JP2016131068A - Lighting-controlled illumination device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a low-cost lighting-controlled illumination device that can perform such rendering lighting control that the brightness varies naturally for human visibility.SOLUTION: Brightness data for setting gradation of brightness are stored in a brightness data table 23a. Index data for specifying the brightness data of the brightness data table 23a in a predetermined time-sequence for rendering lighting control are stored in the index data table 23b to be arranged time-sequentially. A control circuit 20 successively reads out the time-sequential index data from the index data table 23b every PWM period, and the brightness data are read out from the brightness data table 23a according to the specification of the read-out index data, and a lighting control signal based on a PWM mode for performing lighting control on an LED 40 is generated on the basis of the read-out brightness data. A driving circuit 30 controls power to be supplied to the LED 40 on the basis of the lighting control signal of the control circuit 20 to turn on the LED 40.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a dimming illumination device.

  Patent Document 1 discloses a light source having a plurality of emission colors, a dimmer that controls each light source to an arbitrary dimming level, a storage unit that stores the dimming amount of each light source as bit data, and a storage unit And a dimming signal converter that converts bit data from the dimming signal into a dimming signal, and in a variable color lighting device capable of changing the color temperature of the illumination light by mixing the light colors of the light sources, the dimming of each light source A dimming characteristic converter that outputs the dimming signal by analog processing so that the dimming ratio change width is small when the level is low and the dimming ratio change width is large when the dimming level is high A variable color illumination device provided between a dimming signal converter and a dimmer is disclosed.

  In Patent Document 2, the illumination is adjusted using a dimming curve in which the relationship between the adjustment amount for adjusting the amount of light and the logarithmic value of the physical intensity of light is a quadratic function, so A light amount adjusting device is disclosed in which the visual perceptual light amount and the adjustment amount of illumination are linearly related by smoothly changing.

  In Patent Document 3, the stimulus amount and sensory amount are corrected using Stevens's law or Weber-Fechner's law for the desired brightness change of the light emitting diode, and light emission is performed based on the correction result. A light emitting diode control method for controlling a change in luminance of a diode with time is disclosed.

  In Patent Document 4, in an LED dimming illumination system that dimmes an LED (Light Emitting Diode) using a pulse width modulation (PWM) method, the brightness gradation is set to 10 to 12 bits (bits). By doing so, a technique has been disclosed in which the rate of change in the amount of light emission is reduced in the vicinity of the light-off region of the LED to achieve visually continuous light control.

JP-A-6-96871 Japanese Patent Laid-Open No. 9-139289 JP 2004-273522 A JP 2009-259598 A

  Conventionally, in dimming control of a dimming lighting device, when performing dimming by changing the brightness arbitrarily over time, the change in brightness is referred to as a microcomputer (hereinafter referred to as “microcomputer”). The technology of controlling by the following two methods is known.

Method 1: A method using a data table listing brightness with respect to the elapsed time from the start time of effect dimming. In this method, the microcomputer reads brightness data corresponding to the elapsed time from the data table, and controls dimming based on the data.
The techniques of Patent Document 1 and Patent Document 4 use Method 1.

Method 2: A method of functionalizing brightness with respect to an elapsed time from the start time of effect dimming. In this method, the microcomputer calculates brightness data corresponding to the elapsed time using a function set in advance, and controls dimming based on the data.
The techniques of Patent Document 2 and Patent Document 3 use Method 2.

In Method 2, since the function calculation process is performed, it is necessary to increase the storage capacity of a RAM (Random Access Memory) included in the microcomputer.
In Method 2, it is necessary to increase the processing performance of a CPU (Central Processing Unit) included in the microcomputer in order to ensure a sufficient processing speed of the function calculation.
For this reason, Method 2 has a drawback that it is difficult to realize with a low-performance and inexpensive microcomputer, and that the cost of the dimming lighting device is increased by using a high-performance and expensive microcomputer.

