JP2005243314A - Lighting fixture - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lighting fixture capable of automatically setting a target value of an output value of an illumination sensor to set illuminance of an illuminated surface nearly constant, and maintaining the illuminance of the illuminated surface nearly constant even if a reflection factor of the illuminated surface is changed by a change of a layout or the like. <P>SOLUTION: A control part is structured by an amplifier circuit 13, a central processing part 14, and a light adjusting control part 15. The central processing part 14 calculates a corresponding relation between a light output ratio of a light source 11 in a condition without outside light against the illuminated surface based on an output value of the illumination sensor 12 in a condition without a light output of the light source 11 and an output value of the illumination sensor 12 in a condition with light output of the light source 11, and an output value of the illumination sensor 12, by directing the light adjusting control part 15 to change the light output of the light source 11 for every input of a power source, and after a target value corresponding with a given light output ratio based on the corresponding relation, the light output of the light source 11 is controlled to make the output value of the illumination sensor 12 be a target value. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a lighting fixture.

  Conventionally, for the purpose of keeping the illuminance of a surface to be illuminated by a lamp, which is a light source of a lighting fixture installed on a ceiling in an office or the like, as shown in FIG. A controller 2 having an illuminance sensor 3 for measuring the illuminance of the irradiated surface is installed on the ceiling as a separate body from the luminaire 1, and the light output of the lamp is maintained so that the illuminance detected by the illuminance sensor 3 is maintained at a constant target illuminance. There is known a lighting device that transmits a dimming control signal for adjusting the light from the controller 2 to the lighting fixture 1 (see, for example, Patent Documents 1 and 2).

The illuminance sensor 3 in the illuminating device having the configuration shown in FIG. 8 outputs a voltage value (analog signal) corresponding to the amount of reflected light from the irradiated surface, and the controller 2 has a rated light output of the lamp. Based on the output value of the illuminance sensor 3 when the light output is 100% and the output value of the illuminance sensor 3 when the light output of the lamp is 25% of the rating, The illuminance of the surface to be irradiated by only the luminaire 1 when the lamp is lit at 100% of the rated value is obtained, and 70% of the output value of the illuminance sensor 3 corresponding to the latter illuminance is a target value corresponding to the target illuminance. Then, the dimming control signal is output so that the output value of the illuminance sensor 3 becomes the set value. In short, in the illumination device having the configuration shown in FIG. 8, the target value can be set without being affected by external light by setting the target value in the above-described process, and the illuminance of the irradiated surface. Can be kept almost constant.
JP-A-11-214179 JP 2001-345186 A

  By the way, in the above-described lighting device, after the setting of the target value is performed at the time of installing the lighting fixture 1, when the reflectance of the irradiated surface changes due to a change in the office layout or the like, the irradiation surface is changed before and after the layout change. There was a problem that the illuminance changed. For example, the illuminance of the irradiated surface before the layout change and the output value (sensor voltage) of the illuminance sensor 3 are in a relationship like the straight line A in FIG. 9, and the reflectance of the irradiated surface increased by 10% due to the layout change. In this case, the relationship between the illuminance of the irradiated surface and the output value of the illuminance sensor 3 changes as shown by the straight line B in FIG. That is, the output value of the illuminance sensor 3 is proportional to the illuminance of the illuminated surface, but the slopes of the straight lines i and b change due to the difference in the reflectance of the illuminated surface. Here, when the target illuminance of the irradiated surface before the layout change is 700 lx and the sensor voltage (that is, the target value) when the illuminance of the irradiated surface is 700 lx is 3.5 V, the target illuminance is changed by the layout change. When the reflectance of the irradiated surface is increased by 10%, the sensor voltage when the illuminance of the irradiated surface is 700 lx is also increased by about 10% (3.5 × 1.1 = 3.85V). However, in the above-described lighting device, even if the layout is changed, the target value is not changed. Therefore, the light output of the lamp is set so that the output value of the illuminance sensor 3 becomes 3.5 V, which is the target value before the layout change. Therefore, the illuminance of the irradiated surface is controlled to be about 10% darker than before the layout change (700 ÷ 1.1 = 636 lx). Conversely, when the reflectance of the irradiated surface is reduced by 10% due to the layout change, the illuminance of the irradiated surface is controlled to be about 10% brighter. In an actual environment, since the influence of the reflectance of the floor, wall, ceiling, etc. is mutually received, it is needless to say that it is not obtained by the simple calculation as described above.

