GB2065916A - Infrared condensing lenses - Google Patents

Infrared condensing lenses Download PDF

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Publication number
GB2065916A
GB2065916A GB8038325A GB8038325A GB2065916A GB 2065916 A GB2065916 A GB 2065916A GB 8038325 A GB8038325 A GB 8038325A GB 8038325 A GB8038325 A GB 8038325A GB 2065916 A GB2065916 A GB 2065916A
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Prior art keywords
infrared
rays
condensing lens
membrane
infrared rays
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GB8038325A
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Kureha Corp
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Kureha Corp
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    • GPHYSICS
    • G02OPTICS
    • G02BOPTICAL ELEMENTS, SYSTEMS, OR APPARATUS
    • G02B19/00Condensers, e.g. light collectors or similar non-imaging optics
    • G02B19/0033Condensers, e.g. light collectors or similar non-imaging optics characterised by the use
    • G02B19/009Condensers, e.g. light collectors or similar non-imaging optics characterised by the use for use with infra-red radiation
    • GPHYSICS
    • G02OPTICS
    • G02BOPTICAL ELEMENTS, SYSTEMS, OR APPARATUS
    • G02B1/00Optical elements characterised by the material of which they are made
    • GPHYSICS
    • G02OPTICS
    • G02BOPTICAL ELEMENTS, SYSTEMS, OR APPARATUS
    • G02B1/00Optical elements characterised by the material of which they are made
    • G02B1/04Optical elements characterised by the material of which they are made made of organic materials, e.g. plastics
    • GPHYSICS
    • G02OPTICS
    • G02BOPTICAL ELEMENTS, SYSTEMS, OR APPARATUS
    • G02B13/00Optical objectives specially designed for the purposes specified below
    • G02B13/14Optical objectives specially designed for the purposes specified below for use with infra-red or ultra-violet radiation
    • GPHYSICS
    • G02OPTICS
    • G02BOPTICAL ELEMENTS, SYSTEMS, OR APPARATUS
    • G02B19/00Condensers, e.g. light collectors or similar non-imaging optics
    • G02B19/0004Condensers, e.g. light collectors or similar non-imaging optics characterised by the optical means employed
    • G02B19/0009Condensers, e.g. light collectors or similar non-imaging optics characterised by the optical means employed having refractive surfaces only
    • G02B19/0014Condensers, e.g. light collectors or similar non-imaging optics characterised by the optical means employed having refractive surfaces only at least one surface having optical power

Abstract

The infrared rays condensing lens 20, for use in an infrared ray sensor 10, contains a Fresnel convex lens 34 composed of a synthetic resin capable of transmitting infrared rays and a membrane or film 36 for preventing the penetration of visible rays disposed of at least one of the surfaces thereof. The membrane or film 36 is formed by spattering or vacuum evaporating an inorganic material e.g. Ge, Si, an In compound or a Ga compound, capable of substantially interrupting visible rays and transmitting at least a portion of rays in the infrared range. The infrared rays condensing lens has a large amount of the infrared ray transmission, a short focal length and a small transmittance of visible rays. It has advantages that it can be manufactured by simple manufacturing steps using cheap materials. <IMAGE>

Description

SPECIFICATION Infrared condensing lenses The present invention relates to an infrared condensing lens (hereinafter referred to also as an infrared rays condensing lens).

It is known of infrared rays sensing elements composed of materials giving some electrical response upon the radiation of infrared rays, such materials being as a pyroelectric material producing electric charges by the radiation of infrared rays and a photoconductive material changing its electroconductivity by the radiation of infrared rays.The infrared rays sensing elements have been used in a combination with infrared ray condensers for a variety of infrared ray sensors which have been employed as an infrared ray detecting part in apparatuses such as, for example, a fire alarm for detecting a fire; an invader detecting device for detecting the infrared rays radiating from the human body or other living bodies; a transfer detecting device for detecting a transferring object such as human beings, vehicles or the like passing through a passage or the like on which infrared rays are being radiated; an infrared ray image pickup unit for producing electrical signals corresponding to optical images of infrared rays; an infrared ray communication unit for communicating apart with infrared rays and so on.