  In Method 1, compared with Method 2, the RAM storage capacity is small and the CPU processing performance is low. Therefore, a low-performance and inexpensive microcomputer can be used, and the dimming lighting device can be manufactured at low cost. Can be

However, in Method 1, since the data table is stored in a PROM (Programmable Read Only Memory) included in the microcomputer, it is necessary to increase the storage capacity of the PROM in order to lengthen the effect dimming time.
Therefore, in the method 1, when extending the time of effect dimming, it is necessary to use a microcomputer having a large storage capacity and an expensive PROM, and there is a problem that the cost of the dimming lighting device increases.
Note that when there are a plurality of sets of effect dimming patterns, the total time of each pattern becomes the total time of effect dimming, so the problem becomes more prominent.

  For example, when the PWM period of the microcomputer is 10 msec (PWM frequency is 100 Hz) and the PWM resolution is 14 bits, the storage capacity M of the data table necessary for effect dimming for 10 seconds can be obtained by the following equation.

    M = 10 sec ÷ 10 msec × 14 bit ÷ (8 bit × 1024) = 1.7 kbyte

When the microcomputer includes a 14-bit CPU (1 word = 14-bit microcomputer), 1.7 kbytes corresponds to 1000 words (words).
In general, since the storage capacity of a PROM provided in an inexpensive microcomputer is at most about 2000 words, when the storage capacity M of the data table is 1000 words, the data table occupies half of the storage capacity of the PROM, and the remaining PROM Since the control program for dimming control must be stored in the storage capacity, it is difficult to create the control program.

By the way, in the technique of Patent Document 1, the dimming signal conversion unit converts bit data from the storage unit into a dimming signal, and the dimming characteristic conversion unit performs analog processing.
Therefore, it is considered that the dimming signal is an analog signal, and the dimming signal conversion unit includes a D / A (Digital-to-Analog) conversion circuit.
Here, since the D / A conversion circuit is expensive, there is a problem that the variable color illumination device of Patent Document 1 is also expensive.

In addition, since the dimming characteristic converter performs analog processing, the dimmer does not dimm the light source using the PWM method, but the dimmer controls the current value supplied to the light source. It is thought that dimming control is performed using this method.
Although a specific example of the light source is not described in Patent Document 1, when the light source is an LED, the light emission wavelength of the LED changes when the current value changes. Therefore, if the light emission wavelength is not desired to be changed, the PWM method is preferable.

As disclosed in Patent Documents 2 to 4, it is known that the lower the brightness of the human eye, the more sensitive it is to changes in brightness.
Therefore, if the dimming ratio is simply changed as in the technique of Patent Document 1, if the dimming ratio change width is too large, the brightness change may be felt greatly, and the dimming quality may be degraded. is there. In addition, when the dimming ratio change width is too small, excessive light amount data is required, which may increase the cost due to over-spec and decrease the dimming processing speed.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a dimming lighting device capable of effect dimming in which brightness changes naturally to human eyes at low cost. is there.

  As a result of intensive studies in order to solve the above-mentioned problems, the present inventors have arrived at each aspect of the present invention as follows.

<First aspect>
The first aspect is
A light source;
A brightness data table in which brightness data for setting brightness gradation is stored;
An index data table in which index data for specifying brightness data of the brightness data table in a predetermined time series for effect dimming is stored in time series;
The time-series index data is sequentially read from the index data table every PWM cycle, the brightness data is read from the brightness data table according to the designation of the read index data, and the light source is adjusted based on the read brightness data. A control circuit for generating a PWM dimming signal for light;
The light control signal generated and output by the control circuit is demodulated by the PWM method to obtain the duty ratio that is the light control data, and the power supplied to the light source is controlled based on the duty ratio to turn on the light source A dimming illumination device including a driving circuit for driving.