  Further, in the above-described illumination device, based on the output value of the illuminance sensor 3 when the light output of the lamp as the light source is 100% and the output value of the illuminance sensor 3 when the light output of the lamp is 25%. The output value of the illuminance sensor 3 when the light output of the lamp is 0% (that is, the output value of the illuminance sensor 3 due to the influence of external light) is obtained by calculation, but when the light output is 100% or 25% If an error occurs in the output value of the illuminance sensor 3 for some reason, an error also occurs in the output value of the illuminance sensor 3 when the light output of the lamp obtained by calculation is 0%, and the target value remains unchanged. turn into.

  The present invention has been made in view of the above reasons, and its purpose is to automatically set the target value of the output value of the illuminance sensor that is set to make the illuminance of the irradiated surface substantially constant and to change the layout. An object of the present invention is to provide a lighting fixture that can keep the illuminance of the irradiated surface substantially constant even if the reflectance of the irradiated surface changes due to the above.

  The invention according to claim 1 is a light source, an illuminance sensor that measures the illuminance of the illuminated surface illuminated by the light source with reflected light, and a light source so that the illuminance of the illuminated surface is constant based on the output value of the illuminance sensor A control unit that controls the light output of the illuminance sensor in a state where there is no light output of the light source by changing the light output of the light source every time the power is turned on, and a state in which the light output of the light source is present The correspondence between the light output ratio of the light source and the output value of the illuminance sensor is obtained based on the output value of the illuminance sensor in the state where there is no outside light on the irradiated surface, and the predetermined light output ratio is supported based on the correspondence relation After the target value to be set is set, the light output of the light source is controlled so that the output value of the illuminance sensor becomes the target value.

  According to the present invention, the control unit generates external light on the irradiated surface based on the output value of the illuminance sensor in a state where there is no light output of the light source and the output value of the illuminance sensor in a state where the light output of the light source is present. The correspondence between the light output ratio of the light source and the output value of the illuminance sensor is determined in the absence of light, and a target value corresponding to a predetermined light output ratio is set based on the correspondence. The correspondence between the light output ratio of the light source and the output value of the illuminance sensor in the state where there is no external light is accurately obtained and a target value is set, and the above correspondence is obtained every time the power is turned on and the target value is obtained. Therefore, even if the reflectance of the irradiated surface changes due to a layout change or the like, it is possible to prevent the illuminance of the irradiated surface from changing, and the illuminance of the irradiated surface can be kept substantially constant. .

  According to a second aspect of the present invention, in the first aspect of the invention, the light source changes a relationship between light output and power consumption according to a cumulative lighting time, and the predetermined light output ratio is a secular change of the light source. Regardless of this, the illumination surface is set based on the relationship between the cumulative lighting time of the light source and the luminous flux reduction rate so that the illuminance of the irradiated surface can be made constant.

  According to this invention, even if the luminous flux of the light source decreases due to the secular change of the light source, the illuminance of the irradiated surface can be kept substantially constant.

  According to a third aspect of the present invention, in the first or second aspect of the present invention, the control unit controls the light source to have no light output in a process from when the power is turned on until the correspondence is obtained. Then, after reading the output value of the illuminance sensor, the light source is controlled to have a light output, the output value of the illuminance sensor is read, and the correspondence relationship is obtained.

  According to the present invention, in the process of obtaining the correspondence relationship when the power is turned on, the light source is controlled to a state where there is no light output after the light source is controlled, so that the light output of the light source is turned on after the power is turned on. As a result, the room is not brightened after the room is brightened, and the occupant can be given an impression that does not replace the normal lighting, so as not to feel uncomfortable.

  According to a fourth aspect of the present invention, in the first to third aspects of the invention, the illuminance sensor outputs an analog voltage value corresponding to the amount of reflected light from the irradiated surface, and the control unit Based on an amplifier circuit that can vary the gain for amplifying the output of the illuminance sensor in a plurality of stages, an A / D converter that converts the output value of the amplifier circuit into a digital value, and a digital value output from the AD converter A central processing unit having a function of setting the target value, wherein the central processing unit is in a state in which there is no light output of the light source and the light source in a process from when the power is turned on until the correspondence is obtained. The gain of the amplifier circuit is changed in all stages for each of the optical output states, and the output value of the amplifier circuit is read so that the output value of the amplifier circuit does not exceed the upper limit of the input of the AD converter. And selecting the gain of the amplifier circuit so that the maximum value in the range.

  According to the present invention, the gain of the amplifier circuit is set every time the power is turned on, and the gain of the amplifier circuit is set so that the input value of the AD converter is optimized. The resolution of the value can be increased, and the light output of the light source can be finely controlled with respect to fluctuations in ambient illuminance.

  In the first aspect of the present invention, the target value of the output value of the illuminance sensor that is set to make the illuminance of the illuminated surface substantially constant can be automatically set, and the reflectance of the illuminated surface changes due to a layout change or the like. Also, there is an effect that the illuminance of the irradiated surface can be kept at an appropriate illuminance.

(Embodiment 1)
Hereinafter, the lighting fixture A of this embodiment is demonstrated, referring FIG. 1 and FIG.

  Each lighting fixture A of this embodiment is integrally provided with an illuminance sensor (light quantity sensor) 12 and is attached to a ceiling B such as an office as shown in FIG. A voltage value (analog signal) corresponding to the amount of reflected light from the irradiated surface F such as the floor surface of the floor is output. Here, the illuminance sensor 12 includes not only reflected light from the illuminated surface F of light output from the luminaire A but also reflected light from the illuminated surface F of external light such as daylight entering through an office window. Incident.

  The luminaire A includes a light source 11 that illuminates the illuminated surface F, a dimming control unit 15 that adjusts the light output of the light source 11, and the above-described illuminance sensor 12 that detects the illuminance of the illuminated surface F by reflected light. An amplifying circuit 13 that amplifies the output of the illuminance sensor 12, a central processing unit 14 that provides a dimming signal for keeping the illuminance detected by the illuminance sensor 12 constant (constant target illuminance), and a central processing And a rewritable memory 16 for storing data used in the unit 14 (a target value corresponding to the target illuminance, data necessary for setting the target value, etc.). Here, the light source 11 only needs to be capable of adjusting the light output. For example, a halogen bulb, an incandescent bulb, a fluorescent lamp, or the like can be used. In the present embodiment, the light output of the light source 11 is made constant by the central processing unit 14, the amplifier circuit 13, and the dimming control unit 15 so that the illuminance of the irradiated surface F is constant based on the output value of the illuminance sensor 12. The control part which controls is comprised.

  By the way, the central processing unit 14 sets a target value corresponding to a predetermined light output ratio (ratio of the light output output from the light source 11 to the rated light output of the light source 11) every time the lighting fixture A is turned on. The dimming signal created so that the output of the amplifier circuit 13 becomes the target value is fed to the dimming control unit 15 to feedback control the light output of the light source 11.

  The basic setting procedure of the target value in the central processing unit 14 will be described. Hereinafter, a voltage output from the amplifier circuit 13 will be referred to as a sensor voltage.

  When the lighting apparatus A is turned on, the central processing unit 14 resets the target value stored in the memory 16 as the first step. That is, the target value stored in the memory 16 before the power is turned on is deleted.

  Next, as a second step, the central processing unit 14 sends the dimming signal created so that the light output of the light source 11 is 0% of the rating (that is, the light output ratio is 0%) to the dimming control unit 15. After the application, the sensor voltage V 0 input from the amplifier circuit 13 is stored in the memory 16. In short, in the second step, the illuminance of the irradiated surface F measured by the illuminance sensor 12 in a state where the light source 11 is not turned on (that is, the illuminance of the light irradiation surface F due to external light) is stored in the memory 16.

  Thereafter, as a third step, the central processing unit 14 provides the dimming control unit 15 with a dimming signal created so that the light output of the light source 11 is 100% of the rating (that is, the light output ratio is 100%). After that, the sensor voltage V <b> 1 input from the amplifier circuit 13 is stored in the memory 16. In short, in the third step, the memory 16 stores the illuminance of the irradiated surface F measured by the illuminance sensor 12 when the light source 11 is rated-lit in the presence of external light.

  After that, as a fourth step, the central processing unit 14 reads the sensor voltages V1 and V0 stored in the memory 16 and sets the light output ratio of the light source 11 to 100% (the light output of the light source 11 in the absence of external light). The sensor voltage V1 ′ is calculated by the calculation of V1 ′ = V1−V0, and the sensor voltage V1 ′ is stored in the memory 16.

  Subsequently, as the fifth step, the central processing unit 14 sets αV1 ′ obtained by multiplying the sensor voltage V1 ′ by a predetermined multiplication factor α to a target value corresponding to a predetermined light output ratio (that is, α as a predetermined light output ratio). The target value corresponding to the predetermined light output ratio is set as αV1 ′) and stored in the memory 16.

