JP2008066350A - Led color adjusting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an LED color adjusting device which can easily adjust the variation of the light emission of respective LEDs to obtain an optional color when mixing colors emitted from the LEDs of RGB colors to obtain a specified color. <P>SOLUTION: A surface resistor 2 is provided with three fixed electrodes corresponding to LEDs of R, G and B colors at apexes of a triangle, and a slider 3 which has a movable contact S that can move while being in contact with an optional position on the surface resistor 2 is provided. The respective electrodes outputs to the LEDs to adjust their colors according to rates of resistance between R and S, between G and S and between B and S as a resistance value relevant to a distance between the movable contact S and the respective electrodes when applying electricity between the movable contact S and the electrodes RGB. When adjusting colors, a current of each LED is directly controlled by the resistance of the surface resistors, or the conduction of the current control semiconductor of the LED is controlled, or the conduction pulse of the current control semiconductor of the LED is controlled, or storage data of memory data concerning the controlled values of the conduction pulse is used to adjust a color. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an LED color adjustment apparatus for adjusting a light emission to a desired color by using a plurality of LEDs which are semiconductor elements that emit light.

  LEDs (Light Emitting Diodes), which are semiconductor elements that emit light in a predetermined color when an electric current is applied, have a longer life than incandescent and fluorescent lamps, have good visibility, and can be used widely both indoors and outdoors. It is easy to miniaturize and can be freely designed as a lighting fixture. It can be turned on even with low power, has almost no heat rays or ultraviolet rays, and has many advantages such as dimming and blinking. For this reason, in order to enhance the design effect of various electrical products, a variety of illuminations are designed by combining multi-color LEDs with knob illuminations, etc., and they are also used as traffic signals that emit light of a predetermined color. Yes.

  Moreover, such LEDs have come to be used as backlight light sources for LCDs (Liquid Crystal Displays). In other words, the LCD has a structure in which a specific liquid is sealed between two glass plates, an image is displayed by changing the direction of liquid crystal molecules by applying a voltage, and increasing or decreasing the light transmittance. Since the light does not emit light, reflected light of natural light can be used in a bright place, but it is necessary to provide a backlight as a light source for illumination behind in a dark place. Conventionally, cold cathode fluorescent lamps (CCFLs) have been used as backlights for such LCDs, but LEDs have attracted attention as light sources with better color reproducibility and have gradually been used.

  The “whiteness” of the light source is important as the LED used for the backlight of the LCD, and this white color can be obtained by mixing the light of the three types of RGB LEDs. An LED that emits each color is slightly different even in the same color depending on the difference in characteristics that occur during the manufacture of the LED and the current supplied to the LED. Therefore, when three colors emitted from each of the R, G, and B semiconductors are mixed to obtain a white color, there is a large variation in brightness for each manufacturing lot or for each part due to variations in characteristics that occur in the manufacturing process of each semiconductor. Tend. Moreover, even if an LED having very similar characteristics is selected and used, a desired white color cannot be obtained due to the balance of the supply current to each LED.

In order to improve the color unevenness performance of the LED backlight system, an LED module in which R, G, and B LEDs are arranged is arranged symmetrically with respect to the center point of the LCD panel screen, The brightness and chromaticity are detected at the center of the screen, and a color sensor is installed at the center of the screen, and each LED module is adjusted to the same brightness and chromaticity when viewed from the center of the screen based on the detected value. The technique made to do so is disclosed in Patent Document 1.
JP 2006-119268 A

  As described above, LEDs in recent years have been used as light sources in a wide range of fields, and are particularly attracting attention as LCD backlights. Therefore, even if the characteristics of the LCD are almost equal, if the current balance supplied to each LED is different, the whiteness will be different and the color reproducibility of the LCD will be poor. In particular, when the characteristics of the LCD are greatly different, it is necessary to adjust the current supplied to each LED in accordance with the difference in the characteristics to balance the current.

