JPH06183779A - Method for manufacturing infrared transparent glass - Google Patents

Abstract

(57) [Summary] [Object] The present invention relates to a method for producing an infrared-transparent glass, and an object thereof is to provide a chalcogenide glass for infrared transmission, which has excellent transparency particularly in the infrared region and has no cracks. [Constitution] A crushed germanium ingot having a purity of 99.999% or more and a selenium pellet having a purity of 99.999% or more are used as a raw material, and a silica glass ampoule is vacuum sealed and melted. Also, the enclosed vacuum degree is 1
It is characterized in that it is not more than × 10 ^-3 Torr. Further, the melting temperature is 900 to 1000 ° C., and the melting time is at least 1 hour. It is also characterized in that it takes at least 4 hours from room temperature to the melting temperature. Further, the glass after the melting was moved to a furnace set at a temperature lower than the crystallization temperature of the glass by 10 ° C. or more and kept at the temperature for 3 hours or more,
It is characterized by slow cooling to a temperature lower than the glass transition point by 20 ° C or more.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing an infrared ray transmitting lens using chalcogenide glass.

[0002]

2. Description of the Related Art A human body sensor using a pyroelectric infrared sensor is widely used in home electric appliances and industrial equipment. For example, opening and closing doors, water taps in toilets, and air conditioners.

Generally, 8 to 12 that come out from the human body in front of the sensor
In order to collect μm infrared rays efficiently, a lens that transmits only infrared rays is provided. Silicon, germanium, heavy metal halides, zinc selenide, chalcogenide glass, etc. are used as the material of the lens, but in recent years chalcogenide glass that can be directly press-molded has attracted attention. A typical method for producing chalcogenide glass is to melt a raw material vacuum-sealed in a silica glass ampoule in an oscillating electric furnace called a rocking furnace.

[0004]

However, in the conventional method, the absorption of impurities derived from the bond between oxygen and the raw material may occur in the infrared region depending on the type of the raw material used and the degree of vacuum at the time of encapsulation. In this case, it became impossible to efficiently collect infrared rays of 8 to 12 μm emitted from the human body. Also, if the glass after melting is not slowly cooled appropriately, many cracks will occur,
Sometimes the best glass for direct press could not be made.

It is an object of the present invention to provide a method for manufacturing an infrared transmissive glass in consideration of the above problems of the conventional manufacturing method.

[0006]

The present invention solves the above problems by appropriately selecting the raw materials, the degree of vacuum at the time of sealing, and the cooling after melting.

[0007]

According to the present invention, the absorption of the impurities does not occur in the infrared region, and a glass free from cracks can be obtained.

[0008]

Embodiments of the present invention will be described below with reference to the drawings.

(Example 1) FIG. 1 is an infrared spectrum showing an example of the present invention. 99.999% for germanium
An ingot having the above-mentioned purity (square rod having a cross section of 30 × 30 mm) was crushed with a mortar and a pestle. As selenium, pellets having a purity of 99.999% by a wet or dry shot method were used as they were after breaking the vacuum pack. These raw materials were quickly weighed and put in a silica glass ampoule so that the composition of the glass would be GeSe _4, and then the ampoule was immediately connected to an exhaust device and the inside was evacuated to 5 × 10 ⁻⁴ Torr.
Enclosed with r. Transfer ampoule to electric furnace, room temperature to 950 ℃
Up to 4 hours and melted at 950 ° C. for 2 hours. The infrared spectrum of the obtained glass (thickness: 3 mm) is as shown in FIG. 1, and the transmittance at 800 cm ⁻¹ is 67%.
The transmittance was 50% or more up to μm. The reason why the transmittance at 800 cm ^-1 is taken here is that impurity absorption of germanium and oxygen (Ge-O) exists at 780 cm ^-1 (12.8 μm).

(Comparative Example 1) 99.999% as germanium
The powdered reagent having the purity of 1 was used, and the selenium used in Example 1 was used. Fig. 2 shows the infrared spectrum of the glass. The transmittance at 800 cm ^-1 is 28% and the transmittance is 50%.
The above wavelength was only 11.9 μm. Germanium is easy to combine with oxygen in the air, especially when it is powdery and has a little moisture. The above results indicate that the surface of germanium of the powdered reagent was oxidized, so 780 cm ^-1 (1
2.8 μm) Ge-O has a larger impurity absorption. Also, when the powdered reagent having a purity of 99.999% was used as selenium and the one of Example 1 was used as germanium, the result was almost the same. The surface of selenium, which is a powder reagent, was also oxidized, so 780 cm ^-1 (12.8 μ
It is considered that the absorption of impurities of Ge-O in m) is increased.

(Comparative Example 2) In Example 1, the degree of vacuum at the time of encapsulation was adjusted to the order of 10 ^-3 Torr and encapsulation was performed. The resulting glass had a low transmittance of 45% at 800 cm ^-1 . This is because the oxygen remaining in the ampoule and the raw material increased the absorption of impurities in Ge—O at 780 cm ⁻¹ (12.8 μm). On the contrary, the result of encapsulation at a vacuum degree of 10 ^-5 or 10 ^-6 Torr was not much different from that of Example 1. You need at least 10 ^-4 Torr units.