  When the setting of the target value is completed, the central processing unit 14 feedback-controls the light output of the light source 11 via the dimming control unit 15 so that the sensor voltage input from the amplifier circuit 13 approaches the target value αV1 ′. To do. That is, the central processing unit 14 creates a dimming signal that increases the dimming rate (light output ratio) of the light source 11 if the sensor voltage is lower than the target value, and the light source 11 if the sensor voltage is higher than the target value. Create a dimming signal that lowers the dimming rate.

  The correspondence relationship between the optical output ratio and the sensor voltage is summarized as shown in FIG. In FIG. 3, the horizontal axis represents the light output ratio, and the vertical axis represents the sensor voltage. Here, the straight line A in FIG. 3 is 2 of the sensor voltage V0 when the light output ratio is 0% in the second step and the sensor voltage V1 when the light output ratio is 100% in the third step. A straight line obtained from a point and showing a correspondence relationship between the light output ratio and the sensor voltage when there is external light. The straight line B represents the sensor voltage V1 ′ obtained by calculation in the fourth step and the sensor obtained in the fifth step. A straight line obtained from two points with respect to the voltage αV1 ′ (that is, a straight line obtained by using the sensor voltage αV1 ′ as a sensor voltage when the light output ratio is α) and the light output ratio and the sensor voltage when there is no external light The correspondence relationship is shown. In the above-described straight line A, the light output ratio of the light source 11 is changed in two steps of 0% and 100%, but it is not limited to two steps, and may be at least two steps.

  By the way, when the light source 11 is a halogen bulb or an incandescent bulb (incandescent lamp), the luminous flux hardly changes throughout the life of the light source 11 (the luminous flux hardly decreases due to the secular change of the light source 11). For example, a maintenance rate used at the time of lighting design may be adopted. In general, in the case of an exposed type lighting fixture that is used for indoor lighting and uses an incandescent lamp as a light source, a maintenance rate of 0.88 is used. Here, the maintenance rate is generally defined as “average illuminance on the work surface after being used in a lighting facility for a period of time / initial illuminance under the same lighting conditions”.

  The central processing unit 14 is mainly composed of a microcomputer and includes an A-D converter for converting the output value of the amplifier circuit 13 into a digital value (that is, analog-digital conversion). The upper limit of the input of the A-D converter is 5V, and the lower the voltage when the light output of the light source 11 is 100% of the rating, the lower the resolution becomes, and the brightness (illuminance) per bit becomes lower. It gets bigger. Therefore, the amplifier circuit 13 uses a gain whose gain is variable in a plurality of stages (in this embodiment, 5 stages), and the sensor voltage exceeds 5 V when the light output ratio is 100% in the third step described above. The gain in the amplifying circuit 13 is selected so as to be a value close to 5 V in a non-existing range.

  More specifically, the amplification circuit 13 can select five gains, and the central processing unit 14 performs amplification in a state where the light output ratio of the light source 11 is 0% in the second step described above. The gain of the circuit 13 is sequentially changed, and sensor voltages amplified by the respective gains are stored in the memory 16 as V01, V02, V03, V04, and V05, respectively.

  Further, in the third step, the central processing unit 14 sequentially changes the gain of the amplifier circuit 13 in a state where the light output ratio of the light source 11 is 100%, and the sensor voltage amplified by each gain is set to V11. , V12, V13, V14, V15 are stored in the memory 16.

  Here, the correspondence relationship between the optical output ratio and the sensor voltage is as shown in FIG. 4, and the correspondence relationship when the amplification circuit 13 is set to the largest gain G1 among the five gains G1, G2, G3, G4, and G5 is as follows. In the figure, the correspondence when C1, the second largest gain G2 is C2, and the correspondence when the third largest gain G3 is C3, the fourth largest gain G4. If the corresponding relationship is C4 in the figure and C5 in the figure is the fifth largest gain G5, the sensor voltage V1 when the light output ratio is 100% is assumed. The sensor voltage V13 having the maximum value in a range not exceeding 5V is stored as the sensor voltage V1.

  In the fourth step, the central processing unit 14 reads the sensor voltages V03 and V13 as the sensor voltages V0 and V1, and the sensor voltage when the light output of the light source 11 is set to 100% of the rating in the absence of external light. V1 ′ is calculated by the calculation of V1 ′ = V1−V0, and the sensor voltage V1 ′ is stored in the memory 16.