As an infrared ray condenser, there has been used a convex lens in a usual form or a concave mirror. Where it is used merely for the detection of infrared rays, the infrared condenser is designed in a manner adaptable to receive infrared rays from their source at an area as wide as possible and condense them on an infrared rays sensing element, whereby the sensitivity of the infrared ray sensor is rendered high. Where it is employed for picking up infrared ray images, the infrared ray condenser can provide a function to focus an outside infrared ray image into the image on the sensing surface of its infrared ray sensing element.

In either case, the surface of the condenser receiving infrared rays is preferably as big as possible within the scope acceptable from the design of an apparatus or device.

Both the pyroelectric and photoconductive materials constituting the infrared rays sensing elements are also highly sensitive to visible rays so that it is desired to remove noises resulting from the visible rays with the infrared ray condenser in an infrared ray sensor particularly where accurate information with respect to the infrared rays to be sensed is required.

Where prior art infrared ray condensers are composed of convex lenses or spherical lenses, materials capable of transmitting a wide range of infrared rays and interrupting visible rays have heretofore been used, such material being as crystalline materials such as silicone, germanium, sapphire or the like. When such an extremely hard and nevertheless brittle material is used to give a convex lens or a spherical lens, however, many skilled laborious work is required to cut the single crystal plate of the crystalline material into a convex shape and then grind and poiish it elaborately, thereby causing the manufacturing and material costs to rise. Accordingly, the use of such crystalline material for usual infrared ray condensers other than high-quality ones such as the infrared ray image pickup unit is not very appropriate.

On the other hand, where the infrared ray condensers have been of a condensing mirror or a convex mirror, it is required to provide an infrared rays sensing element at the side of the mirror receiving the infrared rays so that the shadow of the infrared rays sensing element falling on the mirror surface becomes the dead angle. Therefore, where the condensing mirror is used, for example, the infrared ray image pickup unit presents problems that the image are broken or get blurred so that it is inappropriate to apply the condensing mirror to such a unit. And, where the condensing mirror is applied to an apparatus or device which is used merely for the detection of infrared rays, it causes a defect that an amount of the infrared rays to be sensed is reduced.Furthermore, where the condensing point of the condensing mirror is adjacent to the surface of the mirror receiving the infrared rays, it is necessary to mount the infrared rays sensing element adjacent to the infrared rays receiving surface so that it causes disadvantages that there are many limits in manufacturing and designing on procedures for mounting the sensing element and wiring.

In order to improve the defects and disadvantages presented in the convex lens and the concave mirror as stated hereinabove, it has now been found that a convex lens composed of a synthetic resin which is very easy to be processed to form a desired shape can be used for an infrared ray condenser in an infrared ray sensor. It has been found, however, that as the transmittance of infrared rays of the synethetic resin is unexpectedly poor and the synthetic resin having a little bit greater thickness does not permeate or transmit most of the effective infrared rays, it is found difficult to provide a practically applicable infrared ray condenser with a high condensing efficiency from a convex lens prepared as from such a synthetic resin.

Thus, wavelengths of predominant infrared rays radiating from the human body that is the object for detection by means of an invader detecting device are from 8 to 13 microns and average about 10 microns. The wavelength of the infrared rays from carbon dioxide flame that is the main object for detection by means of a fire alarm is about 4.3 microns. Currently known synthetic resins, however, absorb well infrared rays having wavelengths ranging from several microns to several tens microns.Among those synthetic resins, a polyethylene which is relatively small in absorbing the infrared rays in the above wavelength range can transmit only from 28 to 30 percent of the infrared rays having the wavelength of 10 microns when the polyethylene lens is 1 mm thick, although the polyethylene lens having a thickness of 0.1 mm can transmit from 85 to 90 percent of the 10 microns infrared rays.

Where a convex lens is prepared from a material having a poor transmittance of infrared rays, the size of the lens having a thin thickness as stated hereinabove and a desired shape is rendered se larger while keeping its similar figures that its thickness is further increased, whereby the convex lens cannot allow most of the effective infrared rays at its central portion to transmit therethrough. Furthermore, the enlargement of the size of the lens while keeping its similar figures lengthens its focal length so that, in order to control an increase in the focal length, the enlargement of the curvature of the lens causes a further increase in the thickness thereof at its center portion.

