JP5008261B2 - Floodlight for surveillance camera - Google Patents

Description

  The present invention relates to a projector for a surveillance camera, and more particularly to a projector for a surveillance camera using an LED as a light source for enabling imaging by a surveillance camera even in a dark place.

  A surveillance camera always captures a predetermined space area, day or night, and monitors images captured by the surveillance camera in real time to prevent accidents, crimes, etc., or images recorded on a video tape Can be a clue to criminal investigations.

  In addition, it is installed on the road and reads the number of the license plate of the traveling vehicle, or is mounted on the vehicle and monitors the direction of the forward route, and is used greatly in the traffic field.

  By the way, in the camera imaging in a dark place, a projector that irradiates a subject is necessary, and there is a projector that uses an LED that emits infrared light as a light source.

  For example, as shown in FIG. 24, a plurality of LEDs 52 emitting infrared rays are mounted on a substrate 51 having an opening 50 in the center to form a light emitter 53, and a camera lens is fixed to the hole 50 of the light emitter 53. Then, it is assembled in a cylindrical outer case 54. In this case, the irradiation direction of infrared rays by the light emitter 53 on which the LED 52 is mounted moves in conjunction with the imaging direction of the camera lens, and the light distribution pattern of the irradiation light is a direct superimposition of the directivity characteristic of each LED 52 ( For example, see Patent Document 1.)

As another example, as shown in FIG. 25, an LED module 61 that emits infrared rays and is mounted with a plurality of LEDs 60 having different directivity characteristics is divided and arranged along the optical filter 62 at a predetermined horizontal angle and inclination angle. There are also things. In this case, the irradiation direction of infrared rays by the LED module 61 on which the LED 60 is mounted is determined by the arrangement direction of the LED module 61, and the light distribution pattern is obtained by superimposing the directivity characteristic of each LED 60 as it is (see, for example, Patent Document 2). .)
JP-A-6-85331 JP 2000-113351 A

  The projector for a monitoring camera shown in FIG. 24 has a simple configuration and can be manufactured at a low cost because it forms an irradiation pattern using the directivity characteristics of the LED that is the light source.

  However, in the projector having such a configuration, the half-value angle of the LED is extremely small with respect to the angle of view of the monitoring camera, and the irradiation pattern obtained by the directivity characteristics of the LED covers the entire area of the angle of view of the monitoring camera. It is impossible to illuminate.

  Further, the projector for the monitoring camera shown in FIG. 25 has a plurality of LED modules mounted with LEDs arranged at different angles, and controls the irradiation direction and irradiation pattern according to the LED module arrangement direction and LED directivity characteristics. In this case as well, the configuration can be made relatively simple.

  However, in the projector having such a configuration, the irradiation direction is different for each LED module mounted with the LED, and a region that does not overlap with the adjacent irradiation patterns is generated at the time of light projection, and uniform irradiation may be difficult. is there.

  Therefore, it is conceivable to mount the LEDs mounted on the LED module in different directions, but in that case, it is difficult to ensure high mounting accuracy of the LEDs, and the designed irradiation pattern is highly accurate. Since it cannot be obtained with good reproducibility, the entire area within the angle of view cannot be irradiated uniformly.

  Therefore, the present invention was devised in view of the above problems, and the object of the present invention is to provide an LED that can project an entire area within the angle of view of a surveillance camera with an irradiation pattern and irradiation energy distribution that are close to ideal. The object is to provide a projector for a surveillance camera as a light source.

In order to solve the above-mentioned problems, the invention described in claim 1 of the present invention is a projector for a surveillance camera in which at least three LEDs are mounted on a substrate and a matrix Fresnel lens is disposed above the LEDs. The matrix Fresnel lens is composed of at least three or more Fresnel lens elements corresponding to the LEDs in a one-to-one relationship, and the Fresnel lens element has a substantially triangular cross-section on the surface facing the LEDs . A plurality of convex prism lenses are continuously adjacent to each other, at least two of the Fresnel lens elements are arranged so that directions of the prism lenses are substantially perpendicular to each other, and among the other Fresnel lens elements At least one of the prism lenses is one of the prism lenses of the substantially right angle. And it is characterized in that it is arranged to face the direction of approximately 30 ° to the direction of Zumurenzu.

