TWI580004B - Panel display device and backlighting method using the same - Google Patents

Description

Flat display device and backlight generating method applied thereto

The present invention relates to a flat display device and a backlight generating method applied thereto, and more particularly to a method for setting a wavelength of blue light emitted from a blue LED chip, thereby effectively removing or reducing harmful effects. A device for protecting the eyes of a user and a method thereof in the blue light band.

Light Emitting Diode (LED) is a solid-state light-emitting element made of semiconductor material. It has small volume, low heat generation, high illumination, low power consumption, suitable for mass production and long life. Therefore, in the current industry, various lighting devices or backlight modules have been widely used as light-emitting sources for light-emitting diodes; for example, general flat-panel display devices are mostly used as backlight modules. In order to enable such a backlight module to provide better display illumination in a flat display device, how to uniformly mix the various colors of light into desired white light has become an important development goal of the industry.

At present, a technology in which a light-emitting diode is used as a backlight module to generate white light is used, and one of them is a light-emitting diode chip that emits blue light (for example, InGaN (Indium Gallium Nitride) blue LED), and is used in combination. Fluorescent powder (for example, YAG (yttrium aluminum garnet) phosphor) which is excited by blue light to generate yellow light, so that the blue light and the generated yellow light are mixed with each other to form white light. On the other hand, it is possible to directly mix white light into a combination of three kinds of LED chips of red light, green light, and blue light (which can be individually combined or the same package).

In addition, since white light is composed of red (Red) light, green (Green) light, and blue (Blue) light, a mixture of red light and green light is formed. Yellow light, so three kinds of phosphors which can be excited by ultraviolet light or near-ultraviolet light to generate red light, green light and blue light respectively can be used in the backlight module, and the three color lights are mixed with each other to form white light. In addition, the current technology has also been able to form white light by combining a blue LED chip with two kinds of phosphors that can be excited by blue light to generate red light and green light, respectively.

Therefore, this white light is the backlight of the backlight module. However, the related light mixing structure in the backlight module may cause uneven mixing of the respective color lights, so that the mixed white light has a color shift; for example, the blue color shift, thereby affecting the color rendering property on the image display. In addition, since the blue light has a relatively short wavelength, it is more likely to cause scattering or diffusion, etc., and the phosphor is not effectively excited, thereby generating a blue color shift.

On the other hand, in terms of the color setting of the display device, there are currently several types including NTSC (National Television System Committee), sRGB (Standard Red Green Blue), and Adobe RGB, each type being in a color space. Have their own color gamut. The color gamut of sRGB is about 72% of the color gamut of NTSC, while the color gamut of Adobe RGB is wider than the color gamut of sRGB and has high color rendering. According to the current technology, a flat display device of the sRGB type is generally used, wherein the blue LED chip of the backlight module can operate in a wavelength range of 445 to 455 nanometers (nm), and the Adobe RGB type is in the range of 445 to 450 nm. Between meters (nm).

The actual measurement result of the brightness (unit lumen) of the light formed by the general flat display device in front of the general flat display device may be as shown in FIGS. 1 and 2; wherein the first picture is a plane of the sRGB type. The actual measurement results of the display device are displayed, and the second image is the actual measurement result of the Adobe RGB type flat display device. As can be seen from the above two figures, the measured light system correspondingly forms three peaks of red light, green light and blue light. In addition, in the above two figures, the blue LED chip used in the backlight module is set to emit blue light having a wavelength of 445 nm (nm), that is, the peak position of the measured blue light. The wavelength is about 445 nanometers (nm).

As mentioned above, the brightness of each color light corresponding to the distribution is related to the color rendering of the mixed white light. Whether it is sRGB type or Adobe RGB type, it can be seen that its blue light has relatively high brightness, and due to the mixing mechanism, both types generate light having a shorter wavelength than the peak of blue light; for example, purple light. As can be seen from Figures 1 and 2, the wavelength of the light measured in front of the planar display device can be as short as about 410 nanometers (nm).

However, according to medical research, when the wavelength of the emitted light falls within the range of 380 to 420 nanometers (nm), that is, the relatively shortest wavelength band in the visible light spectrum, the energy of the light will cause fatigue to the user's eyes. Aches and other effects, even in severe cases, may cause vision loss or retinopathy. For the actual measurement results of the above two types of flat display devices, the affected part is light with a wavelength between 410 and 420 nanometers (nm). Although the brightness of the light in this band is not large, it is still not suitable for viewing; and if the backlight module exhibits a blue color shift for any reason, the damage caused will be greater.

