JP2006003103A - Lighting unit and imaging device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a small-size imaging device having a uniform optical intensity distribution inside a prescribed plane nearly perpendicular to an optical axis, having a reduced light intensity change in a direction along the optical axis, and capable of measuring a color distribution of the surface of an object with high accuracy, and to provide a lighting unit used for the imaging device. <P>SOLUTION: This lighting unit has: a light source part 210 supplying illumination light; a diffusion part 211 reflecting and diffusing the illumination light from the light source part 210; and aperture parts 212a, 212b emitting the diffused illumination light. The aperture parts 212a, 212b each have an aperture diameter D for emitting the diffused illumination light as nearly parallel light. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an illumination unit and an imaging apparatus including the illumination unit.

  Conventionally, for example, the painting of the surface of a passenger car, the color of human teeth, the gloss, and the like are measured over a predetermined range. Then, based on the measurement result, unevenness in the coating of the object, unevenness in the color of the teeth, unevenness in gloss, and the like are calculated. In particular, in the field of dentistry, dentists often determine the color, tone, and gloss of teeth. For this reason, a predetermined range of teeth is illuminated by the illumination unit. A light emitting diode (hereinafter referred to as “LED”) can be used as a light source of the lighting unit. A configuration of a color measuring device using LEDs is proposed in, for example, Patent Document 1.

Japanese Patent No. 3218601

  The color, tone, and gloss unevenness of the object are calculated based on scattered light from the surface. The optical characteristics of the surface of the object, for example, “distribution of color, color tone, gloss, etc.” are hereinafter collectively referred to as “color distribution”. For this reason, in order to accurately measure the color distribution on the surface of the object, it is necessary to illuminate with light having a uniform intensity distribution.

  However, in general, the spatial light distribution characteristic of light from the LED is not uniform. For this reason, the intensity distribution of light from the LED has a certain degree of non-uniformity. In the configuration of the above-mentioned Japanese Patent No. 3218601, the three primary color lights from the LEDs are directly irradiated onto the irradiated surface of the object. For this reason, unevenness of the light intensity distribution occurs on the irradiated surface of the object. As a result, the color distribution on the surface of the object cannot be measured accurately.

  For example, a dentist often measures the color distribution of a tooth by holding the imaging device by hand. At this time, the imaging device is not mechanically fixed. As a result, the distance between the imaging device and the target tooth, that is, the imaging distance along the optical axis direction, may change during the measurement of the color distribution. In the configuration of Japanese Patent No. 3218601, when the distance between the colorimetric device and the object is different, the variation in the light intensity distribution unevenness of the illumination light becomes large. As described above, the configuration of Japanese Patent No. 3218601 causes uneven light intensity distribution of illumination light in a predetermined plane perpendicular to the optical axis and uneven light intensity distribution due to different imaging distances along the optical axis direction. This is a problem. This problem becomes more prominent when the object has a three-dimensional shape.

  Furthermore, when the illumination unit illuminates the surface of the object, scattered light and specular reflection light are generated on the surface of the object. The unevenness of the coating of the object or the unevenness of color, color tone, and gloss is calculated based on the scattered light from the surface. For this reason, when measuring the color distribution of the surface of an object, it is necessary to image scattered light from the surface. On the other hand, specularly reflected light from the surface of the object has a considerably higher light intensity than scattered light. As a result, when regular reflection light from the surface is incident on the imaging optical system, the state of the color distribution on the surface cannot be measured accurately.

  In the configuration of Japanese Patent No. 3218601, the angle formed by the optical axis of the LED that is the illumination optical system and the central axis of the photodiode of the image sensor is small. For this reason, of the illumination light from the LED, specularly reflected light generated on the surface of the object is incident on the photodiode. As a result, color unevenness on the surface of the object cannot be accurately measured, which is a problem. In particular, when the object is glossy, the light intensity of the regular reflection light is further increased. For this reason, in the structure of a prior art, this problem becomes more remarkable when it is the target object which has glossiness.

  The present invention has been made in view of the above, and the light intensity distribution in a predetermined plane in a direction substantially perpendicular to the optical axis is uniform, and the change in the amount of light in the direction along the optical axis is reduced. It is an object of the present invention to provide a small imaging device capable of measuring the color distribution of the surface of an object with high accuracy and an illumination unit used in the imaging device.

  In order to solve the above-described problems and achieve the object, according to the first invention, the light source unit that supplies the illumination light, the diffusion unit that reflects and diffuses the illumination light from the light source unit, and the diffused It is possible to provide an illumination unit including an opening for emitting illumination light, and the opening has an opening diameter for emitting diffused illumination light as substantially parallel light.

  Moreover, according to 2nd invention, it has the above-mentioned illumination unit and the imaging optical system which images the reflected light from the to-be-irradiated surface illuminated by the illumination unit, The reflected light obtained by the imaging optical system Based on the above, it is possible to provide an imaging device that calculates the color distribution of the irradiated surface.

  In the imaging device according to the present invention, the light intensity distribution in a predetermined plane in a direction substantially perpendicular to the optical axis is uniform, the change in the light amount in the direction along the optical axis is reduced, and the color distribution on the surface of the object is reduced. The effect is that measurement can be performed with high accuracy.