Further, the invention described in claim 2 of the present invention, in claim 1, at least one prism lens of the other of said Fresnel lens element, the either one of the substantially perpendicular prism lens The prism lens is arranged so as to face in a direction within a range of approximately 35 ° to 55 ° with respect to the direction of the prism lens.

The invention described in claim 3 of the present invention is that, in any one of claims 1 and 2 , the LEDs are arranged on both sides of the surveillance camera, and a pair of the LEDs is placed above the LEDs. In the Fresnel lens element disposed at a position corresponding to 1, the light amount distribution of light emitted from the Fresnel lens element is directed toward the monitoring camera with respect to a line perpendicular to the flat light emitting surface of the Fresnel lens element. Further, the lens cut of the prism lens is performed so that the amount of light directed to the opposite side of the surveillance camera is increased.

Further, in the invention described in claim 4 of the present invention, in any one of claims 1 to 3 , the central upper portion when the image of the installed monitoring camera is monitored is irradiated with the maximum irradiation light intensity. It is characterized by this.

The invention described in claim 5 of the present invention is characterized in that, in any one of claims 1 to 4 , the LED is a surface-mounted LED that emits infrared rays.

Further, in the invention described in claim 6 of the present invention, in any one of claims 1 to 5 , the matrix Fresnel lens is provided with a locking claw provided on the matrix Fresnel lens. By being locked in the through hole, it can be mounted on the substrate with a single touch.

  In the projector for a surveillance camera according to the present invention, a Fresnel lens element having a desired lens cut is arranged above the LED serving as a light source mounted on the substrate on a one-to-one basis. For this reason, since light emitted from each LED can be individually controlled for light distribution, there is an advantage that the degree of freedom of light distribution design is high, and an ideal irradiation pattern and irradiation energy distribution can be realized.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to FIGS. 1 to 23 (the same parts are denoted by the same reference numerals). The embodiments described below are preferred specific examples of the present invention, and thus various technically preferable limitations are given. However, the scope of the present invention particularly limits the present invention in the following description. Unless stated to the effect, the present invention is not limited to these embodiments.

  FIG. 1 is a diagram in which a surveillance camera 2 is installed at one corner assuming a room 1 having a length, width and height of 2 m, and numbers 1 to 10 are assigned to representative positions in the room. Indicates a room image within the camera angle of view when the room is imaged from the installed surveillance camera 2.

  As shown in FIG. 1, the room is surrounded by a ceiling 3, a floor 4, a wall A 5, a wall B 6, a wall C 7, and a wall D 8. It is installed in one corner. The representative positions of the room 1 are represented by numbers 1-10.

  FIG. 2 shows a room image within the camera angle of view when the room 1 shown in FIG. The floor 4, except for the ceiling 3, the wall A5, the wall B6, the wall C7, and the wall D8 form the field angle area of the camera, and the area surrounded by the indoor positions 4, 5, 6, 7, 8, and 9 is the camera. Are configured. The other positions 1, 2, 3, and 10 are located inside the field angle region.

  Surveillance cameras are often used for crime prevention in the room, and it is required to reliably and clearly detect suspicious persons who have entered the field of view of the surveillance camera in the room regardless of day or night. . For this purpose, it is important that infrared rays serving as illumination light irradiate uniformly the room serving as a monitoring area, especially at night.

  By the way, generally, the relationship between the distance from the light source and the irradiation energy of the light reaching the position is such that the irradiation energy of the light reaching in inverse proportion to the square of the distance from the light source is small. That is, in order to irradiate uniformly within the field angle area of the camera, control is performed so that irradiation energy proportional to the square of the distance from the light source to each irradiation position is emitted from the light source toward each irradiation position. It will be necessary. For example, if there are two irradiation positions near and far from the light source, and the positional relationship is far from the light source, the irradiation energy at the two positions is the same. In order to achieve this, it is necessary to make the irradiation energy radiated toward the position far from the light source four times as large as the irradiation energy radiated toward the near position.

