JPH0958052A - Led array head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an LED(light emitting diode) array head which can reduce the crosstalk of a luminous flux with a simple constitution. SOLUTION: To prevent lens slots from being blocked, a cylindrical light shielding member 3 is constituted by thin plates 31, 32 such as thin sheets or resin sheets. Since such thin plates 31, 32 has flexibility, if the member 3 that the size of a lens array in the longitudinal direction is slightly larger than the distance of the adjacent lens slots is formed, the dimensional difference is absorbed by slightly deflecting, and the plate 31 of the member 3 can be effectively engaged with the slot.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an LED printer,
The present invention relates to an LED array head used as an optical writing unit of an image forming apparatus such as a digital copying machine or a facsimile.

[0002]

LE having an LED (light emitting diode) array chip and a lens array for focusing a light beam emitted from each LED element of the LED array chip at a predetermined position.
The D array head is more reliable against vibration and noise than the raster scanning method using an LD (laser diode) and a scanning optical system, and has an advantage that it is advantageous in downsizing. Widely used as an optical writing unit.

[0003]

SUMMARY OF THE INVENTION However, LEDs
The array head has the above-mentioned advantages, but has a problem that the light amount variation within one line is large and the beam spot shape is likely to be non-uniform among dots. The present invention has been made in view of such a background, and an object thereof is to provide an LED array head capable of reducing crosstalk of a light flux with a simple configuration.

[0004]

In order to achieve the above object, a first invention is a lens array in which an LED array chip and a lens groove which is a joint between lens portions and adjacent lens portions are alternately continuous. In the LED array head including the above, the LED elements on the LED array chip are grouped so as to match the arrangement period of the lens array, and the lens array is provided between each LED element group and the corresponding lens part. Is characterized in that a thin-plate cylindrical light shielding member capable of bending in the longitudinal direction is continuously and integrally provided.

A second invention is an LE having an LED array chip and a lens array in which lens portions and lens grooves which are joints between adjacent lens portions are alternately continuous.
In the D array head, the LED elements on the LED array chip are grouped so as to match the arrangement period of the lens array, and the LED element groups and the corresponding lens portions are arranged in the longitudinal direction of the lens array. It is characterized in that a stretchable thin-plate tubular light shielding member is continuously and integrally provided.

In the first aspect of the invention, in order to prevent the lens groove from being blocked, the tubular light shielding member is made of a thin plate such as thin paper or a resin sheet (for example, a thickness of 0.1 to 0.5 mm). . Since such a thin plate is flexible, if a light shielding member having a dimension in the longitudinal direction of the lens array that is slightly larger than the distance between the adjacent lens grooves is made, dimensional error may occur due to some bending. Therefore, the thin plate of the light shielding member can be reliably fitted into the lens groove. Further, by providing a slit in one of a pair of thin plates that are perpendicular to the thin plate fitted in the lens groove, it is possible to absorb an error when the dimension of the light shielding member in the longitudinal direction of the lens array is insufficient.

In the second aspect of the present invention, the light shielding member is formed, for example, in a bellows shape and is expandable / contractible in the longitudinal direction of the lens array, so that the dimensional error in the longitudinal direction of the lens array is absorbed and the lens is surely provided. A thin plate of the light shielding member can be fitted in the groove.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a configuration diagram showing an embodiment of an LED array head of the present invention. The LED array head includes an LED array chip 1 and a lens array 2
And The LED array chip 1 has a large number of LEs.
Although the D elements are arranged, they are divided into several LED element groups 1a so as to coincide with the arrangement period of the lens array 2, that is, so as to coincide with the lens portion 2a. In the lens array 2, a lens groove 2b is formed between the adjacent lens portions 2a.

The light flux emitted from the LED array chip 1 passes through the lens array 2 and then forms an image on the surface of the photoconductor 4 to perform optical writing of an image.

Here, the adjacent LED element groups 1a, 1a
In order to prevent and reduce crosstalk of the light flux between
A cylindrical light shielding member 3 is continuously provided between the ED element group 1a and the lens portion 2a facing the LED element group 1a. The light shielding member 3 is fitted and positioned in the lens groove 2b.

FIG. 2 is a perspective view showing a first example of the light shielding member 3, (a) is a perspective view in a normal state (when in use),
(B) is a perspective view of a folded state (when not in use).
The light shielding member 3 has a rectangular tubular shape, and
A pair of first thin plates 31 perpendicular to the longitudinal direction of the array head
And a pair of second thin plates 32 that are also parallel to each other. However, since the light shielding member 3 is continuously and integrally configured as a unit in the longitudinal direction, the first thin plate 31 between the adjacent light shielding members 3 is commonly used. There is.

