. it can.

[Brief description of the drawings]

1, 2 and 3 are explanatory exploded perspective views, plan explanatory views, and cross sectional explanatory views showing an example of the structure of an optical writing / exposure apparatus to which the present invention is applied, and FIG. FIG. 2 is an explanatory side view showing an example of a recording apparatus provided with the exposure device shown in FIGS. 2 and 3, FIG. 5 is a diagram showing a light emission luminance distribution of a phosphor dot array, and FIG. 7 and 8 are diagrams showing the light utilization distribution of the imaging optical system, and FIG.
FIG. 9 and FIGS. 9A and 9B are diagrams showing the light output distribution on the photosensitive member. DESCRIPTION OF SYMBOLS 1 ... Exposure apparatus, 2 ... Photoconductor drum, 101 ... Phosphor dot array, 102 ... Roof mirror lens array.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) B41J 2/447-2/45 H04N 1/036 H01J 31/15

Claims (2)

(57) [Claims] A light generated in a pixel unit from a minute light emitting segment array arranged on a predetermined straight line is modulated according to image information, and the modulated light is exposed on a photosensitive member surface via an image forming optical system. In an exposure apparatus configured to form an electrostatic latent image by scanning, the effective image height line of the imaging optical system, such that the light amount distribution from the minute light emitting segment array on the photoconductor surface becomes uniform, An exposure apparatus, wherein the exposure apparatus is arranged so as to form a predetermined angle with respect to the direction in which the minute light emitting segment arrays are linearly arranged. 2. A method according to claim 1, further comprising modulating light generated in units of pixels from a minute light-emitting segment array arranged on a predetermined straight line in accordance with image information, and exposing the modulated light onto a photosensitive member surface via an imaging optical system. In an exposure apparatus configured to form an electrostatic latent image by scanning, the effective image height line of the imaging optical system, such that the light amount distribution from the minute light emitting segment array on the photoconductor surface becomes uniform, A control circuit that is arranged so as to form a predetermined angle with respect to the linear array direction of the minute light emitting segment array, and corrects the voltage or current for driving the minute light emitting segment array for correcting the light amount distribution of the minute light emitting segment array. An exposure apparatus comprising: