Illumination system and illumination control method for adaptively adjusting color temperature

This invention discloses an illumination method and an illumination control method. An embodiment of the illumination system includes two light detection modules for detecting a light produced by a light emitting diode and an ambient light, calculating a reference spectral distribution based on a detection result of the ambient light, comparing the detection result of the light emitting diode with the reference spectral distribution, and driving the illumination module to emit a light matching with the reference spectral distribution based on a comparison result. Another embodiment of the illumination system includes a light detection module for periodically switching the light emitting diode to emit light and stop emitting light. When the light emitting diode stops an illumination period, the light detection module detects an ambient light, and when the light emitting diode continues an illumination period, the light detection module detects a light produced by the light emitting diode.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an illumination system and an illumination control method, and more particularly to a technical field of controlling a light emitting diode dynamically based on the detection of ambient light.

2. Description of the Related Art

Please referring toFIG. 1for a block diagram of an illumination system in accordance with the prior art, the illumination system comprises a control module11, an illumination module12and a light detection module13. The illumination module12comprises a red light emitting diode121, a green light emitting diode122and a blue light emitting diode123. The control module11comprises a microprocessor111and three driving modules113,114,115. The driving module113,114,115generate PWM signals to drive a red light emitting diode121, a green light emitting diode122and a blue light emitting diode123to emit lights respectively. The light detection module13comprises a red light sensor131, a green light sensor132and a blue light sensor133, for detecting the intensity of lights produced by the red light emitting diode121, the green light emitting diode122and the blue light emitting diode123respectively. The microprocessor111compares the detection results of these optical sensors with a predetermined spectral distribution112and controls the driving module113,114,115to adjust the intensity of lights produced by the light emitting diodes121,122,123based on the comparison results respectively. For example, the microprocessor11can control the length or proportion of a duty cycle of a PWM signal generated by the driving module to change the illumination intensity of the light emitting diodes.

With the foregoing technical content, the illumination system in accordance with the prior art can emit a light matching with the predetermined spectral distribution112. Even if some of the light emitting diodes have a drop of illumination intensity caused by a temperature factor or aged material, the microprocessor11still can adjust the PWM signal to improve the illumination intensity of these light emitting diodes, and further maintain the light produced by the illumination module12to match with the predetermined spectral distribution112. For instance, if the illumination system is applied to an LCD screen, the light on the screen is maintained as white light to provide comfortable viewing for users. However, if the color temperature of the ambient light is changed, for example a bulb having higher color temperature is used in a room, and emits a slightly red light, so that the screen will show a slightly red phenomenon even if the foregoing illumination system is used. If a bulb having a lower color temperature is used in a room, and emits a slightly blue light, and the screen will show a slightly blue phenomenon, and thus the colors of an image cannot be displayed correctly.

In view of the drawbacks of the prior art, the inventor of the present invention based on years of experience in the related field to propose an illumination method and an illumination control method to overcome the foregoing drawbacks of the prior art.

SUMMARY OF THE INVENTION

Therefore, it is one of objective of the present invention to provide an illumination system and an illumination control method to maintain good performance of the illumination system in different ambient lights environment for overcoming the foregoing drawbacks of the prior art.

To achieve the foregoing objective, the present invention provides an illumination system comprising an illumination module, a control module, a first light detection module and a second light detection module. The control module is provided for driving the illumination module to emit light. The first light detection module is provided for detecting the light produced by the illumination module to produce a first detection result, and the second light detection module is provided for detecting an ambient light to produce a second detection result. The control module is provided for calculating a reference spectral distribution at least based on the second detection result, and comparing the first detection result with the reference spectral distribution, and then driving the illumination module to emit a light matching with the reference spectral distribution based on the comparison result.

The invention further provides an illumination system comprising an illumination module, a control module and a light detection module. The control module is provided for controlling the illumination module to emit light or not to emit light. While the illumination module is emitting light, the light detection module is provided for detecting the light produced by the illumination module to produce a first detection result. While the illumination module is not emitting light, the light detection module is provided for detecting an ambient light to produce a second detection result. The control module is provided for calculating a reference spectral distribution at least based on the second detection result, and comparing the first detection result with the reference spectral distribution, and then driving the illumination module to emit a light matching with the reference spectral distribution based on the comparison result.

In addition, the present invention further provides an illumination control method comprising the steps of: detecting an ambient light to produce a first detection result; calculating a reference spectral distribution at least based on the first detection result; detecting the light produced by the illumination module to produce a second detection result; comparing the second detection result with the reference spectral distribution to drive the illumination module to emit a light matching with the reference spectral distribution based on the comparison result.

To make it easy for our examiner to understand the technical features and effects of the present invention, we use preferred embodiments together with attached drawings for the detailed description of the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The description of an illumination system and an illumination method in accordance with a preferred embodiment of the present invention will be illustrated by the following figures. Please referring toFIG. 2for a block diagram of a preferred embodiment of an illumination system in accordance with the present invention, the illumination system2comprises a control module21, an illumination module22, a first light detection module23and a second light detection module24. The illumination module22comprises a red light emitting diode221, a green light emitting diode222and a blue light emitting diode223, for emitting different lights to be mixed into a desired light, and the control module21is provided for driving the illumination module22to emit light. In this embodiment, the control module21comprises a microprocessor211and three driving modules213,214,215. The microprocessor211is provided for controlling the driving module to generate a driving signal to the light emitting diode and drive the light emitting diode to emit light. The driving module preferably comprises a PWM signal generator and a switch, and the driving signal is preferably a PWM signal, and the switch is preferably a transistor, and the microprocessor211can control the PWM signal generator to generate a PWM signal having a different duty cycle for adjusting the illumination intensity of the light emitting diode. The first light detection module23is provided for detecting the light produced by the illumination module22to produce a first detection result. The first light detection module23includes an optical sensor of a light emitting diode corresponding to different colors such as a red light sensor231, a green light sensor232and a blue light sensor233implemented by a filter and a light-dependent resistor.

The second light detection module24is provided for detecting an ambient light to produce detection result of the ambient light. In this embodiment, the second light detection module24comprises a red light sensor241, a green light sensor242and a blue light sensor243, for detecting a red light intensity, green light intensity and blue light intensity of the ambient light respectively. The control module21calculates a reference spectral distribution at least based on a detection result of the ambient light outputted by the second light detection module24and a compensation procedure212, and compares the first detection result outputted by the first light detection module23with the reference spectral distribution, and then drives the illumination module22to emit a light matching with the reference spectral distribution based on a comparison result.

Please referring toFIG. 3for a block diagram of an illumination system in accordance with another preferred embodiment of the present invention, the illumination system3comprises a control module31, an illumination module32and a light detection module33. The illumination module32comprises a red light emitting diode321, a green light emitting diode322and a blue light emitting diode323. The control module31comprises a microprocessor311, three PWM signal generators313,314,315and three switches317,318,319. The PWM signal generators313,314,315produces PWM signals, and the switches317,318,319are provided for driving the light emitting diodes321,322,323to emit lights. The microprocessor311builds in a compensation procedure312and a switch control procedure316, wherein the microprocessor311executes a switch control procedure316to control the illumination module32to emit light or not emit light. The light detection module33comprises a red light sensor331, a green light sensor332and a blue light sensor333.

While the microprocessor311controls the illumination module32not to emit light, the microprocessor311also controls the light detection module33to detect an ambient light, and produce an ambient light detection result which is then transmitted to the microprocessor311. The microprocessor311calculates a reference spectral distribution based on the ambient light detection result and the compensation procedure312. While the microprocessor311controls the illumination module32to emit light, the light detection module33is controlled to detect a light produced by the illumination module32for producing a first detection result which is then transmitted to the microprocessor311. The microprocessor311compares the first detection result with the reference spectral distribution, and drives the illumination module32to emit a light matching with the reference spectral distribution based on a comparison result.

The switch control procedure316can be any or a combination of the following procedures:1. A triggered event is used for controlling the illumination module32to emit light/not emit light, such as a user manually starting a function of detecting an ambient light, so that the microprocessor311will control the illumination module32not to emit light, and let the light detection module33detect an ambient light.2. The illumination module32is controlled periodically to emit light/not to emit light.3. The high potential and low potential of the PWM signal are used for controlling the illumination module32to emit light/not to emit light.

Please referring toFIG. 4for a block diagram of an illumination system in accordance with a further preferred embodiment of the present invention, the illumination system4comprises a control module41, an illumination module42and a light detection module43. The illumination module42comprises a red light emitting diode421, a green light emitting diode422and a blue light emitting diode423. The control module41comprises a microprocessor411, three PWM signal generators413,414,415and three transistors417,418,419. The PWM signal generators413,414,415generate PWM signals, and three transistors417,418,419are used for driving the light emitting diodes421,422,423to emit light. The microprocessor411builds in a compensation procedure412. The light detection module43comprises a red light sensor431, a green light sensor432and a blue light sensor433, and the PWM signals generated by the PWM signal generators413,414,415are transmitted to the red light sensor431, green light sensor432and blue light sensor433respectively.

The PWM signal includes a high potential and a low potential, wherein the transistor is electrically conducted at the high potential to pass current through the light emitting diode to drive the light emitting diode to emit light. The transistor is electrically disconnected at a low potential to stop passing current through the light emitting diode, such that the light emitting diode stops emitting light. Therefore, the sensors431,432,433can selectively detect an ambient light or a light generated by the light emitting diode421,422,423based on the received PWM signal. Referring toFIG. 5for a schematic view of a PWM signal of the present invention, the PWM_R stands for the PWM signal generated by the PWM signal generator413, the PWM_G for the PWM signal generated by the PWM signal generator414, and the PWM_B for the PWM signal generated by the PWM signal generator415. Since different light emitting diodes come with different illumination intensities, therefore the ratios of the high potential and the low potential of the PWM_R, the PWM_G and the PWM_B are different. A time period of any one of the three PWM signals at a high potential is used as a first time period, and a time period of three PWM signals at a low potential is used as a second time period. In the first time period, the sensors431,432,433detect a first detection result of the lights produced by the light emitting diodes421,422,423, and transmits the first detection result to the microprocessor411. On the other hand, in the second time period, the sensors431,432,433detect an ambient light to produce an ambient light detection result and transmit the ambient light detection result to the microprocessor411. The microprocessor411calculates a reference spectral distribution based on the ambient light detection result and the compensation procedure412, and then the microprocessor411compares the first detection result with the reference spectral distribution, and drives the illumination module42to emit a light matching with the reference spectral distribution based on a comparison result.

