JP2013016693A - Method for selecting led and method for manufacturing led light source unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for selecting an LED mounted on an LED light source unit which aims to suppress variations in LED characteristics while reducing a product cost.SOLUTION: A method for selecting an LED includes: a characteristic value measuring step for measuring a predetermined characteristic value of each LED of an LED group in the vicinity of at least one wavelength of light in a predetermined reference light emission spectrum characteristic as a reference of LED selection; and an LED selecting step for selecting a combination of LEDs from the LED group in which the characteristic value is measured in the characteristic value measuring step so that an average characteristic of complex light emission spectra by a combination fits within a predetermined allowance with respect to the reference light emission spectrum characteristic when light emission spectrum characteristics of a plurality of LEDs are combined.

Description

  The present invention relates to a method for manufacturing an LED (Light Emitting Diode) light source unit and a method for selecting an LED mounted on the LED light source unit.

  With the advent of pseudo-white LEDs and the improvement in luminous efficiency accompanying technological advances, various attempts have been made to commercialize lighting devices using LEDs as light sources. By using an LED as a light source, it is possible to achieve higher energy efficiency than incandescent light bulbs that have been frequently used as a conventional light source, and it is possible to reduce the size and weight of the device and extend its life.

  Unlike a voltage-driven incandescent bulb, the brightness and color tone of an LED are adjusted by controlling the current flowing through the LED. For this reason, a driving circuit suitable for driving the LED, which is different from the driving circuit of the lighting device using the incandescent lamp as the light source, is required. As an LED drive circuit, for example, a resistance type drive circuit is known in which a plurality of series circuits in which a plurality of LEDs and current limiting resistors are connected in series are connected in parallel and driven. In this type of resistance type driving circuit, the value of the current limiting resistance is set so that the rated current flows through the LEDs in the series circuit. There is also known a circuit that drives LEDs at a constant current by connecting a plurality of LEDs and a constant current circuit in series. Patent Document 1 describes a specific configuration example of a drive circuit using a constant current circuit. The drive circuit described in Patent Document 1 has a configuration in which a plurality of LED arrays and a plurality of LED arrays in which constant current drivers for supplying a constant current to each LED are connected in series are connected in parallel.

JP 2004-319583 A

  By the way, since an LED is a semiconductor product manufactured through a complicated process, there are large individual differences in characteristics such as color temperature and luminance. Therefore, in the assembly process of the LED light source unit, various characteristics of the LED are measured, and only the LED that matches the product specification is carefully selected and used, and the other LEDs are not used. However, when such sorting is performed, the yield of LEDs is significantly reduced, and the product cost is significantly increased. On the other hand, even if it is possible to reduce the cost of the product without such sorting, there is a large variation in color temperature, brightness, etc. even though the product is the same, and lighting with the same color tone and color temperature is available. It becomes a product that cannot be an industrial product.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a method of manufacturing an LED light source unit suitable for suppressing variation in LED characteristics while reducing product cost, and the LED light source. It is to provide a method for selecting an LED mounted on a unit.

  An LED selection method according to an embodiment of the present invention that solves the above-described problem is a predetermined reference emission spectral characteristic that is a reference for LED selection, in the vicinity of a wavelength of at least one light, a predetermined LED of each LED of the LED group. When the characteristic value measurement step for measuring the characteristic value and the emission spectrum characteristics of a plurality of LEDs are combined, the average characteristic of the composite emission spectrum by the combination falls within a predetermined allowable value with respect to the reference emission spectrum characteristic. As described above, the method includes an LED selection step of selecting a combination of LEDs from the LED group whose characteristic value is measured in the characteristic value measurement step. The predetermined characteristic value is, for example, the light emission intensity of the LED in the vicinity of the wavelength of at least one light.

  In addition, the LED selection method according to an aspect of the present invention that solves the above-described problem is a composite that combines a classification management step for classifying and managing an LED group into a plurality of chromaticity coordinate sections and LEDs having different chromaticity coordinates. An LED selection step of selecting a combination of LEDs from the LED group classified and managed in the classification management step so that the correct chromaticity coordinates are within a predetermined allowable range with respect to the predetermined target chromaticity coordinates. Is the method.

  According to the LED selection method of the present invention, an LED chip that achieves a desired average emission spectrum characteristic or chromaticity coordinate is selected by effectively using an LED chip having a large variation in characteristics such as chromaticity coordinates. Therefore, it is suitable for the manufacture of an LED light source unit in which variations in color tone and chromaticity coordinates are suppressed as well as cost reduction by improving the yield of LEDs.