  Embodiments of an illumination unit and an imaging apparatus according to the present invention will be described below in detail with reference to the drawings. Note that the present invention is not limited to the embodiments.

  FIG. 1 shows a usage pattern of the imaging apparatus 100. The imaging apparatus 100 is used for the purpose of accurately measuring the color and gloss of a human tooth as an object OBJ, for example.

  As shown in FIG. 1, the system using the imaging apparatus 100 includes an imaging apparatus 100, a cradle 101, and a computer 102. The imaging device 100 images an object OBJ such as a tooth. After imaging, the imaging device 100 is placed on the cradle 102. As a result, the cradle 101 is electrically connected to the imaging device 100. By being electrically connected, the cradle 102 receives imaging data from the imaging device 100. At the same time, the cradle 101 charges the imaging device 100.

  A computer 102 is connected to the cradle 101. The computer 102 receives imaging data through the cradle 101. Then, the computer 102 performs a predetermined analysis process based on the imaging data.

  Using such a system, for example, a dentist images the surface of a human tooth and performs an analysis process. Now consider dental treatment to repair damaged teeth. At this time, it is desirable that the original tooth before restoration and the tooth after restoration, for example, a denture, have substantially the same color distribution. Conventionally, dentures are manufactured based on the subjective judgment of a dentist. At that time, if the original tooth is observed and the denture is manufactured, the lighting environment is different and the difference in the observer makes a denture whose color distribution does not match that of the adjacent tooth and must be remade. There are things that must be done.

  In contrast, a dentist using the present system measures the color distribution of the original tooth before restoration or the color distribution of the tooth adjacent to the tooth to be restored. Then, a denture having a color distribution that matches the color distribution obtained by the analysis process is manufactured. Thus, according to the present system, the color distribution of the tooth after restoration is compared with the color distribution of the tooth before restoration based on objective imaging data without depending on the subjective judgment of the dentist. can do. As a result, by using this system, it is possible to prevent inconsistencies in the color of the denture due to differences in people and lighting environments, and reduce the possibility of recreating the denture.

  Further, in recent years, in dentistry, a process for processing a tooth surface into a natural white, that is, a so-called whitening process is performed. If the patient gets used to the color of the teeth after the treatment, the illusion that this color was the original color may appear, and the effect of the treatment may be suspected. When performing the whitening process, the dentist can use this system to objectively check the whiteness of the teeth after the process, depending on the case. Therefore, a patient who has undergone whitening can recognize the effect as an objective numerical value, and can reduce unnecessary dissatisfaction and doubt due to ambiguous memories and assumptions.

  Next, a system using the imaging apparatus 100 will be described with reference to FIG. FIG. 2 is a block diagram showing a schematic configuration of the present system.

  In the main body 105 of the imaging apparatus 100, a hood 106 is formed to extend with respect to the object OBJ. The object OBJ is, for example, a tooth in dental treatment. A power switch 107, a shutter button 108, a contact 109, an LCD unit 110, and a focus ring 111 are formed on the outer surface of the main body 105. The power switch 107 turns on or off the power of the imaging apparatus 100.

  The shutter button 108 inputs an instruction for an imaging operation. The contact 109 electrically connects the cradle 101 and the imaging device 100. The LCD unit 110 displays a captured image and various types of information regarding the imaging device 100. Then, the focus position of the imaging optical system 121 described later can be manually adjusted by operating the focus ring 111.

  Inside the main body 105, an illumination unit 200, an image pickup optical system 121, and a CCD 113 are arranged. The illumination unit 200 emits illumination light that illuminates the object OBJ. The detailed configuration of the illumination unit 200 will be described later. The imaging optical system 121 forms an image of scattered light from the surface of the illuminated object OBJ on a predetermined surface. The imaging optical system 121 has a lens configuration that can form an image of an object OBJ at a close distance. The CCD 113 that is an imaging device images the object OBJ with light transmitted through the imaging optical system 121. Here, the predetermined surface or the vicinity of the predetermined surface is arranged so that the light receiving surface of the CCD 113 coincides. The CCD 113 converts the image of the object OBJ imaged by the imaging optical system 121 into an electrical image signal.

  The hood 106 shields unnecessary external light. As a result, the hood 106 can efficiently guide only the scattered light resulting from the reflection from the surface of the object OBJ to the imaging optical system 121. In addition, the position of the imaging optical system 121 can be adjusted by manually operating the focus ring 111 by an operator, for example, a dentist. By operating the focus ring 111, the imaging position of the object OBJ by the imaging optical system 121 and the light receiving surface of the CCD 113 are matched. In addition, the structure which can adjust an automatic focus by a well-known autofocus mechanism may be sufficient even if it does not use the focus ring 111.

  Further, an electric circuit board 112 is provided inside the main body 105. On the electric circuit board 112, a signal processing circuit 114, an LED controller 115, a control circuit 118, a memory 116, and a power supply circuit 117 are mounted.

  The signal processing circuit 114 performs various types of signal processing on the image signal output from the CCD 113. The LED controller 115 controls the light emission state of the LEDs provided in the lighting unit 200. The memory 116 stores the image data processed by the signal processing circuit 114 and stores a processing program executed by the control circuit 118 described later, data, and the like. The battery 119 accumulates power supplied from the cradle 101 to the imaging device 100 via the contact 109. The power supply circuit 117 supplies power supplied from the battery 119 to each circuit inside the imaging apparatus 100. The control circuit 118 is bidirectionally connected to the lighting unit 100, the signal processing circuit 114, the LED controller 115, the memory 116, and the power supply circuit 117 via a bus or the like. The control circuit 118 comprehensively controls the entire imaging apparatus 100.