In the method 1, the brightness data is stored in the brightness data table in a predetermined time series for effect dimming without using the index data and the index data table.
On the other hand, since the index data and the index data table are used in the first aspect, the brightness data is set finely when the brightness of the light source is low, corresponding to the sensory value for the brightness of the human eye. When the brightness of the light source is high, the brightness data table is set coarsely, so that the storage capacity of the brightness data table can be greatly reduced as compared with the method 1.

Further, in the first aspect, the number of brightness data can be reduced as compared with the method 1, so that the data amount of the index data for designating the brightness data is reduced and the brightness is increased. The total storage capacity of the data table and the index data table can be made smaller than the storage capacity of the brightness data table in the method 1.
Therefore, in the first aspect, even when the time of effect dimming is lengthened, since a microcomputer with a small storage capacity can be used to store each data table, the brightness naturally changes in human appearance. Therefore, a dimming illumination device capable of effect dimming can be provided at low cost.

<Second aspect>
According to a second aspect, in the first aspect, the control circuit includes a microcomputer, the brightness gradation is set to be smaller than the PWM resolution of the microcomputer, and the ratio of the sensory value to the brightness of the human eye is It is set to be almost equally divided.
According to the second aspect, the action and effect of the first aspect can be obtained with certainty.

<Third aspect>
In a third aspect, in the first aspect or the second aspect, the data amount of the index data is smaller than the data amount of one word in the index data table.
In the third aspect, since the usage efficiency of the index data table can be increased, the operation and effect of the first aspect can be obtained with certainty.

<Fourth aspect>
In a fourth aspect according to the third aspect, the data amount of one word in the index data table is a multiple of the data amount of the index data.
According to the fourth aspect, the action and effect of the third aspect can be obtained with certainty.

<5th aspect>
The fifth aspect is that in the second to fourth aspects, the brightness gradation is such that the ratio of the sensory value to the brightness of the human eye is almost equally divided using Stevens' power law. Is set.
According to the fifth aspect, the operations and effects of the second to fourth aspects can be obtained with certainty.

<Sixth aspect>
In a sixth aspect, in the second to fifth aspects, the PWM resolution of the microcomputer is 10 bits or more, and the data amount of the index data is 6 bits or more.
According to the sixth aspect, the operations and effects of the second to fifth aspects can be obtained with certainty.

The block diagram which shows the structure of the light control lighting apparatus 10 of one Embodiment which actualized this invention. FIG. 2A is an explanatory diagram illustrating an example of the configuration of the brightness data table 23a stored in the PROM 23 of the control circuit 20 included in the dimming / lighting device 10. FIG. 2B is an explanatory diagram showing an example of the configuration of the index data table 23 b stored in the PROM 23. Explanatory drawing which shows an example of the table calculation result for setting the brightness data table 23a memorize | stored in PROM23. 4A is an explanatory diagram showing another example of the configuration of the brightness data table 23a stored in the PROM 23 of the control circuit 20 included in the dimming / lighting device 10. FIG. FIG. 4B is an explanatory diagram showing another example of the configuration of the index data table 23 b stored in the PROM 23.

As shown in FIG. 1, the dimming / lighting device 10 of this embodiment includes a control circuit 20, a drive circuit 30, an LED 40, and the like.
The control circuit 20 is configured by a known microcomputer system including a CPU 21, RAM 22, PROM 23 (brightness data table 23a, index data table 23b), input / output device (I / O) 24, and the like.
The control circuit 20 loads a computer program of software stored (recorded) in the PROM 23 onto the CPU 21 and executes various arithmetic processes according to the computer program, thereby performing operations described later.

By the way, the computer program is not a PROM 23 but an external recording device (not shown) having a backup RAM (not shown) built in the control circuit 20 and a computer-readable recording medium (for example, a semiconductor memory, an optical disk, a hard disk, etc.) The computer program may be recorded (stored) in an external storage device, and the computer program may be loaded into the CPU 21 from a backup RAM or an external recording device as needed.
Alternatively, the control circuit 20 may be connected to an Internet line (not shown), and the computer program may be loaded from the Internet line to the CPU 21 as necessary.