  Table 1 shows the distance from the monitoring camera in FIG. 2 to the position assigned with each number, and the irradiation energy of the light irradiated to the position (number 6) at the shortest distance from the monitoring camera, as 1. The irradiation energy radiated toward other positions is shown. That is, the irradiation energy received at each position can be made uniform by radiating the relative irradiation energy shown in Table 1 toward each of the positions of number 1 to number 10 from the light source. Therefore, it is necessary to control the irradiation energy radiated from the light source toward the direction at the position of the shortest distance number 6 and the position of the longest distance number 2 with a magnitude of about 3.5 times. is there.

  Therefore, in order to compare with the performance of the projector of the present invention, the performance of the conventional projector was verified as a comparative example. In the first comparative example, as shown in FIG. 3, a projector 11 in which a plurality of LEDs 10 called bullet-types are mounted on a printed circuit board 9 in the same direction is created, and the projector 11 is installed in one corner of the room. Then, the irradiation area 12 and the energy distribution are measured, and the result is superimposed on the field angle area of the camera.

  Since the projector 11 has a structure in which a plurality of LEDs 10 are simply arranged on the substrate 9, the irradiation area is narrow and the irradiation energy radiated from the projector 11 is not controlled. Therefore, as shown in FIG. 3, the region with a large irradiation energy is narrow, and the region with a small irradiation energy on the outside is also narrow, and it can be seen that there are a wide range of unirradiated portions where the light from the projector does not reach. Accordingly, it has been found that such a monitoring camera using the projector 11 as a light source has a position where the imaging range is limited and cannot be monitored, and cannot be reliably detected, and thus is not suitable as a projector for a monitoring camera.

  In the second comparative example, as shown in FIG. 4, a plurality of bullet-type LEDs 10 are mounted in the same direction on each of the three printed boards 9, and the three LED-mounted boards are little by little. A projector 11 having a structure in which a Fresnel lens 13 having the same lens cut is provided on the front surface of each LED mounting board by changing the angle is created, and the projector 11 is installed in one corner of the room to distribute the energy distribution with the irradiation region 12. And the result is superimposed on the field angle area of the camera.

  The projector 11 extends the irradiation region 12 in the left-right direction by arranging the three LED mounting substrates at slightly different angles, and provides a vertical irradiation region by providing a Fresnel lens 13 on the front surface of each LED mounting substrate. Is intended to spread. Therefore, as shown in FIG. 3, a region having a large irradiation energy formed by light emitted from the LED 10 in a portion where the Fresnel lens 13 is not provided, a region having a small irradiation energy outside the region, and the LED 10 radiating from the region. Two irradiation regions, a region having a large irradiation energy formed by light spread through the Fresnel lens 13 and a region having a small irradiation energy outside thereof, are formed, and the irradiation region is expanded as compared with the first comparative example. I can see that

  However, even in the second comparative example, there is an unirradiated portion where the light from the projector does not reach. Therefore, it has been found that even a surveillance camera using such a projector as a light source has insufficient imaging range and is not suitable as a projector for a surveillance camera that requires reliable detection. did.

  FIG. 5 shows an ideal irradiation range of the projector for the surveillance camera. An ideal projector for a surveillance camera has a basic requirement that it can illuminate the entire field of view area of the camera, and as shown in FIG. It is required to have a good performance.

  Hereinafter, embodiments of a projector for a surveillance camera according to the present invention will be described. FIG. 6 is an exploded view showing the embodiment. In this embodiment, the printed circuit board 9, the LED 10, and the matrix Fresnel lens 14 are configured by three elements.

  First, the printed circuit board 9 will be described. The printed circuit board 9 is provided with a circular through hole 15 for fixing the camera at the center. Further, on the surface of the printed circuit board 9, an LED 10 (not shown) that is a light source is mounted and electrically connected to the electrode pad, and an electric power is supplied from the outside connected to the electrode pad. A wiring pattern for turning on the LED 10 is formed. Further, a rectangular through hole 16 for fixing a pair of matrix Fresnel lenses 14 along both ends of the printed circuit board 9 is provided on both sides of the circular through hole 15.

  Since a plurality of LEDs are mounted on the printed board, a considerable amount of heat is generated when they are lit simultaneously. And the heat reduces the luminous efficiency of the LED, and reduces the amount of light emitted by the LED. That is, the amount of light emitted from the projector is reduced by the heat generated by the LED.