  As shown in FIG. 1, the imaging apparatus 100 is provided with a grip portion 105 b for an operator to hold by hand. The shutter button 108 is disposed at a position where the shutter button 108 can be operated with the index finger or the like of the hand holding the grip portion 105b. Further, the power switch 107 is disposed at a position opposite to the shutter button 108, for example, a position where the power switch 107 can be operated with a thumb of a hand holding the grip portion 105b. Further, a contact 109 is provided on the grip portion 105b. The battery 119 is disposed inside the grip portion 105b. The LCD unit 110 is disposed at a position on the back side of the main body 105 of the imaging device 100 that can be easily observed.

  Next, the cradle 101 will be described. The cradle 101 is provided with a contact point 139, an AC adapter 135, an A / D conversion circuit 134, and a power supply circuit 136. The contact 139 is electrically connected to the contact 109 of the imaging device 100. The AC adapter 135 converts alternating current of a predetermined voltage supplied from the AC power source into an appropriate direct current voltage. The A / D conversion circuit 134 performs conversion into digital data when the image data transmitted from the imaging apparatus 100 is analog data. The power supply circuit 136 supplies the power supplied from the AC adapter 135 to each internal circuit.

  In the cradle 101, an SRAM 133, a FPGA (Field Programmable Gate Array) 132, a USB2 interface (I / F) 137, and a CPU 131 are further arranged. The SRAM 133 stores image data, and stores processing programs and data executed by the CPU 131 described later. The FPGA 132 performs image data compression processing and the like. The USB2 I / F 137 communicates with the computer 102 by, for example, USB2. The CPU 131 is bidirectionally connected to the FPGA 132, the SRAM 133, the A / D conversion circuit 134, the power supply circuit 136, and the I / F 137 via a bus or the like. The CPU 131 performs overall control of the entire cradle 102, controls communication with the imaging apparatus 100, and controls communication with the computer 102.

  The cradle 101 is connected to a computer 102 via, for example, a USB2 cable. Color analysis software 141 is installed in the computer 102. The color analysis software 141 analyzes the image data received from the imaging device 100. Thereby, the color distribution of the object OBJ can be calculated. A color database 142 is stored in a memory (not shown) of the computer 102. The color analysis software 141 refers to the color database 142 when performing image data analysis processing.

  FIG. 3 schematically shows a configuration of an optical system mainly in the system using the imaging apparatus 100 according to the present embodiment. The illumination unit 200 illuminates the object OBJ. Details of the lighting unit 200 will be described with reference to FIGS. 4, 5, and 6. Scattered light from the object OBJ passes through the central portion of the illumination unit 200. The passed scattered light is incident on the imaging optical system 121. The light emitted from the imaging optical system 121 is imaged by the CCD 113. The illumination unit 200 is provided in the optical path between the CCD 113 that is an imaging optical system and the surface to be irradiated of the object OBJ.

  As will be described later, the illumination unit 200 sequentially illuminates the object OBJ with light in a predetermined wavelength region. Scattered light reflected from the object OBJ illuminated with light of a predetermined wavelength region enters the imaging optical system 121. Next, the light from the imaging optical system 121 is received by the CCD 113. As described above, the computer 102 performs color distribution analysis processing on the surface of the object OBJ based on the image data from the CCD 113. The tooth color distribution, which is the analysis result, is displayed on the display 102d.

(Configuration of lighting unit)
FIG. 4 shows a perspective configuration of the illumination unit 200 viewed from the object OBJ side. The lighting unit 200 includes a light source unit 210, a diffusion unit 211, a first opening 212a, and a second opening 212b. The light source unit 210 includes a plurality of LEDs that supply illumination light. The diffusion unit 211 reflects and diffuses the illumination light from the light source unit 210. The first opening 212a and the second opening 212b emit diffused illumination light. The diffusion part 211 is configured to have a rectangular cylindrical shape. In addition, the approximate center of the hollow portion of the diffusing portion 211 and the optical axis AX of the imaging optical system (not shown) are substantially matched.

  Next, a more detailed configuration of the lighting unit 200 will be described with reference to FIGS. FIG. 5 shows a configuration in which the illumination unit 200 is viewed from the object OBJ side. The diffusion part 211 is configured to have a rectangular cylindrical shape. And the light source part 210 is arrange | positioned at four sides of the inner periphery of a square cylindrical shape. The light source unit 210 includes eight LEDs 210a, 210b, 210c, 210d, 210e, 210f, 210g, and 210h as a set, and three sets of LEDs. That is, the light source unit 210 includes a total of 24 (= 3 sets × 8) LEDs. Each of the LEDs 210a to 210h emits illumination light toward the four sides of the outer periphery of the square cylindrical diffusion portion 211.