The current technology has been able to take several countermeasures against the blue light damage situation of the flat display device: one is to perform a low blue light mode on the device, that is, to adopt an application method to control the brightness of the blue light emitted by the backlight module; However, since the brightness of the blue light is lowered, the brightness of the yellow light (which can be mixed by the red light and the green light) is relatively high, so that the mixed white light may have a yellow color shift. Alternatively, the diaphragm of the relevant wavelength can be filtered out so that the specific short-wave light is not emitted; however, this method requires additional preparation of the hardware component, thereby increasing the production cost.

It can be seen from this that there are still many shortcomings to be improved in response to this problem, so it is not the best solution.

It is an object of the present invention to provide a flat display device and a backlight generating method applied thereto. The main feature is that by setting the wavelength of the blue light emitted by the blue LED chip, the harmful blue light band can be effectively removed or reduced to protect the user's eyes.

The present invention is a flat display device comprising a frame and a display panel disposed on the frame and a backlight module. The backlight module corresponds to the display panel for providing backlight of the display panel. The backlight module has a light source capable of generating a first color light beam, and the wavelength of the first color light beam falls within an emission wavelength range, and the emission wavelength range is from 457.5 nanometers (nm) to 465 nm. .

Another aspect of the present invention is a backlight generating method, which is applied to a flat display device, the flat display device includes a display panel and a backlight module, and the backlight module is configured to provide backlight of the display panel, and the method The method includes the steps of: causing a light source of the backlight module to generate a first color light beam at one of a range of emission wavelengths; wherein the emission wavelength range is from 457.5 nanometers (nm) to 465 nanometers.

In order to better understand the above and other aspects of the present invention, the preferred embodiments are described below, and in conjunction with the drawings, the detailed description is as follows:

1‧‧‧Flat display device

10‧‧‧Backlight module

11‧‧‧ frame

12‧‧‧Light source

14‧‧‧Hybrid unit

16‧‧‧Light guide

17‧‧‧Diffusion components

18‧‧‧ display panel

C11, C21‧‧‧ dotted line

C12, C22‧‧‧ thick solid line

L1, L2‧‧‧ marking line

Fig. 1 is a measurement result of the brightness of the light formed by the sRGB type flat display device corresponding to the actual wavelength.

Fig. 2 is a measurement result of the brightness of the light formed by the Adobe RGB type flat display device corresponding to the actual wavelength.

Fig. 3 is a cross-sectional view showing a flat display device 1 according to a first embodiment of the present invention.

Fig. 4 is a view showing the actual measurement result of the brightness of the light formed by the flat display device 1 of the first embodiment of the present invention corresponding to the wavelength.

Fig. 5 is a view showing the actual measurement result of the brightness of the light formed by the flat display device according to the second embodiment of the present invention corresponding to the wavelength.

The embodiments are described in detail below, and the embodiments are merely illustrative and not intended to limit the scope of the invention. In addition, in the embodiment The drawings omit unnecessary elements to clearly show the technical features of the present invention.

The implementation of the flat display device of the present invention and the backlight generating method applied thereto will now be described in a first embodiment.

Referring to Fig. 3, there is shown a cross-sectional view of a flat display device 1 proposed in the first embodiment. As shown in FIG. 3 , the flat display device 1 mainly includes a backlight module 10 , a frame 11 , a light guide plate 16 , a diffusion component 17 , and a display panel 18 . The backlight module 10 includes a light source 12 . And a light mixing unit 14. The backlight module 10 , the light guide plate 16 , the diffusion component 17 and the display panel 18 are disposed on the frame 11 , and the backlight module 10 is corresponding to the display panel 18 for providing the display panel 18 . Backlighting.

In the first embodiment, FIG. 3 is a side-by-side backlight structure, that is, the backlight module 10 is located on the side of the integrated device and is opposite to the diffusion assembly 17 by the light guide plate 16. The light is homogenized. The main feature of the present invention is that a first color light beam generated by the light source 12, specifically blue light, is set for the operable wavelength, thereby achieving the purpose of avoiding eye damage of the user. Therefore, the concept of the present invention is not limited to the structure shown in FIG. 3, that is, a direct-lit backlight structure can also be employed.

As described above, the light source 12 used in the present invention is a blue LED chip which generates blue light according to an emission wavelength range. The value of the emission wavelength range is from 457.5 nanometers (nm) to 465 nanometers (nm); after actual testing and comparison analysis, the value can indeed achieve the purpose of removing short-wave blue light of the present invention. Therefore, the backlight generating method of the present invention mainly causes the light source 12 to generate blue light and mix at one of the emission wavelength ranges. Detailed settings and measurement results are described below.

