JPH0632336B2 - Semiconductor laser device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a temperature-controlled semiconductor laser device,
In particular, the present invention relates to a semiconductor laser device which is preferably used as a light source of a laser printer.

<Prior Art> In recent years, a laser printer using a laser beam as a light source has been developed. The use of semiconductor lasers to generate laser light is increasing from the viewpoint of downsizing of light sources.

By the way, since this semiconductor laser has a characteristic that the output changes when the temperature changes even if the injection current is kept constant, the output change of the semiconductor laser is prevented and the predetermined output is maintained. Therefore, various techniques for maintaining the temperature of the semiconductor laser at a constant value have been proposed (JP-A-54-13343, JP-A-57-63879, JP-A-57-9).
9791, JP-A-57-136382, etc.). That is,
By attaching a Peltier element to the semiconductor laser,
Regardless of ambient temperature, constant temperature, for example 20 ° C
I try to keep it.

Therefore, it is possible to maintain the semiconductor laser at a constant temperature and maintain a constant output regardless of external conditions. However, if the difference between the ambient temperature and the maintenance temperature becomes large, it may be affected by humidity conditions. However, the maintenance temperature may become lower than the dew point temperature, causing dew condensation on the surface of the semiconductor laser.

In this case, water droplets due to dew condensation adhere to the emission window of the semiconductor laser, and the laser light is scattered by the water droplets, which causes a fatal inconvenience that the laser light source cannot function. become.

<Purpose> The present invention has been made in view of the above problems,
It is an object of the present invention to provide a semiconductor laser device capable of fulfilling a function as a laser light source regardless of atmospheric temperature, humidity and the like.

<Structure> To achieve the above object, a semiconductor laser device of the present invention is a semiconductor laser, a cooling means for cooling the semiconductor laser, a temperature detecting means for detecting an ambient temperature of the semiconductor laser, and an atmosphere of the semiconductor laser. Humidity detection means for detecting humidity, a memory that stores the dew point temperature characteristic of water with respect to humidity, based on the detected humidity of the humidity detection means, the dew point temperature is calculated by referring to the memory, and the temperature detection means And a control means for controlling the cooling means so that the detected temperature becomes higher than the dew point temperature.

This apparatus sets the temperature of the semiconductor laser to a temperature higher than the dew point temperature when the temperature of the semiconductor laser is lower than the dew point temperature. By controlling the temperature of the semiconductor laser so that the temperature does not fall below the dew point temperature,
It is possible to prevent dew condensation on the surface of the semiconductor laser, particularly on the emission window.

<Example> Hereinafter, detailed description will be given with reference to the accompanying drawings illustrating an example.

FIG. 1 is a schematic diagram clearly showing the configuration of a laser printer. Laser light from a semiconductor laser (1) is irradiated onto a mirror (3) through a condenser (2), and is reflected by the mirror (3). Light is irradiated onto the photoconductor (5) through the light collector (4). An optical sensor (6) that detects the intensity of the laser light reflected by the mirror (3), a temperature sensor (7) that detects the temperature of the atmosphere of the photoconductor (5), and the temperature of the semiconductor laser (1) are detected. The microcomputer outputs the output signals of the temperature sensor (8), the temperature sensor (8 ') that detects the temperature of the semiconductor laser (1) atmosphere, and the humidity sensor (9) that detects the humidity of the semiconductor laser (1) atmosphere. The image signal is being applied to the microcomputer (10) as well as being applied to the semiconductor laser (1).
And applied to the Peltier device (11).

The mirror (3) is formed by forming the outer surface of a polygonal columnar body into a mirror surface. It can be irradiated with light.

The microcomputer (10) stores the sensitivity-temperature curve (see FIG. 3) of the photoconductor (5), the output-temperature curve of the semiconductor laser (1) (see FIG. 4), and the dew point temperature curve for each humidity. The sensitivity of the photoconductor (5) can be calculated by the temperature sensor (7), and the temperature of the semiconductor laser (1) can be calculated by the temperature sensor (8).

Fig. 2 shows the mounting structure of the semiconductor laser (1). The heat sink (15) is attached to the mounting base (12) and the hole (13) formed in the mounting base (12) is penetrated to the Peltier. Heat sink (15) for element (11)
The semiconductor laser (1) is attached to the Peltier device (11) with the holder (14) interposed.

With the above configuration, the dew point temperature can be calculated based on the output signals from the temperature sensor (8 ') and the humidity sensor (9), and the temperature difference between the semiconductor laser (1) temperature and the dew point temperature can be calculated. Can also be calculated.

Therefore, as indicated by the solid line in FIG. 5, the Peltier element (1
By controlling the temperature of the semiconductor laser (1) by driving 1), it is possible to surely prevent dew condensation on the surface of the semiconductor laser (1), particularly on the emission window portion.

In the above cases, the sensitivity of the photoconductor (5) can be calculated based on the output signal of the humidity sensor (7), and the output of the semiconductor laser (1) can be calculated based on the output signal of the optical sensor (6). Therefore, the sensitivity change amount of the photoconductor (5) due to the temperature change is calculated, and only the output change amount of the semiconductor laser (1) more than the amount that can compensate the sensitivity change amount is calculated. It is also possible to control the injection current of the semiconductor laser (1) to correct it, in which case the characteristics of the semiconductor laser (1) and the photoconductor (5) as a whole can be kept constant,
It also has the effect of always exhibiting good printing characteristics.

<Effect> As described above, according to the present invention, since the semiconductor laser is directly exposed to the outside air without being covered with a cap or the like, miniaturization is possible, and when the dew point temperature is equal to or higher than the ambient temperature of the semiconductor laser, the semiconductor laser is The temperature is set higher than the dew point temperature, so that regardless of atmospheric temperature, humidity, etc., it is possible to prevent the occurrence of dew condensation on the surface of the semiconductor laser, especially on the emission window portion, and to fulfill the function as a laser light source. There is a unique effect that can be.

[Brief description of drawings]

FIG. 1 is a schematic view clearly showing the configuration of a laser printer, FIG. 2 is a view showing a mounting structure of a semiconductor laser, FIG. 3 is a view showing a sensitivity-temperature curve of a photoconductor (5), and FIG. 4 is a semiconductor. FIG. 5 is a diagram showing the output-temperature curve of the laser (1) when the injection current is kept constant, and FIG. 5 is a diagram showing the relationship between the temperature of the semiconductor laser (1) and the dew point temperature. 1 ... semiconductor laser, 5 ... photoreceptor.

Claims (1)

[Claims] 1. A semiconductor laser (1), a cooling means (11) for cooling the semiconductor laser (1), a temperature detecting means (8 ') for detecting an ambient temperature of the semiconductor laser (1), and a semiconductor laser ( 1)
Humidity detecting means (9) for detecting the atmospheric humidity of, a memory that stores the dew point temperature characteristics of water with respect to humidity, and a control means (10), the control means (10), the humidity detection means ( Based on the detected humidity of 9), calculate the dew point temperature by referring to the memory, and control the cooling means (11) so that the temperature detected by the temperature detecting means (8 ') becomes higher than this dew point temperature. A semiconductor laser device.