JPH085814Y2 - LED printer head - Google Patents

Description

[Detailed Description of the Invention] [Industrial field of application] The present invention focuses only on the light emitting dots of LEDs (light emitting diodes, the same applies below) on the photoconductor and removes noise due to reflected light to improve print quality. The present invention relates to an LED printer head which can be remarkably improved.

[Prior Art] In recent years, the development and spread of OA equipment have been remarkable, and demands for higher performance of printers, which are the accessories thereof, are increasing.

Along with that, the development perspective of the printer has shifted from the impact type, which has a limit to high speed and high image quality, to the non-impact type, which is quiet and easy to adjust to the high speed, and with the advent of the laser printer, a new era has been marked. It was

However, since the laser printer has a movable part in the optical system, there is a limit to downsizing, and there is no problem in terms of mechanical reliability.

The LED printer has the advantage that the recording head section does not have a moving part and the drum and the head can be brought close to each other, which makes it very easy to make it compact.
As D was proposed, it became possible to secure higher recording speed and higher reliability than semiconductor laser printers.
It suddenly came to the attention.

FIG. 7 is a perspective view showing a specific configuration of such an LED printer head. 1 is an LED array chip fixed on a ceramic substrate 4, 2 is a driver IC electrically connected to the LED array chip 1 by a bonding wire 3 as shown in FIG. It is a condensing rod lens array for condensing light and forming an image on the photosensitive drum 30 shown in FIG.

These are integrally incorporated in the housing 10 and are arranged so as to face the photoconductor drum 30 as shown in FIG.

Specifically, the LED array chips 1 and 1 are connected in a line to form a row of several thousand LEDs, and the driver ICs 2 and 2 are activated by the data control signal input from the line receiver 6 in FIG. As a result, the required LED is caused to emit dot light, and an image thereof is formed on the photoconductor of the drum 30, thereby performing digital electrophotographic printing.

[Problems to be Solved by the Invention] Light emitted from the light emitting region of the LED chip 1 is almost completely diffused light, and there is no directivity of only the output light 20, and a part of the diffused light is generated as shown in FIG. The light is reflected by the bonding wire 3 and the driver IC 2 and becomes the scattered light 21.

Such reflected light 21 enters the condensing rod lens 5 and is transmitted, resulting in the formation of these latent images on the photoconductor drum 30, and when printing is performed in this state, projections commonly called whiskers are formed. Uneven printing occurs, which is a cause of deteriorating printing quality.

The purpose of the present invention is to solve the above-mentioned problems of the prior art, eliminate the above-mentioned reflected and scattered light, and form only the pure output light of the LED dot on the photoconductor to significantly improve the printing quality. The present invention aims to provide a new LED printer head that can be used.

[Means for Solving the Problems] The present invention has a structure in which a pair of light-shielding plates are erected on both sides of an optical path that linearly connects an LED and a condensing rod lens to collect light from the LED. Only the light directed to the optical rod lens is allowed to pass through the optical path, and the ambient light reflected and generated in the housing is blocked by the light shielding plate so as not to reach the condensing rod lens.

[Operation] By installing light-shielding plates that block ambient light on both sides of the optical path that linearly connects the LED and the condensing rod lens, LE
Of the light emitted from D, the light that goes to the condensing rod lens passes through the optical path and enters the condensing rod lens, and the ambient light is blocked by the light blocking plate and enters the condensing rod lens. Therefore, it is possible to prevent the occurrence of printing unevenness, and it is possible to remarkably improve the image quality.

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

FIG. 1 is an explanatory diagram showing the construction of an embodiment of a printer head according to the present invention. In the present embodiment, as shown in the figure, the optical path between the light emitting region of the LED array chip 1 and the condensing rod lens array 5 is left (that is, the LED
A pair of light-shielding plates 7 and 7 are provided upright on both sides of an optical path that linearly connects the array chip 1 and the light-collecting rod lens array 5. In this embodiment, the light-shielding plates 7 and 7 are condensed. It is fixed to the sex rod lens array 5 side. As shown in the figure, the light shielding plates 7 and 7 are configured to block the reflected light from the driver IC 2 and allow only the pure output light of the LED array chip 1 to pass through the optical path.