  Adjustment of the current supplied to each LED is performed as shown in FIG. That is, in FIG. 10A, a red LED (R), a green LED (G), and a blue LED (B) are arranged side by side and each emits light to emit light of a mixed color. The current can be supplied from a common power source, a current control element is arranged in the ground circuit portion of each LED extending from the light emitting portion, and the amount of current is controlled by an external signal to cause each LED to emit light in a desired color tone. White or a desired color. For example, when a large amount of light is required as in an LCD backlight, a plurality of LEDs are connected in series for each of R, G, and B to form an R group, a G group, and a B group. By arranging the current control element similar to the above for each group and controlling the amount of current for each group by an external signal, each group of LEDs emits light in a desired color tone, and as a whole, a desired white or other desired color is emitted. Try to be a color.

  The adjustment of the currents of R, G, and B as described above is based on the deviation of the characteristics of the LEDs in the international color space RGB standard having a substantially triangular shape as shown in FIG. Accordingly, the light intensity of each LED is shifted from the outer edge with the highest color saturation to the inside, and the light emission intensity of each LED, that is, the ratio of the light emission intensity of each LED is adjusted. To obtain the desired color within the triangle. By such adjustment, even if there is a variation in the performance of each LED, it is possible to obtain, for example, white located at the center of the triangle by adjusting the amount of current, and also obtain a desired color at a predetermined position of the triangle. be able to.

  In this color adjustment, for example, as shown in FIG. 12 corresponding to the international color space RGB standard in FIG. 11, when only the red LED has a good luminous efficiency or the red LED has too much current, the color balance is lost. The screen becomes reddish white and the white balance is poor. As a correction for that, it is necessary to reduce the amount of light of the “red LED”. In this case, it is only necessary to adjust only red, but blue and green are not necessarily the desired values, so it is necessary to control each current for three LEDs to create “white”. is there. At this time, there is a problem that a high level of technology is required for individual adjustment, and a very long work time is required.

  Such a balance adjustment of the current supplied to each LED of RGB not only becomes a problem when the LED is adjusted to obtain the white color in the backlight of the LCD as described above, but also requires another white color. When using an LED as the light source of a lighting device, the same problem occurs, and in addition to mixing the light of each LED of RGB to obtain white, these colors are mixed to obtain a light of a predetermined color For example, the same problem occurs when used for mood lighting.

  Therefore, the present invention uses LEDs that emit RGB colors and mixes the emission colors of the LEDs to obtain a predetermined color, thereby adjusting variations in the emission color characteristics of the LEDs and variations in the emission intensity of the LEDs. The main object of the present invention is to provide an LED color adjustment device capable of performing accurate color adjustment by a simple operation with a simple device when a desired color is obtained.

  In order to solve the above-described problem, an LED color adjusting device according to the present invention includes a surface resistor including three electrodes corresponding to LEDs of three colors R, G, and B at the apex of a triangle, and the surface. A slider having a movable contact that contacts the resistor and is movable to an arbitrary position, and from each electrode by a resistance value according to the distance between the movable contact and each electrode when the electrode is energized from the movable contact Color adjustment output is performed on each LED.

  According to another LED color adjustment device of the present invention, in the LED color adjustment device, the color adjustment output is a resistance value of a surface resistor, and the current of each LED is directly controlled by the resistance value. Adjustment is performed.

  Another LED color adjusting apparatus according to the present invention is characterized in that, in the LED color adjusting apparatus, the current adjustment semiconductor is energized and controlled by the color adjustment output to perform color adjustment.

  Another LED color adjustment device according to the present invention is characterized in that, in the LED color adjustment device, the color adjustment is performed by controlling the energization pulse of the current control semiconductor of each LED by the color adjustment output. To do.

  In addition, another LED color adjustment device according to the present invention includes storage means for storing the color adjustment output value for each LED in the LED color adjustment device, and each color adjustment output value when color adjustment is performed in advance. Is stored, and color adjustment is performed using the stored output value.

  According to another LED color adjustment device of the present invention, in the LED color adjustment device, a frame having an inner surface that regulates a movable range of the movable electrode is provided on the surface resistor, and at least an inner surface of the frame is provided on the inner surface of the frame. A recess is provided in which the movable electrode or a part of the slider enters corresponding to the position of the three electrodes.

  Further, another LED color adjusting device according to the present invention is characterized in that in the LED color adjusting device, the surface resistor is formed thicker as it goes away from the center.

