JPS59204292A - Semiconductor device - Google Patents

Abstract

PURPOSE:To obtain lights of a plurality of wavelengths by independently controlling temperatures of a plurality of semconductor light emitting elements on the same substrate. CONSTITUTION:The light emitting part A consists of array form semiconductor elements on the substrate 15, and individual lasers have a hetero structure. The heating part B independently provided to each laser consists of an insulation member 7, a heat generating member 8, an electrode 9, and a protection film 10. The temperature adjusting part C is composed of a supporting member 11, a temperature sensitive element 12 detecting the temperature of the member 11, a thermoelectric element 13 heating and cooling the member 11 based on the information of the element 12, and a heat dissipating fin 14 diffusing the heat from the element 13 to the atmosphere. The oscillation wavelength of the semiconductor laser can be independently controlled by changing the current impressed on respective heat generating member 8.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a semiconductor device suitable for use as a light source for a laser beam printer or the like.

Conventionally, helium-cadmium, argon,
Gas lasers such as helium-neon were used, and semiconductor lasers, which were smaller, lower cost, and capable of direct modulation, began to be used.

Furthermore, as photoconductors for the above-mentioned recording devices, laminated photoconductors with a charge transfer layer and a charge generation layer are attracting attention in order to obtain sufficient sensitivity and charging characteristics depending on the wavelength of the laser light used. .

The charge generation layer of the laminated photoreceptor has the role of absorbing light and generating free charges, and has a thickness of 0.1 to 5 gm.
It is usually thin.

The charge transfer layer has the role of accepting static charges and transporting free charges, and is made of a material that hardly absorbs image forming light, and its thickness is usually 5 to 30 gm.

By the way, when using such a laminated photoreceptor.

When an image is produced by scanning a line with a laser beam, there is no problem with line images such as characters, but in the case of solid images, density unevenness in the form of interference fringes appears.

The cause of this is thought to be interference between the light reflected on the surface of the charge transfer layer and the light reflected on the surface of the substrate such as metal.

That is, the laminated electrophotographic photoreceptor has a structure in which a charge generation layer 2 and a charge transfer layer 3 are laminated on a base 1, as shown in FIG. When laser light 4 (emission wavelength is approximately 0.8 pm for a semiconductor laser, for example) is incident on this laminated photoreceptor, as shown in FIG. ) Interference with the light 6 reflected from the surface of the charge transfer layer 3 and coming out from the surface of the charge transfer layer 3 occurs. Assuming that the refractive index of the laminated layer of the charge generation layer 2 and the charge transfer layer 3 is n, the thickness difference is d+, and the wavelength of the laser beam is I, when ndl is an integral multiple of I/2, the intensity of the reflected light is maximum, In other words, when the intensity of the light entering the charge transfer layer 3 is minimal (according to the law of conservation of energy), the reflected light is minimal when the intensity of the light entering the charge transfer layer 3 is ten times as large as ndl, which means that the intensity of the light entering the layer is minimal (according to the law of conservation of energy). becomes. By the way, the DL does not have any unevenness or tearing in some places due to the manufacturing process.

Laser light is monochromatic and coherent.

The above-mentioned interference condition changes in response to the unevenness of dl, and 1
1 is thought to be caused by unevenness in the location of the laser beam absorption needle in the particle generation layer 2, which appears as an interference ring-like unevenness in the density of the evening image.

In order to prevent density unevenness as described above, it is possible to record with recording light that contains light of different wavelengths, but with conventional semiconductor devices, only light of a single wavelength can be obtained, and as mentioned above, In order to print a recording beam with a certain amount of light, it is necessary to use a method such as combining the beams from a plurality of devices, which has the disadvantage that the structure is complicated and the light source becomes large.

An object of the present invention is to provide a compact semiconductor device that can obtain light of multiple wavelengths.

The present invention achieves the above object with a semiconductor device comprising a plurality of semiconductor light emitting elements formed on the same substrate and means for independently controlling the temperature of the plurality of semiconductor light emitting elements.

Hereinafter, the present invention will be explained using the drawings.

FIG. 3 is a schematic diagram showing an embodiment of the present invention. Here, A is a light emitting section, which is composed of an array of semiconductor lasers formed on a substrate 15''. The individual semiconductor lasers have a conventional double heterostructure. B is a heating section independently provided in each semiconductor laser, and is composed of an insulating member 7 for electrically insulating A and B, a heat generating member 8, an electrode 9 of the heat generating member, and a protective film 10 of the heat generating member. Further, C is a temperature control section consisting of a support member 11 for the light emitting section and means for keeping the temperature of this support member constant. Further, the means includes a temperature sensing element 12 that detects the temperature of the support member 11, a thermoelectric element 13 that heats and cools the support member based on information from the temperature sensing element 12, and a thermoelectric element 13 that diffuses the heat from the thermoelectric element 13 into the atmosphere. The heat dissipation fins 14 are arranged in a row.

