TWI433598B - Light emitting apparatus - Google Patents

Description

The present invention relates to a light emitting device, and more particularly to a light emitting device having a light sensing element.

A light emitting diode (LED) is a light-emitting element made of a semiconductor material. Since the light-emitting diode system is a cold light-emitting system, it has the advantages of low power consumption, long component life, fast reaction speed, and the like, and the small size is easy to be made into a very small or array element, so that the technology has been continuously improved in recent years. Its application range covers the indicators of computers or home appliances, the backlight of liquid crystal display devices, traffic signs or vehicle lights.

In some products, the average brightness control system with a plurality of light-emitting diodes is quite important. Taking a liquid crystal television as an example, the number of light-emitting diodes required for the backlight module usually needs to be tens to hundreds, and the light-emitting diodes are controlled in order to enable them to display true colors or better display images. The average brightness becomes a very important technology.

Referring to FIG. 1A , the backlight module of the prior art has a plurality of LEDs 11 , a photo sensor 12 , and a controller 13 . The light sensor 12 receives the light generated by each of the light-emitting diodes 11 when it emits light, and generates a feedback signal to the controller 13, and then the controller 13 adjusts the corresponding light according to the feedback signal. The brightness of the diode 11.

Recently, another backlight module is known from the prior art, which divides a plurality of light-emitting diodes 11 into a plurality of regions, as shown in FIG. 1B, for example, a plurality of light-emitting diodes 11 are used. It is divided into 12 regions, each of which is composed of four light-emitting diodes 11 and a light sensor 12 to adjust the brightness of the light-emitting diodes in a partition. However, since the light-emitting diode 11 is divided into 12 regions, a controller (not shown) for adjusting the brightness of the light-emitting diode 11 requires 12 channels to respectively control the illumination of 12 regions. The brightness of the polar body 11. When the number of the light-emitting diodes 11 of the backlight module is divided into more regions, the number of channels required by the controller increases, which increases the cost of the controller.

In addition, as shown in FIG. 1B, the light emitting diode 11 and the photo sensor 12 are separately disposed, so as to increase the size of each area, thereby increasing the size of the backlight module, and the light emitting diode 11 and the photo sensor The distance between 12 also causes the photo sensor 12 to be susceptible to ambient light, resulting in a decrease in the accuracy of the photo sensor 12.

According to the above, regardless of the above methods, the light intensity of the light emitting diode must be detected by the light sensor, and after the feedback, the light emitting light is adjusted according to the calibration data preset in the controller 13. The power of the polar body requires very high costs for the purpose of the prior art. Therefore, how to make the brightness of the light-emitting device be well controlled and to reduce the cost of expenditure is one of the current important issues.

In view of the above problems, an object of the present invention is to provide a light-emitting device capable of accurately controlling the brightness of a light-emitting device and reducing the cost.

To achieve the above object, a light emitting device according to the present invention comprises at least one light emitting unit, at least one first switching unit, at least one energy storage unit, and at least one light sensing control unit. The first switching unit is electrically connected to the light emitting unit. The energy storage unit is electrically connected to the first switching unit and stores an electric energy. The light sensing control unit has a light sensing component, the light emitting unit is disposed on the light sensing component, and the light sensing control unit is electrically connected to the energy storage unit, and senses one of the light emitting energy of the light emitting unit, and is based on The illuminating energy adjusts the magnitude of the electric energy, and the first switching unit controls the illuminating unit according to the magnitude of the electric energy.

According to the above description, a light-emitting device according to the present invention utilizes a light-sensing control unit to receive a characteristic of leakage current after receiving light from a light-emitting unit after lighting, thereby consuming or adjusting storage in an energy storage unit. The electric energy in the electric energy is turned off after the electric energy is consumed, whereby the electric energy stored by the energy storage unit can determine the lighting time of the light emitting unit to control the brightness of the light emitting unit. Alternatively, the light sensing element can be used to adjust the electrical energy in the energy storage unit to control the light emitting unit after receiving the illumination of the light emitting unit. Therefore, the present invention continuously monitors the illumination state of the illumination unit and "automatically compensates" the brightness of the illumination unit, instead of compensating according to the preset calibration data, so that the present invention can be controlled without using feedback and controller. This greatly reduces costs. In addition, the light emitting unit of the present invention is disposed on the light sensing component, which not only reduces the distance between the light emitting unit and the light sensing component, but also improves the accuracy of the light sensing, and can reduce the size of the light emitting device, thereby improving Product competitiveness.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a light-emitting device according to a preferred embodiment of the present invention will be described with reference to the accompanying drawings, wherein the same elements will be described with the same reference numerals.