  Another LED color adjusting device according to the present invention is the LED color adjusting device, wherein the surface resistor is provided on the surface, a case that covers the substrate and has an opening at the center, and the opening. An operation shaft having a movable electrode inserted into the lower end, a movable cover disposed between a stopper fixed to the operation shaft and the back surface of the case, and pressing the movable contact toward the surface resistance side, And a spring for pressing the movable cover against the back of the case.

  Another LED color adjusting apparatus according to the present invention is the LED color adjusting apparatus according to the above-described LED color adjusting apparatus, which includes a movable electrode at an end, an operation shaft that swings back and forth and right and left around a fulcrum, and a locus of the movable electrode. And a sheet resistor formed in a spherical shape.

  Since the LED color adjusting device according to the present invention is configured as described above, when the LEDs emitting light of RGB are used and the emission colors of the LEDs are mixed to obtain a predetermined color, the emission color characteristics of the LEDs are adjusted. When a desired color is obtained by adjusting variations and variations in emission intensity of each LED, accurate color adjustment can be performed by a simple operation with a simple device.

  When mixing the emission colors of LEDs that emit RGB colors to obtain a predetermined color, the problem of easily adjusting the emission variation of each LED to obtain a desired color is given to R, G at the apex of the triangle. , B comprising a surface resistor having three electrodes corresponding to the three colors of LEDs, and a slider having a movable contact that contacts the surface resistor and can be moved to an arbitrary position. This was realized by performing color adjustment output from each electrode to each LED with a resistance value corresponding to the distance between the movable contact when each electrode was energized and each electrode.

  Embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows a basic structure of an LED color adjusting device according to the present invention, which is a two-dimensional surface resistance type that supplies control current to three LEDs of red (R), green (G), and blue (B). The structural example of the potentiometer 1 is shown. In the example of FIG. 1A, a red fixed electrode (R), a green fixed electrode (G), and a blue fixed electrode (B) are provided at three vertices of a sheet resistor 2 indicated by a regular triangle in the figure, and each electrode is provided. Are connected to output lines for controlling currents to the LEDs of the respective colors. A movable electrode 3 that can be moved by a user to an arbitrary position on the surface resistor 2 is provided, and a power source that supplies current to the movable electrode 3 is connected. Depending on the position of the movable contact S that is a contact point, for example, as shown in FIG. 1B, the resistance between R and S by the surface resistor 2 between the movable contact S and each electrode, between G and S, as shown in FIG. Resistance and B-S resistance can be obtained.

  Each electrode of RGB is arranged at the apex of a triangle in such a surface resistor 2, and the movable contact S serving as a movable electrode that supplies current to an arbitrary position on the surface resistance is moved, so that it corresponds to the position. The resistance between the electrodes is obtained, and the resistance value is such that when the position of the movable contact moves to the R side, for example, when the resistance value is decreased and the control current of R is increased, at least one of G and B is correspondingly increased. Alternatively, both resistances can be increased to reduce each control current, the overall control current ratio can be controlled, and the control current to each electrode can be adjusted while maintaining the overall balance. it can. This control current can be used in various ways as will be described later.

  One embodiment is shown in FIG. In the example shown in FIG. 2, the red LED (R), the green LED (G), and the blue LED (B) are arranged side by side and mixed as in the conventional example of FIG. 10 (a). A current can be supplied from a common power source to the light emitting portion 5 that performs illumination of the selected color. Further, the ground circuit portion of each LED extending from the RGB light emitting portion 5 is connected to the RGB fixed electrode on the surface resistance of the two-dimensional surface resistance potentiometer 1 similar to that shown in FIG. The movable electrode S that is in contact with any upper point is installed with a common ground wire.

  As a result, the currents for the LEDs emitting RGB colors are controlled by the R-S resistance, the G-S resistance, and the B-S resistance according to the position of the movable contact S in the surface resistance. For example, when the desired color is white, it is possible to absorb the difference in the light emission characteristics due to the color characteristic difference in the manufacture of each LED and easily adjust to a predetermined white color. This operation can be performed in the same way when a desired color is obtained by the light emission of the three LEDs. In this case, the desired color is placed close to and easily adjusted to match the color. That adjustment can be made. This mode is a method that uses the basic principle of the present invention almost as it is, and can be adopted as the simplest method when the entire LED has a small current.

