JP2015232506A - Array mirror system and infrared ray detection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an array mirror system, an array optical device equipped with the same, an infrared ray detection device, and an infrared ray detection system, capable of efficiently guiding infrared ray in a range which is to be observed with no light collecting component such as a lens, and preventing occurrence of crosstalk and ghost by cutting off the infrared ray from the outside of the observation range.SOLUTION: An array mirror system MA guides infrared ray from a plurality of areas from an object by a plurality of tubular mirrors Mi respectively. Each tubular mirror Mi includes an inside surface that inclines in such a manner as gradually opens toward an object side, as a reflecting surface Ms.

Description

  The present invention relates to an array mirror system and an infrared detector. More specifically, an array mirror system that guides infrared rays (for example, near infrared rays, middle infrared rays, far infrared rays) from a plurality of areas of an object with a plurality of mirrors, and an infrared ray from each area captured by the array mirror system is an image sensor. An array optical device that converts the electrical signal into an electrical signal and outputs it, an infrared detection device that detects a temperature change in each area using an output signal obtained from the infrared, and an infrared including the infrared detection device And a detection system.

  The far-infrared region in the wavelength band of 8 to 12 μm is a range in which the temperature of the substance can be detected, and there are many things that can be applied such as temperature measurement, human detection in the dark, and security. The sensitivity of such a far-infrared camera is determined by the brightness of the lens together with the sensor specifications. In order to secure the brightness of the far-infrared lens, it is necessary to have a configuration without vignetting off the axis. However, it is difficult to obtain a wide-angle far-infrared optical system. That is, it is difficult to obtain an optical system with sufficient performance with a wide-angle lens system, since it is necessary to correct aberrations with a light flux that is obliquely incident on the lens system with the same light flux width as that on the axis.

  Further, in a conventional inexpensive human body detection device, a pyroelectric sensor or the like is used as a sensor. The pyroelectric sensor uses a pyroelectric effect in which ceramics including lead zirconate titanate or the like spontaneously polarizes due to a temperature change, and is an inexpensive temperature sensor having a single light receiving surface in most cases. In order to increase the sensitivity of human body detection, it is also known to divide the range in which the temperature change is detected by dividing the light receiving surface of the pyroelectric sensor from 2 to 4, but the detection circuit has a light receiving surface of 1 Since it is the same as the case of the individual, the same signal is generated no matter where it is detected in the observation range, and the position of the human body cannot be detected. For this reason, a human body detection device capable of detecting a position (from which direction a person has entered) is desired.

  In order to cope with such a problem, it is conceivable to use a so-called array optical system in which a plurality of imaging optical systems are arranged in parallel as a single-eye optical system. In the array optical system, it is possible to divide the screen in which each single-eye optical system captures a different range, and to capture a discrete range in each single-eye optical system. Further, in human body detection, a temperature difference from the surroundings cannot be detected unless the range of the target human body is imaged on one or more pixels on the screen (that is, detection within the error range). )). However, also by using the array optical system, it is possible to achieve both ensuring a wide-angle observation range and photographing a human body with a size of one pixel or more.

  When the array optical system is used, there is a so-called crosstalk problem that light rays coming from adjacent single-eye optical systems are mixed. In order to prevent crosstalk, a light shielding member may be used between the single-eye optical systems. In a visible optical system, it is possible to prevent crosstalk by using a black material for light shielding. However, far-infrared rays, which are also heat rays, are absorbed as heat and become a heat source even if their progress is blocked by a black material, so that they reach the sensor and eventually cause ghosting. In addition, when a material that reflects far infrared rays is used for the light shielding member, infrared rays from any heat source such as the observation object and the structural parts of the optical system are reflected, resulting in a ghost. Thus, in order to use an array lens system as an infrared optical system, light shielding becomes a big problem.

  Patent Document 1 describes an array lens system designed for visible light. The single-lens lenses are arranged in an array so as to have different observation ranges, and the outer single-eye lenses are inclined so that the wide-angle range is photographed by tilting the optical axis. In addition, the incident angle to the sensor due to the tilt of the optical axis is corrected to be close to vertical by inserting a triangular prism.

  Patent Document 2 describes a hood for preventing visible light reflection provided on an infrared lens. Visible light is reflected by the infrared lens surface in the back of the hood, and for example, when used as a vehicle-mounted lens, it is prevented from being irradiated toward the oncoming vehicle. The inner surface of the light shielding hood has a low reflectance, and a filter that does not transmit visible light is mounted inside.

  Patent Document 3 describes an optical system for an image reading apparatus in which an array lens and a light guide member corresponding to the array lens are arranged. The light guide member guides the light beam while reflecting the light from the inner reflection surfaces facing in parallel.