Please referring toFIG. 6for a block diagram of PWM signals of an illumination system in accordance with a further preferred embodiment of the present invention, the difference of this embodiment with the embodiment illustrated inFIG. 4resides on that the first time period of this embodiment includes at least one PWM signal, and the sensors431,432,433in the first time period detect lights produced by the light emitting diodes421,422,423to produce a first detection result and transmit the first detection result to the microprocessor411. In the second time period, the PWM signal generators413,414,415do not generate a PWM signal, such that the transistor is off, no current passes through the light emitting diodes, and the light emitting diodes will stop emitting light. With this switching procedure, the illumination system can use the same set of sensors for alternatively detecting the ambient light and the light of the light emitting diode to perform a later procedure of adjusting the illumination.

The illumination system of the invention can be applied to an LCD screen or an illumination device. For instance, if a user is operating an LCD screen in an environment with a slightly red (or slightly warm) light, the control module will drive the illumination module to emit a slightly blue (or slightly cold) and compensate the slightly red phenomenon caused by the ambient light and allow the LCD screen to display the color of an image correctly. If the LCD screen is situated in an environment with a slightly blue (or slightly cold) light, the control module will drive the illumination module to emit a slightly red (or slightly warm) light to compensate the slightly blue phenomenon caused by the ambient light and allow the LCD screen to display the color of an image correctly.

For example, in a preferred embodiment of a compensation procedure, the following formula is used for calculating the warm light parameter of an ambient light:
Warm Light Parameter=(Red Light Intensity of Ambient Light×RF1−Blue Light Intensity of Ambient Light×BF1)/(Red Light Intensity of Ambient Light×RF2+Blue Light Intensity of Ambient Light×BF2)

where, RF1and RF2are red warm light weight parameters, and BF1and BF2are blue warm light weight parameter.

The corresponding compensated warm light parameter is calculated based on the warm light parameter of an ambient light. For example, if the warm light parameter of an ambient light is greater than a threshold, then a value lower than the threshold is used as the compensated warm light parameter, and the reference spectral distribution is calculated based on the compensated warm light parameter. In other words, the intensities of the red light, green light and blue light corresponding to the warm light parameters are compensated. Then, the control module adjusts the illumination module to emit a light matching with the reference spectral distribution. In a slightly red ambient light wherein the warm light parameter of the ambient light is relatively higher, then the control module will drive the illumination module to emit a light lower than the warm light parameter, so that such arrangement allows viewers to sense the normal white light without being affected by the ambient light.

In a compensation procedure of another preferred embodiment, the following formula is used for calculating the intensity parameter of the ambient light:
Intensity Parameter=(Red Light Intensity of Ambient Light×RF3+Blue Light Intensity of Ambient Light×BF3+Green Light Intensity of Ambient Light×GF3)

where RF3, BF3and GF3are intensity weight parameters of red, blue and green lights respectively.

The corresponding compensated intensity parameter is calculated based on the intensity parameter of the ambient light. For example, if the intensity parameter of an ambient light is greater than a threshold, then a value smaller than the threshold is used as a compensated intensity parameter, and the reference spectral distribution is calculated based on the compensated intensity parameter, so that the intensities of the red light, green light and blue light corresponding to the intensity parameters can be compensated.

Please referring toFIG. 7for a flow diagram of an illumination control method in accordance with a preferred embodiment of the present invention, the method is corresponsive to the illumination system2as illustrated inFIG. 2, and the method comprises the steps of:

Step 71: using a second light detection module24to detect an ambient light to produce an ambient light detection result;

Step 72: using a microprocessor211to execute a compensation procedure212, and calculating a reference spectral distribution at least based on the ambient light detection result;

Step 73: detecting a light emitted by the illumination module22to produce a first detection result; and

Step 74: comparing the first detection result with the reference spectral distribution, and driving the illumination module22to emit a light matching with the reference spectral distribution based on a comparison result.

Referring toFIG. 8for a flow diagram of an illumination control method in accordance with another preferred embodiment of the present invention, the method corresponds to the illumination system3as illustrated inFIG. 3, and the method comprises the steps of:

Step 81: using a microprocessor311to execute a switch control procedure316, and periodically control the illumination module32to emit light and not to emit light;

Step 82: using the light detection module33to detect an ambient light to produce an ambient light detection result during the period when the illumination module 32stops emitting illumination;

Step 83: using the microprocessor311to execute a compensation procedure212to calculate a reference spectral distribution at least based on the ambient light detection result;

Step 84: detecting a light produced by the illumination module32to produce a first detection result during the illumination period of the illumination module32; and

Step 85: using the microprocessor311to compare the first detection result with the reference spectral distribution, and driving the illumination module32to emit a light matching with the reference spectral distribution based on a comparison result.