For example, when a convex lens for condensing infrared rays, having the focal length of 50 mm, capable of transmitting 50% or more of the infrared rays having a wavelength of 10 microns at the maximal thickness portion thereof is prepared by a polyethylene, the thickness of the lens should be at largest 600 microns when calculated from the transmittance of infrared rays of the polyethylene so that its maximum size is restricted to about 11 mm. Such a lens is too small in a condensing area and its transmittance of infrared rays is poor. When such a lens having the focal length of 300 microns is prepared, its transmittance of infrared rays is increased to about 70%, but the size of the lens is reduced to 7.7 mm so that the condensing area is half as much as a lens having the thickness of 600 microns.

As stated already hereinabove, infrared ray condensers for use in an infrared ray sensor is necessarily designed so as not to transmit visible rays. Since a synthetic resin such as a polyethylene has a transmittance of visible rays larger than silicon, germanium or sapphire, this all the more prevents the synthetic resinous convex lens from being employed as an infrared ray condenser.

Therefore, an object of the present invention is to provide a infrared condensing lens having a large aperture and a great transmittance of infrared rays, thus a large amount of transmission of the infrared rays.

Another object of the present invention is to provide a infrared condensing lens having a short focal length in comparison with a large amount of the transmission of the infrared rays.

A further object of the present invention is to provide a infrared condensing lens having a small transmittance of visible rays in comparison with a favourable transmittance of infrared rays.

A still further object of the present invention is to provide an infrared rays condensing lens which can be manufactured by means of simple manufacturing steps with a cheap material.

Various other objects, advantages and features of the present invention will become readily apparent from the ensuring detailed description, and the novel features will be particularly pointed out in the appended claims.

FIG. 1 is a schematic representation illustrating an example of the infrared ray sensors using an infrared rays condensing lens according to the present invention.

FIG. 2 is a partially notched perspective view illustrating one embodiment of the structure of the infrared ray sensor of FIG. 1.

FIG. 3 is a cross-sectional view illustrating the infrared rays condensing lens shown in FIGS. 1 and 2.

FIG. 4 is a schematic representation illustrating another embodiment using the infrared rays condensing lens according to the present invention.

FIG. 5 is a schematic representation in perspective illustrating an example of an infrared ray image pickup unit to which the infrared rays condensing lens according to the present invention is adaptable.

FIG. 6 is an exploded perspective view illustrating infrared rays sensing elements and electrodes in the infrared ray image pickup unit shown in FIG. 5.

The infrared ray sensors as shown in FIGS. 1 to 3 will be described in detail hereinafter.

Referring to FIG. 1 showing the schematic representation illustrating the infrared ray sensor, an infrared rays sensing element 10 is composed of a pyroelectric membrane 12 obtainable from a pyroelectric polymer such as, for example, a fluorine compound, e.g., polyvinylidene fluoride, polyvinyl fluoride, a vinylidene fluoridetrifluoroethylene copolymer or the like, a pyroelectric inorganic material such as, for example, a titan compound, e.g., lead titanate, barium titanate, lead titanzirconate or the like or other pyroelectric materials.

The pyroelectric membrane 12 is provided at its both sides with electrodes 1 4a and 1 4b. The electrode 1 4b at the side receiving the infrared rays may be composed of a thin layer prepared from a material capable of absorbing infrared rays well, such as gold black or the like. The electrode 1 4a at the side opposite to the side receiving infrared rays may be composed of a material reflecting the infrared rays such as aluminum or the like. Both of the electrodes 1 4a and 1 4b are preferably designed so as to allow their surfaces to introduce the infrared rays in an effective manner to the pyroelectric membrane 12. As long as the purpose is fulfilled, any variation and modification may be made in a manner, for example, such that the electrode 1 4b at the side receiving the infrared rays may be a transparent electrode, while the electrode 1 4a at the side opposite to the infrared rays receiving side is composed of an infrared rays absorbing material as stated hereinabove or such that the electrode 1 4b may be a transparent electrode, while a pigment capable of absorbing infrared rays may be mixed in pyroelectric membrane 12 or coated thereon.

