JPH0325965Y2 - - Google Patents

Description

[Detailed description of the invention] A. Field of industrial application The present invention relates to an optical printer head with excellent sealing properties.

B. Conventional technology Conventionally, a light emitting diode 2 as shown in Fig. 2 has been used.
There are optical printer heads that utilize 2, 22, etc.
Such an optical printer head was developed in Japanese Patent Application Laid-Open No. 59-195885.
Although the printer is covered with a frame having a short focal length lens array connection part on its surface as shown in the above publication, the printer is used in a normal indoor environment and there is a heat generating part inside the printer. Condensation tends to form inside the frame of the optical printer head. In particular, the connecting part of the short focus lens array is formed of a transparent plate, for example, but it faces the light emitting diode and is most susceptible to condensation due to the heat generated by the light emitting diode.Moreover, condensation can cause light scattering, etc. This is undesirable because it causes a decrease in the brightness of a given dot or a leakage of light to adjacent dots.

In order to prevent this, it was found that it was possible to lower the pressure inside the frame or fill it with nitrogen, but to do so, it was necessary to seal it airtight. Therefore, a glass plate was attached using an epoxy adhesive to a circuit board with a metal base, but since it was long (approximately 6 times the length or more than the width), the difference in thermal expansion coefficient caused deformation. This caused the short focus lens array to be out of focus, resulting in distorted printed dot fonts and insufficient brightness, which was inconvenient.

C. Problems that the invention aims to solve This invention was made in consideration of the above points.
To provide an optical printer head with good airtightness and less deformation of the substrate.

D. Means for solving the problem The present invention was made by focusing on the difference in coefficient of thermal expansion between the light emitting diode and the cover glass placed on the surface of the substrate. And, even after adhesion, it is hermetically sealed using a silicone adhesive that has soft rubber-like properties, and more preferably, it does not deform even if stress is applied to the cover glass, which affects the optical path or optical image. The cross-section of the cover glass is approximately square to prevent this from happening.

E. Effect With the above-described configuration, thermal deformation does not occur even when the cover glass and the metal base substrate having different coefficients of thermal expansion are bonded together.

F. Embodiment Figure 1 is a sectional view of the main parts of an optical printer head according to an embodiment of the present invention. Reference numeral 11 is a metal base made of a metal material with excellent thermal conductivity such as aluminum, and the surface of the head is 60 to 100 μm thick. A substrate 1 is formed of a coated epoxy resin resin layer 12 and patterned and plated conductive foils 13, 13, . . . . Reference numeral 2 denotes a monolithic light emitting diode in which the light emitting portion is aligned and fixed in a straight line in the approximate center of the substrate 1, and wiring is provided so as to cover the entire length of the optical printer in the main scanning direction as illustrated in FIG. Multiple pieces are arranged. Reference numerals 3 and 3 designate driving elements for the light emitting diode 2, which are also placed on the substrate 1. Reference numeral 4 denotes a cover glass having a square cross section for transmitting light and for airtight sealing, such as BLC glass or BD-65 glass manufactured by Nippon Electric Glass Co., Ltd. 5 is a silicone-based adhesive for bonding the cover glass 4 to the resin layer 12 of the substrate 1, and is an oxime-free silicone rubber (for example, KE441T from Shin-Etsu Chemical Co., Ltd.).

Effects of the invention With this configuration, the coefficient of thermal expansion is 29×
10 ^-6 K ^-1 aluminum, 26 x 10 ^-6 K ^-1 resin layer, 20 x 10 ^-6 K ^-1 copper foil, thermal expansion coefficient 8 x 10 ^-6 K ^-1 Even if the pieces of glass are long, they can be bonded without warping or peeling of parts due to heat, and as a result, an optical printer head with excellent optical properties can be provided.

Furthermore, in the present invention, even if a thin silicon adhesive is used to bond between the cover glass and the resin layer, airtightness is maintained because the adhesive enters the small recesses in the cover glass and the resin layer. Since the adhesive is thin, the light emitting diode and the cover glass can be placed close to each other. Therefore, it is possible to solve the problem that the light emitting diode and the cover glass are too far apart and the light emitted image is reflected on the cover glass, causing the image to be enlarged and blurred by the lens effect.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a main part of an optical printer head according to an embodiment of the present invention, and FIG. 2 is a perspective view of a general optical printer head. DESCRIPTION OF SYMBOLS 1... Substrate, 11... Metal base, 12... Resin layer, 2... Light emitting diode, 3, 3... Drive element, 4... Cover glass, 5... Adhesive.

Claims (1)

[Scope of utility model registration request] A substrate consisting of a metal base having a resin layer on its surface, a plurality of monolithic light emitting diodes aligned and fixed on the substrate, a driving element for the light emitting diode fixed on the substrate, and a light emitting diode and a driving element. An optical printer head characterized by comprising a long cover glass that covers the substrate and is bonded and sealed with a silicone adhesive onto a substrate.