Further, the present invention further divides the emission wavelength range into three bands, a first band, a second band, and a third band, based on the error that can be allowed for the blue LED chip to emit blue light; The one wavelength band ranges from 457.5 nanometers (nm) to 460 nanometers (nm), and the second wavelength band ranges from 460 nm to 462.5 nanometers (nm), and the third wavelength band ranges from 462.5 nm to 465 nm (nm). ). Need to pay attention In the present invention, the size setting of the relevant wavelength range or band includes respective boundary extreme values.

In general, if the same color of light emitted by a plurality of crystal grains is not uniform in wavelength or excessively large, there is a case where color shift occurs. Therefore, the maximum distance between the wavelengths of the present invention is designed to be 2.5 nanometers (nm), so that the color shift of the same color can be effectively avoided. In actual production, a wafer can be divided into three regions to correspond to the above three bands, and then the wafer is cut so that each wafer corresponds to only one band. In other words, the wavelength of the blue light emitted by the wafer during operation is one of the first wavelength band, the second wavelength band, and the third wavelength band; that is, the light source 12 only corresponds to the three wavelength bands. A band.

In the first embodiment, the flat display device 1 is of the sRGB type, and the two kinds of phosphor powders that can be excited by blue light to generate green light and red light respectively are used in the light mixing unit 14 Implementation instructions. The light mixing unit 14 located in front of the light source 12 is formed by a hollow transparent material; for example, a glass tube for accommodating the two types of phosphor powder. As described in the prior art, the light mixing unit 14 excites the phosphors by the blue light emitted by the light source 12 to generate a second color beam and a third color beam, that is, green light. And the red light; the green light and the red light that are excited to be emitted are mixed with the blue light to form white light, and are emitted from the front side of the light mixing unit 14 to provide backlight of the display panel 18.

According to the above description, in the design of green and red phosphors, the wavelength of green light generated can range from 500 nanometers (nm) to 590 nanometers (nm), and the wavelength of red light generated. Available from 570 nm to 760 nm. The application of this part is the same as the prior art, that is, the wavelength range of green light and red light excited by the blue light generated by applying the emission wavelength range of the present invention can still effectively mix the required White light. Of course, the concept of the present invention is not limited to being accommodated in the form of green and red phosphors. Fluorescent powders (e.g., YAG (yttrium aluminum garnet) phosphors) which are excited by blue light to produce yellow light can also be used in conjunction with the present invention as described in the prior art. And the mixture of green light and red light in the first embodiment The result is actually yellow light.

Referring to FIG. 4, the brightness (unit lumen) of the light formed by the flat display device 1 of the first embodiment is measured in advance to correspond to the actual measurement result of the wavelength. In the diagram of Fig. 4, there are two curves, wherein a broken line portion C11 is the measurement result of the prior art Fig. 1, and a thick solid line portion C12 is the quantity of the first embodiment of the present invention. The results are measured to compare the differences between the two. In the figure, the blue LED chip used by the light source 12 is set to emit blue light having a wavelength of 460 nanometers (nm), that is, the maximum value of the first wavelength band or the minimum value of the second wavelength band is used. The peak position of the measured blue light corresponds to a wavelength of about 460 nanometers (nm).

As shown in FIG. 4, similarly, the thick solid line portion C12 also forms three peaks of red light, green light, and blue light. Compared with the dotted line portion C11 of the prior art, the peak luminances of the red light, the green light and the blue light have different heights; wherein the red light of the present invention has a low peak brightness but a long peak wavelength; The green light of the invention has a higher peak brightness, but the peak wavelength is similar. However, for the portion of the blue light, although the peak luminance of the blue light of the present invention is high, since the blue light used is 460 nm (nm), the peak wavelength is long (the blue light of FIG. 1 is 445). Nano (nm)), thereby successfully shifting the range of blue light to long wavelengths, that is, the wavelength of light measured before the flat display device 1 is only about 425 nm (nm). .

In other words, for this band of 380-420 nm (nm), which is most vulnerable to human damage, its more energetic blue light (or purple light in the spectrum) can be completely removed. Furthermore, a marked line L1 indicated in FIG. 4 indicates a position having a wavelength of 450 nm (nm), and the thick solid line portion C12 is far less in the left occupied area of the marked line L1. The area occupied by the broken line portion C11, that is, the present invention can effectively reduce the blue light having a wavelength of less than 450 nm. According to an actual measurement result, the present invention can reduce the blue light of this portion by about 60% compared to the prior art.

