JPS61166194A - Semiconductor laser device - Google Patents

Abstract

PURPOSE:To simplify the construction by driving a positive temperature coefficient thermistor disposed through a thermal conductor near a semiconductor laser, and controlling the temperature of the laser to the arbitrary set temperature. CONSTITUTION:A semiconductor laser 1 is bonded to a submount 2 of a silicon substrate, and the submount 2 is bonded to a heat sink 3. The light emitted from the laser is passed through a window glass 5 bonded to a metal cap 4 and emitted out of the cap. The light from the end of the glass 5 at opposite side is incident to a photodiode 6 for partly controlling the light to detect the output of the laser 1. The sink 3 and the diode 6 are mounted on a stem 7 mounted, the stem 7 is mounted on a power terminal 8. The sink 3 can be controlled to the prescribed set temperature range by the variation in the heat generated from a positive temperature coefficient thermistor 9.

Description

Detailed Description of the Invention (Technical Field) The present invention relates to a semiconductor laser device, and more particularly, a semiconductor laser device that can be applied to a semiconductor laser device for optically writing onto a photoreceptor with a laser beam. It is related to.

In an electrostatic recording device using a semiconductor laser as a light source, the amount of laser light irradiated onto a photoreceptor has a very large effect on image density, and slight variations in the amount of light cause changes in the density of the image. Furthermore, since the sensitivity characteristics of current photoreceptors decrease in the infrared region, variations in the wavelength of laser light from a semiconductor laser affect image density.

The semiconductor laser device in the currently known recording apparatus using a semiconductor laser is as follows.

That is, a semiconductor laser is mounted on a member having a Peltier effect, and a thermistor for detecting the temperature of the semiconductor laser is provided to control the temperature of the semiconductor laser to be kept constant.

This is intended to suppress fluctuations in the temperature of the semiconductor laser, which is the biggest cause of fluctuations in the amount and wavelength of laser light.

Even if a semiconductor laser is driven with a constant current, the amount of emitted light fluctuates significantly due to temperature fluctuations.

It is also known that the wavelength varies somewhat (0.3 nm/'C).

Therefore, the conventional device using the Peltier effect element as described above is an effective means for suppressing variations in the amount and wavelength of laser light.

However, elements having the Peltier effect are expensive and require a large-capacity power source to drive them. Furthermore, control using the thermistor output requires additional control members, such as a reference level circuit, comparison circuit, and switch circuit, resulting in mechanical complexity and electrical circuitry near the semiconductor laser. .

(Objective) Therefore, an object of the present invention is to provide a semiconductor laser device that can control the temperature of a semiconductor laser by simpler means.

(Structure) The present invention is characterized in that a positive temperature characteristic thermistor is used as a temperature control means in order to achieve the second object.

Hereinafter, a detailed explanation will be given based on one embodiment of the present invention.

The positive temperature characteristic thermistor used in the present invention is a heat-sensitive resistance element with positive temperature characteristics that shows a steep increase in resistance value when it reaches a certain temperature, and self-heats while current flows, and when the temperature reaches a certain temperature. It has a constant temperature heating characteristic that automatically compensates for the temperature and keeps the temperature constant through a mechanism in which the resistance value shows a steep increase, the current value drops sharply, and the amount of heat generated becomes small.

In FIG. 1 showing an example of a semiconductor laser device, a semiconductor laser 1 is bonded to a submount 1-2 of a silicon substrate, and this submount 2 is also bonded to a pin 1 to a sink 3.

This heat sink 3 is for diffusing the heat of the semiconductor laser, and is made of copper having high thermal conductivity.

The light emitted from the semiconductor laser passes through an antireflection-treated window glass 5 bonded to a metal cap 4 and is emitted to the outside of the cap. Camp 4 is semiconductor laser 1
It has the function of shielding and protecting from the outside air.

Note that a part of the light emitted from the end face of the semiconductor laser on the opposite side to the window glass 5 is used as a photodiode for controlling light.
The light enters the diode 6 and detects the output level of the semiconductor laser 1.

Here, the photodiode 6 is arranged at an angle so that its reflected light does not overlap with the emitted light emitted to the outside of the cap.

P1 to sink 3 and FOL-diode 6 are stem 7
is installed on top.

In other words, the stem 7 functions as a reference for mounting the semiconductor laser 1, and a power supply terminal 8 is attached thereto.

In such a configuration, the positive temperature characteristic thermistor 9 is installed on the heat sink 3 and adjacent to the submounts I to 2.