The PROM 23 of the control circuit 20 stores a brightness data table 23a and an index data table 23b.
The brightness data table 23a stores “brightness data” which is a data value for setting the gradation of brightness (light emission brightness) (state in which brightness varies in stages).
In the index data table 23b, "index data" that is data values for designating the brightness data of the brightness data table 23a in a predetermined time series for effect dimming is stored in time series. .

  The control circuit 20 sequentially reads time-series index data from the index data table 23b every PWM cycle, reads brightness data from the brightness data table 23a in accordance with the designation of the read index data, and reads the read brightness data. Based on the above, a PWM dimming signal S for dimming the LED 40 is generated.

  The drive circuit 30 demodulates the dimming signal S generated and output by the control circuit 20 by the PWM method to obtain a duty ratio (demodulation result) that is dimming data, and is supplied to the LED 40 based on the duty ratio. The LED 40 is driven to turn on by controlling the electric power.

As a result, the brightness of the LED 40 changes with time based on the brightness data read from the brightness data table 23a corresponding to the index data stored in time series in the index data table 23b. Light is done.
Here, the index data stored side by side in the index data table 23b is a pattern of effect dimming.
Therefore, in order to change the effect dimming pattern, it is only necessary to change the index data stored in the index data table 23b, and it is not necessary to change the brightness data stored in the brightness data table 23a.

Further, by storing a plurality of sets of time-series index data in the index data table 23b, a plurality of effect dimming patterns corresponding to each set of time-series index data can be set.
In this case, if an input device (not shown) is used and the start address of each set of time-series index data is designated to the control circuit 20, the time-series index data in the designated group is sequentially read out. The effect dimming pattern corresponding to the designated set is executed.

In the following description, as a specific example of the microcomputer specification of the control circuit 20, the PWM cycle is 10 msec (PWM frequency is 100 Hz), the PWM resolution is 10 bits, and the CPU 21 is a 14-bit CPU and 1 word = 14 bits.
The gradation of brightness is 7 bits (= 128 ways).
And the duration of effect dimming is between 10 seconds.

[Configuration of Brightness Data Table 23a and Index Data Table 23b and Operation of Control Circuit 20]
As shown in FIG. 2A, the brightness data table 23a stored in the PROM 23 stores 128 pieces of brightness data corresponding to 7 bits (= 128) which are brightness gradations. ing.
Here, since the CPU 21 is a 14-bit CPU and 1 word = 14 bits and each ROM address of the PROM 23 is 1 word, one brightness data corresponds to one ROM address, and one brightness data is One word (= 14 bits).
Therefore, 128 pieces of brightness data are 128 words.

In the example shown in FIG. 2A, brightness data = 0 at the ROM address start address “XXX”, brightness data = 1 at the ROM address “XXXXXX”, and ROM address “XXX”. Brightness data = 2 in...,... Brightness data = 949 in ROM address "OOOO + 125", brightness data = 987 in ROM address "OOOO + 126", ROM address "OO. Brightness data = 1023 is stored in “OO + 127”.
A specific method for setting brightness data will be described later.

As shown in FIG. 2B, the index data table 23b stored in the PROM 23 has a division value (= 10 sec ÷ 10 msec) obtained by dividing the effect dimming time (= 10 sec) by the PWM cycle (= 10 msec). 1000 index data corresponding to is stored in time series.
Here, since the index data designates one piece of brightness data from among 128 pieces (= 7 bits) of brightness data, one piece of index data is 7 bits.
Further, since the CPU 21 is a 14-bit CPU and 1 word = 14 bits and each ROM address of the PROM 23 is 1 word, two index data are set in one ROM address, and one index data is 0.5 word ( = 7 bits).
Therefore, 1000 pieces of index data are 500 words.
Therefore, the total storage capacity of the data tables 23a and 23b of the PROM 23 is 628 words (= 128 words + 500 words).

