JP2000085180A - Led printer head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an LED printer head having an accuracy of a light collecting position and capable of accurately adjusting the light collecting position corresponding to all of the light emitting points in the printer head. SOLUTION: A base housing 20 of an LED printer head 32 and a light collecting lens array 24 are urged by a spring 26 such that they are always separated from each other. As a result, it is possible to facilitate adjustment of the light collecting lens array 24 by aligning a focal point in a condition that housing members 23a, 23b are entirely pressed against a side of the base housing 20. Since each of the housing members 23a, 23b for holding the light collecting lens array 24 possesses respective section 33a, 33b each having an L-shaped cross section for supporting a side face in the longitudinal direction of the light collecting lens array 24, the light collecting lens array 24 is not curved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to an LED printer head.

[0002]

2. Description of the Related Art Optical printers using a light emitting diode (LED) or laser light as a light source are widely used.
An LED printer using an LED array as a printer head of this optical printer has high reliability because the LED is a solid-state element.

FIG. 2 is a sectional view of a conventional LED printer head.

An LED array chip 1 serving as a light source is mounted on a wiring board 3 together with a driver IC 2, fixed on an upper surface of a base case 4, and a housing member holding a condenser lens array 5 on the upper portion of the base case 4. 6a and 6b are attached so as to cover them (in a non-contact manner).

In an optical printer, it is necessary to accurately condense light 8 from an LED printer head 7 on the surface of a photosensitive drum 9 of the optical printer.

Usually, the conjugate length of the condenser lens array 5 (distance between object image planes, indicated by the dimension a in the figure) can be known in advance. Therefore, when mounting the condenser lens array 5, the head housing structure is such that the condenser lens array 5 is located at an intermediate point (a / 2 in the figure) between the LED array chip 1 and the surface of the photosensitive drum 9. It just needs to be.

Generally, a mounting hole 11 provided at the position of a / 2 (1/2 of the conjugate length) of the condenser lens array 5 shown in FIG.
, The position of the condenser lens array 5 is obtained. In addition, 1
Reference numeral 0 denotes a set screw for fixing the condenser lens array 5 to the housing members 6a and 6b.

[0008]

By the way, as the print quality of the optical printer has been improved, it has become necessary to improve the accuracy of the light condensing position on the surface of the photosensitive drum 9. That is, variations in the conjugate length of the actually manufactured condensing lens array 5, variations in the machining of the base housing 4 and the housing members 6a and 6b due to machining, and the surface height of the LED array chip 1 on the wiring board 3 The conjugate length a of the manufactured printer head fluctuates due to variations in length.

Therefore, in mounting the condenser lens array 5, it is not possible to cope with high-definition printing without variation at a uniform mounting position such as the a / 2 position according to the design dimensions.

On the other hand, as a method of individually adjusting the condenser lens array, Japanese Utility Model Laid-Open No. 2-1845 discloses a method of individually adjusting the position of the condenser lens array after assembling the head. A method is disclosed in which a rod is brought into contact with a condenser lens array, and the support rod is pushed up by screwing from the back surface of a base housing to adjust the support rod.

However, adjustment from the back side of the printer head is complicated, and it is difficult to adjust the conjugate length over the entire length of the head. In addition, when the two ends of the condenser lens array are adjusted, the condenser lens array may be curved, and there is a problem that uniformity of the condenser section over the entire light emitting section of the printer head cannot be realized.

Accordingly, a main object of the present invention is to solve the above-mentioned problems and to provide an LED printer head having a high light-collecting position accuracy. L that can be adjusted with high accuracy according to the light emitting point
An ED printer head is provided.

[0013]

In order to achieve the above object, an LED printer head according to the present invention has a housing in which a wiring board on which an LED array chip is mounted is fixed on a base housing and a condenser lens array is held. In the LED printer head mounted on the base case so that the focal position can be adjusted on the optical axis of the LED array chip, the base case and the condenser lens array are interposed between the base case and the condenser lens array. A spring for biasing in a separating direction is arranged.

In addition to the above configuration, the housing for holding the condenser lens array of the LED printer head according to the present invention preferably has an L-shaped cross-section for horizontally supporting the condenser lens array.

Generally, the allowable range of the conjugation length of the condenser lens array used for the printer head is about ± 0.1 mm, and various measures have been taken to set the condenser lens array within this allowable range when assembling the printer head. is necessary.

According to the present invention, a spring is disposed between the base housing of the LED printer head and the condenser lens array so as to bias the two in a direction of separating them. Therefore, by adjusting the focal position while the entire housing is pressed against the base housing, adjustment of the condenser lens array becomes easy. Also, the housing holding the condenser lens array is
L for supporting the converging lens array on the longitudinal side surface
The converging lens array is not curved since it has the U-shaped cross section.

[0017]

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings.