The electrodes 1 4a and 1 4b may be substantially the same in shape and form as the pyroelectric membrane 12 where the infrared ray sensor is employed merely for the purpose of detecting a fire or detecting an invader. However, where the infrared ray sensor is employed for the infrared ray image pickup unit or for detecting the position of a fire for an automatic fireextinguishing unit, at least one of the electrodes may be preferably a structure comprised of a plurality of divided strips or pieces. Accordingly, the shape, size and number of the electrodes may vary in an appropriate manner according to the purpose of use, design and the like of the infrared ray sensors.When the electrodes 1 4a and/or 1 4b are divided into plural strips or pieces, impedance converting circuits 1 6 and detecting circuits 18 may be provided according to the number of the divided electrodes.

One of the electrode 14a of the infrared rays sensing element 10 is grounded and the other of the electrode 1 4b is connected to the impedance converting circuit 1 6 comprised of a field effect transistor (FET). The output side of the impedance converting circuit 1 6 is in turn connected to the detecting circuit 1 8 for detecting electric signals (electric current or voltage) from which a desired output can be obtained. The structure as stated hereinabove is generally known so that a detailed description thereon is omitted herein.

The condensing of infrared rays on the infrared rays sensing element 10 may be conducted by means of the infrared rays condensing lens 20 according to the present invention which is disposed in front of the infrared rays sensing element.

Turning now to FIG: 2, there is shown an embodiment illustrating the structure of an infrared ray sensor 24 in which the infrared rays sensing element 10 and the infrared rays condensing lens 20 are assembled in a cylindrical housing 22.

As shown in FIG. 2, the infrared rays condensing lens 20 is provided at the front open side of the cylindrical case 22. At the middle portion of the cylindrical housing 22 is provided with a printed circuit board 26 in an arrangement substantially parallel to the lens 20. At the front side of the printed circuit board 26 facing the lens 20, there is attached the infrared rays sensing element 10, and at the rear or back side thereof opposite to the above front side, there are attached electrical parts 28 constituting necessary circuits. A signal line or code 30 is drawn to the outside from the rear or back end portion of the cylindrical housing 22 opposite to the front end portion where the lens 20 is mounted.The signal line or code is connected at the other end to a signal presenting unit 32 for indicating signals to the outside such as an alarm, a display device or a voice producing device or a computer or the like.

Referring to FIG. 3, there is shown a detail of the infrared rays condensing lens according to the present invention. The lens 20 is composed of a Fresnel convex lens 34 and a membrane or film 36 for preventing the penetration or transmission of visible rays, said membrane or film being provided on the flat surface of the lens 34. The lens 34 may be comprised of a synthetic resin having a favorable transmittance of infrared rays including a thermoplastic resin such as, for example, olefinic resins, e.g., polyethylene, polypropylene or ethylene-propylene copolymer; fluorine-containing resins, e.g., polyvinyl fluoride, polyvinylidene fluoride or polytetrafluoroethylene; or an acetylenic resin, e.g., polyacetylene.The membrane or film 36 for preventing the penetration of visible rays may be comprised of an inorganic material capable of substantially interrupting the visible rays and penetrating or transmitting at least a portion of rays in the infrared range, said inorganic material being, for example, germanium, silicon, an indium compound, e.g., indium antimonide, indium phosphide or indium arsenide or a gallium compound, e.g., gallium antimonide or gallium arsenide. The inorganic material may be allowed to adhere to the flat surface of the lens 34 indirectly or directly by spattering, vacuum deposition or other appropriate techniques. The membrane or film 36 is not necessarily provided on the flat surface of the lens and may be disposed on a surface opposite to the flat surface thereof or on both of the surfaces thereof.