  In the luminaire A of the present embodiment described above, the target value setting operation described above is automatically performed by the luminaire A when the power is turned on. Therefore, in a general office, the target value is set almost every day. Done. Therefore, in the lighting fixture A of this embodiment, even if there is external light, the correspondence between the light output ratio of the light source 11 and the output value of the illuminance sensor 12 in a state where there is no external light is accurately obtained. Since the target value is set every time the power is turned on, and the target value is set every time the power is turned on, the illuminance of the irradiated surface F is changed even if the reflectance of the irradiated surface F changes due to a layout change or the like. Can be prevented, and the illuminance of the irradiated surface F can be kept substantially constant (keep appropriate illuminance).

  Further, in the lighting fixture A of the present embodiment, in the process from when the power is turned on until the correspondence is obtained, the light source 11 is controlled to have no light output and the output value of the illuminance sensor 12 is read. Since the light source 11 is controlled to have a light output and the output value of the illuminance sensor 12 is read and the above correspondence is obtained, the room is brightened by the light output of the light source 11 after the power is turned on, and then the room is temporarily darkened. Therefore, it is possible to give the occupant an impression that does not replace the normal lighting, and to avoid feeling uncomfortable.

(Embodiment 2)
By the way, in the lighting apparatus having the conventional configuration shown in FIG. 8, the target illuminance is set to the illuminance when the light output ratio of the light source is set to 70% of the rating. If the target illuminance is changed in about one day, there is no difference in the luminous flux of the light source and the illuminance of the irradiated surface when the light source is lit at the rated value, but the light source is accumulated like a fluorescent lamp If the light source changes the relationship between light output and power consumption according to the lighting time, when the setting is changed after the cumulative lighting time reaches several thousand hours, the luminous flux of the light source is larger than that at the beginning of lighting. Since it is decreasing, the target illuminance becomes lower than before the setting is changed. In addition, the phenomenon in which the target illuminance after the cumulative lighting time reaches several thousand hours in this way is lower than the target illuminance at the beginning of lighting also occurs in the lighting fixture A of the first embodiment.

  On the other hand, FIG. 7 shows the change in illuminance (change in the luminous flux of the light source) according to the cumulative lighting time when the power consumption is constant regardless of the cumulative lighting time for a general lighting fixture using a fluorescent lamp as the light source. It is a figure to explain, and the horizontal axis represents the cumulative lighting time of the light source, and the vertical axis represents the ratio of the illuminance to the initial illuminance and the ratio of the power consumption to the rated power consumption. In a general lighting fixture using a fluorescent lamp as a light source, the luminous flux of the light source decreases according to the luminous flux decay curve as the cumulative lighting time increases, and the luminous flux decreases to about 70% of the initial luminous flux at the end of the life of the light source. Therefore, when the layout design of the lighting fixture is performed with the illuminance at the end of the life as the design illuminance, the illuminance on the irradiated surface becomes excessively large at the beginning of lighting.

  The basic configuration of the lighting fixture A of the present embodiment is the same as that of the first embodiment, and the multiplication rate (that is, a predetermined light output ratio) α multiplied by the sensor voltage V1 ′ in the fourth step described in the first embodiment is set. It is characterized in that it is changed according to the relationship between the cumulative lighting time and the luminous flux decay rate. In short, in the present embodiment, the predetermined light output ratio is such that the illuminance of the irradiated surface F can be set to a constant target illuminance regardless of the secular change of the light source 11, and the cumulative lighting time and the luminous flux reduction rate of the light source 11. It is set based on the relationship.