FIG. 1A is a front view showing an embodiment of an LED printer head according to the present invention, and FIG. 1B is a sectional view taken along line AA of FIG. 1A.

The LED printer head includes a base housing 20 also serving as a heat sink, and a wiring board 2 mounted on an upper surface of the base housing 20 and having an LED array chip 21 mounted thereon.
2, housing members 23a and 23b which are mounted on the upper side of the base housing 20 so as to cover the wiring board 22 (in a non-contact manner) and have two crank cross-sectional shapes;
A condenser lens array 24 sandwiched between the upper sides 3a and 23b and held on the optical axis of the LED array chip 21 for condensing light from the LED array chip 21;
0, supporting rods 25 vertically attached to both ends,
Disposed between the support rod 25 and the condenser lens array 24,
Direction in which the base housing 20 and the condenser lens array 24 are separated,
That is, it is constituted by a spring 26 that urges the housing members 23a and 23b in a direction of pushing up (upward in the figure).

The wiring board 22 is made of resin (or ceramic), and has a large number of LED array chips 21 and a driver IC 27 for controlling blinking of the LEDs on the surface thereof.
Are mounted, and the LED array chip 21 and the driver IC 27 are connected by bonding with gold wires 28.

The support rods 25 (in this embodiment, stainless steel rods having a diameter of 2 mm are used, but not limited to) are provided at both ends of the base casing 20. It is inserted so as to stand upright in a hole having a concave cross-sectional shape of 3 mm. Housing member 23
a, 23b are formed with long holes 31a, 31b,
When the housing members 23a and 23b are fixed to the base housing 20, the positions of the LEDs can be adjusted in the optical axis direction of the LED.

Inside the upper sides of the two housing members 23a and 23b, L-shaped cross-section portions 33a and 33b are formed so as to face each other to horizontally support the condenser lens array 24. The condenser lens array 24 is fixed with an adhesive 30 between the upper side of the housing member 23a and the upper side of the housing member 23b.

The LED printer head 32 is urged by a spring 26 disposed between the base casing 20 and the condenser lens array 24 in a direction in which the condenser lens array 24 is always separated from the base casing 20. I have. Therefore, the housing set screw 29 is loosened and the housing member 23 is removed.
The LED array chip 21 is turned on in a state in which the whole of a and 23b is pressed toward the base housing 20 side, and the light transmitted through the condenser lens array 24 is collected while being observed by a condenser section (not shown). The height of the lens array 24 can be adjusted. After adjusting the height of the condenser lens array 24, that is, the focal point, the housing can be fixed by tightening the housing set screw 29. For this reason, LE with high focusing position accuracy
The provision of the D printer head 32 can be realized.

The housing members 23a and 23b are
Since the L-shaped section 33a, 33b for supporting the side surface in the longitudinal direction of the condenser lens array 24 is provided, the condenser lens array 24 does not curve. For this reason,
It is possible to realize the provision of the LED printer head 32 that can adjust the focusing position with high accuracy corresponding to all the light emitting points.

As described above, according to the present invention, the condenser lens array of the printer head can be mounted on the base housing without being curved, and the height of the condenser lens array of the printer head can be individually adjusted. it can. Therefore, the light from the LED array chip can be accurately irradiated onto the surface of the photosensitive drum after passing through the condenser lens, and a high-definition optical printer can be obtained.

In the present embodiment, the material and the number of the support rods and springs are not limited. For example, the support rods may be made of ceramic or resin.
Regarding the shape of the spring, a rod-shaped spring in which the spring is embedded in a pipe having a diameter of, for example, 2 mm that also serves as a support rod may be used.

[0027]

In summary, according to the present invention, the following excellent effects are exhibited.

(1) It is possible to provide an LED printer head having a high focusing position accuracy.

(2) It is possible to provide an LED printer head which can be adjusted with high precision in correspondence with all light emitting points of the printer head.

[Brief description of the drawings]

FIG. 1A is a front view showing an embodiment of an LED printer head according to the present invention, and FIG.
It is a line sectional view.

FIG. 2 is a sectional view of a conventional LED printer head.

[Explanation of symbols]

 Reference Signs List 20 base housing 21 LED array chip 22 wiring board 23a, 23b housing member 24 condensing lens array 25 support rod 26 spring 32 LED printer head 33a, 33b L-shaped cross section

Claims (2)

[Claims] 1. A wiring board on which an LED array chip is mounted is fixed on a base housing, and the base holding a condenser lens array is adjusted so that a focus position can be adjusted on an optical axis of the LED array chip. In the LED printer head mounted on the housing, a spring is arranged between the base housing and the condensing lens array to bias the base housing and the condensing lens array in a separating direction. LED printer head. 2. The LED printer head according to claim 1, wherein the housing for holding the condenser lens array has an L-shaped cross-section for horizontally supporting the condenser lens array.