As shown in FIG. 2 which is a cross section taken along the line AA in FIG. 1, the light shielding plates 7 and 7 have a length capable of blocking the reflected light over the entire length of the row of the LED array chips 1.

The material of the light-shielding plate 7 is not particularly selected as long as it is opaque such as plastic, metal, or ceramic, and it is desirable to reduce the reflection by roughening the surface thereof.

FIG. 4 is an explanatory view showing the construction of another embodiment of the printer head according to the present invention. In the embodiment shown in FIG. 1, the LED chip portion is left as a space, but as shown in FIG. 4, the semiconductor element on the substrate is covered with a transparent glass cover 8 to protect it from moisture and dust. You may install the light-shielding plates 7 on the transparent glass cover 8.

FIG. 5 is an explanatory view showing the construction of still another embodiment of the printer head according to the present invention, in which the lower part of the light-shielding plate 7 itself is formed in a shape capable of covering the semiconductor element, and protecting the semiconductor element and reflecting light. You may make it serve as the both of the disturbance prevention by this.

[Advantages of Device] As described above, according to the LED printer head of the present invention, noise caused by scattered light from the bonding wire, driver IC, etc. is significantly reduced, and a clear LED emission dot is always imaged. As a result, the printing becomes clearer and the printing quality can be greatly improved.

[Brief description of drawings]

FIG. 1 is an explanatory view showing an embodiment of a printer head according to the present invention, FIG. 2 is a sectional view taken along the line AA of FIG. 1, and FIG. 3 is an explanatory view showing a reflection state by light emission of a conventional printer head. ,
4 and 5 are explanatory views showing another embodiment according to the present invention, FIG. 6 is an explanatory view showing the positional relationship between the printer head and the photosensitive drum, and FIG. 7 is a conventional LED printer head. It is a perspective view which shows a concrete structure. 1: LED array chip, 2: Driver IC, 3: Bonding wire, 4: Ceramic substrate, 5: Condensing rod lens, 7: Shading plate, 8: Transparent glass cover, 10: Housing, 20: Output light, twenty one:
reflected light. 30: Photosensitive drum.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Reference number within the agency FI technical display location H04N 1/036 A (72) Inventor Takashi Shimada 5-1-1 Hidakacho, Hitachi City, Ibaraki Prefecture Hitachi Cable Co., Ltd. Hidaka Plant (72) Inventor Norihiro Ashizuka 5-1-1 Hidaka Town, Hitachi City, Ibaraki Prefecture Hitachi Cable Co., Ltd. Hidaka Plant (72) Inventor Yoshiyuki Sakamoto Hidaka, Ibaraki Prefecture 5-1-1, Machi, Hitachi Cable Co., Ltd., Hidaka Plant (72) Inventor, Eiichi Kunitake 5-1-1, Hidaka Town, Hitachi City, Ibaraki, Hitachi Cable, Hidaka Plant (56) References 61-209176 (JP, A) JP-A 62-248271 (JP, A) JP-A 63-47172 (JP, A) Actual opening 61-2941 (JP, U) Actual opening 63-106647 (JP , U)

Claims (1)

[Scope of utility model registration request] 1. A ceramic substrate on which an LED is mounted is housed inside a housing, and the LED is located above the LED in the housing.
In an LED printer head provided with a condensing rod lens for condensing the light emitted from the lens and forming an image on a photoconductor, both sides of an optical path that linearly connects the LED and the condensing rod lens Install a pair of light shields on the
Out of the light emitted from D, the light directed to the light-collecting rod lens is passed through the optical path, and the disturbance light generated by being reflected in the housing is blocked by the light shielding plate to the light-collecting rod lens. LED printer head characterized by not reaching.