As a material for forming the thin plate of the light shielding member 3, paper, resin sheet or the like is used, and its thickness is 0.1 to prevent the lens groove 2b from being blocked.
It can be suppressed to about 0.5 mm.

The light shielding member 3 is positioned by fitting the first thin plate 31 into the lens groove 2b. here,
Dimension a between adjacent lens grooves 2b, 2b (see FIG. 1)
And the dimension between the adjacent first thin plates 31 and 31 (dimension in the longitudinal direction of the second thin plate 32) [see (a) of FIG. 2] is equal, the first thin plate 31 smoothly moves into the lens groove. Although it is fitted to 2b, a dimensional error may occur between the two.
Therefore, if the dimension b is set slightly longer than the dimension a,
By utilizing the flexibility of the light shielding member 3 and bending the first thin plate 31, it is possible to fit the first thin plate 31 into the lens groove 2b.

Further, on one of the pair of second thin plates 32,
Vertical slits 32a are formed so that the adjacent light blocking members 3 have alternating surfaces. By doing so, the slit 32a is opened while preventing the light shielding member 3 continuous in the longitudinal direction from bending to one side.
The error when the dimension a is longer than the dimension b can be absorbed.

The light shielding member 3 can be folded as shown in FIG. In this way, the width d in the folded state (when not in use) is reduced to 1/5 to 1/20 of the width c in use (see (a) of FIG. 2). It is possible to reduce transportation and storage costs.

3A and 3B are perspective views showing a second example of the light shielding member 3, where FIG. 3A is a perspective view in a normal state and FIG. 3B is a perspective view in a folded state. The same reference numerals as those in FIG. 2 are used. The light shielding plate 3 shown in this example has a bellows shape and is extendable and contractible in the longitudinal direction. That is, the second thin plate 32 is bent from the center, and the dimension e between the tops thereof is set to be larger than the width f of the first thin plate 31.

By making the light-shielding member 3 expandable and contractable in the longitudinal direction in this way, the light-shielding member 3 can be extended or contracted as necessary regardless of the error between the dimension a and the dimension b. The thin plate 31 of No. 1 can be easily fitted into the lens groove 2b. Further, the width h when not in use is reduced to 1/5 to 1/20 with respect to the width g when in use, and it is possible to reduce transportation and storage costs in parts. 2 and 3, the ghost can be prevented by blackening the inner surface of the light shielding member 3 or by flocking the inner surface with less light reflection.

[0018]

According to the first aspect of the invention, since the light shielding member is adapted to bend in the longitudinal direction of the lens array, the case where the dimension between the lens grooves is shorter than the longitudinal dimension of the light shielding member. However, the thin plate of the light shielding member can be easily fitted and positioned in the lens groove. Thereby, the crosstalk of the light flux can be effectively reduced.

According to the second aspect of the present invention, by providing the slit, even if the dimension of the light shielding member in the longitudinal direction is shorter than the dimension between the lens grooves, the error can be absorbed. .

According to the third aspect of the present invention, by making the light shielding member extendable and contractible in the longitudinal direction, the light shielding member can always be reliably positioned, and the reliability of crosstalk reduction of the light flux can be improved. Can be increased.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an embodiment of an LED array head of the present invention.

FIG. 2 is a perspective view showing a first example of a light shielding member.

FIG. 3 is a perspective view showing a second example of a light shielding member.

[Explanation of symbols]

 1 LED Array Chip 1a LED Element Group 2 Lens Array 2a Lens Part 2b Lens Groove 3 Light Shielding Member 31 First Thin Plate 32 Second Thin Plate 32a Slit 4 Photoreceptor

Claims (3)

[Claims] 1. An LED array head comprising an LED array chip and a lens array in which lens portions and lens grooves which are joints between adjacent lens portions are alternately continuous so that the cycle of the arrangement of lens arrays is matched. The LED elements on the LED array chip are divided into groups, and a thin-plate cylindrical light-shielding member that can be bent in the longitudinal direction of the lens array is connected between each LED element group and the corresponding lens portion. An LED array head characterized by being integrally provided as one. 2. The LED array head according to claim 1, wherein one thin plate of the pair of thin plates of the light shield member parallel to the longitudinal direction of the lens array is orthogonal to the longitudinal direction of the lens array. L is characterized in that slits are formed at both ends in the direction, and the slits are formed in alternate positions by adjacent light shielding members.
ED array head. 3. An LED array head comprising an LED array chip and a lens array in which lens portions and lens grooves which are joints between adjacent lens portions are alternately continuous so that the lens array arrangement period is matched. The LED elements on the LED array chip are divided into groups, and a thin-plate tubular light-shielding member that can expand and contract in the longitudinal direction of the lens array is continuously integrated between each LED element group and the corresponding lens portion. An LED array head, which is characterized in that