JP 2012-151798 A JP 2003-241260 A JP 2000-244704 A

  The array lens system described in Patent Document 1 requires a structure that prevents light beams from crosstalk between adjacent single-lens lenses. Since the images formed by the individual lenses are formed adjacent to each other, unnecessary light beams may be formed from the adjacent individual lenses. In order to prevent this, a light shielding member is disposed between the individual lenses. Since it is an optical system used for visible light, it can serve as a light shield if the reflectance of the surface of the black material is lowered. However, infrared rays are absorbed as heat by the light shielding member made of such a black material, and further, the absorbed heat is radiated as infrared light, so that it reaches the sensor surface as a ghost as described above.

  The infrared lens described in Patent Document 2 is provided with a hood for preventing visible light reflection. The inner surface of the hood is slanted so that it opens toward the object side, but because it is configured to suppress reflectivity, it does not reflect infrared light, and only a small amount is guided to the back of the hood. . Further, since there is only one hood provided for the entire lens system, it is not possible to acquire the position information of the infrared object in the observation range.

  In the image reading apparatus described in Patent Document 3, the light beam is limited by the array lens, so that the light beam does not enter the light guide member from the outside. However, in a light guide member having parallel reflecting surfaces facing each other, even if a light beam enters from outside the observation range, the light beam reaches the other end without changing the angle.

  The present invention has been made in view of such a situation, and its purpose is to efficiently guide infrared rays in a range desired to be observed without a condensing part such as a lens and to block infrared rays from outside the observation range, An object of the present invention is to provide an array mirror system capable of preventing the occurrence of crosstalk and ghost, an array optical device including the same, an infrared detection device, and an infrared detection system.

To achieve the above object, the array mirror system of the first invention is an array mirror system that guides infrared rays from a plurality of areas of an object by a plurality of mirrors, respectively.
Each of the mirrors is a cylindrical mirror having an inner surface inclined so as to gradually open toward the object side as a reflection surface.

  An array mirror system according to a second invention is characterized in that, in the first invention, the cylindrical mirror is made of a hollow member or a transparent member, and the shape of the reflecting surface is a columnar shape, an elliptical columnar shape or a prismatic shape. To do.

The array mirror system of the third invention is characterized in that, in the first or second invention, the following conditional expression (1) is satisfied.
0 <θ ≦ 15 (1)
However,
θ: Opening angle of the tip (°) with the reflecting surface facing the object side,
It is.

  An array optical device according to a fourth aspect of the invention includes an array mirror system according to any one of the first to third aspects of the invention, and an image sensor that converts infrared light guided onto the sensor surface into an electrical signal. The cylindrical mirror is provided so that one cylindrical mirror corresponds to one to several pixels on the sensor surface, and an end of the cylindrical mirror is close to the sensor surface. It is characterized by being.

  According to a fifth aspect of the present invention, there is provided an infrared detecting device comprising the array optical device according to the fourth aspect of the invention, wherein the temperature change in each area is detected using an output signal from the image sensor.

An infrared detection system according to a sixth aspect includes the infrared detection apparatus according to the fifth aspect, wherein each cylindrical mirror satisfies the following conditional expression (2).
0 <tan θ <L / S (2)
However,
θ: Opening angle of the tip (°) with the reflecting surface facing the object side,
L: maximum width of the object,
S: distance from the sensor surface to the object,
It is.

  According to the present invention, an array mirror capable of efficiently guiding infrared rays in a range desired to be observed without a condensing component such as a lens and blocking the infrared rays from outside the observation range to prevent occurrence of crosstalk and ghosts. System, array optical device, infrared detection device and infrared detection system including the same can be realized.

Sectional drawing which shows typically one Embodiment of an array mirror system and an array optical apparatus. Sectional drawing which shows typically a cylindrical mirror with an axis | shaft perpendicular | vertical with respect to a sensor surface. Sectional drawing which shows typically the cylindrical mirror in which the axis | shaft inclined with respect to the sensor surface. Sectional drawing which shows the inclination angle of the axis | shaft of a cylindrical mirror. The optical path figure which shows a mode that the infrared rays which injected into the cylindrical mirror from the outside of an observation range are reflected and returned to the original direction on the same optical path. The schematic diagram which shows the relationship between arrangement | positioning of the image sensor in an infrared detection system, and the tip opening angle of a reflective surface. The schematic diagram which shows one Embodiment of an infrared rays detection apparatus. The schematic diagram shown in the state which looked at the edge part by the side of the sensor surface of an array mirror type | system | group from the perpendicular direction with respect to the sensor surface. The optical path figure which shows the cross section whose inclination of the axis | shaft of the cylindrical mirror in Example 1, 2 is 5 degrees. The optical path figure which shows the cross section whose inclination of the axis | shaft of the cylindrical mirror in Example 1, 2 is 15 degrees. The optical path figure which shows the cross section whose inclination of the axis | shaft of the cylindrical mirror in Example 1, 2 is 45 degrees.