(Comparative Example 3) In Example 1, the melting temperature was changed.
As a result of heating at 850 ° C, the glass became insufficiently molten and exhibited an immiscible state, resulting in two layers. At 1050 ° C, the glass and ampoule reacted excessively and the ampoule broke. Further, when the melting temperature was 900 to 1000 ° C. and the melting time was less than 1 hour, the glass was insufficiently melted and the glass was bilayered.

(Comparative Example 4) In Example 1, from room temperature to 95
If the temperature was reduced to 0 ° C for less than 4 hours, the glass was insufficiently melted to form a double layer. Also, ampoules sometimes exploded during the temperature rise. This is because the vapor pressure of selenium is high (920 ℃
At 10 atm, 20 at 1010 ℃) because it explodes due to rapid temperature rise. Therefore, it is necessary to raise the temperature slowly until the melting temperature is reached. At least 4 hours is required.

Example 2 The glass melted in Example 1 was transferred to an electric furnace maintained at a slow cooling temperature. The slow cooling temperature was 260 ° C. The reason for setting the temperature to 260 ° C is that the crystallization temperature of glass is 273 ° C. After holding at 260 ℃ for 3 hours, 130
It cooled to 9 degreeC over 9 hours, and cooled the furnace after that. The reason why the temperature is 130 ° C is that the glass transition point is 154 ° C.
The glass thus obtained was free of cracks.

(Comparative Example 5) In Example 2, the slow cooling temperature was changed.
At 270 ° C, part of the glass was crystallized and the transmittance was 5
It fell to 1%. When the holding time at 260 ° C was less than 3 hours, the glass cracked. When the glass was kept at 260 ° C for 3 hours and then cooled to 160 ° C over 9 hours, many microcracks were generated in the glass.

The glass raw material in the above embodiment can be considered as follows. Lenses used for human body sensors used in home appliances and industrial equipment should preferably contain non-toxic elements as main components. The main elements of chalcogenide glass are sulfur, selenium, tellurium, germanium, arsenic and antimony. Of these, arsenic and selenium are designated as poisons, but arsenic is particularly toxic. Selenium is 1 to 1.5 ppm in sea fish and eggs
Since it is included and is an essential nutrient for livestock, its toxicity is considered to be weak. Therefore, germanium and selenium will be the main components under the condition that 8-12 μm infrared rays emitted from the human body are efficiently collected from the elements excluding arsenic. In addition to these, sulfur, iodine, antimony, tellurium, and the like may be contained in order to expand the infrared transmission region and suppress crystallization. In addition, a small amount of lithium, sodium, copper, silver, boron, gallium, indium, silicon, tin, lead, bismuth, to optimize the coefficient of thermal expansion,
The present invention does not exclude the inclusion of phosphorus and bromine. The composition of this glass is an example, and selenium-arsenic system, germanium-selenium-tellurium system, germanium-selenium-arsenic system, etc., which are used for applications such as energy transmission, can be manufactured in the same manner.

[0017]

As described above, according to the present invention, there is obtained a chalcogenide glass for infrared ray transmission, which has excellent transparency in the infrared region and is free from cracks. As a result, a lens with excellent performance can be manufactured. Further, when the glass raw material contains at least germanium or selenium as a main component, it has characteristics that it is safe for the human body and infrared rays emitted from the human body can be efficiently collected.

[Brief description of drawings]

FIG. 1 is an infrared transmission spectrum of glass according to an embodiment of the present invention.

FIG. 2 is an infrared transmission spectrum of a glass of a comparative example.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Akihiko Yoshida 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd.

Claims (5)

[Claims] 1. A raw material for the production of an infrared-transparent glass containing germanium or selenium as a main component.
Manufacture of infrared transmissive glass characterized by crushing germanium ingot having a purity of 99.999% or more and selenium pellets having a purity of 99.999% or more, vacuum sealing in a silica glass ampoule and melting Method. 2. The method for producing infrared transmissive glass according to claim 1, wherein the degree of enclosure vacuum is 10 ⁻⁴ Torr or less. 3. The method for producing infrared transmissive glass according to claim 1, wherein the melting temperature is 900 to 1000 ° C. and the melting time is at least 1 hour. 4. The method for producing an infrared-transparent glass according to claim 1, wherein the temperature is from room temperature to the melting temperature for at least 4 hours. 5. The glass after melting is transferred to a furnace set at a temperature lower than the crystallization temperature of glass by 10 ° C. or more and kept at the temperature for 3 hours or more, and then at a temperature 20 ° C. or more lower than the glass transition point. 4. The method of claim 1, 2, 3 characterized by slow cooling to
The method for producing the infrared-transparent glass according to item 4 or 5.