Next, the operation of this embodiment will be explained in order.

The characteristics of the semiconductor laser in the light emitting section A vary considerably depending on the environmental temperature. Furthermore, if heat is exchanged between individual semiconductor lasers, independent temperature control is difficult. Therefore, the board 15
A groove is provided to thermally separate adjacent semiconductor lasers,
First, the support member 11 is maintained at a constant temperature by the thermoelectric element 13. Next, a plurality of semiconductor lasers are caused to emit light at the same time, but since these semiconductor lasers are made of the same -tJ material, they emit light of the same wavelength. By operating the heating section B on the semiconductor laser, light of multiple wavelengths is obtained. The oscillation wavelength of a semiconductor laser changes with a temperature coefficient of about 3λ/'C, so by changing the current applied to each heat generating member 8, the temperature of each semiconductor laser can be controlled independently, and the oscillation wavelength can be changed at different wavelengths. It can be made to emit light.

Next, a method for manufacturing the heating section B in the above embodiment will be explained.

FIG. 4 is a partial view showing one of the semiconductor lasers formed in an array. First, an SiO film is applied as an insulating member 7 on a light emitting part A consisting of a semiconductor laser by sputtering in order to electrically isolate the light emitting part from the heat generating member 8. Ta or HfB2 is sputtered thereon as a heat generating member 8, and furthermore, An is deposited thereon by EB evaporation and etched to form a 1L pole 9. Finally, the heating section B is formed by applying the protective film 10. In this way, the heating section B of the above embodiment can be manufactured very easily using a normal thin film forming method.

The emission wavelength of the semiconductor device of the present invention should be set depending on the application, but when used in a recording device having a photoreceptor with sensitivity characteristics as shown in FIG. , just choose the bottom. Here, the difference between the input value and the value may be set in consideration of the laser wavelength, the thickness of the photoreceptor, the refractive index, etc., so that density unevenness due to interference will not occur. In such a recording device, since the image becomes more uniform with multiple wavelengths, the number of semiconductor light emitting elements in the present invention is also large.1.
), the greater the effect in the recording apparatus.

The emission wavelength can be adjusted to a set value in advance by measurement, but from the viewpoint of cost, it is preferable to adjust each emission wavelength while looking at the image after installing it in the recording device and set it to an arbitrary wavelength. . Furthermore, the photoreceptor is manufactured within the lot and at the time of production. Since the sensitivity varies greatly between photoreceptors, it is best to change the temperature of the semiconductor laser and shift the wavelength to match the sensitivity of the photoreceptor when replacing the photoreceptor.

Note that the maximum operating temperature of a semiconductor laser can be considered to be about 70°C, although it depends on the required life span. On the other hand, the minimum temperature is determined by the ability of the temperature adjustment means, the capacity of the power supply, etc., but it is also possible to lower it to 0°C or lower.

FIG. 6 is a schematic diagram showing another embodiment of the present invention, in which parts common to those in FIG. 3 are given the same reference numerals and detailed explanations will be omitted. Here, 16 is a thermoelectric element, 17 is a heat radiation fin, and 18 is a temperature sensing element. In this embodiment, the temperature of each semiconductor laser is detected by a temperature sensing element 18 and then controlled by a thermoelectric element 16 to obtain light of a mysterious wavelength.

The configuration of the present invention is not limited to the above-described embodiments.

For example, a light emitting diode (LED) is used as a semiconductor light emitting device.
) and /! Variations of the 1A degree control semi-control means are conceivable.

As explained above, the present invention makes it possible to independently control the temperature of a plurality of semiconductor light emitting elements on the same substrate, so that light of a plurality of wavelengths can be obtained with a single semiconductor device.

[Brief explanation of the drawing]

Figure 1 is a schematic cross-sectional view showing the structure of a laminated photoreceptor in an electrophotographic recording device, and Figure 2 explains how light emitted from a conventional semiconductor device is applied to the photoreceptor in Figure 1. Figure, 3rd
4 is a perspective view showing a part of the embodiment of FIG. 3, FIG. 5 is a diagram showing the sensitivity characteristics of the photoreceptor, and FIG. 6 is a diagram showing an embodiment of the present invention. FIG. 7---Insulating member, 8-111 heat generating member, 9---1 electrode 10---protective film, ti---1 supporting member, 12
．． 18---One temperature sensing element, 13.16---Thermoelectric element, 14.17---Radiation fin, 15---One substrate. Hiroshi book one step &, [屹

Claims (1)

[Claims] (1) A semiconductor device comprising a plurality of semiconductor light emitting elements formed on the same substrate and means for independently controlling the temperature of each of the several conductor light emitting elements.