Referring to FIG. 2, the illuminating device 2 according to the preferred embodiment of the present invention includes at least one illuminating unit 21, a first switching unit 22, an energy storage unit 23, and a light sensing control unit 24.

The light emitting unit 21 can include at least one cold cathode fluorescent lamp, a hot cathode fluorescent lamp or a light emitting diode. In the embodiment, the light-emitting unit 21 is exemplified by one light-emitting diode. In addition, the light emitting diode may be a white light emitting diode, a red light emitting diode, a green light emitting diode, a blue light emitting diode or other color light diode. Of course, the light emitting unit 21 also has a plurality of light emitting diodes. The polar body, and the light emitting diodes may be mixed into white light, color light of other wavelengths or single color light. In addition, the light emitting diode in the light emitting unit 21 may be a bare crystal or a package component, and the light emitting diode is a bare crystal as an example.

The first switching unit 22 is electrically connected to the light emitting unit 21, and the two can be connected in parallel or in series, and the serial connection is taken as an example. The first switching unit 22 includes a switching element, which may be, for example, a bipolar transistor (BJT) or a field effect transistor (FET). In the embodiment, the first switching unit 22 is exemplified by a MOS field effect transistor.

The energy storage unit 23 is electrically connected to the first switching unit 22 and stores an electric energy. In this embodiment, the energy storage unit 23 is, for example, a charge storage unit, and the charge storage unit includes a capacitor, and the electrical energy is stored in the capacitor in a voltage form. Of course, depending on the characteristics of the different energy storage units 23, the electrical energy can be stored in the energy storage unit 23 in different types (eg, current). Further, the energy storage unit 23 may be a flat capacitor if it exists in the form of an integrated circuit.

The light sensing control unit 24 is electrically connected to the energy storage unit 23, and senses one of the light-emitting energy of the light-emitting unit 21, and adjusts the electric energy according to the light-emitting energy, and the first switch unit 22 is configured according to the energy storage unit 23. The stored electric energy amount is turned on and turned off to control whether the light emitting unit 21 emits light or not. The so-called on and off actions herein refer to the actions performed by the first switching unit 22 in accordance with a large amplitude of electrical energy. In this embodiment, the light sensing control unit 24 can include a light sensing component, which can be, for example, a photo diode or a photoresistor. Here, the light sensing control unit 24 is connected in parallel with the energy storage unit 23. In addition, the light sensing control unit 24 can also include a control loop and electrically connect it to the light sensing component for additional control.

It should be noted that the electrical connection described herein may be a direct electrical connection or an indirect electrical connection, and the so-called indirect electrical connection means that the two components are electrically connected to each other by another component. meaning.

Hereinafter, please refer to FIG. 3A and FIG. 3B , which are schematic structural diagrams of a light-emitting device according to a preferred embodiment of the present invention.

As shown in FIG. 2 and FIG. 3A , the light sensing control unit 24 and the light sensing component of the embodiment are located in an integrated circuit IC, and the light emitting unit 21 is disposed on the integrated circuit IC, that is, the light is emitted. The unit 21 is disposed on the light sensing element, and the two can be directly connected or indirectly connected through an element. In this embodiment, the photo sensing element is located in the integrated circuit IC, and the first switching unit 22 and/or the energy storage unit 23 may be located in the integrated circuit IC or in another integrated circuit. Here, the photo sensing element, the first switching unit 22 and the energy storage unit 23 are all located in the integrated circuit IC. The light emitting unit 21 is electrically connected to the first switching unit 22 in the integrated circuit IC by wire bonding. Of course, in the integrated circuit IC, the photo sensing element and the first switching unit 22 and the energy storage unit 23 are electrically connected by a line in the integrated circuit IC. Further, the integrated circuit IC is electrically connected to a line on a circuit board 25 by wire bonding.