Generally, a Fresnel lens can be greatly reduced in weight by dividing the continuous lens surface into a succession of concentric rings having a cross section as indicated in FIG. 3, the rings being assembled in correct relationship on the flat surface thereof. The surface of the ring is not necessarily a surface (for example, a portion of a sphere) whose cross section in the radial direction has a curved line like the continuous lens surface. The ring surface may be in a form of the circumferential surface of a truncated cone. In other words, it may be a surface whose cross section has a straight line (or a tangent line) represented by differentiating the above curved line. Accordingly, the ring may be a small prism in the form of a ring having the surface as described hereinabove.The Fresnel convex lens is a Fresnel lens of the type having the continuous lens surface which corresponds to a surface of a convex lens.

As a Fresnel convex lens is designed by removing portions as much as possible where the rays are penetrating or transmitting straight through, as compared with usual convex lenses or spherical lenses, it may be rendered considerably thinner than usual convex lenses having the identical focal length and a ratio of the central portion to the circumferential portion thereof in thickness may be rendered small. Accordingly, for example, where a Fresnel convex lens having a lens diameter of several tens mm is prepared by, for example, a polyethylene, the thickness of the Fresnel convex lens may be to the extent of several tens microns to several hundreds microns and the Fresnel lens can provide a good transmittance of infrared rays and allow a small difference in the infrared ray transmittance between the central portion and the circumferential portion thereof.

Referring to FIG. 3, the thickness of the Fresnel convex lens 34 may be determined according to the thickness of a flat plate or a base plate excluding nearly triangular cross-sectional portions 34a, the lens size, the focal length, the number of the concentric rings or the like. If the number of the concentric rings would be increased, it is theoretically possible to provide a Fresnel convex lens having any thin triangular cross-sectional portions 34a. However, if the number of the concentric rings would be too many, there may be a case where the annular concentric grooves 34c between each adjacent rings formed on the surface thereof may act as a lattice.Accordingly, as it is difficult to assemble too many concentric rings on the lens surface in order to make the triangular cross-sectional portions 34a extremely thin, the thickness of the Fresnel convex lens may range generally about 10 microns or more, preferably from about 10 microns to 1,000 microns, and more preferably from about 50 microns to 500 microns. A Fresnel lens composed of a synthetic resin having a thickness thicker than 1 ,000 microns is not practical because of poor transmittance resulting from the absorption of infrared rays by the synthetic resin used. For example, where a polyethylene which is said to be least in the absorption of infrared rays, it can transmit or penetrate only 20 to 30% of the infrared rays when its thickness is 1,000 microns, although it can penetrate 85 to 90% of the rays when its thickness is 100 microns.Although the infrared ray absorption of Fresnel convex lenses 34 may vary greatly with the type and kind of synthetic resins to be used as a material therefor, it is preferred that the Fresnel convex lenses have 30% or more, preferably 50% or more, of the transmittance of infrared rays having a wavelength of at least one of 4.3 microns and 10 microns.

The Fresnel convex lens 34 may be designed so as to have, for example, a focal length of 40 mm, a diameter of about 50 mm, a pitch width (a distance between the grooves 34c) of about 0.2 mm (200 microns) and a thickness of about 0.4 mm (400 microns). In this case, the number of the concentric rings may be about 250. The thickness of the lens may be such that the thickness of the flat portion or base portion 34b is about 0.2 mm and the both thickest or outermost triangular cross-sectional portions 34a may be about 0.2 mm (200 microns) thick.

The membrane or film 36 for preventing the penetration or transmission of visible rays may be preferably 0.02 micron or thicker, although a membrane or film having a thickness of 0.01 micron may be optionally used because it can interrupt a considerable amount of visible rays.

The upper limit on the thickness of the membrane or film 36 is not particularly necessary; however, the thicker the membrane or film is, the more the differential thickness due to irregularity in thicknesses may also be. Accordingly, the reflective index of the infrared rays in the membrane or film 36 composed of germanium, silicon or the like is so irregular that the condensing performance or effect of the lens is impaired. It is accordingly disadvantageous to thicken the membrane or film 36 to an unnecessary level and its thickness may be preferably about 1 micron or thinner.