In the example shown in FIG. 2B, the upper 0.5 word (= 7 bits) of the start address “ΔΔΔΔ” of the ROM address is set to index data = 0 and the lower 0.5 word of the start address “ΔΔΔΔ”. Index data = 2, index data = 5 in the upper 0.5 word of ROM address “ΔΔΔΔ + 1”, index data = 8 in the lower 0.5 word of ROM address “ΔΔΔΔ + 1”, ROM address “ΔΔ” Index data = 12 in the upper 0.5 words of "△△ + 2", index data = 20 in the lower 0.5 words of the ROM address "△△△△ + 2", ... ROM address "△△△△ + □□" The upper 0.5 words of the index data = 120, the lower 0.5 words of the ROM address “△△△△ + □□”, the index data = 123, and the ROM address of “△△△△ + □□ + 1” Index data = 125 at the 0.5th place, index data = 127 at the lower 0.5 word of the ROM address “ΔΔΔΔ + □□ + 1”, and the upper 0.5 word at the ROM address “ΔΔΔΔ + □□ + 2” Index data = 127, and index data = 127 is stored in the lower 0.5 words of the ROM address “ΔΔΔΔ + □□ + 2”.
Here, since the index data designates the brightness data of the brightness data table 23a, it corresponds to the ROM address of the brightness data table 23a.

The control circuit 20 reads the index data stored in the time series in the index data table 23b for each PWM cycle in the order of the time series.
That is, in the example shown in FIG. 2B, the index data is read in the order of 0 → 2 → 5 → 8 → 12 → 20 →... 120 → 123 → 125 → 127 → 127 → 127.

The control circuit 20 reads the brightness data of the ROM address corresponding to the read index data from the ROM address of the brightness data table 23a every PWM cycle.
That is, in the example shown in FIG. 2, the brightness data = 0 of the start address “XXX” of the ROM address corresponding to the index data = 0 is read in the first PWM cycle, and the second PWM cycle In addition, the brightness data = 2 of the ROM address “◯◯◯◯ + 2” corresponding to the index data = 2 is read,..., The ROM address “◯◯ corresponding to the index data = 125 in the 997th PWM cycle. Brightness data = 949 of “XXX + 125” is read out, and brightness data = 1023 of the ROM address “XXXXX + 127” corresponding to the index data = 127 is read out in the 998th PWM cycle, In the 999th PWM cycle, the brightness data = 1023 of the ROM address “◯◯◯◯ 127” corresponding to the index data = 127 is read. Issued, the PWM period of the 1000th, the ROM address "OOOO + 127" Brightness data = 1023 corresponding to the index data = 127 is read, rendering the light control is ended.

[Setting Method of Brightness Data Table 23a]
In order to set 7-bit (= 128) brightness data for 10-bit (= 1024) PWM resolution, a sensory value for the brightness of human eyes is obtained.
Here, Stevens' power low is known as a law representing the relationship between the actual size of a physical stimulus and the strength at which it is perceived.
In Stevens' power law, as a condition for stimulating luminance (brightness), the function index is set to 0.33 for a 5 ° target in the dark, and this setting is the dimming function of this embodiment. It is suitable for the lighting device 10.

Therefore, in the example illustrated in FIG. 3, a sensory value having a multiplier of 0.33 is calculated for 10-bit PWM control value = 0 to 1023.
In addition, about 0.33 power, it describes as "^ 0.33" using symbol "^".
For example, for PWM control value = 2, the sensory value is 2 ^ 0.33≈1.2557013375.
Further, for the PWM control value = 1023, the sensed value is 1023 ^ 0.33≈9.84980224.