  In addition, an LED light source unit manufacturing method according to an embodiment of the present invention that solves the above-described problems includes an LED mounting step of mounting a combination of LEDs selected by the LED selection method on a circuit board in a predetermined layout. It is the method which has.

  According to the method for manufacturing an LED light source unit according to the present invention, an LED light source unit that achieves a desired average emission spectrum characteristic or chromaticity coordinate by effectively using an LED having a large variation in characteristics such as chromaticity coordinates. Therefore, it is possible to suitably achieve both the manufacturing cost of the LED and the suppression of variations in characteristics.

  In the LED mounting step, for example, LEDs having various characteristics related to the combination selected by the above-described LED selection method are mounted evenly and continuously on the circuit board. Therefore, unevenness such as chromaticity coordinates and color tone in the entire LED light source unit due to a mixture of LEDs having different characteristics can be effectively suppressed.

  ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method of the LED light source unit suitable for suppressing the dispersion | variation in the characteristic of LED, reducing a product cost, and the selection method of LED mounted in this LED light source unit are provided.

It is a circuit diagram which shows the structure of the LED light source device which concerns on embodiment of this invention. It is a graph which shows an example of the emission spectrum of the LED chip which concerns on embodiment of this invention. It is a figure which shows the flowchart of the manufacturing process of the LED array light source in embodiment of this invention.

  Hereinafter, an LED light source device equipped with an LED light source unit according to an embodiment of the present invention will be described with reference to the drawings.

  FIG. 1 is a circuit diagram showing a configuration of an LED light source device 100 according to an embodiment of the present invention. As shown in FIG. 1, the LED light source device 100 includes a set of an LED array light source 10, a plurality of LED driving units 20, and a current control unit 30. In FIG. 1, symbol VD indicates a power source for the LED array light source 10, and symbol VE indicates a power source for the LED drive unit 20.

  The LED array light source 10 is a light source unit in which a plurality of LED arrays 2 in which a plurality of LED chips 1 emitting white light are connected in series are mounted on a circuit board 3 (dashed line in FIG. 1). The LED chip 1 is, for example, a pseudo white LED chip in which a phosphor having high visual sensitivity that fluoresces yellow and a blue LED (or an ultraviolet light emitting LED) are combined.

Each LED drive unit 20 supplies a drive current to each LED array 2 of the LED array light source 10. Each current control unit 30 is a feedback type constant current circuit that sets a current flowing through each LED drive unit 20 to a predetermined value. Specifically, the current control unit 30 includes a reference voltage setting unit 35 for setting a current value. The reference voltage setting unit 35 includes a variable resistor Rv, and changes the reference voltage by changing the value of the variable resistor Rv. The reference voltage setting unit 35 controls the variable resistor Rv so that the drive current to the LED array 2 of the LED array light source 10 is maintained at a predetermined value. In addition, the current control unit 30 includes an amplifier 31. The amplifier 31 receives the reference voltage set by the reference voltage setting unit 35 as one input, and obtains information on the current value of the LED drive unit 20 connected to the LED array light source 10 from the feedback resistors Rf ₁ and Rf _2. The other input via the feedback circuit.

  Each LED driving unit 20 includes a driving transistor Tr in the current output stage of the amplifier 31. An emitter resistor Re is connected to the emitter of the driving transistor Tr, and a base resistor Rb is connected to the base of the driving transistor Tr. The current value supplied to the LED array light source 10 is detected as a voltage generated across the emitter resistor Re. When the detected voltage value is input to the amplifier 31, the current supplied to the LED array light source 10 is controlled.

  Each LED array 2 of the LED array light source 10 is connected to a driving transistor Tr. The number and pitch of the LED chips 1, the number of LED arrays 2, and the like are appropriately set based on the specifications of the LED light source device 100. The power supply voltage value increases as the number of LED chips 1 connected in series or the number of LED arrays 2 connected in parallel increases. The number of LED chips 1 in series and the number of LED arrays 2 in parallel are desirably set so that the power supply voltage value falls within a predetermined value (for example, 50 to 60 V), for example.

  FIG. 2 is a graph showing an example of an emission spectrum of the LED chip 1 manufactured through a predetermined process under a certain environment. In FIG. 2, the vertical axis represents relative emission intensity (no unit because it is normalized), and the horizontal axis represents wavelength (unit: nm). For example, the LED chip 1 varies in the same lot due to slight variations in characteristics such as emission spectrum and luminance, such as process conditions. In FIG. 2, the emission spectra of the selected products A to C among the already selected products are shown as representatives in order to simplify the drawing. In FIG. 2, the solid line shows the emission spectrum of the selected product A, the broken line shows the emission spectrum of the selected product B, and the dotted line shows the emission spectrum of the selected product C.