For example, another membrane or film for the prevention of reflection may be provided on the membrane or film 36 for preventing the penetration of visible rays. The reflection preventing membrane or film may be composed of, for example, silicon monoxide, cerium dioxide, zinc sulfide or the like and disposed on the surface of the membrane or film 36 for preventing the penetration of the visible rays by means of vacuum deposition or other suitable techniques.

As the reflection preventing membrane or film is required to be provided at the incidence side of the Fresnel convex lens 34, it is at the side of the flat surface of the lens when the rays are falling upon the flat surface thereof and vice versa.

Accordingly, where the membrane or film 36 is at a side opposite to the incidence side of the Fresnel convex lens 34, the membrane or film for the prevention of reflection is provided at the side opposite to the membrane or film 36. As shown in FIG. 3, however, the reflection preventing membrane or film may be provided on the surface of the membrane or film 36 for preventing the penetration or transmission ot visible rays, whereby both of the membranes or films having uniform thicknesses may be easily formed.

The thickness of the reflection preventing membrane or film may be, in the visible range, as conventionally presented, as follows: d 4n were: d = thickness, A = wavelength of infrared rays whose incidence should be prevented, and n = reflective index.

The thickness of the reflection preventing film or membrane may be, for example, about 0.1 micron.

In the infrared ray sensors as shown in FIGS. 1 to 3, infrared rays 40 is radiated from the side of the visible rays preventing membrane or film 36 on the infrared rays condensing lens 20. The infrared rays 40 is condensed by means of the Fresnel convex lens 34 after the penetration or transmission of the membrane or film 36 and then introduced into the pyroelectric membrane 12 of the infrared rays sensing element 10. The infrared rays which fell upon the sensing element 10 cause the production of electric charges due to polarization and produce a potential between the electrodes 1 4a and 1 4b on the sensing element 10. This potential or electric signals are fed through the impedance converting circuit 1 6 to the detecting unit 1 8 from which the detecting signals are dispatched.The detecting signals are then fed to the signal presenting unit 32, thereby giving a desired presentation or producing a necessary representation.

In place of the pyroelectric light sensing element as employed in the infrared ray sensors shown in FIGS. 1 to 3, inclusive, an infrared photoconductive material comprising an infrared semiconductor such as an infrared photo diode, an infrared photo transistor, an infrared photo thyristor or the like may be employed as an infrared rays sensing element.

FIG. 4 illustrates an example of an infrared ray sensor that uses as an infrared rays sensing element an infrared photoconductive material such as, for example, lead sulfide (PbS), indium antimonide (InSb), cadmium sulfide (CdS) or the like. In FIG. 4, the parts in common with the infrared sensors presented in FIGS. 1 to 3 are indicated by the same numerals. Accordingly, a description thereon is omitted from the description which follows.

In the infrared ray sensor illustrated in FIG. 4, too, the same infrared rays condensing lens 20 as used in the infrared ray sensors illustrated in FIGS.

1 to 3 is employed. A pair of the electrodes 1 4a and 1 4b are provided at the both sides thereof and connected in series to a bias power source 52 and an ampere meter 54 and, when necessary, to the signal presenting unit 32. In this case, where the infrared ray sensor is used merely for the detection of a fire or for the detection of an invader, the electrodes 1 4a and 1 4b may be in each case a solid electrode which may be composed of one piece and which may have a margin portion for the protection of a short circuit at the peripheral portion thereof when needed.

Accordingly, when infrared rays 40 are radiated upon the infrared photoconductive material 50, the electric current flowing through the ampere meter 54 is increased so that the measurement of the current can detect the amount of the infrared rays.

In FIGS. 5 and 6 there is shown an example of the infrared ray image pickup unit in which the same infrared rays condensing lens as used in the infrared ray sensors illustrated in FIGS. 1 to 3 is mounted at the front side of an infrared rays sensing element 60, although an illustration thereon is omitted in the drawings for brevity. In this example, the parts in common with the infrared ray sensor illustrated in FIG. 4 are indicated by the same numericals, and a description thereon is omitted for avoiding duplicate explanation.