In order to set the brightness data, it is necessary to appropriately select 128 kinds of brightness data from 1024 kinds of PWM control values = 0 to 1023 so that the ratio of the sensory values becomes substantially equal.
For this purpose, a general commercial spreadsheet software macro program is used and, as shown in FIG. 3, if the calculation result of the ratio of sensory values is displayed as a list, the designer of the dimming lighting device 10 can be selected from the list display. However, it is possible to easily select optimal brightness data by visual inspection.
In the example shown in FIG. 3, it has been found that the value of the PWM control may be selected so that the ratio of the sensory values becomes the provisional value = 1.013 to 1.014.
The dimming / lighting device 10 does not select the PWM control value after the provisional determination value is determined first, but selects the brightness data of 128 ways by roughly dividing the ratio of the sensory values. The designer of [5] selects the optimum brightness data by cut-and-try while repeating the operation of changing the provisional value and recalculating the ratio of the sensory values with spreadsheet software.

First, the value of PWM control = 0 and the value of PWM control = 1 are selected unconditionally regardless of the ratio of sensory values in order to increase the resolution.
Next, the ratio of the sensory value between the PWM control value = 1 and the PWM control value = 2 is 2 ^ 0.33 / 1 ^ 0.33 = 1.257013375, and the provisional value = 1.003 to 1 .014 is greatly exceeded, but with a 10-bit PWM resolution there is no higher resolution, so the value of PWM control = 2 is selected.
Similarly, some PWM control values = 3 to 46 are far from the tentative values = 1.013 to 1.014, but they are unavoidably selected for the same reason.

The ratio of the sensory value between the PWM control value = 46 and the PWM control value = 47 is 47 ^ 0.33 / 46 ^ 0.33 = 1.007122291, and the provisional value = 1.013 to 1.014 Get smaller.
The ratio of the sensory value between the PWM control value = 46 and the PWM control value = 48 is 48 ^ 0.33 / 46 ^ 0.33 = 1.01414376, and the provisional value = 1.003 to 1.014 is obtained. Slightly exceeding, but closer to the provisional value than the ratio of the sensory value between PWM control value = 46 and PWM control value = 47.
Therefore, as shown in FIG. 3, the value of PWM control = 47 is not selected, and the value of PWM control = 48 is selected.

Similarly, when 128 PWM control values having a sensory value ratio close to a provisional value are selected from 1024 PWM control values = 0 to 1023, the selected PWM control value becomes brightness data. (See FIG. 2 (A)).
As shown in FIG. 3, the larger the PWM control value is, the larger the interval between the selected values becomes.

[Operations and effects of the embodiment]
According to the light control lighting device 10 of this embodiment, the following operations and effects can be obtained.

[1] In the method 1, if the microcomputer has a PWM resolution of 10 bits or more, it is possible to achieve effect dimming in which the brightness naturally changes in human appearance, but if the microcomputer has a PWM resolution of 8 bits or less, the brightness changes. The present inventors have experimentally confirmed that is very unnatural.
Further, although the PWM resolution of the microcomputer is required to be 10 bits or more, if the brightness gradation is 7 bits (= 128 ways) or more, the present inventor can realize the effect dimming with a sufficiently natural change in brightness. I thought.

That is, the sense of brightness of the human eye is not directly proportional to the brightness of the LED 40 and is non-linear. As described above, according to Stevens' power law, the brightness (brightness) is 0.33 to the power. .
Therefore, the lower the brightness of the LED 40, the more sensitive the human eye reacts to the change in brightness and feels as a large change in brightness. When the brightness of the LED 40 increases to a certain extent (in the example shown in FIG. 3, PWM control value = brightness data = 48 or more), it becomes difficult for human eyes to perceive the change in brightness.
This means that it is necessary to increase the PWM resolution when the brightness of the LED 40 is low, but it is not necessary to increase the PWM resolution when the brightness of the LED 40 is high.

The PWM resolution of the microcomputer of the control circuit 20 is a fixed value (= 10 bits) and cannot be varied.
Therefore, although the PWM resolution needs to be 10 bits or more according to the case where the brightness of the LED 40 is low, it is not necessary to adjust the brightness data to the PWM resolution, and it is sufficient that the brightness data is 7 bits.