  Still another control mode is shown in FIG. In the embodiment shown in FIG. 3, the same two-dimensional surface resistance potentiometer 1 as described above is used, and a current can be supplied from the power source to the movable electrode S. Each adjustment voltage can be output through a resistor, and this voltage is connected to each base of current control transistors Tr.B, Tr.R, and Tr.G as current control semiconductors. Thereby, the current of each RGB LED can be controlled by the current control transistor according to the position of the movable contact S of the two-dimensional surface resistance potentiometer 1.

  This control mode is effective in the case of a medium-current LED that supplies more current to all LEDs than in the mode of FIG. 2, and less current flows through the two-dimensional surface resistance potentiometer 1 than the mode shown in FIG. Can be reduced in size. In addition, this adjustment operation can be performed at an arbitrary position away from the position where the LED is placed.

  Still another control mode is shown in FIG. In the embodiment shown in FIG. 4, the two-dimensional surface resistance potentiometer 1 is used in the same manner as described above, and the analog adjustment voltage output is digitized using the adjustment voltage output method shown in FIG. 3, and PWM (Pulse Width Modulation) control is performed. Are respectively input to the pulse control circuit 6 that performs the above-described operations, and pulses having different energization widths are output in accordance with the RGB adjustment voltages. In the example shown in FIG. 4, as in the case of FIG. 10B, when a large amount of light such as an LCD backlight is required, a plurality of LEDs are connected in series for each R, G, and B, respectively. A pulse having a predetermined width is output from the pulse control circuit 6 for each of the transistors Tr.R, Tr.G, and Tr.B that configures the R group, the G group, and the B group, and controls the current of each group.

  The control pulse output from the pulse control circuit 6 may be controlled by the number of times a pulse having a predetermined width is output in a fixed time, in addition to controlling the energization width of the pulse output in a fixed cycle. By controlling the amount of current for each group of RGB by such pulse control, each group of LEDs emits light in a desired color tone, and as a whole, a desired color such as white is obtained. This control mode is particularly effective in the case of a high-current LED that supplies more current to all LEDs than in the mode of FIG.

  Yet another control mode is shown in FIG. The embodiment shown in FIG. 5 includes a microcomputer control circuit 7 that performs A / D conversion and PWM control similar to the control embodiment of FIG. That is, a control circuit that performs the same function as the pulse control circuit 6 of FIG. 4 is made into a microcomputer, and further, control values for adjusting values stored in the R group, G group, and B group of LEDs in this PWM control are separately provided. The function of storing in the EEPROM 8 is also performed. By storing the adjustment value in the adjustment value storing EEPROM 8 in this way, the adjustment by the two-dimensional surface resistance potentiometer 1 is not necessary thereafter, and it may be removed.

  Therefore, in the case where the microcomputer control circuit 7 and the adjustment value storage EEPROM 8 for storing the adjustment value in the control circuit are provided on the device side provided with the LED, the two-dimensional surface resistance potentiometer 1 is used at a factory or the like. After adjusting and storing the adjustment value as described above, the microcomputer control circuit 7 reads the value of the adjustment value storage EEPROM after that and removes the adjustment value. Control can be performed.

  In the various control modes as described above, the two-dimensional surface resistance potentiometer 1 used in the LED color adjusting apparatus of the present invention can have a structure as shown in FIG. 6, for example. That is, in the two-dimensional surface resistance potentiometer 1 shown in FIG. 6, the bottom surface is provided with a surface resistance region 10 made of a surface resistor similar to the above, and a frame for restricting the movable range of the slider as the variable position electrode is provided above the surface resistance region 10. The slider inner surface 11 restricts the movable range of the slider that moves at right angles to the surface resistance region 10.