FIG. 3B shows another aspect in which the light emitting unit 21 is wire bonded to the circuit substrate 25a, and is electrically connected to the first switching unit 22 of the integrated circuit IC by a line on the circuit substrate 25a.

In the embodiment, the light-emitting device 2 further includes an encapsulant 26 covering the light-emitting unit 21 and the light sensing element. Here, the encapsulant 26 covers the light emitting unit 21 and the integrated circuit IC, that is, the encapsulant 26 also covers the first switching unit 22 and the energy storage unit 23.

In addition, if the light emitting diode system is a color light emitting diode, the light sensing control unit 24 may further include a color filter or a color filter layer in order to be sensitive to a specific wavelength range. The color filter (layer) corresponds to the light-emitting wavelength of the light-emitting diode, which may be a red filter (layer), a green filter (layer), a blue filter (layer) or a white filter ( Layer), even an infrared filter (layer).

As described above, in the present embodiment, regardless of whether the illuminating device 2, 2a, 2b has a single illuminating unit 21 or a plurality of illuminating units 21, the illuminating devices 2, 2a, 2b can maintain their total illuminating energy consistent. Hereinafter, the light-emitting devices 2, 2a, 2b of the present invention will be further described by the circuit shown in FIG. Q represents the charge stored by the capacitor, that is, the amount of charge stored in the energy storage unit 23; C represents the capacitance of the capacitor, that is, the capacitance of the energy storage unit 23; V represents the voltage across the capacitor That is, the voltage across the energy storage unit 23; t represents the capacitance discharge time; α represents the known coefficient; I represents the current flowing through the light sensing control unit 24; L represents the luminous power of the light-emitting unit 21; E represents the light-emitting unit The total luminescence energy, and the equation of its total luminescence energy is derived as follows:

Q = I * t = C * V (1)

I =α* L (3)

It can be seen from the formulas (1) to (4) that since the current I flowing through the light sensing control unit 24 is proportional to the luminous power L of the light emitting unit 21, and the capacitance value C of the capacitor is a fixed value, Therefore, the total luminous energy E of the light-emitting unit 21 can be determined by the voltage across the capacitor V (i.e., the voltage of the input capacitor), and thus it is possible to eliminate the necessity of maintaining the luminous energy by controlling the luminous power of the light-emitting unit 21. In other words, when the light-emitting power of the light-emitting unit 21 is relatively large, the light-sensing control unit 24 will cause the electrical energy stored in the capacitor to be consumed relatively quickly; conversely, when the light-emitting power of the light-emitting unit 21 is relatively small, the light-sensing control The unit 24 will make the electrical energy stored by the capacitor relatively slow to consume, thereby achieving the effect of maintaining the uniform luminous energy of the light-emitting unit 21 at different luminous powers.

When the electrical energy stored by the energy storage unit 23 is sufficient to turn on the first switching unit 22, the first switching unit 22 is turned on and the light emitting unit 21 is simultaneously illuminated, while the light sensing control unit 24 accepts the light emitting unit 21 The generated light is irradiated to start leakage and consume the electric energy stored in the energy storage unit 23. In the present embodiment, the light sensing control unit 24 consumes electrical energy by constant current discharge, and its discharge rate is approximately proportional to the brightness of the light emitting unit 21. In addition, the stronger the illuminating energy of the light emitting unit 21, the faster the rate at which the light sensing control unit 24 consumes electric energy. When the electrical energy is consumed (ie, the voltage is less than the conduction threshold voltage of the first switching unit 22), the first switching unit 22 is turned off, and the lighting unit 21 is also turned off to terminate the illumination. As described above, the present invention continuously monitors the light-emitting state of the light-emitting unit 21 and "automatically compensates" the brightness of the light-emitting unit 21, instead of compensating according to preset calibration data.