In other words, since the PWM resolution of the microcomputer of the control circuit 20 is linear (equal intervals), it is not compatible with the non-linear human eye perception of brightness.
Therefore, the PWM resolution can only be set when the brightness of the LED 40 is low, which is why it requires 10 bits or more.
However, among 10 bits (= 1024), the resolution is required only when the brightness of the LED 40 is low, and when the brightness of the LED 40 is high, the resolution becomes unnecessarily high.

In this embodiment, the characteristic of the sensory value with respect to the brightness of the human eye is used, and the storage capacity of the brightness data table 23a is greatly reduced compared to the method 1.
That is, since the PWM resolution of the microcomputer of the control circuit 20 is 10 bits, the brightness gradation can be set to 10 bits (= 1024), but the brightness gradation is 7 bits (= 128). By suppressing the storage capacity, the storage capacity of the brightness data table 23a is reduced.

In this embodiment, the index data for designating the brightness data of the brightness data table 23a in a predetermined time series for effect dimming is used. The data amount of the index data is the brightness scale. What is necessary is just to match 7bit which is a key.
Here, since the CPU 21 is a 14-bit CPU and 1 word = 14 bits, and each ROM address of the PROM 23 is 1 word, two index data can be set to one ROM address.

On the other hand, in the method 1, the brightness data is stored in the brightness data table 23a in a predetermined time series for effect dimming without using the index data and the index data table 23b.
Therefore, when the PWM cycle of the microcomputer of the control circuit 20 is 10 msec and the effect dimming time is 10 sec, the storage capacity of the brightness data table 23a needs 1000 words (= 10 sec ÷ 10 msec) in the method 1.
In the present embodiment, as described above, the total value of the storage capacities of the data tables 23a and 23b of the PROM 23 is 628 words, and the storage capacity of the PROM 23 can be reduced by about 37% compared to the method 1, so that the PROM 23 Use efficiency can be increased.

As described above, since the index data and the index data table 23b are used in the present embodiment, the brightness data is finely set when the brightness of the light source is low corresponding to the sensory value for the brightness of the human eye. When the brightness of the light source is high, the storage capacity of the brightness data table 23a can be greatly reduced by setting the brightness data coarsely as compared with the method 1.
In the present embodiment, since the number of brightness data can be reduced as compared with the method 1, the data amount of index data for designating brightness data is reduced, and each data table. The total value of the storage capacities 23a and 23b can be made smaller than the storage capacity of the brightness data table in the method 1.
Therefore, in the present embodiment, even when the effect dimming time is lengthened, since the memory capacity is small and a microcomputer can be used to store the data tables 23a and 23b, the brightness changes naturally to the human appearance. The dimming / lighting device 10 capable of performing effect dimming can be provided at low cost.

  [2] The brightness gradation (= 7 bits or more) is set to be smaller than the PWM resolution (= 10 bits or more) of the microcomputer of the control circuit 20, and the ratio of the sensory value to the brightness of the human eye is substantially equal. Since it is set to be minutes (= 1.013 to 1.014), the operation and effect of [1] can be obtained with certainty.

[3] The data amount of index data (= 7 bits) is smaller than the data amount of one word (= 14 bits) in the index data table 23b, and the data amount of one word in the index data table 23b (the data amount of one word in the CPU 21). Is twice the amount of index data.
Therefore, as described above, two index data can be set in one ROM address of the PROM 23, and the use efficiency of the PROM 23 (index data table 23b) can be increased.

  [4] The gradation of brightness is set so that the ratio of the sensory value to the brightness of the human eye is almost equally divided using Stevens' power law.・ Effects can be obtained with certainty.

<Another embodiment>
The present invention is not limited to the above-described embodiment, and may be embodied as follows, and even in that case, operations and effects equivalent to or higher than those of the above-described embodiment can be obtained.