  The point which becomes the above-mentioned characteristic is demonstrated referring the example of FIG. FIG. 5 is a diagram showing a correspondence relationship between the light output ratio of the light source 11 made of a fluorescent lamp and the illuminance of the illuminated surface F. In FIG. The straight line B shows the correspondence after the cumulative lighting time has passed 2000 hours. In FIG. 5, when the illuminance of the irradiated surface F is 1000 lx when the light output ratio is 100% at the beginning of lighting, the target illuminance is the illuminance when the predetermined light output ratio is 70% at the beginning of lighting. In other words (if the above-mentioned multiplication factor α is 0.7), the illuminance of the irradiated surface F is 700 lx (= 1000 × 0.7). Also, assuming that the luminous flux decay rate after 2000 hours of cumulative lighting is 10%, the illuminance of the illuminated surface F when the light output ratio is 100% is reduced to 900 lx (= 1000 × 0.9). Will do. Here, if the predetermined light output ratio (that is, the multiplication factor α) is constant (that is, 0.7), the target illuminance is 630 lx (= 900 × 0.7), which is based on the target illuminance set at the beginning of lighting. Is also reduced by 10%. On the other hand, in order to set the target illuminance to 700 lx as in the initial stage of lighting, the predetermined light output ratio (that is, the multiplication factor α) may be set to 78% (= 700 ÷ 900). In short, the predetermined light output ratio should be increased so that the target illuminance is constant regardless of the luminous flux decline rate in accordance with the increase in luminous flux decline rate (decrease in luminous flux at the rating) accompanying the increase in cumulative lighting time. .

  Therefore, if the reflectance of the irradiated surface F is constant from the beginning of lighting of the light source 11 to the end of its lifetime, the slope of the straight line in FIG. Since the electric power increases as shown in FIG. 6B, αV1 ′ can be kept substantially constant until the end of the life of the light source 11, so that the illuminance of the irradiated surface F is constant as shown in FIG. It can be kept.

Thus, in the lighting fixture A of the present embodiment, the cumulative lighting of the light source 11 is performed so that the predetermined light output ratio allows the illuminance of the irradiated surface F to be a constant target illuminance regardless of aging of the light source 11. Since the target value corresponding to the predetermined light output ratio is set based on the relationship between the time and the luminous flux decay rate, even if the luminous flux at the rated lighting of the light source 11 decreases due to the secular change of the light source 11, The illuminance of the irradiated surface F can be kept substantially constant.

1 is a block diagram illustrating a first embodiment. It is explanatory drawing of the example of installation same as the above. It is operation | movement explanatory drawing same as the above. It is operation | movement explanatory drawing same as the above. FIG. 9 is an operation explanatory diagram of the second embodiment. It is characteristic explanatory drawing same as the above. It is characteristic explanatory drawing of a general lighting fixture. It is a schematic block diagram of the illuminating device which shows a prior art example. It is operation | movement explanatory drawing same as the above.

Explanation of symbols

A lighting fixture 11 light source 12 illuminance sensor 13 amplifier circuit 14 central processing unit 15 dimming control unit 16 memory

Claims (4)

  A light source, an illuminance sensor that measures the illuminance of the illuminated surface illuminated by the light source with reflected light, and a control that controls the light output of the light source so that the illuminance of the illuminated surface is constant based on the output value of the illuminance sensor The control unit changes the light output of the light source every time the power is turned on, and the output value of the illuminance sensor without the light output of the light source and the output value of the illuminance sensor with the light output of the light source And obtaining a correspondence between the light output ratio of the light source and the output value of the illuminance sensor in a state where there is no external light on the irradiated surface, and setting a target value corresponding to a predetermined light output ratio based on the correspondence The light output of the light source is controlled so that the output value of the illuminance sensor becomes a target value.   The relationship between the light output and the power consumption changes according to the cumulative lighting time of the light source, and the predetermined light output ratio makes the illuminance of the irradiated surface constant irrespective of the secular change of the light source. The lighting fixture according to claim 1, wherein the lighting fixture is set based on a relationship between a cumulative lighting time of the light source and a luminous flux reduction rate.   The control unit reads the output value of the illuminance sensor by controlling the light source to have no light output in the process from when the power is turned on until the correspondence is obtained, and then outputs the light source to the light output. The lighting apparatus according to claim 1 or 2, wherein an output value of the illuminance sensor is read under control to obtain the correspondence relationship.   The illuminance sensor outputs an analog voltage value corresponding to the amount of reflected light from the irradiated surface, and the control unit is an amplification circuit that can change a gain for amplifying the output of the illuminance sensor in a plurality of stages. An AD converter that converts an output value of the amplifier circuit into a digital value, and a central processing unit that has a function of setting the target value based on the digital value output from the AD converter, The processing unit changes the gain of the amplification circuit in all stages for each of a state where the light source does not output light and a state where the light source outputs light in the process from when the power is turned on until the correspondence is obtained. The output value of the amplifier circuit is read, and the gain of the amplifier circuit is selected so that the output value of the amplifier circuit becomes the maximum value within the range not exceeding the upper limit value of the input of the AD converter. Lighting device according to any of claims 1 to 3, characterized.

Images