  The inner surface 11 of the frame is provided with depressions at R, G, and B positions indicated as slider movement positions in the figure, and red, green, and blue electrodes are disposed corresponding to these positions. When the slider enters, a click feeling is given, and when the slider is placed at each predetermined position, it can come into contact with each electrode. Thereby, each predetermined color of R, G, and B can be output at a position in contact with each electrode. Also, between the electrodes, as shown in the figure, a recess is provided in the frame inner surface 11 at an intermediate position, and each position is set to a position corresponding to yellow, cyan, and magenta. Therefore, the slider is moved along the frame inner surface 11. When the user senses that the user has entered the image by clicking, the predetermined colors can be output.

  By using the two-dimensional surface resistance potentiometer 1 as described above, a predetermined cyan color can be obtained, for example, in addition to moving the movable electrode to the center position and obtaining white by light emission of three LEDs, It can be surely prevented that the position is shifted and white cyan is obtained.

  Further, in such a two-dimensional surface resistance potentiometer 1, as is apparent from the PWM control diagrams of the large current LEDs in FIGS. 4 and 5, the resistors R1.R connected to the fixed electrodes R, G, B are used. , R1.G and R1.B are connected in series with the variable resistor between the contact S of the movable electrode and each fixed electrode. Therefore, for example, a control signal taken from between the R-S resistance and the R1.R resistance becomes a divided value of both resistances, and R1.R acts as a voltage dividing resistance. Accordingly, since the output voltage varies depending on the ratio of the variable resistance of the surface resistance and the voltage dividing resistance, the movable electrode is moved to the cyan position in FIG. 6, for example, by making this voltage dividing resistance sufficiently smaller than the surface resistance. At this time, it is possible to reduce the red mixing at the opposite position.

  The above-described two-dimensional surface resistance type potentiometer has shown an example in which the surface resistance is created with a uniform thickness with respect to the plane. For example, as shown in FIG. 7, the required area portion with high color purity in the peripheral area is formed thick. You may do it. Such a surface resistance is represented by a resistance value “R = ρ · L / A”. Here, ρ is a specific resistance of the resistor, L is a distance between two points, and A is a resistance cross-sectional area. A can also be expressed as width × thickness. Therefore, the resistance characteristics can be changed by partially controlling the thickness of the resistor by vapor deposition or coating. Therefore, as shown in FIG. 7, when the thickness of the surface resistance is controlled to be a concave lens shape, the surface resistivity of the peripheral portion can be lowered, and the surface resistivity can be increased toward the center portion. Thereby, the mixing of the R component can be reduced in proportion when a cyan color is created with G + B.

  A more specific example of the two-dimensional surface resistance potentiometer according to the present invention will be described with reference to FIG. In the example shown in FIG. 8, a substrate 22 having a surface resistance film 21 provided on the surface is covered with a case 23, an opening 24 is formed at the center of the case 23, and the inner peripheral surface of the opening 24 is a frame. The inner surface 25 is used. An operating shaft 26 is inserted into the case 23 from the opening 24, and a movable contact 27 is fitted to the lower end of the operating shaft 26 so as to be movable up and down with respect to the operating shaft 26. A spring 28 is shrunk between the two. A stopper 29 is fixed to the lower end of the operation shaft 26, and the movable cover 30 is sandwiched between the upper surface of the stopper 29 and the back surface of the case 23 by the force of the spring 28.

  As described above, the surface resistance film 21 is formed of three electrodes of RGB by silver electrodes, and each is connected to a terminal 31 protruding outside the case 23. The movable contact 27 is also connected to a terminal 31 protruding outside the case by a flexible wiring 32. As a result, there are four terminals protruding out of the case, each terminal for RGB and a terminal for movable contact. In the frame inner surface 25 that forms the inner peripheral surface of the opening 24, as in the example of FIG. 6, depressions 33 that give a click feeling to each electrode position and six intermediate positions thereof are formed. The side surface of the operation shaft 26 is received.

  In the two-dimensional surface resistance potentiometer 1 configured as described above, when the user picks the knob 34 of the operation shaft 26 and moves in an arbitrary direction, the movable contact 27 comes into contact with the surface resistance film 21 by the spring 28. Move while. At that time, the movable cover 30 also moves while covering the opening while contacting the back surface of the cover 23 by the reaction force of the spring 28. At that time, the movable contact 27 is kept connected to the terminal 31 by the flexible wiring 32. With such a simple structure, it is possible to adjust the energization amount of each of the RGB LEDs as described above and obtain a predetermined color including white by mixing light. The signal obtained from the terminal 31 can be used for direct current adjustment or as an adjustment voltage signal in each of the embodiments shown in FIGS.