[A] In the above embodiment, the brightness gradation is set to 7 bits. However, even when the brightness gradation is set to 6 bits, it is possible to realize effect dimming in which the change in brightness is almost natural.
However, when the brightness gradation is set to 5 bits, the change in brightness becomes unnatural.
Further, if the brightness gradation is set to 8 bits, it is possible to realize effect dimming in which the change in brightness of the LED 40 is further naturally changed.

  [B] In the above embodiment, the PWM resolution of the microcomputer of the control circuit 20 is set to 10 bits. However, it may be 10 bits or more, and the brightness change of the LED 40 is more naturally changed as the PWM resolution is increased. Production dimming can be realized.

[C] In the above embodiment, the data amount of 1 word (the data amount of 1 word of the CPU 21) of the index data table 23b is set to 14 bits, and the data amount of the index data is doubled to 7 bits.
However, the data amount of 1 word may be 12 bits or 16 bits or more depending on the microcomputer.
For example, if the data amount of 1 word is a microcomputer of 12 bits, the data amount of index data may be set to 6 bits.

Further, the data amount of 1 word in the index data table may be set to a multiple of 3 times or more the data amount of the index data.
For example, as shown in FIG. 4, when a microcomputer with 1 word data amount of 18 bits is used, the index data amount is set to 6 bits, and three index data are set to one ROM address of the PROM 23. May be.

The data amount of the index data may be set smaller than the data amount of 1 word of the microcomputer, and the data amount of 1 word of the microcomputer is not necessarily set to a multiple of the data amount of the index data.
For example, the data amount of index data may be set to 6 bits or 8 bits for a microcomputer having a data amount of 1 word of 14 bits.

  [D] The LED 40 may be replaced with any light source (for example, a semiconductor light emitting element such as an EL (Electro Luminescence) element, a light bulb, etc.) as long as it can be dimmed with a PWM dimming signal.

  The present invention is not limited to the description of each aspect and the embodiment. Various modifications are also included in the present invention as long as those skilled in the art can easily conceive without departing from the scope of the claims. The contents of publications and the like specified in the present specification are all incorporated by reference.

DESCRIPTION OF SYMBOLS 10 ... Light control lighting apparatus 20 ... Control circuit 21 ... CPU
23 ... PROM
23a ... Brightness data table 23b ... Index data table 30 ... Drive circuit 40 ... LED (light source)

Claims (6)

A light source;
A brightness data table in which brightness data for setting brightness gradation is stored;
An index data table in which index data for designating the brightness data of the brightness data table in a predetermined time series for effect dimming is stored in time series; and
The time-series index data is sequentially read from the index data table every PWM (Pulse Width Modulation) period, and the brightness data is read from the brightness data table in accordance with the designation of the read index data, and the read brightness A control circuit that generates a PWM dimming signal for dimming the light source based on the data;
By demodulating the dimming signal generated and output by the control circuit by a PWM method to obtain a duty ratio which is dimming data, and controlling the power supplied to the light source based on the duty ratio, A dimming illumination device comprising: a drive circuit that drives and turns on the light source. The control circuit is constituted by a microcomputer,
The brightness gradation is set to be smaller than the PWM resolution of the microcomputer, and the ratio of the sensory value to the brightness of the human eye is set to be approximately equal.
The dimming illumination device according to claim 1. The data amount of the index data is smaller than the data amount of one word of the index data table.
The dimming illumination device according to claim 1 or 2. The data amount of one word in the index data table is a multiple of the data amount of the index data.
The dimming illumination device according to claim 3. The brightness gradation is set so that the ratio of the sensory value to the brightness of the human eye is almost equally divided using Stevens' power law.
The light control lighting apparatus as described in any one of Claims 2-4. The PWM resolution of the microcomputer is 10 bits or more,
The data amount of the index data is 6 bits or more.
The light control illumination apparatus as described in any one of Claims 2-5.

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