In this embodiment, in the embodiment, the light-emitting energy of the light-emitting unit 21 is sensed by the light-sensing control unit 24, and the electrical energy of the capacitor is consumed; otherwise, the light is sensed. The control unit 24 senses the illuminating energy of the illuminating unit 21 and accordingly increases the electric energy of the capacitor. At this time, the above t represents the charging time. In summary, the illuminating energy of the illuminating unit 21 can be sensed by the photo sensing control unit 24 to adjust the electric energy of the energy storage unit 23.

In this embodiment, by disposing the light emitting unit 21 on the light sensing element (on the integrated circuit IC), not only the distance between the light emitting unit 21 and the light sensing element can be reduced, but the accuracy of the light sensing is improved. Moreover, the range occupied by the light-emitting unit and the light sensing element can be reduced, thereby reducing the size of the light-emitting device. In this embodiment, the light sensing element senses the illuminating energy of the illuminating unit 21 in various ways, which is exemplified below.

As shown in FIG. 4A, the light emitting unit 21 is disposed on an upper surface S1 of the integrated circuit IC, one photosensitive region of the light sensing element is located on the upper surface S1, and the light emitting unit 21 has a projection area on the upper surface S1 ( For vertical projection, for example, the photosensitive area and the projection area at least partially overlap, and the area of the photosensitive area and the projection area may be different. Here, the light-emitting unit 21 is directly disposed on the upper surface S1, and the projection area and the photosensitive area are completely overlapped as an example. In this embodiment, the light-emitting diode of the light-emitting unit 21 needs to remove the light-shielding substrate or the light-shielding layer near the surface S1, so that the light-sensing element can sense the bottom of the light-emitting diode, thereby adjusting the energy storage unit. The amount of electrical energy (not shown).

As shown in FIG. 4B, it is a top view of the light-emitting unit 21 and the integrated circuit IC1 to illustrate another configuration of the photosensitive region, wherein the light sensing control unit 24, the energy storage unit 23, and the first switching unit 22 are located in the product. Inside the body circuit IC1. The light emitting unit 21 has a projection area, and the photosensitive area (hatched portion) of the light sensing element is located around the projection area. In this aspect, the bottom surface of the light emitting diode does not emit light, and the light sensing component senses the side light of the light emitting diode, thereby adjusting the electrical energy of the energy storage unit (not shown).

In addition, in the embodiment, the light emitting unit 21, the first switching unit 22, the energy storage unit 23, and the light sensing control unit 24 have various setting manners, which are exemplified below.

As shown in FIG. 5A, the first switching unit 22, the energy storage unit 23, and the light sensing control unit 24 are located in the same integrated circuit IC, and the integrated circuit IC is disposed on a lead frame 27 and bonded by wire bonding. The lead frame 27 is electrically connected. The light emitting unit 21 is disposed on the integrated circuit IC and is wire bonded to the integrated circuit IC. The encapsulant 26a encapsulates the light-emitting unit 21 and the integrated circuit IC to form a package.

As shown in FIG. 5B, the photo sensing control unit 24 is located in an integrated circuit IC2, and the integrated circuit IC2 is disposed on a circuit substrate 25b. The first switching unit 22 and the energy storage unit 23 are located in the other integrated circuit IC3, and the integrated circuit IC3 is also disposed on the circuit substrate 25b. The light-emitting unit 21 is electrically connected to the integrated circuit IC3 by wire bonding. The integrated circuit IC2 is electrically connected to the first switching unit 22 of the integrated circuit IC3 and the energy storage unit 23 by the circuit of the circuit substrate 25b. The bulk circuit IC3 is electrically connected to the circuit board 25b by wire bonding. It should be noted that the integrated circuit IC3 may be electrically connected to the circuit board 25b by flip chip bonding. The light emitting unit 21 can be electrically connected to the circuit substrate 25b by first wire bonding.

As shown in FIG. 5C, unlike the above aspect, the light-emitting unit 21 and the integrated circuit IC3 are electrically connected to the circuit board 25c by wire bonding.