  The array mirror system and array optical device according to the present invention will be described below. The array mirror system according to the present invention is an optical system that guides infrared rays from a plurality of areas of an object by a plurality of mirrors, respectively. And each said mirror is a cylindrical mirror which has an inner surface inclined so that it may open gradually toward an object side as a reflective surface, It is characterized by the above-mentioned. The cylindrical mirror is made of, for example, a hollow member or a transparent member, and the shape of the reflecting surface is, for example, a columnar shape, an elliptical columnar shape, or a prismatic shape. When the cylindrical mirror is made of a hollow member, the inner reflective surface is formed by applying a mirror coating to the inner surface of the hollow member. When the cylindrical mirror is made of a transparent member, the outer surface of the transparent member is coated with a mirror. Constitutes the inner reflection surface.

  An array optical apparatus according to the present invention includes the above array mirror system and an image sensor that converts infrared light guided onto the sensor surface into an electrical signal, and for one to several pixels on the sensor surface. The cylindrical mirror is provided so that one cylindrical mirror corresponds and the end of the cylindrical mirror is close to the sensor surface. In addition, an infrared detection apparatus according to the present invention includes the array optical device, and detects a temperature change in each area using an output signal from the image sensor, and includes the infrared detection apparatus. Thus, the infrared detection system can be configured from the positional relationship with the object to be measured.

  In general, an array optical system is also referred to as a compound eye optical system, and each optical system constituting the array optical system is also referred to as a single eye optical system or a monocular optical system. The array optical system is configured by arranging a plurality of single-eye optical systems in parallel in one dimension (one row) or two dimensions (multiple rows), and the same number of single-eye optical systems as a result of image formation in each single-eye optical system. In general, an optical image is formed. On the other hand, in the array mirror system according to the present invention, image formation by the cylindrical mirror which is a single-eye optical system is not performed, and each cylindrical mirror only guides infrared rays in the range desired to be observed to the image sensor. In other words, it is an idea that image formation is not necessary to perform infrared detection in a predetermined range with a predetermined accuracy, and infrared light from the predetermined range may be guided to a predetermined range of the image sensor. For example, it is possible to detect in which area the human body is located depending on which temperature change is detected by infrared rays emitted from which cylindrical mirror.

  Since each cylindrical mirror has an inner surface inclined so as to gradually open toward the object side as a reflecting surface, the above-described ghost problem can be solved. As shown in FIG. 5, when the reflecting surface Ms of the cylindrical mirror Mi is inclined so as to gradually open toward the object side, the infrared light incident on the reflecting surface Ms from outside the observation range is reflected several times. In the meantime, the incident angle with respect to the reflecting surface Ms changes, and finally, it is incident perpendicularly on the reflecting surface Ms and reflected, and returns to the original direction along the same optical path. That is, of the infrared rays that are incident on the cylindrical mirror Mi from one end, the infrared rays that are emitted only from the range where the object is to be observed can be emitted from the other end of the cylindrical mirror Mi. Therefore, an array mirror system capable of efficiently guiding infrared rays in the range desired to be observed without a condensing part such as a lens and blocking infrared rays from outside the observation range to prevent crosstalk and ghosting is realized. be able to.

  If the end of the cylindrical mirror is arranged so as to be close to the sensor surface, and one cylindrical mirror is made to correspond to one to several pixels on the sensor surface, the object can be observed from outside the desired range. The infrared rays that do not reach the sensor surface, but are reflected from the inner surface of the cylindrical mirror and reach the image sensor, can all be emitted from the range to be observed. Therefore, it is possible to efficiently guide the infrared ray in the range to be observed to the sensor surface and cut off the light beam from outside the observation range to prevent the occurrence of ghost images without having a condensing part such as a lens.

  The cylindrical mirror also functions as a light shielding member for preventing crosstalk. For this reason, although it is an array optical system, the light shielding member for preventing crosstalk is unnecessary. Also, it is possible to suppress the absorption of heat on the reflecting surface to the limit by the mirror coating having a high reflectance. Therefore, since the cylindrical mirror can be prevented from becoming a heat source, the occurrence of ghost can be further effectively prevented.

  Further, in order to efficiently guide the light beam from the observation range to the sensor surface, the length M (FIGS. 2 and 3) of the cylindrical mirror Mi is set to the light beam having the most angle (that is, the first to the reflection surface Ms). It is preferable to set the length such that the light beam having the smallest incident angle is reflected four times or more. With this setting, all light rays having a gentler angle than the light ray having the most angle (that is, light rays having a large incident angle with respect to the reflection surface Ms) reach the sensor surface SS, and at the same time from outside the observation range. It is possible to secure a sufficient length M of the cylindrical mirror Mi for returning the light beam to the original direction.