  FIG. 8 shows emission spectra of eight LEDs 210a, 210b, 210c, 210d, 210e, 210f, 210g, and 210h. In FIG. 8, the horizontal axis represents wavelength (unit: nm) and the vertical axis represents light intensity (unit: arbitrary). As shown by the curve Sa, the LED 210a has a spectral distribution in which the central emission wavelength is around 450 nm. As shown by the curve Sb, the LED 210b has a spectral distribution with a central emission wavelength in the vicinity of 505 nm. As shown by the curve Sc, the LED 210c has a spectral distribution with a central emission wavelength in the vicinity of 525 nm. The LED 210d has a spectral distribution with a central emission wavelength in the vicinity of 560 nm, as indicated by the curve Sd. The LED 210e has a spectral distribution with a central emission wavelength in the vicinity of 575 nm, as shown by the curve Se. As shown by the curve Sf, the LED 210f has a spectral distribution with a central emission wavelength in the vicinity of 609 nm. As shown by the curve Sg, the LED 210g has a spectral distribution in which the central emission wavelength is around 635 nm. The LED 210h has a spectral distribution with a central emission wavelength in the vicinity of 670 nm as shown by the curve Sh. The curve Si is used in Example 3 described later.

  Returning to FIG. As described above, the LED controller 115 controls the light emission states of the LEDs 210a to 210h. For example, the LED controller 115 turns on the LEDs 210a having the spectrum distribution shown by the curve Sa and turns off the other LEDs 210b to 210h. Then, the CCD 113 captures image data with illumination light having a spectral distribution indicated by the curve Sa.

  Next, the LED controller 115 turns off the LED 210a and turns on the LED 210b having the spectrum distribution shown by the curve Sb. The CCD 113 images image data with illumination light having a spectral distribution indicated by the curve Sb. Then, the procedure of turning on and off is repeated for all the LEDs 210a to 210h. The LED is suitable for high-speed lighting / extinguishing control.

  Light from the LEDs 210a to 210h travels toward the four sides of the outer periphery of the rectangular cylindrical shape of the diffusing unit 211. Then, a diffusion action is received on the inner surface of the diffusion portion 211. The diffused light is emitted from the first opening 212a or the second opening 212b. The first opening 212a and the second opening 212b constitute an opening. Each of the first opening 212a and the second opening 212b has a rectangular injection portion.

  FIG. 6 shows a cross-sectional configuration of the lighting unit 200. The diffusion part 211 has a hollow cylindrical shape with a quadrangular prism. The detailed configuration of the diffusion unit 221 will be described later.

  Here, consider the axes La and Lb parallel to the optical axis AX of the imaging optical system 121 (not shown). The light beam La emitted from the first opening 212a travels from left to right in FIG. The light beam La makes an angle θa with the axis AXa and illuminates the object OBJ. Similarly, the light beam Lb emitted from the second opening 212b travels from right to left in FIG. The light beam Lb makes an angle θb with the axis AXb and illuminates the object OBJ.

  As described above, the first opening 212a and the second opening 212b are provided at positions facing the optical axis AX of the imaging optical system 121. For this reason, it is possible to illuminate the object OBJ at the predetermined angles θa and θb from the two opposing directions with the optical axis AX of the imaging optical system 121 as the center. As a result, the object OBJ is illuminated by being superimposed with the light from the first opening 212a and the light from the second opening 212b. The angles θa and θb are set to, for example, approximately 45 ° or greater than 45 °.

  Thereby, it can reduce that the regular reflection light from the to-be-irradiated surface of the target object OBJ injects into the imaging optical system 121. FIG. As a result, the imaging optical system 121 can capture only scattered light from the irradiated surface of the object OBJ with high efficiency. Therefore, it is possible to obtain the imaging device 100 that can reduce the regular reflection light and can measure the color distribution of the surface of the object OBJ with high accuracy. Furthermore, the illumination unit 200 illuminates from two different directions. For this reason, even a three-dimensional object OBJ like a tooth does not cause a shadow.

  The illumination unit 200 is provided in the optical path between the imaging optical system 121 and the irradiated surface of the object OBJ. More preferably, the illumination unit 200 is desirably disposed in the vicinity of the incident side of the imaging optical system 121. For this reason, the illumination unit 200 can illuminate from two directions. Furthermore, the imaging optical system 121 images the scattered light that has passed through the illumination unit 200. For this reason, the configuration around the imaging optical system 121 can be simplified. Accordingly, a small imaging device 100 can be obtained.

  Further, a roof portion 213a is formed on the outer peripheral side of the first opening 212a. Further, a roof portion 213b is formed on the outer peripheral side of the second opening 212b. The roof portions 213a and 213b are formed to have an inclination angle and size that efficiently guide the diffused light emitted from the first opening 212a and the second opening 212b in the direction of the object OBJ. .

  FIGS. 7A and 7B show the relationship between the size of the first opening 212a and the emitted light. Note that the second opening 212b has the same configuration as the first opening 212a, and therefore the first opening 212a will be described as a representative example. As described above, the diffusing portion 211 has a hollow cylindrical shape with a quadrangular prism. As illustrated in FIG. 7A, the cross-sectional shape of the diffusing portion 211 on the xz plane is a quadrangular shape. The length in the direction along the square x-axis is L, and the opening diameter (length) of the first opening 212a is D1. FIG. 7-2 illustrates a configuration of the first opening 212a having an opening diameter D2 that is larger than the opening diameter D1.