As shown in FIG. 5D, the light sensing control unit 24a is in the form of a package, and the light emitting unit 21 is disposed on the light sensing control unit 24a. The first switching unit 22 and the energy storage unit 23 are located in the integrated circuit IC3. The light-emitting unit 21 is electrically connected to the integrated circuit IC3 by wire bonding, and the light sensing control unit 24a is electrically connected to the circuit substrate 25d by surface bonding, and is integrated with the circuit on the circuit substrate 25d. The circuit IC3 is electrically connected. In the aspect of FIG. 5B to FIG. 5D, the encapsulant can selectively cover the light emitting unit 21 and the integrated circuit IC2, and/or the integrated circuit IC3.

Finally, in the implementation of the circuit, the embodiment can have various aspects, which are exemplified below, but are not intended to limit the present invention.

As shown in FIG. 6A, the illuminating device 2 further includes a second switching unit 28, a power supply unit 30, and a current limiting unit 29. The second switch unit 28 is electrically connected to the energy storage unit 23 and controls the second switch unit 28 to input electrical energy into the energy storage unit 23 . The power supply unit 30 is electrically connected to the light emitting unit 21 and supplies a power source to the light emitting unit 21. The current limiting unit 29 is electrically connected to the power supply unit 30 and the light emitting unit 21, respectively, to limit the power intensity of the light that drives the light emitting unit 21 to emit light, and to avoid damaging the light emitting unit 21 by excessive power intensity. In this embodiment, the second switching unit 28 can be the same as the first switching unit 22, including a bipolar transistor or a field effect transistor; the power supply unit 30 is, for example, a voltage source or a current source, which provides The power is supplied to the light emitting unit 21; the current limiting unit 29 is a resistor.

In addition, in this embodiment, at least two of the first switching unit 22, the energy storage unit 23, the light sensing control unit 24, and the second switching unit 28 may be disposed in an integrated circuit. Further, at least two of the first switching unit 22, the energy storage unit 23, the light sensing control unit 24, the second switching unit 28, and the current limiting unit 29 may be disposed in an integrated circuit.

When the second switching unit 28 is turned on, the light-emitting device 2 inputs electric energy (voltage) to the energy storage unit 23 via the second switching unit 28. When the electric energy stored in the energy storage unit 23 is sufficient to turn on the first switching unit 22, the light emitting unit 21 is simultaneously illuminated when the first switching unit 22 is turned on, and at the same time, the light sensing control unit 24 accepts the light emitting unit. The light generated by the 21 is irradiated to start leakage and consumes the electric energy stored in the energy storage unit 23. In the present embodiment, the light sensing control unit 24 consumes electrical energy by constant current discharge, and its discharge rate is approximately proportional to the brightness of the light emitting unit 21. In addition, the stronger the illuminating energy of the light emitting unit 21, the faster the rate at which the light sensing control unit 24 consumes electric energy. When the electrical energy is consumed (ie, the voltage is less than the conduction threshold voltage of the first switching unit 22), the first switching unit 22 is turned off, and the lighting unit 21 is also turned off to terminate the illumination.

However, in actual design considerations, as shown in FIG. 6B, the first switch unit 22 and the light-emitting unit 21 can also be connected in parallel, and the light-emitting energy of the light-emitting unit 21 can still be sensed by the light-sensing control unit 24. In order to adjust the electrical energy of the capacitor, thereby controlling the efficacy of the light-emitting unit 21.

In summary, the illuminating device according to the present invention uses the light sensing control unit to receive the light of the illuminating unit after the lighting, and then generates a leakage current characteristic to consume or adjust the storage in the energy storage unit. The electric energy in the electric energy is turned off after the electric energy is consumed, whereby the electric energy stored by the energy storage unit can determine the lighting time of the light emitting unit to control the brightness of the light emitting unit. Alternatively, the light sensing element can be used to adjust the electrical energy in the energy storage unit to control the light emitting unit after receiving the illumination of the light emitting unit. Therefore, the present invention continuously monitors the illumination state of the illumination unit and "automatically compensates" the brightness of the illumination unit, instead of compensating according to the preset calibration data, so that the present invention can be controlled without using feedback and controller. This greatly reduces costs. In addition, the light emitting unit of the present invention is disposed on the light sensing component, which not only reduces the distance between the light emitting unit and the light sensing component, but also improves the accuracy of the light sensing, and can reduce the size of the light emitting device, thereby improving Product competitiveness.