It is preferable that the following conditional expression (1) is satisfied.
0 <θ ≦ 15 (1)
However,
θ: Opening angle of the tip (°) with the reflecting surface facing the object side,
It is.

  The cylindrical mirror has an inner surface inclined so as to gradually open toward the object side as a reflection surface, but the tip opening angle θ formed by the opposite inclined reflection surface (FIGS. 2, 3 and 3) 5 is small, and is preferably 15 ° or less as defined by the conditional expression (1).

  For example, when detecting the position of a human body by arranging cylindrical mirrors in an array, the infrared detector is generally installed near the ceiling of a room. As shown in FIG. 6, the height from the floor to the ceiling (the distance from the sensor surface SS to the object) S is 2000 mm, and the size L of the human body viewed from the ceiling is 500 × 500 mm. In order to detect a person so as not to cause an error, the observation range with one set of cylindrical mirrors is set to 500 × 500 mm, which is the same as the size of the human body, and the pixel size of the image sensor SR is sufficiently smaller than the detection range (1 / 100 or less). The opening angle of the tip of the cylindrical mirror is defined as an angle θ on both sides where the tip facing the object side is open from the parallel axis ax of the inner side surface (axis parallel to the central axis of the cylindrical mirror Mi) ( (See FIGS. 2 and 3). If the extension line of the inner surface of the cylindrical mirror Mi on the ceiling is directed to 500 × 500 on the floor surface, this range is observed, and tan θ = 500/2000, θ = 14.03 °. .

  Therefore, the tip opening angle θ is preferably 15 degrees or less in normal use. In addition, when the tip opening angle θ becomes zero, the light incident from outside the observation range has the same incident angle and reflection angle on the inner surface of the cylindrical mirror, so that it reaches the sensor surface while being reflected many times. End up. If the tip opening angle is made slightly larger than zero, by taking sufficient length of the cylindrical mirror, the reflection angle on the inner surface will gradually become larger than the incident angle, and finally it will be reversed to the original direction Can return.

Each cylindrical mirror preferably satisfies the following conditional expression (2).
0 <tan θ <L / S (2)
However,
θ: Opening angle of the tip (°) with the reflecting surface facing the object side,
L: maximum width of the object,
S: distance from the sensor surface to the object,
It is.

  Between the maximum width L of the object to be detected by the cylindrical mirror facing directly below and the distance S to the object, an angle of an isosceles triangle and the length of the side are represented as shown in FIG. There is a relationship. In an infrared detecting device using an array mirror system, it can be considered that each cylindrical mirror faces a different direction. Since each cylindrical mirror has an inner surface inclination that opens toward the object side, the outermost one of the plurality of cylindrical mirrors arranged in an array is directed toward the wide-angle side of the observation range. . At this time, the cylindrical mirror located outside has a greater distance S to the object to be detected than that facing directly below. In such a case, by setting the tip opening angle θ of each cylindrical mirror to satisfy the conditional expression (2), any cylindrical mirror can have the same observation range, and the same detection accuracy over the entire observation range. Can be realized.

  In the array mirror system in which the cylindrical mirror as described above is arranged for each one to several pixels on the sensor surface, the length of the cylindrical mirror is longer than the size of the pixel. It seems to grow. However, when the infrared optical system is composed of a lens system, the lens may be larger than the cylindrical mirror because a bright F-number must be secured off-axis as compared with a visible light photographing lens. . In particular, wide-angle infrared lens systems tend to be larger. The reason why the infrared photographing lens must secure a bright F-number is that when detecting temperature, the resolution is proportional to the amount of light reaching the sensor surface, so a bright optical system is required to increase the resolution. is there. That is, the use of an optical system in which cylindrical mirrors are arranged in an array does not increase the size of the infrared detection device. In addition, the arrayed optical system can achieve both a wide observation range and sufficient resolution of the object to be detected, so it can be realized using inexpensive infrared sensors such as a thermopile with a relatively small number of pixels. Thus, it is possible to realize an infrared detection device that is inexpensive and capable of position detection.

  The array mirror system described above is suitable for use as an optical system for an infrared detection device (for example, a night vision device, a thermography, a surveillance camera, a security camera, a vehicle-mounted camera, etc.), and this is used as an image sensor (for example, an infrared sensor). ) Etc., an array optical device that optically captures an infrared image of a detection object and outputs it as an electrical signal can be configured.