  Therefore, it is an effective method to use a material having a high thermal conductivity for the base constituting the printed circuit board so that the heat generated from the LEDs is released to the outside so that the heat is not trapped in the printed circuit board. For example, a metal base such as Al, Fe, or Cu, or a ceramic base is used. Even an insulating resin base such as paper phenol resin, paper epoxy resin, glass epoxy resin or the like generally used as a printed circuit board can be used if there is no problem of heat.

  Next, the LED 10 will be described. The LEDs 10 are mounted in a vertical and horizontal matrix form on both sides of the circular through hole 15 of the printed circuit board 9, and the used LED 10 is a surface mount type. This is because it can be mounted on the printed circuit board 9 by reflow, and a plurality of LEDs 10 can be mounted on the printed circuit board 9 at the same time, and such a highly productive mounting method can be implemented. Further, the surface-mounted LED 10 is extremely small and thin as compared with the bullet-type LED, and greatly contributes to the thinness of the projector. Furthermore, the printed circuit board 9 on which the LEDs 10 are mounted can be formed of a single-sided board, and the manufacturing cost can be reduced.

  As the LED chip incorporated in the LED 10, one that emits light in the near infrared to infrared region is used. The number of LED chips incorporated in one LED 10 is not limited to one, and a plurality of LED chips may be incorporated depending on the required light quantity.

  Next, the matrix Fresnel lens 14 will be described. The matrix Fresnel lens 14 is composed of a pair, and each matrix Fresnel lens 14 is arranged on the LED 10 mounted on the printed circuit board 9 so that the irradiation light emitted from each LED 10 has an individual desired light distribution pattern and a desired light distribution pattern. It is intended to turn in the direction.

  Therefore, Fresnel lens elements 17 each having a predetermined lens cut are arranged in a vertical and horizontal matrix at positions corresponding to the LEDs 10 on a one-to-one basis to constitute a matrix Fresnel lens 14. A pair of opposite leg portions of the matrix Fresnel lens 14 are provided with a pair of leg portions 18 extending in a direction substantially perpendicular to the surface of the matrix Fresnel lens. The distance to the 14th surface is kept constant. Further, a locking claw 19 is provided at the tip of each leg portion 18. The locking claw 19 is inserted into the rectangular through hole 16 of the printed circuit board 9, and the Matrix Fresnel lens 14 is engaged with the printed circuit board 9. It comes to stop.

  Here, the Fresnel lens element which comprises a matrix Fresnel lens is demonstrated based on FIGS. The Fresnel lens segment has a substantially rectangular outer diameter, and a large number of prism lenses are arranged in parallel on the surface facing the LED so as to form a convex substantially triangular shape with a continuous cross section. The direction of the emitted light emitted from the lower LED is controlled by the lens direction of the prism lens, and the light distribution pattern is controlled by the shape of the substantially triangular prism lens. That is, the direction and the lens shape of the prism lens formed in the Fresnel lens element are designed so as to accurately irradiate the irradiation area of each LED.

  In the case of the present embodiment, an ideal irradiation area is realized when assuming that the indoor size is 2 m in length, width, and height, and a surveillance camera and a projector are installed at one corner. Therefore, an ideal prism lens is designed for each Fresnel lens element and verified by simulation.

  In the verification method, when a projector is arranged at a position corresponding to the installation position of the surveillance camera shown in FIG. 1 and a screen corresponding to the camera field angle area of the surveillance camera as shown in FIG. The analysis is performed by simulating the irradiation pattern and the irradiation energy distribution formed on the screen by the irradiation light emitted through the Fresnel lens element.

  First, as shown in FIG. 8 showing the AA cross section of FIGS. 7 and 7, the first Fresnel lens element 17 has a substantially rectangular Fresnel lens element 17 in the direction of the plural prism lenses 20 arranged side by side. Are designed so that the angles of the apexes of the substantially triangular shape of the prism lens 20 are different from each other on both ends. . The emission direction and light quantity distribution of the light emitted from the Fresnel lens element 17 are indicated by arrows in FIG. 7, and the direction of the arrow is the emission direction of the emitted light with respect to the normal line of the light emission surface 22 of the Fresnel lens element 17. The thickness of the arrow represents the amount of emitted light relative to that direction. A thick arrow indicates a larger irradiation energy than a thin arrow. In the case of this Fresnel lens element 17, most of the irradiation light emitted from the Fresnel lens element 17 is radiated along a surface perpendicular to the prism lens 20, and the light amount distribution is in the normal line of the light emission surface 22 of the Fresnel lens element 17. In contrast, it is more on the upper side of the screen 21 and less on the lower side.