As shown in FIGS. 5 and 6, there are provided at either of the both sides of the sensing element 60 a number of strip electrodes 62a, 62b, ...., and 62n which are arranged in a relationship parallel to each other and also at the other side thereof a number of strip electrodes 64a, 64b,...., and 64n which are in turn arranged parallel to each other.

In FIGS. 5 and 6, the strip electrodes 62a, 62b, ...,and 62n are arranged in a relationship substantially orthogonally intersecting the other group of the strip electrodes 64a, 64b . . ., and 64n. However, this orthogonally intersecting arrangement between the two groups of the strip electrodes is not required and one of the groups of the strip electrodes may be arranged in an intersecting relationship with the other group of the strip electrodes obiiquely at an appropriate angle to each other.

The strip electrodes 62, 62b . . ., and 62n are commonly connected to each other through ON-OFF switches 66a, 66b . . ., and 66n, respectively. Similarly, the strip electrodes 64a, 64b,...., and 64n are commonly connected to each other through ON-OFF switches 66a, 66b, . . ., and 66n, respectively. One of the common connections is connected in series through the bias power source 52 and the ampere meter 54 to the other common connection and, when necessary, to the signal presenting unit 32.

Thus, when the ON-OFF switches 66a, 66b, . . ., and and 66n are turned on and off in turn at constant time intervals and the other group of the ON-OFF switches 68a, 68b,..., 68n is turned on and off in turn at intervals of a period of time for which the ON-OFF switches 66a, 66b .

and 66n are being turned on and off in turn in the whole round, image pickup signals corresponding to the shape, distribution and the like of an infrared ray image in front of the infrared condensing lens are produced. Accordingly, with a picture receiving device or unit as the signal presenting unit, the respective infrared ray image can be reproduced.

Either of the groups of the strip electrodes may be replaced by a printed electrode as in the case of FIG. 4. In this case, there may be provided a slit plate having a slit extending in directions perpendicularly or obliquely intersecting the lengthwise directions of the rest of the strip electrodes. As the slit plate is moved or transferred in a straight direction at a constant speed, an infrared ray image can be produced in such a mode as in FIGS. 5 and 6.

Where an optical chopper capable of introducing infrared rays intermittently into the infrared rays sensing element is disposed in front of the sensing element as in the example illustrated in FIGS. 5 and 6 as well as in the examples illustrated in FIGS. 1 to 4, intermittent infrared ray detecting signals can be produced.

While the present invention is illustrated with specific embodiments, it will be recognized by those skilled in the art that any variation thereon and modification therefrom may be made therein without departing from the scope of the present inventive concepts of the present invention as defined by the following claims.

Claims (12)

1. An infrared condensing lens comprising a Fresnel convex lens comprising a synthetic resin capable of transmitting infrared rays and a membrane or film for preventing the penetration or transmission of visible rays, said membrane or film being disposed on at least one of the surfaces of said Fresnel convex lens and comprising an inorganic material capable of substantially interrupting visible rays and providing a transmittance of at least a portion of rays in the infrared range.
2. The infrared condensing lens according to Claim 1, wherein said one of the surfaces of the Fresnel convex lens is a flat surface.
3. The infrared condensing lens according to Claim 1, where said Fresnel convex lens has a 30% or more transmittance of at least one of the infrared rays having wavelengths of 4.3 microns and 10 microns.
4. The infrared condensing lens according to Claim 1, wherein said synthetic resin is a thermoplastic resin selected from the group consisting of an olefinic resin, a fluorinecontaining resin and an acetylenic resin.
5. The infrared condensing lens according to Claim 4, wherein said synthetic resin is a polyethylene.
6. The infrared condensing lens according to Claim 1, wherein said inorganic material is germanium, silicon, an indium compound or a gallium compound.
7. The infrared condensing lens according to Claim 6, wherein the indium compound is indium phosphide, indium arsenide or indium antimonide.
8. The infrared condensing lens according to Claim 6, wherein the gallium compound is gallium antimonide or gallium arsenide.
9. The infrared condensing lens according to Claim 1, wherein said Fresnel lens has a maximal thickness of from about 10 to 1,000 microns.
10. The infrared condensing lens according to Claim 1, wherein said membrane or film for preventing the penetration or transmission of visible rays is provided at the surface thereof with a membrane or film for preventing the refelection of rays.
11. The infrared condensing lens according to Claim 10, wherein said membrane or film for preventing the reflection of rays is comprised of silicon monoxide, cerium dioxide or zinc sulfide.
12. The infrared condensing lens according to Claim 1, wherein said lens is constructed for use in condensing infrared rays in an infrared ray sensor and said infrared rays sensing element is disposed close to a point where the rays through the lens is condensed.
GB8038325A 1979-11-30 1980-11-28 Infrared condensing lenses Withdrawn GB2065916A (en)