The above is intended to be illustrative only and not limiting. Any equivalent modifications or alterations to the spirit and scope of the invention are intended to be included in the scope of the appended claims.

11. . . Light-emitting diode

12. . . Light sensor

13. . . Controller

2, 2a ~ 2f. . . Illuminating device

twenty one. . . Light unit

twenty two. . . First switch unit

twenty three. . . Energy storage unit

24, 24a. . . Light sensing control unit

25, 25a, 25b, 25c, 25d. . . Circuit substrate

26, 26a. . . Packaging adhesive

27. . . Lead frame

28. . . Second switching unit

29. . . Current limiting unit

30. . . Power supply unit

IC, IC1, IC2, IC3. . . Integrated circuit

S1. . . Upper surface

1A is a schematic diagram of brightness control of a conventional backlight module;

FIG. 1B is a schematic diagram of a partition of a conventional backlight module; FIG.

2 is a block diagram of a light emitting device according to a preferred embodiment of the present invention;

3A and 3B are schematic diagrams showing the arrangement of a light emitting unit and a light sensing element according to a preferred embodiment of the present invention;

4A and FIG. 4B are schematic diagrams showing the relationship between a projection area of a light emitting unit and a photosensitive area of a light sensing element according to a preferred embodiment of the present invention;

5A to 5D are schematic diagrams showing different arrangements of components of a light-emitting device according to a preferred embodiment of the present invention;

6A and 6B are block diagrams showing different aspects of a light-emitting device according to a preferred embodiment of the present invention.

2. . . Illuminating device

twenty one. . . Light unit

twenty two. . . First switch unit

twenty three. . . Energy storage unit

twenty four. . . Light sensing control unit

Claims (16)

A light-emitting device comprising: at least one light-emitting unit; at least one first switch unit electrically connected to the light-emitting unit; at least one energy storage unit electrically connected to the first switch unit and storing an electric energy; And the at least one light sensing control unit has a light sensing component disposed on the light sensing component, the light sensing control unit is electrically connected to the energy storage unit, and senses the One of the illuminating units emits energy, and the electric energy is adjusted according to the illuminating energy, and the first switching unit controls the illuminating unit according to the electric energy. The illuminating device of claim 1, wherein the photo sensing element is located in an integrated circuit. The illuminating device of claim 2, wherein the first switching unit and/or the energy storage unit are located in the integrated circuit. The illuminating device of claim 2, wherein the first switching unit and/or the energy storage unit are located in another integrated circuit. The illuminating device of claim 2, wherein the illuminating unit is disposed on a surface of one of the integrated circuits, and one of the photo sensing elements is located on the surface. The illuminating device of claim 5, wherein the illuminating unit has a projection area on the surface, the photosensitive area at least partially overlapping the projection area. The illuminating device of claim 5, wherein the illuminating unit has a projection area on the surface, the photographic area being located around the projection area. The illuminating device of claim 1, further comprising: an encapsulant covering the illuminating unit and the photo sensing element. The illuminating device of claim 8, wherein the encapsulant further covers the first switching unit and/or the energy storage unit. The illuminating device of claim 1, wherein the illuminating unit comprises at least one illuminating diode. The illuminating device of claim 1, wherein the photo sensing element is a photosensitive diode or a photoresistor. The illuminating device of claim 1, wherein the energy storage unit is a charge storage unit. The illuminating device of claim 12, wherein the charge storage unit comprises a capacitor. The illuminating device of claim 1, wherein the first switching unit has a switching element. The illuminating device of claim 1, wherein the first switching unit is connected in parallel or in series with the illuminating unit. The illuminating device of claim 1, further comprising: a second switching unit electrically connected to the energy storage unit, and inputting the electric energy into the energy storage by the second switching unit unit.