  FIG. 9 shows a simulation of the irradiation pattern and irradiation energy distribution formed on the screen 21 by the irradiation light emitted from the Fresnel lens element 17 having such a configuration. As a result, it was verified that the central upper side of the screen 21 was concentratedly irradiated.

  The second Fresnel lens element 17 includes a plurality of prism lenses 20 arranged in parallel in the substantially rectangular Fresnel lens element 17 as shown in FIG. The first Fresnel lens element 17 is formed in a direction substantially perpendicular to the direction of the prism lens 20 (substantially parallel to the longitudinal direction of the screen 21), and the angle of the apex of the substantially triangular shape of the prism lens 20 is different at both ends. It is designed to be at an angle. Therefore, the emission direction and light amount distribution of the light emitted from the Fresnel lens element 17 are also indicated by arrows in FIG. 10, and most of the irradiation light emitted from the Fresnel lens element 17 is on a surface perpendicular to the prism lens 20. The amount of light distribution is greater on the right side of the screen 21 and less on the left side with respect to the normal of the light exit surface 22 of the Fresnel lens element 17. The emission direction of the light emitted from the second Fresnel lens element 17 is substantially perpendicular to the emission direction of the light emitted from the first Fresnel lens element 17.

  FIG. 12 is a simulation of the irradiation pattern and irradiation energy distribution formed on the screen 21 by the irradiation light emitted from the Fresnel lens element 17 having such a configuration. As a result, it was verified that the central right side of the screen 21 was concentratedly irradiated.

  The third Fresnel lens element is a substantially rectangular Fresnel lens element 17 as shown in FIG. 14 showing a C-C cross section of FIG. 13 and FIG. The second Fresnel lens element 17 is formed in a direction inclined by approximately 40 ° with respect to the prism lens 20 direction (approximately 40 ° with respect to the vertical direction of the screen 21), and the angles of the apexes of the substantially triangular shape of the prism lens 20 are all set. The prism lens 20 is designed to have the same angle, and the height of the substantially triangular shape of the prism lens 20 is different from each other on both end sides. Therefore, the emission direction and light amount distribution of the light emitted from the Fresnel lens element 17 are also indicated by arrows in FIG. 13, and most of the irradiation light emitted from the Fresnel lens element 17 is on a surface perpendicular to the prism lens 20. The distribution of the light quantity is larger in the upper right direction of the screen 21 and lower in the lower left direction with respect to the normal line of the light exit surface 22 of the Fresnel lens element 17. The emission direction of the light emitted from the third Fresnel lens element 17 is inclined by approximately 40 ° with respect to the emission direction of the light emitted from the first Fresnel lens element 17.

  FIG. 15 is a simulation of the irradiation pattern and irradiation energy distribution formed on the screen 21 by the irradiation light emitted from the Fresnel lens element 17 having such a configuration. As a result, it was verified that the diagonal right side slightly above the center of the screen 21 was concentrated and irradiated.

  As shown in FIG. 17 showing the DD cross section of FIGS. 16 and 16, the fourth Fresnel lens element includes a plurality of prism lenses 20 arranged in parallel in the substantially rectangular Fresnel lens element 17. The second Fresnel lens element 17 is formed in a direction inclined by about 30 ° with respect to the prism lens 20 direction (about 30 ° with respect to the vertical direction of the screen 21), and all the angles of the apexes of the substantially triangular shape of the prism lens 20 are all formed. The prisms 20 are designed to have the same angle, and the heights of the substantially triangular prisms 20 are all different. Accordingly, the emission direction and light amount distribution of the light emitted from the Fresnel lens element 17 are also indicated by arrows in FIG. 16, and most of the irradiation light emitted from the Fresnel lens element 17 is on a surface perpendicular to the prism lens 20. The distribution of the light quantity is larger in the upper right direction of the screen 21 and lower in the lower left direction with respect to the normal line of the light exit surface 22 of the Fresnel lens element 17. The emission direction of the light emitted from the fourth Fresnel lens element 17 is inclined by approximately 30 ° with respect to the emission direction of the light emitted from the first Fresnel lens element 17.