  As shown in FIG. 2, the emission spectrum (particularly, the ratio of blue (for example, 440 nm to 450 nm) and yellow (for example, 550 nm to 600 nm)) varies between each of the selected products A to C, so that the color tone (chromaticity coordinates, According to another expression, the color temperature) is different. Conventionally, since LED chips having a color tone that does not satisfy the specifications have not been used, the yield of LEDs is low, leading to a significant increase in product cost. Here, the chromaticity coordinates are coordinates (X, Y) on the well-known CIE chromaticity diagram, and the area around (0.33, 0.33) is defined as white.

<Manufacturing process of LED array light source>
Therefore, in the present embodiment, the LED array light source 10 is manufactured in which variation in characteristics such as chromaticity coordinates is suppressed while using the LED chips 1 having various characteristics. FIG. 3 shows a flowchart of the manufacturing process of the LED array light source 10. For convenience of explanation, each step is abbreviated as “Sn (n is a natural number)” in the description and drawings in this specification.

<S1 in FIG. 3 (LED chip classification / management process)>
In this step, each LED chip 1 is classified and managed for each chromaticity coordinate (in another aspect, emission intensity for each predetermined emission wavelength). The chromaticity coordinates of the emitted light of the LED chip 1 are inspected for each lot as necessary. The LED chips 1 of each lot whose classification is confirmed are classified and managed in predetermined chromaticity coordinate categories. Note that, for example, all the LED chips 1 may be inspected and individually classified into predetermined chromaticity coordinate categories and managed.

  In the present embodiment, the LED chip 1 is a pseudo-white LED chip in which a phosphor that fluoresces yellow and a blue LED are combined. Therefore, the LED chip 1 has emission intensity peaks at wavelengths of around 450 nm and around 600 nm, for example. Here, the closer to the peak wavelength, the larger the difference in emission intensity between products (in another aspect, the difference in chromaticity coordinates). Therefore, the closer the wavelength of the emission intensity to be measured is to the peak wavelength, the easier the classification and management for each chromaticity coordinate. Therefore, in this embodiment, the emission intensity is measured at two points of 450 nm and 600 nm which are peak wavelengths.

  In addition, the measurement point of emitted light intensity is good also as 3 or more points. As the number of measurement points increases, classification and management for each chromaticity coordinate of the LED chip 1 can be performed more precisely and accurately. Also, the emission intensity measurement point may be limited to one point in order to improve work efficiency. Further, the measurement point may have a wavelength different from the above example. Here, measuring the emission intensity of wavelengths around 450 nm and 600 nm is equivalent to measuring the chromaticity coordinates of the emission color of the LED (in another aspect, the emission spectrum), for each wavelength of light. It is easier than measuring the emission intensity. For this reason, the LED chip may be classified and managed by measuring the chromaticity coordinates of the LED chip after previously grasping the correlation between the emission intensity around the wavelength of 450 nm and 600 nm and the chromaticity coordinates of the light.

<S2 in FIG. 3 (LED chip selection process)>
In this step, the LED chip 1 mounted on the circuit board 3 is selected from each LED chip 1 group classified and managed in the predetermined chromaticity coordinates in the step S1 in FIG. For example, when the LED chip 1 is laid out on the circuit board 3 according to a predetermined layout design drawing, chromaticity coordinates (another viewpoint) that integrate individual light (an emission spectrum in another aspect) emitted by each LED chip 1. Then, the LED chip 1 is selected so that the emission spectrum) falls within an allowable range based on a predetermined chromaticity coordinate as a target.

  For example, consider a case where the predetermined chromaticity coordinate condition is a chromaticity coordinate corresponding to the reference emission spectrum D (a chain line in FIG. 2). In such a case, if only the LED chip 1 having the characteristics of the selected product A is laid out on the circuit board 3, the chromaticity coordinates of the LED array light source 10 greatly deviate from the chromaticity coordinates corresponding to the reference emission spectrum D, resulting in a defective product. . Similarly, when only the LED chip 1 having the characteristics of the sorted product B or C is laid out on the circuit board 3, the chromaticity coordinates corresponding to the reference emission spectrum D are greatly different from the chromaticity coordinates of the LED array light source 10. Become a product. However, for example, when the LED chips 1 having the characteristics of the sorted products A and B are alternately laid out on the circuit board 3, the chromaticity coordinates of the LED array light source 10 as a whole are the individual LED chips 1 of the sorted products A and B. It is a composite that combines the chromaticity coordinates of the light of (the coordinate value obtained by mixing and averaging the light of the LED chips 1 of the selected products A and B), and close to the chromaticity coordinates corresponding to the reference emission spectrum D Become.

