KR20050022011A - A system for maintaining light characteristics from a multi-chip led package - Google Patents

Abstract

The present invention provides methods, systems, and structures for maintaining optical properties from multichip LED package 102. This can be done by selecting the desired light output from the plurality of light emitting diodes in the multichip LED package and limiting the light. This may also be done by measuring the limited light, comparing the measured output light with the desired light, and adjusting the current to the LED 150 in the multichip LED package based on the measured light.

Description

A SYSTEM FOR MAINTAINING LIGHT CHARACTERISTICS FROM A MULTI-CHIP LED PACKAGE}

The present invention relates generally to LED power supply lighting systems. In particular, the present invention relates to a system for maintaining optical properties from a multichip LED package.

Light-emitting diodes (LEDs) are used more often in general lighting applications that must provide high levels of consistent, user-specific color. To provide high levels of light, a package containing multiple LED chips (of the same or different colors) must be used to avoid bulky lamps. We will call these "multichip LED packages".

Light intensity and other characteristics vary with LED chips. This can cause color variations in the light coming from the multichip LED package. The light intensity and color of a multichip LED package can be measured and kept constant using a light sensor, supporting electronics and a control system placed in a package separate from the LED chip. In order to obtain LED lamps that are compact, have a constant light output, and require minimal design work from the lamp designer using a multichip LED package, the integration of sensors (and possibly other electronic devices) in the LED package is desirable. . Thereafter, it becomes important to place the sensor so that the sensor provides a useful signal for controlling the light output.

Therefore, it would be desirable to provide a system for maintaining the optical properties of a multichip LED package that overcomes these and other disadvantages.

1 is a schematic diagram of one embodiment of a system for maintaining optical characteristics from a multichip LED package according to the present invention;

2 is a flow diagram of one embodiment of a system for maintaining optical characteristics from a multichip LED package according to the present invention.

3-6 are schematic diagrams of various embodiments of a system for maintaining optical properties within a multichip LED package according to the present invention.

One aspect of the invention provides a system for maintaining optical characteristics from a multichip LED package. The system includes means for limiting light transmitted to at least one light sensor to produce a limited light signal, and means for measuring light signal limited by the at least one light sensor to produce a sensed light signal. It may include. The system also includes means for comparing the sensed optical signal with a desired optical signal and means for adjusting the current to at least one light emitting diode on the multichip LED package based on the comparison.

Another aspect of the invention provides a structure for maintaining optical properties from a multichip LED package. This structure comprises a plurality of LEDs; At least one enclosure arranged to receive a certain amount of light from the plurality of LEDs; At least one optical sensor disposed in the enclosure for measuring light from the plurality of LEDs; And a controller operably connected to the LED chip for controlling the current into the LED chip based on the measured light.

Other features and advantages of the present invention will become apparent from the following detailed description of the embodiments of the present invention, taken in conjunction with the accompanying drawings. The detailed description and drawings are merely illustrative of the invention and are not intended to limit the scope of the invention as defined by the appended claims and their equivalents.

1 is a diagram illustrating an embodiment of a system 100 for maintaining optical characteristics from a multichip LED package according to the present invention. In one embodiment, the system 100 may include a multichip LED package 102 and an input device 140.

The multichip LED package 102 may include a control system 130, a temperature sensing device 120, a light emitting diode (LED) 150, and a light sensing device 110.

The multichip LED package 102 includes at least one light emitting diode chip 150 with a connecting electronic device 135. The LEDs can be, for example, red, green or blue, and in another example a plurality of LEDs can be all one color or a combination of colors. Other embodiments of the system 100 may include white LED chips, LED chips of different colors, or a combination of colored and white LED chips.

Multichip LED package 102 also includes a control system 130. In one embodiment, such a control system may be any suitable hardware or software or combination of hardware and software that performs logic processing, such as a computer chip with RAM. Such control system 130 may be operatively connected to system components 110, 120, 140, 150 with control system electronics wiring 115, 125, 135 or any other suitable connection known in the art. Can be. The control system 130 can alter the current flow to various system components through the connections 115, 125, 135. For example, the control system electronic device 130 may change the flow of current to the LED chip 150 through the electronic device connection 135. Computer software in control system 130 may include instructions for controlling the flow of current to various system components by any suitable means known in the art.

The multichip LED package 102 may also include an enclosure 105 that surrounds the light sensing device 110. Referring now to FIGS. 1 and 3, which illustrate one exemplary embodiment of the enclosure 105, the enclosure 310 is directed toward the LED, which sends light emitted from the light source (LED) to the light sensing device 110. It includes at least one opening 320 that opens. The opening 320 can have various sizes and shapes depending on the arrangement and number of LEDs associated with each enclosure, which are discussed in more detail below with respect to FIGS. 4-6. The size of these openings can determine the amount of light that reaches the light sensor. In one embodiment, the enclosure interior 315 is a white interior, which provides a more efficient combination of light from different preferred light sources. The opening determines how much light from the LED will enter the enclosure. Once the light is in the enclosure, the white inner surface mixes the incoming light. The purpose of this internal mixing is to make the photodiode less sensitive to changes between the LEDs being measured.