  FIG. 18 shows a simulation of the irradiation pattern and irradiation energy distribution formed on the screen 21 by the irradiation light emitted from the Fresnel lens element 17 having such a configuration. As a result, it was verified that the diagonally upper right part of the screen 21 was concentrated.

  FIG. 19 shows a matrix Fresnel lens in which the right half of the screen is irradiated by combining the first to fourth types of Fresnel lens elements. a is a first matrix element, b is a second matrix element, c is a third matrix element, and d is a fourth matrix element. FIG. 20 shows a simulation of the irradiation pattern and irradiation energy distribution formed on the screen 21 by the irradiation light emitted from the matrix Fresnel lens 14. As a result, it was verified that the right side from the center of the screen 21 is concentrated.

  FIG. 21 shows a matrix that illuminates the left half screen by changing the arrangement of the Fresnel lens elements constituting the matrix Fresnel lens that illuminates the right half of the screen and changing the orientation of some of the Fresnel lens elements. A state is shown in which a lens is designed and a pair of matrix Fresnel lenses are arranged above the LEDs.

  FIG. 22 shows a simulation of the irradiation pattern and irradiation energy distribution formed on the screen 21 by the irradiation light emitted from the two matrix Fresnel lenses 14 at that time. As a result, the irradiation pattern and the irradiation energy distribution formed on the screen 21 are substantially symmetric with respect to the vertical center line of the screen 21 as the axis of symmetry.

  Here, as a comparative example, a plurality of bullet-type LEDs are mounted in the same direction on each of the three printed circuit boards, and the three LED mounting boards are arranged at slightly different angles to mount each LED. FIG. 23 shows a simulation of an irradiation pattern and irradiation energy distribution of a projector having a structure in which a Fresnel lens is provided on the front surface of the substrate on a screen.

  That is, the irradiation pattern and the irradiation energy distribution shown on the clean by FIG. 22 are the results of the simulation of the irradiation pattern and the irradiation energy distribution irradiated by the projector of the present invention, and the irradiation shown on the clean by the FIG. The pattern and the irradiation energy distribution are simulation results of the irradiation pattern and the irradiation energy distribution irradiated by the conventional projector.

Therefore, the simulation result of the irradiation pattern and the irradiation energy distribution by the projector of the present invention shown in FIG. 22 is compared with the simulation result of the irradiation pattern and the irradiation energy distribution by the conventional projector shown in FIG.

  By the way, at the position numbers 1 to 10 in the camera angle-of-view area shown in FIG. 2, the ideal relationship between the position and the irradiation energy is as follows. For example, at three positions of position numbers 1, 2, and 8, the magnitude of irradiation energy is in the order of numbers 2 → 8 → 1, and similarly at numbers 3, 7, and 10, 3 → 10 → 7. In this order, the numbers 4 and 9 are in the order of 9 → 4, and the numbers 5 and 6 are in the order of 5 → 6. The positions of numbers 1 and 3, numbers 7 and 9, and numbers 4 and 5 have the same irradiation energy. Therefore, if the numbers are sequentially displayed from the number of the position where the irradiation energy is large, 2 → 8 → 1 = 3 → 10 → 7 = 9 → 4 = 5 → 6.

  Therefore, when the simulation result of the irradiation energy distribution by the projector of the present invention shown in FIG. 22 is compared with the simulation result of the irradiation energy distribution by the conventional projector shown in FIG. 23, the irradiation to the position of the field angle region in the conventional projector is compared. The order of the magnitudes of energy is in the order of 2 → 8 → 10 → 1 = 3 → 7 = 9 → 6 → 4 = 5, and numbers 2, 8, 7, and 9 for the ideal light distribution. There are no matching areas in only four places.

  On the other hand, the order of the magnitude of the irradiation energy with respect to the position of the field angle region in the projector of the present invention is 2 → 8 → 1 = 3 → 10 → 7 = 9 → 4 = 5 → 6. The light distribution agrees with the whole area.

  From the above simulation results, it was verified that the projector having the structure of the present invention forms a light distribution pattern and light distribution energy distribution that are close to ideal as a light source for a surveillance camera.