Priority Applications (2)

Application Number Priority Date Filing Date Title
JP16585579U JPS5682627U (en) 1979-11-30 1979-11-30
JP16729479U JPS5934881Y2 (en) 1979-12-03 1979-12-03

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DE (1) DE3045203C2 (en)
FR (1) FR2470980A1 (en)
GB (1) GB2065916A (en)

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US20130140297A1 (en) * 2010-08-30 2013-06-06 Panasonic Corporation Induction heating apparatus
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EP1152273A2 (en) * 2000-05-04 2001-11-07 C.R.F. Societa' Consortile per Azioni Objective for infrared vision systems
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US7846131B2 (en) 2005-09-30 2010-12-07 Covidien Ag Administration feeding set and flow control apparatus with secure loading features
US8052642B2 (en) 2006-03-02 2011-11-08 Covidien Ag Pumping apparatus with secure loading features
US7722573B2 (en) 2006-03-02 2010-05-25 Covidien Ag Pumping apparatus with secure loading features
US7758551B2 (en) 2006-03-02 2010-07-20 Covidien Ag Pump set with secure loading features
US7763005B2 (en) 2006-03-02 2010-07-27 Covidien Ag Method for using a pump set having secure loading features
US7722562B2 (en) 2006-03-02 2010-05-25 Tyco Healthcare Group Lp Pump set with safety interlock
US9402789B2 (en) 2006-03-02 2016-08-02 Covidien Ag Pump set having secure loading features
US8142399B2 (en) 2006-03-02 2012-03-27 Tyco Healthcare Group Lp Pump set with safety interlock
US8142404B2 (en) 2006-03-02 2012-03-27 Covidien Ag Controller for pumping apparatus
US8052643B2 (en) 2006-03-02 2011-11-08 Tyco Healthcare Group Lp Enteral feeding set and interlock device therefor
US7927304B2 (en) 2006-03-02 2011-04-19 Tyco Healthcare Group Lp Enteral feeding pump and feeding set therefor
US8053721B2 (en) 2006-12-11 2011-11-08 Tyco Healthcare Group Lp Pump set and pump with electromagnetic radiation operated interlock
US8021336B2 (en) 2007-01-05 2011-09-20 Tyco Healthcare Group Lp Pump set for administering fluid with secure loading features and manufacture of component therefor
US8529511B2 (en) 2007-01-05 2013-09-10 Covidien Lp Pump set with secure loading features and related methods therefor
EP1941923A1 (en) * 2007-01-05 2008-07-09 Covidien AG Pump set for administering fluid with secure loading features and manufacture of component therefor
CN102122060B (en) 2010-01-07 2014-06-25 颖台科技股份有限公司 Composite light condensation device
US8154274B2 (en) 2010-05-11 2012-04-10 Tyco Healthcare Group Lp Safety interlock
US8760146B2 (en) 2010-05-11 2014-06-24 Covidien Lp Safety interlock
US20130140297A1 (en) * 2010-08-30 2013-06-06 Panasonic Corporation Induction heating apparatus
US9426846B2 (en) * 2010-08-30 2016-08-23 Panasonic Intellectual Property Management Co., Ltd. Induction heating apparatus

Also Published As

Publication number Publication date Type
DE3045203C2 (en) 1983-02-24 grant
CA1152789A1 (en) grant
CA1152789A (en) 1983-08-30 grant
DE3045203A1 (en) 1981-06-11 application
FR2470980A1 (en) 1981-06-12 application

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