Thus, by changing the amount of heat generated by the positive temperature characteristic thermistor 9, the temperature of the bee 1 and the sink 3 can be controlled within a predetermined set temperature range.

Other embodiments of the invention are shown in FIGS. 2 and 3.

As shown in the figure, a positive temperature coefficient thermistor 90 is attached to the outside of the stem 70, and a pin 1-1 is mounted on the stem 70.
A sink 30 is provided. And this heat sink 3
A semiconductor laser 10 is bonded onto the top via a submount 20. Further, a photodiode 60 is installed below the semiconductor laser 10. cap 4o
And the window glass 5o is based on the above example. Heat is transferred from the P1-sink 30 to the positive temperature coefficient thermistor 90 via the stem 70, thereby controlling the temperature of the semiconductor laser 10.

In this example, since the positive temperature coefficient thermistor 90 is located close to the terminal 80, wiring of the lead wires becomes easier.

Next, an example shown in FIG. 4 is a case where the present invention is implemented in laser units 1 to 1 of a laser beam printer.

In the figure, a semiconductor laser 100 is pressed against a base 300 made of aluminum so as to be able to conduct heat, and is pressed and screwed from the back side with a holding member 11. Lead wires of the semiconductor laser 100 are soldered to a relay terminal board 13 attached to a holding member 11 via a smoother 12.

Base 30 at a location close to semiconductor laser 100
A positive temperature characteristic thermistor 900 is provided in close contact with the outer surface of 0.

On the other hand, an aluminum flange 15 supporting the collimator lens cell 14 is closely attached to the inner surface of the base 300 so as to be heat conductive.

Inside the collimator lens cell 14, a collimator lens 14a made of a convergent light transmitter is positioned and supported by a cap screw 4b. The collimator lens cell 14 has a screw on its outer periphery screwed into the flange 15, and adjusts the distance between the semiconductor laser 100 and the collimating lens 14a according to rotation. There is. A wave washer 16 interposed between the collimator lens cell 14 and the flange 15 functions to eliminate backlash. In addition, the insulation that covers the whole is 1.7,
] 8 isolates the semiconductor 1 nose 100 and the like, which are the temperature-controlled parts, from the outside air and assists in temperature control, but this is not necessarily necessary.

Also in this example, the semiconductor laser 1 is connected via the base 300.
00 and the positive temperature characteristic thermistor 900 are attached to allow heat transfer, so that the temperature can be controlled to a predetermined constant temperature.

Therefore, the wavelength fluctuation of the semiconductor laser 100 is suppressed, and the semiconductor I-noser 100 and the collimator lens 1/
The distance from Ia is also maintained constant because the influence of thermal expansion and contraction is eliminated.

In general, the back focus of collimator lens] 4a is very shallow, and the tolerance of collimator lens 148 is ±4 μm in the optical axis direction with respect to its ideal position 111t.
degree and very severe. Furthermore, from the point of view of improving image quality, this accuracy is also becoming more severe.

Under such conditions, the positive temperature characteristic thermistor 900
Due to the temperature control function, the positional deviation of the collimator lens 14a due to thermal expansion and contraction is eliminated.

Next, the embodiment shown in FIG. 5 and FIG.
The semiconductor laser 000 and the positive temperature characteristic thermistor 9000 of the sub-mount 1-2001 are attached through the 00.

Note that driving power is supplied to the semiconductor laser 1000 from a cathode 19 provided on the insulating material 2 through a -1 wire (not shown).

(Effects) Positive temperature characteristic thermistors have a simple configuration and high reliability, and do not require additional control members or circuits, so temperature control can be achieved with a simple configuration, which is also advantageous in terms of cost. .

[Brief explanation of the drawings] Figure 1 is a perspective view of a semiconductor laser device, Figure 2 is a front view of a semiconductor laser device as another embodiment, and Figure 3 is the same]
2 is a plan view, FIG. 4 is a sectional view of a semiconductor laser device as yet another embodiment, FIG. 5 is a front view of a semiconductor laser device as yet another embodiment, and FIG. 6 is the same. FIG. 1, ]0,100. ]000... semiconductor laser,
3, 30,300...P1-Sync, 300...
・Base, 9,! ]0,900.9000...Positive temperature characteristic thermistor. −8=

Claims (1)

[Claims] A semiconductor laser device characterized in that the temperature of the semiconductor laser is controlled to an arbitrary set temperature by driving a positive temperature characteristic thermistor placed near the semiconductor laser via a heat transfer body.