  Here, the effect of the projector for the surveillance camera of the present invention will be described. First, as shown in the comparative example, a conventional projector for a surveillance camera performs light distribution control in the horizontal direction within the field of view area of the surveillance camera by bending the LED mounting board, and performs light distribution control in the vertical direction by LED mounting. This was performed using a Fresnel lens with the same lens cut disposed on the front surface of the substrate.

  The light projector having such a structure is difficult to finely control light distribution even though the structure is complicated, and further, reproducibility of light distribution control is poor.

  Further, since the LED mounting substrate is bent and disposed, the Fresnel lens cannot be directly fixed to the LED mounting substrate, and the positional relationship between the LED and the Fresnel lens cannot be set with high accuracy. Therefore, fine light distribution control is difficult and reproducibility of light distribution control is poor.

  In addition, due to the above factors, the light distribution pattern tends to concentrate in the center, and it is difficult to obtain irradiation over a wide range and uniform irradiation energy distribution.

  On the other hand, the projector for a surveillance camera according to the present invention can perform light distribution control close to ideal with a simple structure of an LED mounting substrate and a matrix Fresnel lens arranged in a plane.

  In addition, a Fresnel lens element having a desired lens cut is arranged above the LED serving as the light source in a one-to-one relationship with the LED. As a result, it is possible to individually control the light distribution from each LED, so that the degree of freedom in designing the ideal irradiation pattern is high, and an irradiation pattern close to the ideal can be realized.

  In addition, the Fresnel lens element is arranged on both sides of the surveillance camera, and the LED is disposed above the LED. The light quantity distribution of the light emitted from the Fresnel lens element is perpendicular to the flat light emitting surface of the Fresnel lens element. The prism lens was cut so that the amount of light toward the opposite side of the surveillance camera was greater than the amount of light toward the surveillance camera side with respect to the straight line. As a result, light crossing the front of the surveillance camera is reduced, and erroneous recognition due to the dust floating in front of the surveillance camera being illuminated with infrared rays is reduced, so that reliable imaging can be performed.

  Further, the surface-mount type LED used as the light source is used. As a result, the LED can be mounted on the printed board by reflow, and a plurality of LEDs can be simultaneously mounted on the printed board. Therefore, extremely high production efficiency can be obtained. Further, the surface mount type LED is extremely small and thin compared to the bullet type LED, and greatly contributes to the thinness of the projector. Furthermore, the printed circuit board on which the LED is mounted can be formed of a single-sided board, and the manufacturing cost can be reduced.

  Furthermore, since the matrix Fresnel lens composed of a plurality of Fresnel lens elements can be mounted on the LED mounting substrate with one-touch via the locking claw, the number of assembly steps is reduced and the manufacturing cost can be reduced. At the same time, the matrix Fresnel lens can be accurately mounted on the LED mounting substrate, and the irradiation pattern and the irradiation energy distribution can be obtained with high accuracy and good reproducibility. Many excellent effects are exhibited.