Multichip LED package 102 also includes at least one light sensing device 110 located within enclosure 105. The light sensing device may be a photodiode, photoconductor or any other suitable light sensing device known in the art. The light sensing device may be arranged such that light transmitted from a neighboring LED passes through the opening to the light sensor. The optical sensor 110 converts the transmitted light into a sensed optical signal. The light sensing device 110 may be operatively connected to the control system 130 by electronic connection, optical fiber, or any other suitable connection means known in the art (115). Light transmitted from the LED may be restricted from the light sensor or allowed to impinge on the light sensor. This may be accomplished by placement of the sensor underneath the enclosure 105, placement of the LED chip, shape of the enclosure, or a combination thereof.

The multichip LED package 102 can include a temperature sensing device 120 operatively connected to the control system 130. This temperature sensing device may be a thermocouple or any other suitable means known in the art used to measure the temperature of a component. The temperature sensing device can be used to measure the temperature of the LEDs used in the multichip LED package 102. The temperature sensing device 120 may be configured to measure the LED temperature continuously or at specific time intervals, such as every two seconds, for example. In one embodiment, the temperature sensing device may be included in the multichip LED package 102. In another embodiment, the temperature sensing device may be connected to monitor the temperature of a heat sink, and the multichip LED package system 100 is mounted on the heat sink.

The system may also include an input device 140 in which the user can predetermine the color and intensity of the desired light output. In one embodiment, this input device 140 is a keypad that is portable to a hand with an electronic selection menu. The input device may also be a keypad mounted on a wall or a personal computer operatively connected to the control system 130. In practice, the user can simply press a button on the keypad to select the corresponding profile of the desired light. For example, the user can select a grayish off white color and high intensity bright light. Input device 140 may be any suitable hardware or software, or a combination of hardware and software that allows a user to select a desired profile of light.

Referring now to FIG. 2, a method for maintaining optical characteristics of a multichip LED package is shown generally at 200. In practice, the user selects the desired light profile using input device 140 (block 210). The desired light profile includes the color and concentration of transmitted light.

Once the multichip LED package 102 begins to transmit light, the sensor 110 associated with each LED measures the transmitted light in terms of both color and intensity (block 215). The sensor 110 converts the measured transmitted light into a sensed light signal (block 220). In one embodiment, the overall light color and intensity can be determined by summing up all of the individual light intensities of the individual LEDs. In another embodiment, the individual values of each individual color are combined to obtain the sensed light signal values for the particular color. For example, the sensed light signal for each red LED is summed with respect to the overall sensed signal value.

The determined sensed light signal is then compared to a desired light signal value associated with the desired light profile selected by the user (block 225). The result of this comparison will determine if adjustment of one or more LEDs is required (block 230). If the sensed light value is within a predetermined acceptable range of the desired light signal value, the method returns to block 215. However, if the sensed light signal is not within such predetermined range, the current to one or more LEDs is adjusted (block 235) and the method will return to block 215 for continued monitoring of the multichip LED package.

Changing the current flow into the LED changes the color and intensity of the light emitted from the multichip package. Based on the desired light profile selected, the control system determines the amount of current to be emitted to the various components in the multichip LED package. A profile of the desired optical properties can be used to evaluate the light measured by the light sensor. The current flow into the components of the system can then be adjusted by the control system 130 to alter the light emitted from the LEDs. This process can continue until the desired light is no longer required.

In another embodiment, temperature sensor 120 may also measure the temperature of the LED. As long as the temperature remains constant within acceptable limits for a particular multichip LED package, the rate of current flow into the components will be maintained by the control system. However, if the measured temperature is not within acceptable limits, the control system 130 will change the current flow to the LED as desired.

Referring now to FIG. 4, an exemplary arrangement of light sensors in LED chips, enclosures, and multichip LED packages is shown generally at 400. Optical sensor 412 may be placed on a multichip LED package to measure light concentration from an LED chip located on the package. Sensor 412 may be placed where they can monitor a plurality of LEDs on the package. Sensor 412 may be partially covered by enclosure 402 that sends light entering sensor 412. In one embodiment, the enclosure can control the amount of light impinging on the sensor. The enclosure 402 can have various openings facing neighboring LED chips 403, 405, 411. The total density and color of the multichip LED package 401 may be determined by adding up the concentrations of the respective LED chips.