  As an example of the array optical device, an embodiment of the array optical device DA is schematically shown in FIG. An array optical device DA shown in FIG. 1 is an optical device that is a main component of an infrared detection device. For example, infrared Lr from a plurality of areas of an object is sequentially obtained from the object (corresponding to a detection target) side. An array mirror system MA that is guided by a plurality of cylindrical mirrors Mi, and an image sensor SR that converts infrared Lr guided on a sensor surface (that is, a light receiving surface) SS into an electrical signal. . The array mirror system MA having the above-described characteristic configuration is arranged so that the infrared rays Lr from each area of the object are incident on the sensor surface SS of the image sensor SR, so that no crosstalk or ghost occurs. In addition, it is possible to realize an array optical device DA that can detect infrared Lr from a predetermined area. By providing the array optical device DA, for example, an infrared detection device or an infrared detection system capable of detecting the position of a human body can be configured.

  As an example of the infrared detection device, an embodiment of the infrared detection device DI is schematically shown in FIG. The infrared detection device DI shown in FIG. 7 includes an array optical device DA, a photographing circuit 1 that forms a mosaic infrared image using an output signal from the image sensor SR, and a temperature change in each area from the infrared image. And a determination system 2 that determines whether or not a detection has been made (for example, whether there is a different temperature). The array optical apparatus DA has a structure in which an optical system including an array mirror system MA, an image sensor SR, and the like and its related parts are covered with a hemispherical cover CV made of a thin material (high density polyethylene or the like) that transmits infrared Lr. It has become.

  As described above, the array mirror system MA is configured to guide infrared rays Lr from a plurality of areas of an object onto the light receiving surface SS of the image sensor SR by a plurality of cylindrical mirrors Mi. As the image sensor SR, for example, a far infrared image sensor (such as a temperature sensor) having a plurality of pixels (several tens to hundreds of thousands of pixels) and using a wavelength of about 7 to 10 μm is used. Since the array mirror system MA is provided so that the infrared ray Lr is irradiated onto the light receiving surface SS that is a photoelectric conversion unit of the image sensor SR, the infrared ray Lr emitted from the array mirror system MA is electrically converted by the image sensor SR. Converted to a typical signal.

  Infrared rays Lr used in the infrared detector DI are mainly far infrared rays having a wavelength in the range of 7 to 14 μm. The body temperature of humans and animals is 8 to 12 μm, and most of far-infrared optical systems are used at 8 to 12 μm. The far-infrared region in the wavelength band of 8 to 12 μm is a range in which the temperature of the substance can be detected, and there are many things that can be applied such as temperature measurement, human detection in the dark, and security. In the case of using near-infrared or mid-infrared as the infrared Lr, for example, an object is illuminated with near-infrared or mid-infrared, and the reflected light is reflected on the light receiving surface SS of the image sensor SR by a plurality of cylindrical mirrors Mi. What is necessary is just to make it the structure which guides, respectively.

  When a transparent member is used for the cylindrical mirror Mi constituting the array mirror system MA, a far infrared optical material is used for the transparent member. The refractive index of an optical material is the ratio of the traveling speed of light in a substance to the vacuum, and is displayed for the d-line (587 nm) in the visible region. However, since this value has no meaning in the far-infrared region, the refractive index for a wavelength of 10 μm is typically representative. For example, the refractive index at a wavelength of 10 μm of far-infrared optical materials used conventionally is Ge = 4.004, Si = 3.418, ZnS = 2.200, ZnSe = 2.407, and the like.

  As a value representing the property of dispersion (color dispersion), the Abbe number νd of d-line is used for visible light. This Abbe number is expressed by νd = (Nd−1) / (Nf−Nc) (where Nd: refractive index of d-line, Nf is refractive index of F-line, Nc is refractive index of C-line, is there.). However, since this value has no meaning in the far-infrared region, ν = (N10-1) / (N8-N12) should be used as the value representing the dispersion property in the transparent member to which mirror coating is applied. (N10: refractive index at a wavelength of 10 μm, N8: refractive index at a wavelength of 8 μm, N12: refractive index at a wavelength of 12 μm). The larger this value, the smaller the difference in refractive index between colors, and the smaller the dispersion. For example, dispersions of far-infrared optical materials conventionally used are Ge = 785, Si = 1860, ZnS = 23 (used for achromatic), ZnSe = 57 (used for achromatic), and the like.

  Hereinafter, the configuration of the array mirror system in which the present invention is implemented will be described more specifically with reference to Examples 1 and 2.

  In Examples 1 and 2 described below, a thermopile is used as the image sensor SR, and the size of one pixel is 0.3 × 0.3 (mm) and the number of pixels is 8 × 8, or 1 A pixel in which the size of one pixel is 0.6 × 0.6 (mm) and the number of pixels is 4 × 4 is used. The thermopile is a temperature sensor that uses a thermocouple capable of converting heat into electric energy in series or in parallel to form a sensor surface, and is the second cheapest sensor after the pyroelectric sensor.