  In FIG. 7A, when D1 / L is sufficiently small, the first opening 212a functions as a substantially point light source. For this reason, the light Ls emitted from the first opening 212a is a substantially spherical wave. On the other hand, as shown in FIG. 7B, when D2 / L is a predetermined value, the light Lc emitted from the first opening 212a becomes substantially parallel light.

  In the present embodiment, the length of a predetermined surface (xz plane in FIG. 6) of the diffusing portion 211 is L, and the lengths of the first opening 212a and the second opening 212b are predetermined surfaces (xz plane). When the length is D, the aperture diameter has a D / L ratio that emits substantially parallel light.

  FIG. 9 shows the configuration of the illumination unit 200 together with the light intensity distribution IL of the illumination light on the optical axis AX. The intensity distribution on the optical axis AX of light from the first opening 212a and the second opening 212b is substantially zero in the vicinity of the opening. As the distance from the opening increases, the light intensity distribution IL increases and reaches the maximum value Im at the position Zm. Then, the light intensity distribution gradually attenuates as it moves away from the position Zm. Here, in the range ZL, there is almost no change in the light intensity distribution in the direction along the optical axis AX, which is a substantially constant value. For example, even if the imaging distance between the imaging device 100 and the object OBJ changes within the range ZL, the light intensity distribution of the illumination light is substantially constant. In other words, the imaging apparatus 100 can perform good measurement with a substantially constant intensity distribution of illumination light even if the imaging distance changes within the range ZL in the depth of focus direction.

  Further, the first opening 212a and the second opening 212b are provided apart from each other by a predetermined distance K. By changing the distance K between the two openings, the position Zm of the maximum value Im can be changed. For example, when the interval K is reduced, the position Zm approaches the lighting unit 200. On the contrary, when the interval K is increased, the position Zm moves in a direction away from the lighting unit 200. When the position Zm moves away from the illumination unit 200, the amount of illumination light is attenuated. For this reason, it is necessary to increase the output of the LED. If the position Zm is too close to the illumination unit 200, the illumination unit 200 and the object OBJ may interfere with each other when the object OBJ has a three-dimensional shape. As a specific example, when measuring a tooth as the object OBJ, in the imaging device 100 having a small interval K between the two openings, the human nose and the imaging device 100 are in contact with each other at the time of measurement. As described above, it is desirable to set an appropriate value for the interval K depending on the amount of light and the type of the object OBJ.

  As described with reference to FIG. 7A, when a substantially spherical wave is emitted from the first opening 212a and the second opening 212b, if the position on the optical axis AX is different, the change in the light intensity distribution is large. turn into. On the other hand, as shown in FIG. 7B, when substantially parallel light is emitted from the first opening 212a and the second opening 212b, the light intensity distribution according to the position along the optical axis AX. The change is reduced as compared to FIG.

  Thus, in the present embodiment, the first opening 212a and the second opening 212b have an opening diameter D2 that is large enough to emit the illumination light diffused by the diffusing unit 211 as substantially parallel light (FIG. 7-2). Thereby, the light intensity distribution in the xy plane in the direction substantially perpendicular to the optical axis AX is uniform, and the change in the amount of light in the z direction along the optical axis AX is reduced. For this reason, the color distribution on the surface of the object OBJ can be measured with high accuracy. Note that the first opening 212a and the second opening 212b are not limited to substantially parallel light, and may be, for example, gentle (large curvature radius) convergent light or gentle divergent light.

(Configuration of diffuser)
FIG. 10A illustrates a cross-sectional configuration of the diffusion portion 211. The diffusion part 211 includes a resin part 1000. The thickness of the resin part 1000 is, for example, about 1 to 2 mm. On the surface of the resin part 1000 opposite to the light source part 210, an aluminum layer 1001 is formed by metal vapor deposition. The resin part 1000 diffuses light from the light source part 210. The aluminum layer 1001 reflects light that passes through the thin resin portion 1000. The reflected light is diffused by entering the resin portion 1000 again. Thereby, the light quantity which permeate | transmits the resin part 1000 and is lost can be reduced.

  As described above, the light source unit 210 includes LEDs 210a to 210h that supply light of different wavelength regions. And each LED210a-210h differs in the position arrange | positioned. For this reason, for example, the optical characteristics such as the illuminance distribution differ between the light emitted from the LED 210a and the light emitted from the LED 210h. The resin part 1000 diffuses light from the LEDs 210a to 210h. Thereby, the dispersion | variation in the optical characteristic resulting from the difference in arrangement | positioning of LED210a-210h can be reduced.

  Further, a roof portion 213a is formed in the vicinity of the first opening portion 212a. As described above, the roof portion 213a has an inclination angle and a size that efficiently guide the diffused light toward the object OBJ. For example, if the roof portion 213a is not provided, light that does not travel in the direction of the object OBJ is generated. For this reason, the amount of light is lost. Further, when the roof portion 213a is provided vertically (parallel to the optical axis AX), the light regularly reflected by the roof portion 213a is incident on the object OBJ. As described above, the roof portion 213 a also has a function of returning the light regularly reflected by the roof portion 213 a out of the light from the light source portion 210 to the direction inside the diffusion portion 211. For this reason, it can also reduce that the regular reflection light from the roof 213a injects into the target object OBJ.