It is the schematic which shows the room which installed the projector for surveillance cameras of this invention. It is the schematic which showed the field angle area when the room shown in FIG. 1 was imaged with the surveillance camera. FIG. 3 is a schematic diagram showing an irradiation pattern and an irradiation energy distribution when irradiation is performed by the monitoring camera projector of Comparative Example 1 in the field angle region of FIG. 2. Similarly, it is the schematic which shows the irradiation pattern and irradiation energy distribution when it irradiates with the projector for surveillance cameras of the comparative example 2 in the view angle area | region of FIG. Similarly, it is a schematic diagram showing an ideal irradiation pattern and irradiation energy distribution in the field angle region of FIG. It is an exploded three-dimensional view showing an embodiment of a projector for a surveillance camera of the present invention. It is a top view when the 1st Fresnel lens element which comprises the matrix Fresnel lens in embodiment of the projector for surveillance cameras of this invention is seen from a lens formation surface. It is AA sectional drawing of FIG. It is the projection figure which simulated on the screen the irradiation pattern and irradiation energy distribution by the light radiate | emitted from the Fresnel lens element of FIG. It is a top view when the 2nd Fresnel lens element which comprises the matrix Fresnel lens in embodiment of the projector for surveillance cameras of this invention is seen from a lens formation surface. It is BB sectional drawing of FIG. It is the projection figure which simulated on the screen the irradiation pattern and irradiation energy distribution by the light radiate | emitted from the Fresnel lens element of FIG. It is a top view when the 3rd Fresnel lens element which comprises the matrix Fresnel lens in embodiment of the projector for surveillance cameras of this invention is seen from a lens formation surface. It is CC sectional drawing of FIG. It is the projection figure which simulated on the screen the irradiation pattern and irradiation energy distribution by the light radiate | emitted from the Fresnel lens element of FIG. It is a top view when the 4th Fresnel lens element which comprises the matrix Fresnel lens in embodiment of the projector for surveillance cameras of this invention is seen from a lens formation surface. It is DD sectional drawing of FIG. It is the projection figure which simulated on the screen the irradiation pattern and irradiation energy distribution by the light radiate | emitted from the Fresnel lens element of FIG. It is a top view when one matrix Fresnel lens in embodiment of the projector for surveillance cameras of this invention is seen from the lens formation surface. It is the projection figure which simulated on the screen the irradiation pattern and irradiation energy distribution by the light radiate | emitted from the Fresnel lens element of FIG. It is a top view when a pair of matrix Fresnel lenses in the embodiment of the projector for surveillance cameras of the present invention are seen from the lens formation surface. It is the projection figure which simulated the irradiation pattern and irradiation energy distribution by embodiment of the projector for surveillance cameras of this invention on the screen. It is the projection figure which simulated the irradiation pattern and irradiation energy distribution by the projector for surveillance cameras of the comparative example 2 on the screen. It is a schematic perspective view of the conventional projector for projector cameras. It is a fragmentary sectional view of the other conventional projector for surveillance cameras.

Explanation of symbols

1 Indoor 2 Surveillance Camera 3 Ceiling 4 Floor 5 Wall A
6 Wall B
7 Wall C
8 Wall D
9 Printed circuit board 10 LED
DESCRIPTION OF SYMBOLS 11 Emitter 12 Irradiation area 13 Fresnel lens 14 Matrix Fresnel lens 15 Circular through-hole 16 Rectangular through-hole 17 Fresnel lens element 18 Leg 19 Locking claw 20 Prism lens 21 Screen 22 Light-emitting surface

Claims (6)

A projector for a surveillance camera in which at least three or more LEDs are mounted on a substrate and a matrix Fresnel lens is disposed above the LEDs, and the matrix Fresnel lens has at least three corresponding to each LED one-to-one. The Fresnel lens element is composed of a plurality of prism lenses each having a substantially triangular cross-sectional shape adjacent to the surface facing the LED . At least two of the prism lenses are arranged so that directions of the prism lenses are substantially perpendicular to each other, and at least one of the other Fresnel lens elements is either one of the prism lenses having the substantially right angle. It is arranged so as to face in the direction of about 30 ° with respect to the direction of the prism lens Floodlight for surveillance camera which is characterized in Rukoto. At least one of the other Fresnel lens elements has a prism lens oriented in a direction within a range of approximately 35 ° to 55 ° with respect to the direction of one of the substantially right-angled prism lenses. The projector for a surveillance camera according to claim 1 , wherein the projector is arranged as described above. The LEDs are arranged on both sides of the surveillance camera, and the Fresnel lens element arranged at a position corresponding to the LED above the LED has a light quantity distribution of light emitted from the Fresnel lens element. The prism lens is cut so that the amount of light directed toward the opposite side of the monitoring camera is larger than the amount of light directed toward the monitoring camera relative to the line perpendicular to the flat light exit surface of the Fresnel lens element. surveillance camera projector according to any one of claims 1 or 2, characterized. The projector for a surveillance camera according to any one of claims 1 to 3 , wherein the central upper portion when the image of the installed surveillance camera is monitored is irradiated with the maximum illumination intensity. The LED monitoring camera projector according to any one of claim 1 to 4, characterized in that a surface-mounted LED which emits infrared rays. The matrix Fresnel lens can be mounted on the substrate with a single touch by locking a locking claw provided on the matrix Fresnel lens in a through hole provided on the substrate. The projector for a surveillance camera according to any one of 5 .

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