  The thermopile can directly convert heat into an electrical signal, but in order to obtain a sufficient temperature difference between the two electrodes, it needs to have a certain size in the detection range of one pixel. Therefore, the number of pixels is relatively small, such as 4 × 4, 8 × 8, 16 × 16. For example, when using 8 × 8 thermopile, a set of cylindrical mirrors Mi (1 cylindrical mirror Mi for 4 pixels) is arranged for 2 × 2 pixels, When a thermopile with 4 × 4 pixels is used, one set of cylindrical mirrors is arranged for each pixel. That is, the end of the cylindrical mirror Mi on the image sensor SR side has a size of 0.6 × 0.6 (mm).

  At this time, when the cylindrical mirror Mi is hollow, the thickness of the structural wall of the cylinder is about 0.1 mm. When another cylindrical mirror Mi is arranged next to the wall, the wall can be shared with the adjacent wall. Since the dead zone between the pixels of the thermopile is about 0.08 mm, the amount of light that is cut by the structural wall is small. The structural wall is made of a sufficiently smooth metal or made of another material, and then the inner surface becomes a mirror surface by plating the metal. Further, when the cylindrical mirror Mi that is not hollow and transparent with respect to the wavelength used is used, the outer wall of the transparent object may be sufficiently smoothed and coated with the amount of the reflecting material, so that no structural wall is required.

  In Examples 1 and 2, the transparent material is a material transparent to far infrared rays. For example, germanium (Ge), silicon (Si), zinc selenide (ZnSe), zinc sulfide (ZnS), sodium chloride (NaCl), potassium chloride (KCl), potassium bromide (KBr), or the like is used. Since NaCl, Kcl, KBr, etc. are deliquescent, no reflection coating is applied to the incident end and the exit end of the light beam, but the moisture absorption preventing material is applied to the whole.

  FIG. 8 shows an end portion on the image sensor SR side of the array mirror system MA in the first and second embodiments as seen from a direction perpendicular to the sensor surface SS. In the array mirror system MA, four types of cylindrical mirrors Mi (i = 1, 2, 3, 4) are arranged in parallel in the X and Y directions in the orthogonal coordinate system (X, Y, Z). It has a configuration. The Z direction is the normal direction of the sensor surface SS.

  Table 1 below shows the axis inclination angle α (°) and the tip opening angle θ (°) in Examples 1 and 2 in the X and Y directions, from the sensor surface SS to the object side end of the cylindrical mirror Mi. Distance M (FIGS. 2 and 3). As shown in FIG. 4, the axis inclination angle α is an inclination angle of the axis ax of the cylindrical mirror Mi with respect to the normal line of the sensor surface SS.

  FIG. 9 shows an optical path in a cross section where the inclination of the axis ax of the cylindrical mirror Mi is 5 ° (YZ cross section of the cylindrical mirrors M1 and M2 of Example 2; XZ cross section of the cylindrical mirror M1; XZ of the cylindrical mirror M3). Cross section). FIG. 10 shows an optical path in a cross section where the inclination of the axis ax of the cylindrical mirror Mi is 15 ° (XZ cross section of the cylindrical mirrors M2 and M4 of the second embodiment; YZ cross section of the cylindrical mirrors M3 and M4; YZ cross section of cylindrical mirrors M1 and M2; XZ cross section of cylindrical mirror M1; XZ cross section of cylindrical mirror M3). FIG. 11 shows an optical path (XZ cross section of the cylindrical mirrors M2 and M4 of the first embodiment; YZ cross section of the cylindrical mirrors M3 and M4) in a cross section in which the inclination of the axis ax of the cylindrical mirror Mi is 45 °. In all of the optical path diagrams of FIGS. 9 to 11, the left end is the sensor surface SS.