  FIG. 10-2 shows a cross-sectional configuration of a modified example of the diffusing unit 211. A reflective coat layer 1101 is formed on the inner side surface of the diffusion portion 211. A diffusion coating layer 1100 is further formed on the reflective coating layer 1101. The diffusion coat layer 1100 can be formed by applying barium sulfate, for example. Thereby, the diffusion coat layer 100 diffuses incident light. As described above, another material may be used as long as a high reflectance film (coat layer) and a high diffusivity film (coat layer) are stacked to form a double layer.

  FIG. 10C illustrates a cross-sectional configuration of another modification of the diffusing unit 211. For example, a diffusion coating layer 1150 is formed on an aluminum substrate 1151 that is a reflective surface. Thereby, the diffusion part 211 can be easily manufactured using the aluminum substrate 1151.

  10A to 10C, the intensity distribution of the illumination light can be made uniform by improving the diffusion characteristics of the diffusion unit 211. Moreover, the utilization efficiency of light can be increased by improving the diffusion characteristics. The light source unit 210 can be downsized due to high light utilization efficiency. Further, each of the LEDs 210 a to 210 h is arranged to emit light toward the outer periphery of the diffusing unit 211. Thereby, it can reduce that the light from each LED210a-210h inject | emits directly from the 1st opening part 212a and the 2nd opening part 212b. With this arrangement, the efficiency with which the diffusing unit 211 diffuses light can be improved.

  A lens may be arranged in the vicinity of the first opening 212a and the second opening 212b. The lens has a function of refracting the light diffused by the diffusing unit 211 and guiding it in the direction of the object OBJ. Thereby, the object OBJ can be efficiently illuminated with the diffused light.

  With reference to FIG. 11 and FIG. 12, the structure of the illumination unit 1200 which concerns on Example 2 is demonstrated. Parts that are the same as those in the first embodiment are denoted by the same reference numerals, and redundant descriptions are omitted. FIG. 11 shows a configuration of the illumination unit 1200 viewed from the object OBJ side. FIG. 12 shows a cross-sectional configuration of the lighting unit 1200. As shown in FIG. 11, the diffusion part 211 is configured to have an annular cylindrical shape. And the light source part 210 is arrange | positioned at the edge of the inner periphery of a cylindrical shape of a ring. The light source unit 210 includes LEDs 210a, 210b, 210c, 210d, 210e, 210f, 210g, and 210h. In FIG. 11, two LEDs 210a, 210b, and 210c are illustrated. Thus, the illumination unit 1200 has a total of 12 LEDs arranged at substantially equal intervals. Each of the LEDs 210 a to 210 h is configured to emit light toward the outer periphery of the diffusing unit 211.

  As shown in FIG. 12, the cross section of the diffusion portion 1211 has a circular shape. With this shape, the utilization efficiency of illumination light can be improved. As in the first embodiment, the length of the diffusion surface 1211 on the predetermined surface (the xz plane in FIG. 12) is L, and the length of the first opening 212a and the second opening 212b on the predetermined surface. When the thickness is D, the aperture diameter has a D / L ratio that emits substantially parallel light.

  Further, the first opening 212a and the second opening 212b are provided apart by a predetermined distance K so that the position Zm (see FIG. 9) of the maximum value Im is optimum.

  In this embodiment, the twelve LEDs 802a to 802h are sequentially turned on and off repeatedly. And the target object OBJ is illuminated with the illumination light by LED which has lighted. Moreover, each LED 802a-802h differs in the position arrange | positioned at circular shape, respectively. The diffusion unit 1211 generates diffused light having a substantially uniform intensity distribution regardless of the light distribution characteristics of the LEDs 802a to 802h. For this reason, the dispersion | variation in the optical characteristic of illumination light resulting from the difference in the position of LED can be reduced. Further, the diffusion portion 1211 is not limited to an annular cylindrical shape as shown in FIG. For example, the diffusing unit 1211 may have an elliptical cylindrical shape having a major axis and a minor axis when viewed from the object OBJ side. At this time, the first opening 212a and the second opening 212b are preferably provided in a direction along the long axis. Thereby, it is possible to reduce the size while improving the diffusion efficiency.

  With reference to FIG. 13, the structure of the illumination unit 1300 which concerns on Example 3 is demonstrated. The same parts as those in the first embodiment and the second embodiment are denoted by the same reference numerals, and redundant description is omitted. FIG. 13 shows a configuration of the illumination unit 1300 viewed from the object OBJ side.

  The diffusing portion 211 is formed in a continuous cylindrical shape so as to surround the optical axis AX that is a predetermined axis. Then, a space having a predetermined shape is formed in the vicinity of the optical axis AX, which is a predetermined axis, by the cylindrical diffusion portion 211. Light from the illumination unit 1300 is reflected and scattered by the surface of the object OBJ. The scattered light passes through a space of a predetermined shape of the illumination unit 1300 and enters the imaging optical system 121. As described above, the illumination unit 1300 can be disposed in the vicinity of the incident end face of the imaging optical system 121. As a result, the entire imaging apparatus can be reduced in size.