  In each of the above embodiments, the surface resistor has a planar shape, or the thickness of the surface resistance is changed in order to change the surface resistivity. However, as shown in FIG. 9, for example, the operation knob 35 is rotated. When rotating in a joystick shape around the center portion 36, a surface resistor 38 having a spherical inner surface corresponding to the spherical shape drawn by the movable contact 37 provided at the end thereof may be used.

  Although the present invention can be implemented in various modes as described above, the present invention can be further implemented in various modes in accordance with the above spirit.

  The LED color adjusting device according to the present invention can be effectively used to obtain white color by emitting light from each of RGB LEDs as an LCD backlight. Can be used for equipment.

It is a figure which shows the basic structure of the Example of this invention. It is a figure which shows the 1st Embodiment of this invention. It is a figure which shows the 2nd Embodiment of this invention. It is a figure which shows the 3rd Embodiment of this invention. It is a figure which shows the 4th Embodiment of this invention. It is a figure which shows the structural example of the two-dimensional surface resistance type potentiometer by this invention. It is sectional drawing which shows the example which thickens the film | membrane pressure of a surface resistor to the outer periphery in the two-dimensional surface resistance type potentiometer by this invention. It is a figure which shows the more specific example of the two-dimensional surface resistance type potentiometer 1 by this invention, (a) is a top view, (b) is sectional drawing. It is a figure which shows the other aspect of the two-dimensional surface resistance type potentiometer of this invention. It is a figure which shows a prior art example. It is explanatory drawing of the color adjustment by international color space RGB specification. It is a figure explaining the adjustment to pure white in the same color adjustment.

Explanation of symbols

1 2D surface resistance potentiometer
2 Surface resistor 3 Slider electrode

Claims (9)

A surface resistor having three electrodes corresponding to LEDs of three colors R, G, and B at the apex of the triangle;
A slider having a movable contact that contacts the surface resistor and is movable to an arbitrary position;
An LED color adjustment device for performing color adjustment output from each electrode to each LED according to a resistance value corresponding to a distance between the movable contact and each electrode when the electrodes are energized from the movable contact . The color adjustment output is a resistance value of the surface resistor,
2. The LED color adjusting device according to claim 1, wherein color adjustment is performed by directly controlling the current of each LED by the resistance value.   2. The LED color adjusting apparatus according to claim 1, wherein the color adjustment is performed by performing energization control of a current control semiconductor of each LED by the color adjustment output.   2. The LED color adjustment device according to claim 1, wherein the color adjustment is performed by controlling the energization pulse of the current control semiconductor of each LED by the color adjustment output. Storage means for storing the output value for color adjustment for each LED;
2. The LED color adjustment apparatus according to claim 1, wherein each color adjustment output value when color adjustment is performed in advance is stored, and color adjustment is performed using the stored output value. Provide a frame with an inner surface that regulates the movable range of the movable electrode on the surface resistor,
2. The LED color adjusting device according to claim 1, wherein a recess into which a part of the movable electrode or the slider enters corresponding to the position of at least the three electrodes is provided on the inner surface of the frame.   2. The LED color adjusting device according to claim 1, wherein the surface resistor is formed thicker as it gets farther from the center. A substrate provided with the surface resistor on the surface;
A case covering the substrate and forming an opening in the center;
An operating shaft inserted into the opening and provided with a movable electrode at the lower end;
A movable cover disposed between a stopper fixed to the operation shaft and the back surface of the case;
The LED color adjusting device according to claim 1, further comprising a spring that presses the movable contact toward the surface resistance side and presses the movable cover against the back of the case via a stopper. An operating shaft that has a movable electrode at the end and swings back and forth and left and right around a fulcrum;
The LED color adjusting device according to claim 1, further comprising a sheet resistor formed in a spherical shape corresponding to a locus of the movable electrode.

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