As shown in Table 1, the array mirror system MA in Example 1 has a configuration in which the following four types of cylindrical mirrors Mi are arranged in parallel (see FIGS. 2 to 4). .
Cylindrical mirror M1: The inclination angle α of the axis ax of the cylindrical mirror Mi is a quadrangular column along the axis ax inclined 15 ° in the X direction and 15 ° in the Y direction from the normal perpendicular to the sensor surface SS. It is. The tip opening angle θ is 8 ° in both the X direction and the Y direction. The distance M from the sensor surface SS to the other end of the cylindrical mirror M1 is 16.525 mm (distance perpendicular to the sensor surface SS).
Cylindrical mirror M2: The inclination angle α of the axis ax of the cylindrical mirror Mi is a quadrangular column along the axis ax inclined by 45 ° in the X direction and 15 ° in the Y direction from the normal perpendicular to the sensor surface SS. It is. The tip opening angle θ is 6 ° in the X direction and 8 ° in the Y direction. The distance M from the sensor surface SS to the other end of the cylindrical mirror M2 is 20.991 mm.
Cylindrical mirror M3: The inclination angle α of the axis ax of the cylindrical mirror Mi is a quadrangular column along the axis ax inclined 45 ° in the Y direction and 15 ° in the X direction from the normal perpendicular to the sensor surface SS. It is. The tip opening angle θ is 6 ° in the Y direction and 8 ° in the X direction. The distance M from the sensor surface SS to the other end of the cylindrical mirror M3 is 20.991 mm.
Cylindrical mirror M4: The tilt angle α of the axis ax of the cylindrical mirror Mi is a quadrangular column along the axis ax inclined 45 ° in the X direction and 45 ° in the Y direction from the normal perpendicular to the sensor surface SS. It is. The tip opening angle θ is 6 ° in both the X direction and the Y direction. The distance M from the sensor surface SS to the other end of the cylindrical mirror M4 is 20.991 mm.

  In all of these types of cylindrical mirrors Mi, the opening shape of the end surface on the sensor surface SS side is 0.6 × 0.6 mm (including the thickness of the structure wall). Of these four types of cylindrical mirrors Mi, those having a small inclination are arranged near the center of the sensor surface SS, and those having a large inclination are arranged outside the sensor surface SS. The arrangement is symmetric with respect to the X and Y axes (see FIG. 8). In this configuration, when the infrared detection device DI is installed on the ceiling (FIG. 6), a range of 500 × 500 mm is guided to the sensor surface SS by a set of cylindrical mirrors Mi on the floor surface below 2000 mm.

As shown in Table 1, the array mirror system MA in Embodiment 2 has a configuration in which the following four types of cylindrical mirrors Mi are arranged in parallel (see FIGS. 2 to 4). .
The cylindrical mirror M1: The inclination angle α of the axis ax of the cylindrical mirror Mi is a quadrangular column along the axis ax inclined by 5 ° in the X direction and 5 ° in the Y direction from the normal perpendicular to the sensor surface SS. It is. The tip opening angle θ is 10 ° in both the X direction and the Y direction. The distance M from the sensor surface SS to the other end of the cylindrical mirror M1 is 12.027 mm (distance perpendicular to the sensor surface SS).
Cylindrical mirror M2: The inclination angle α of the axis ax of the cylindrical mirror Mi is a quadrangular column along the axis ax inclined 15 ° in the X direction and 5 ° in the Y direction from the normal perpendicular to the sensor surface SS. It is. The tip opening angle θ is 8 ° in the X direction and 10 ° in the Y direction. The distance M from the sensor surface SS to the other end of the cylindrical mirror M2 is 16.525 mm.
Cylindrical mirror M3: The inclination angle α of the axis ax of the cylindrical mirror Mi is a quadrangular column along the axis ax inclined 15 ° in the Y direction and 5 ° in the X direction from the normal perpendicular to the sensor surface SS. It is. The tip opening angle θ is 8 ° in the Y direction and 10 ° in the X direction. The distance M from the sensor surface SS to the other end of the cylindrical mirror M3 is 16.525 mm.
Cylindrical mirror M4: The inclination angle α of the axis ax of the cylindrical mirror Mi is a quadrangular column along the axis ax inclined 15 ° in the X direction and 15 ° in the Y direction from the normal perpendicular to the sensor surface SS. It is. The tip opening angle θ is 8 ° in both the X direction and the Y direction. A distance M from the sensor surface SS to the other end of the cylindrical mirror M4 is 16.525 mm.

  In all of these types of cylindrical mirrors Mi, the opening shape of the end surface on the sensor surface SS side is 0.6 × 0.6 mm (including the thickness of the structure wall). Of these four types of cylindrical mirrors Mi, those having a small inclination are arranged near the center of the sensor surface SS, and those having a large inclination are arranged outside the sensor surface SS. The arrangement is symmetric with respect to the X and Y axes (see FIG. 8). In this configuration, when the infrared detection device DI is installed on the ceiling (FIG. 6), a range of 500 × 500 mm is guided to the sensor surface SS by a set of cylindrical mirrors Mi on the floor surface below 2000 mm.

  In the first and second embodiments, the cylindrical mirrors Mi having different lengths are arranged. However, the length of the cylindrical mirror Mi may be adjusted to the longest to facilitate manufacture. . Even if it does so, the optical function which guides the light beam from the observation range does not change. The length of the cylindrical mirror Mi in the first and second embodiments is the minimum length for guiding the light beam and returning unnecessary light, and the optical action is the same unless the length is less than this length.