  The space having a predetermined shape is formed in a substantially square shape by four surfaces (sides) 1310a, 1310b, 1310c, and 1310d on the inner periphery of the diffusion portion 211. The imaging surface of the CCD 113 has a quadrangular shape. For this reason, when the image pickup apparatus is downsized, it is possible to reduce the light squeezing caused by the periphery of the rectangular space of the illumination unit 1300.

  The light source unit 210 is composed of four sets of LEDs, with three LEDs 210X, 210Y, and 210Z as a set. That is, the light source unit 210 includes a total of 12 (= 4 sets × 3) LEDs. Each of the LEDs 210X, 210Y, and 210Z is provided on two surfaces 1310b and 1310d on the optical axis AX side of the diffusing unit 211. As described above, the LEDs 210X, 210Y, and 210Z are provided on the inner surfaces 1310b and 1310d of the diffusion portion 211. Each of the LEDs 210X, 210Y, and 210Z emits illumination light from the inner periphery of the cylindrical diffusion portion 211 toward the four sides of the outer periphery. As a result, the width W of the diffusion part 211 can be reduced. Thereby, the illumination unit 1300 can be reduced in size and space saving can be achieved. Furthermore, the light diffusion efficiency in the diffusion part 211 can be improved by arranging the light source part 210 inside. Therefore, the object OBJ can be illuminated with bright illumination light. Compared to the annular cylindrical diffusion portion as in the second embodiment, the light diffusion efficiency can be further increased when the rectangular cylindrical shape is configured as in this embodiment.

  The LEDs 210X, 210Y, and 210Z are provided at positions where the illumination light supplied from the LEDs 210X, 210Y, and 210Z is reflected at the diffusion unit 211 at least once and emitted from the openings 212a and 212b. The openings 212a and 212b desirably emit diffuse light efficiently. In this embodiment, the light supplied from the LEDs 210X, 210Y, and 210Z is always reflected once by the diffusing unit 211 and then emitted from the openings 212a and 212b. For this reason, out of the light emitted from the LEDs 210X, 210Y, and 210Z, the light emitted directly from the openings 212a and 212b without being reflected by the diffusion portion 211 can be reduced. As a result, the illumination unit 1300 can illuminate the object OBJ with good diffused light.

  Next, the configuration of each LED 210X, 210Y, 210Z will be described. 14-1, FIG. 14-2, and FIG. 14-3 show the configurations of LEDs 210X, 210Y, and 210Z viewed from the front, respectively. As illustrated in FIG. 14A, the LED 210X includes three light emitting units 214a, 214b, and 214c. As shown in FIG. 14B, the LED 210Y includes three light emitting units 214d, 214e, and 214f. Furthermore, as illustrated in FIG. 14C, the LED 210Z includes three light emitting units 214g, 214h, and 214i.

  The spectral distribution of illumination light supplied from each light emitting unit will be described with reference to FIG. As shown by the curve Sa, the light emitting unit 214a has a spectral distribution with a central emission wavelength in the vicinity of 450 nm. As shown by the curve Sb, the light emitting unit 214b has a spectral distribution with a central emission wavelength in the vicinity of 505 nm. The light emitting unit 214c has a spectral distribution with a central emission wavelength in the vicinity of 525 nm as shown by the curve Sc. Thus, the LED 210X can supply light of three different wavelength regions from one package.

  In addition, the light emitting unit 214d has a spectral distribution with a central emission wavelength in the vicinity of 560 nm, as indicated by the curve Sd. The light emitting unit 214e has a spectral distribution with a central emission wavelength in the vicinity of 575 nm, as shown by the curve Se. As shown by the curve Sf, the light emitting unit 214f has a spectral distribution with a central emission wavelength in the vicinity of 609 nm. Thus, the LED 210Y can supply light of three different wavelength regions from one package.

  Furthermore, the light emitting part 214g has a spectral distribution with a central emission wavelength in the vicinity of 635 nm, as shown by the curve Sg. The LED 214h has a spectral distribution with a central emission wavelength in the vicinity of 670 nm as shown by the curve Sh. The LED 214i has a spectral distribution with a central emission wavelength in the vicinity of 700 nm as indicated by the curve Si. Thus, the LED 210Z can supply light of three different wavelength regions from one package.

  Accordingly, nine different wavelength regions, that is, nine bands of light can be supplied from the three LEDs 210X, 210Y, and 210Z. As a result, it is possible to reduce variations in the light emission position for each different wavelength region. Therefore, it is possible to reduce the variation in illumination unevenness for each illumination light of different colors. Note that the emission wavelength regions of the nine light emitting units 214a to 214i do not have to be different from each other. For example, the light emission wavelength regions of the two light emitting units out of the nine light emitting units 214a to 214i may be substantially the same. In this case, light of eight different wavelength regions, that is, eight bands can be supplied by the nine light emitting units 214a to 214i.

  Similarly, the number of bands of light supplied from the LEDs 210X, 210Y, and 210Z can be appropriately controlled to a desired number. For example, each of the LEDs 210X, 210Y, and 210Z can be configured to have three light emitting units that supply R light (red), G light (green), and B light (blue), respectively. With this configuration, a three-band color camera of R light, G light, and B light can be obtained.