The enclosure may have a smaller opening facing the LED chip 411. In the LED package 401, the control system can measure the concentration of the LED chips 403, 405, 411. The LED chip 411 can be measured by four sensors 412 that can be covered by the enclosure 402. Since this measurement may result in over-consideration of the LED chip 411, the openings of the enclosure 402 facing the LED chip 411 may have different opening sizes facing the corner LED chip 403. It can be reduced to 1/4 of. This ratio is equal to the inverse of the number of times a particular LED chip is measured. For example, the LED chip 405 may be measured by two sensors such that the opening facing the LED chip 405 can be reduced to one half of the size of another opening facing the corner LED chip 403. . This ratio may not be accurate and may depend on the distribution of light actually emitted by the LED. It is assumed that the LED chips 403, 405, 411 can have the same size and can be disposed equidistant from the sensor 412.

If filtered photodiodes are used in the present system, light emitted from LED chips of various colors can be sampled simultaneously. If an unfiltered photodiode is used on the LED chip, only one color can be measured at a time using a time multiplex sampling method. For example, in a package that includes red, blue and green LEDs, the green and blue LEDs can be turned off and the light intensity of the red LEDs is measured. Immediately after this step, the red and green LEDs can be turned off and the blue LED light concentration is measured. Immediately after this step, the red and blue LEDs can be turned off and the green LED light concentration is measured. The results of these measurements can be sent to the control system 130 and used to determine if the current to the various devices can be changed to achieve the desired light output.

Referring now to FIG. 5, another exemplary arrangement of LED chips, enclosures, and light sensors in a multichip LED package is shown generally at 500.

Since each LED chip 503 faces only one opening of the enclosure 502 in an array of multichip LED packages, the LED can be measured once. Also, since each LED chip 503 has the same size and can be equidistant from each enclosure 502, the openings in the enclosure 502 can be the same size.

Referring now to FIG. 6, another exemplary arrangement of LED chips, enclosures, and light sensors in a multichip LED package is shown generally at 600.

As with the multichip package, generally shown at 400, the system may include LED chips 603, 605, 609, 611 with connecting electronics, enclosure 612, and at least one optical sensor 602. And all of them are operatively connected together and mounted on the multichip package 601. The system may operate like that of the system in FIG. 4, shown generally at 400, but two enclosures may be used instead of four. As in FIG. 4, the ratio of one LED to the number of times measured can be determined to calculate the relative size of the openings facing each LED chip 603, 605, 609, 611 on the LED multichip package 601.

While embodiments of the invention disclosed herein are deemed to be presently preferred, various modifications and changes can be made without departing from the spirit and scope of the invention. The scope of the invention is indicated in the appended claims, and all changes that come within the meaning and range of equivalency are intended to be embraced therein.

The present invention is generally applicable to LED powered lighting systems, in particular systems for maintaining optical characteristics from multichip LED packages.

Claims (13)

A system for maintaining optical characteristics from a multi-chip light emitting diode (LED) package 102, Means for limiting light transmitted to the at least one optical sensor 110 to produce a limited optical signal; Means for measuring an optical signal constrained by the at least one optical sensor to produce a sensed optical signal; Means for comparing the sensed optical signal with a desired optical signal; And Means for adjusting current to at least one light emitting diode on the multichip LED package (102) based on the comparison. 10. The system of claim 1, further comprising means for providing a desired optical signal through the input device to the control device (130). The method according to claim 1 or 2, Means for measuring a temperature in the multichip LED package; Means for comparing the measured temperature with a desired temperature; And And means for adjusting the current to the at least one LED based on the comparison. The system of claim 1, wherein the optical sensor is selected from the group consisting of a photodiode and a photoconductor. 5. The system of claim 1, wherein the system is provided with a filter for filtering the optical sensor. 6. 2. The method of claim 1, wherein the means for limiting transmitted light comprises means for placing at least one optical sensor in an enclosure 105. System. 7. The system of claim 6, wherein the enclosure (105) comprises at least one aperture (320). 7. The system of claim 5 or 6, wherein the enclosure (105) comprises a white inner wall. 2. The light emitting diode of claim 1, wherein the light emitting diode 150 in the multichip LED package 102 comprises a plurality of light emitting diodes emitting red, green and blue light. System for doing so. 10. The apparatus of claim 9, wherein the means for measuring light transmitted by the at least one optical sensor comprises means for time multiplex sampling. system. The system of claim 1, wherein the means for regulating current includes means for regulating current to a selected light emitting diode using control system 130. . A structure for maintaining optical properties from a multichip light emitting diode (LED) package, A plurality of LEDs 150; At least one enclosure 105 disposed to receive a certain amount of light from the plurality of LEDs; At least one optical sensor (110) disposed in the enclosure for measuring light from the plurality of LEDs; And And a controller (130) operably connected to the LED chip for controlling current to the LED chip based on the measured light. At least one temperature sensor (120), And a controller operatively connected to the LED chip for controlling the current into the LED chip based on the measured temperature.