  In these Examples 1 and 2, it is assumed that the far-infrared band having a wavelength of 8 to 12 μm is used. However, when the cylindrical mirror Mi is hollow, it is used as it is for other wavelength bands. be able to. Further, even a cylindrical mirror using a transparent material can be used in an almost intact shape if a material transparent to the used wavelength band is used.

The refractive index N10 for a wavelength of 10 μm and the dispersion ν = (N10-1) / (N8−N12) for a wavelength of 8 to 12 μm of the optical materials used in Examples 1 and 2 are shown below.
ZnS (zinc sulfide) N10 = 2.20017 ν = 22.83
ZnSe (zinc selenide) ... N10 = 2.406651 ν = 57.39
Ge (germanium) N10 = 4.0004312 ν = 784.54
Si (silicon): N10 = 3.4178 ν = 1859.8
NaCl (sodium chloride) N10 = 1.4947 ν = 20.110
KCl (potassium chloride) N10 = 1.456539 ν = 29.99
KBr (potassium bromide) ... N10 = 1.5242 ν = 64.72

  In the first and second embodiments, a thermopile in which pixels are arranged in 4 × 4 or 8 × 8 is used as the image sensor SR. However, other image sensors SR may be used. For example, an array of pyroelectric sensors can be used. Further, even in an image sensor having a large number of pixels, such as a microbolometer, and a small pixel size, as long as 10 × 10 pixels or the like correspond to one set of cylindrical mirrors Mi, individual cylinders are possible. Since the mold mirror Mi has a size that can be manufactured, it can be realized with the same configuration. The microbolometer is a temperature sensor that has a light-receiving surface in which a heat-sensitive material such as amorphous silicon or vanadium oxide is two-dimensionally arrayed by a fine processing technique, and detects a change in resistance value due to a temperature rise. Common microbolometers currently used have 80 × 80, 320 × 240, 640 × 480 and the like. In the same way, if a CCD sensor or a CMOS sensor for visible light is made to correspond to a large number of pixels in one cylindrical mirror, a similar optical system can be configured.

  In the first and second embodiments, the image sensor SR (FIG. 8) having a square pixel is used, but the pixel is not necessarily a square. When the pixel is rectangular, the corresponding cylindrical mirror Mi may be a rectangular column shape.

  In the first and second embodiments, the quadrangular columnar cylindrical mirror Mi is used, but the same effect can be obtained by using a cylindrical mirror or an elliptic columnar cylindrical mirror inscribed in the quadrangular column. Moreover, you may use prismatic shapes (a triangular prism, a hexagonal prism, an octagonal prism, etc.) other than a square prism. When the cylindrical mirror Mi having these shapes is used, a part of the light beam may be vignetted, but there is no problem as long as the necessary light amount is reached.

  Further, when human body detection is performed in the security field, there is a demand that the user wants to know the position and number of human bodies but does not want to capture the face shape that identifies the individual. In such a case, if one set of cylindrical mirrors Mi is arranged for several pixels or more, the obtained image has a mosaic shape and can meet such a demand.

SI Infrared detection system DI Infrared detection device DA Array optical device MA Array mirror system Mi, M1, M2, M3, M4 Cylindrical mirror Ms Reflective surface SR Image sensor SS Sensor surface CV cover ax axis Lr Infrared 1 Imaging circuit 2 Judgment system

Claims (6)

An array mirror system for guiding infrared rays from a plurality of areas of an object with a plurality of mirrors, respectively.
An array mirror system, wherein each of the mirrors is a cylindrical mirror having an inner surface inclined so as to gradually open toward the object side as a reflecting surface.   2. The array mirror system according to claim 1, wherein the cylindrical mirror is made of a hollow member or a transparent member, and the shape of the reflecting surface is a columnar shape, an elliptical columnar shape, or a prismatic shape. The array mirror system according to claim 1, wherein the following conditional expression (1) is satisfied:
0 <θ ≦ 15 (1)
However,
θ: Opening angle of the tip (°) with the reflecting surface facing the object side,
It is.   An array mirror system according to any one of claims 1 to 3, and an image sensor for converting infrared light guided onto the sensor surface into an electrical signal, the number of which is from one pixel on the sensor surface An array optical device in which the cylindrical mirror is provided so that one cylindrical mirror corresponds to each of the mirrors, and an end of the cylindrical mirror is close to the sensor surface .   An infrared detection apparatus comprising the array optical apparatus according to claim 4, wherein a temperature change in each area is detected using an output signal from the image sensor. An infrared detection system comprising the infrared detection device according to claim 5, wherein each cylindrical mirror satisfies the following conditional expression (2):
0 <tan θ <L / S (2)
However,
θ: Opening angle of the tip (°) with the reflecting surface facing the object side,
L: maximum width of the object,
S: distance from the sensor surface to the object,
It is.

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