  Moreover, LED which supplies white light can be used as a light source part. At this time, for example, a color CCD including an R light transmission filter, a G light transmission filter, and a B light transmission filter is used as the CCD 113. Then, the object OBJ is illuminated with white light. Scattered light from the object OBJ is imaged by a color CCD. When three types of color filters are used, this is equivalent to three-band illumination. Therefore, if the number of color filters having different transmission wavelength regions is increased, the number of bands can be increased according to the number of color filters.

  The shape of the diffusing portion, the LED arrangement, and the size and position of the opening are not limited to the above-described embodiments. For example, the diffusion portion is not limited to a continuous cylindrical configuration, and may have any structure as long as it has a space for diffusion.

  Furthermore, an LED having a plurality of light emitting units in one package as shown in the third embodiment may be applied to the lighting unit of the first or second embodiment. Thus, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present invention.

  As described above, the illumination unit according to the present invention can be suitably used when performing illumination in an imaging device that measures the color distribution of the surface of an object.

1 is a diagram illustrating a configuration of a system that uses an imaging apparatus according to Embodiment 1. FIG. 1 is a block diagram of a system that uses an imaging apparatus according to Embodiment 1. FIG. FIG. 2 is a diagram simply showing an optical system portion of Example 1. 1 is a perspective configuration diagram of a lighting unit according to Embodiment 1. FIG. It is a top view of the lighting unit of Example 1. It is a cross-sectional block diagram of the illumination unit of Example 1. It is a figure which shows the relationship between the magnitude | size of an opening part, and emitted light. It is another figure which shows the relationship between the magnitude | size of an opening part, and emitted light. It is a figure which shows the spectrum distribution of LED. It is a figure which shows the relationship between the position of an opening part, and intensity distribution on an optical axis. FIG. 3 is a diagram illustrating a cross-sectional configuration of a diffusion portion according to the first embodiment. It is a figure which shows the cross-sectional structure of the other spreading | diffusion part of Example 1. FIG. FIG. 6 is a diagram illustrating a cross-sectional configuration of still another diffusion portion of Example 1. It is a top view of the illumination unit of Example 2. It is a cross-sectional block diagram of the illumination unit of Example 2. It is a cross-sectional block diagram of the illumination unit of Example 3. FIG. 6 is a diagram showing a configuration of an LED of Example 3. 6 is a diagram showing another configuration of the LED of Example 3. FIG. It is a figure which shows other structure of LED of Example 3. FIG.

Explanation of symbols

100 Imaging Device OBJ Object 101 Cradle 102 Computer 102d Display 105 Main Body 106 Hood 107 Power Switch 108 Shutter Button 109 Contact 110 LCD
111 Focus ring 112 Power circuit board 113 CCD
114 Signal Processing Circuit 115 LED Controller 116 Memory 117 Power Supply Circuit 118 Control Circuit 119 Battery 121 Imaging Optical System 131 CPU
132 FPGA
133 SRAM
134 A / D conversion circuit 135 AC adapter 136 Power supply circuit 137 USB2 I / F
139 Contact point 141 Color analysis software 142 Color database 102d Display 200 Illumination unit 210 Light source part 211 Diffusing part 212a First opening part 212b Second opening part La, Lb Rays θa, θb Angles AXa, AXb axes 210a, 210b, 210c 210d, 210e, 210f, 210g, 210h LED
L Length of diffusion part D, D1, D2 Opening diameter (size) of opening
K distance between openings Zm position ZL range 213a, 213b roof portion 1000 resin portion 1001 aluminum layer 1100 diffusion coating layer 1101 reflection coating layer 1150 diffusion coating layer 1151 aluminum substrate 1200 lighting unit 1211 diffusion portion 1300 lighting unit 1310a, 1310b, 1310c , 1310d surface 210X, 210Y, 210Z LED
214a, 214b, 214c, 214d, 214e, 214f, 214g, 214h, 214i Light emitting part W Width of lighting unit

Claims (9)

A light source unit for supplying illumination light;
A diffusion unit that reflects and diffuses illumination light from the light source unit;
An opening for emitting diffused illumination light;
The opening unit has an opening diameter for emitting the diffused illumination light as substantially parallel light.   The lighting unit according to claim 1, wherein the opening includes a first opening and a second opening provided at a predetermined interval.   The lighting unit according to claim 2, wherein the first opening and the second opening are provided at positions facing each other with respect to a predetermined axis.   The illumination unit according to claim 1, wherein the light source unit includes a plurality of light emitting units that supply light of different wavelength regions.   The said light source part is provided in the position where the said illumination light supplied from the said light source part reflects in the said spreading | diffusion part at least once, and inject | emits from the said opening part. The lighting unit according to any one of claims.   The illumination unit according to claim 3, wherein the light source unit is provided on a surface of the diffusion unit on the predetermined axis side or in the vicinity thereof. The diffusion part is formed in a continuous cylindrical shape surrounding the predetermined axis,
The lighting unit according to any one of claims 3 to 6, wherein a space having a predetermined shape is formed in the vicinity of the predetermined axis by the cylindrical diffusion portion.   The lighting unit according to claim 7, wherein the space having the predetermined shape has a substantially rectangular shape. The lighting unit according to any one of claims 1 to 8,
An imaging optical system that forms an image of reflected light from the illuminated surface illuminated by the illumination unit;
An image pickup apparatus that calculates a color distribution of the irradiated surface based on the reflected light obtained by the image pickup optical system.

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