  Therefore, in this embodiment, each selection is performed so that the chromaticity coordinates of the LED array light source 10 as a whole are chromaticity coordinates that fall within a predetermined allowable tolerance with the chromaticity coordinates corresponding to the reference emission spectrum D as the median value. The combination of the LED chips 1 of the products A to C is determined.

<S3 in FIG. 3 (LED chip mounting process)>
In this process, from the combination of the LED chips 1 of the selected products A to C determined in the step S2 of FIG. 3 and the specifications of the LED array light source 10 to be produced, the LED chips 1 of the selected products A to C are processed. Calculate the required number. Next, the layout of each of the LED chips 1 of the selected products A to C in a predetermined block is such that the arrangement of the LEDs of the selected products A to C in each block is evenly distributed, and the color unevenness of the LEDs is minimized. It is determined. On the circuit board 3, the LED chips 1 are laid out and mounted in units of blocks. Thereby, the LED array light source 10 is completed.

  By laying out the LED chips 1 in predetermined block units, a specific arrangement pattern is continuous over the entire light emitting region of the LED array light source 10 for the plurality of types of LED chips 1 of the sorted products A to C. Therefore, uneven distribution of chromaticity coordinates in the entire LED array light source 10 due to the mixture of LED chips 1 having different chromaticity coordinates can be effectively suppressed.

  In the present embodiment, attention is paid to individual differences in characteristics such as chromaticity coordinates of emitted light of the LED chip 1, and the LED chip 1 that has not been used in the past and has a large variation in chromaticity characteristics is effectively used to obtain a desired color. The LED array light source 10 that satisfies the degree coordinate and the color tone condition is manufactured. In other words, according to the present embodiment, the product cost is reduced by breaking the technical common sense in the relevant field at the time of filing this patent for effectively utilizing the inherent problem (variation in color tone and chromaticity coordinates) inherent in the LED chip 1. A method of manufacturing the LED array light source 10 suitable for suppressing variations in chromaticity coordinates while suppressing an increase in the chromaticity coordinates is provided.

  The above is the description of the embodiment of the present invention. The present invention is not limited to the above-described configuration, and various modifications can be made within the scope of the technical idea of the present invention. For example, the LED chip 1 is not limited to the pseudo white LED chip of the present embodiment, and may be replaced with another form of white LED chip such as an RGB three-color LED chip. Further, the LED array 2 laid out on the circuit board 3 is not limited to a plurality of columns and may be only one column.

DESCRIPTION OF SYMBOLS 1 LED chip 2 LED array 3 Circuit board 10 LED array light source 20 LED drive part 30 Current control part 100 LED light source device

Claims (5)

A characteristic value measuring step for measuring a predetermined characteristic value of each LED of the LED group in the vicinity of the wavelength of at least one light in a predetermined reference emission spectrum characteristic which is a reference for selecting the LED;
When the emission spectrum characteristics of a plurality of LEDs are combined, the characteristic value is measured so that the average characteristic of the composite emission spectrum by the combination falls within a predetermined allowable value with respect to the reference emission spectrum characteristic. An LED selection step of selecting a combination of the LEDs from the LED group;
An LED selection method.   The LED selection method according to claim 1, wherein the characteristic value is a light emission intensity of the LED in the vicinity of a wavelength of the at least one light. A classification management step for classifying and managing the LED group into a plurality of chromaticity coordinate categories;
A combination of LEDs is selected from the group of LEDs that are classified and managed so that a composite chromaticity coordinate obtained by combining LEDs having different chromaticity coordinates is within a predetermined allowable range with respect to a predetermined target chromaticity coordinate. An LED selection step to select;
An LED selection method. The manufacturing method of an LED light source unit which has the LED mounting step which mounts LED of the combination selected by the LED selection method as described in any one of Claim 1 to 3 on a circuit board with a predetermined | prescribed layout.   In the LED mounting step, the LEDs having the respective characteristics related to the combination selected by the LED selection method according to any one of claims 1 to 3 are mounted on the circuit board continuously and evenly. The manufacturing method of the LED light source unit of Claim 4.

Images