The planar display device proposed by the present invention is now implemented in a second embodiment. An implementation description of the backlight generation method applied thereto. The difference between the second embodiment and the first embodiment is only in the type of the flat display device to be applied; the flat display device of the second embodiment is of the Adobe RGB type.

According to the current technology, the Adobe RGB type flat display device is a high-order display with a wide color gamut and high color rendering. In order to achieve this high color rendering standard, the backlight module of the flat display device is the main key. At present, in addition to the backlight module disposed in the form of a cold cathode tube (CCFL), a combination of three types of LED chips of red light, green light, and blue light can be directly used as the backlight. Therefore, the present invention can perform the setting of the operable wavelength as in the first embodiment for the blue LED chip therein, thereby also achieving the purpose of avoiding eye damage of the user.

In the second embodiment, the values including the emission wavelength range and the settings of the three bands are the same as in the first embodiment. Secondly, since the Adobe RGB type flat display device does not use the phosphor powder, the light mixing unit 14 which is a glass tube in Fig. 3 is not used, and an optical film is used for mixing light. In other words, the backlight module of the second embodiment will have three light sources; in addition to the blue LED chip, the green light generated by the green LED chip can have a wavelength of from 500 nanometers (nm) to 580 nm. (nm), and the red light generated by the red LED chip can have a wavelength of from 570 nm to 760 nm, which is also the same as the prior art and can effectively mix white light.

Referring to FIG. 5, the brightness (unit lumen) of the light formed by the flat display device of the second embodiment is measured in advance to correspond to the actual measurement result of the wavelength. Similarly, in the schematic of FIG. 5, two curves are included, wherein a broken line portion C21 is the measurement result of the prior art FIG. 2, and a thick solid line portion C22 is the second implementation of the present invention. The measurement results of the examples are used to compare the differences between the two. In this figure, the blue LED chip used to set the light source is emitted with blue light having a wavelength of 460 nanometers (nm), so that the corresponding peak value measured is also about 460 nanometers (nm).

As shown in FIG. 5, similarly, the thick solid line portion C22 also forms three peaks of red light, green light, and blue light. And prior art Compared with the dotted line portion C21, the difference in peak luminance between the red light, the green light, and the blue light is not large. However, for the portion of blue light, the present invention uses a blue light of 460 nanometers (nm) to make the peak wavelength longer (the blue light of FIG. 2 is 445 nanometers (nm)), and thus also successfully The range of blue light is shifted to long wavelengths, that is, the wavelength of light measured in front of the flat display device is only about 425 nanometers (nm).

Similarly, for this band of 380-420 nm (nm), which is most vulnerable to human damage, its more energetic blue light (or purple light in the spectrum) can be completely removed. Furthermore, a marked line L2 indicated in FIG. 5 indicates a position having a wavelength of 450 nm (nm), and the thick solid line portion C22 is far less in the left occupied area of the marked line L2. The area occupied by the broken line portion C21, that is, the present invention can effectively reduce the blue light having a wavelength of 450 nm or less. According to an actual measurement result, the present invention can reduce the blue light of this portion by about 60% compared to the prior art.

In summary, in a flat display device that requires a blue LED chip as a backlight module, the present invention does not use an application method to control the brightness of the blue light, but directly performs the wavelength of the emitted blue light. Special settings. As such, in addition to avoiding the yellow color shift of the prior art, the actual measurement results also find that the harmful blue light band can be effectively removed or reduced. On the other hand, the present invention does not require the preparation of additional hardware components, that is, it has been possible to propose an optimum solution without increasing the production cost.

Therefore, the present invention can effectively solve the related problems raised in the prior art, and can successfully achieve the main purpose of the development of the present case.

While the invention has been described above in the preferred embodiments, it is not intended to limit the invention. A person skilled in the art can make various changes and modifications without departing from the spirit and scope of the invention. Therefore, the scope of the invention is defined by the scope of the appended claims.

C11‧‧‧dotted section

C12‧‧‧ thick solid line

L1‧‧‧ marking line

Claims (8)

A flat display device includes: a frame; a display panel disposed on the frame; and a backlight module disposed on the frame and corresponding to the display panel for providing backlight of the display panel The backlight module has a light source capable of generating a first color light beam, and the wavelength of the first color light beam falls within an emission wavelength range, and the emission wavelength range is from 457.5 nanometers (nm) to 465 nanometers. The emission wavelength range has a first wavelength band, a second wavelength band, and a third wavelength band, and the wavelength of the first color light beam falls in the first wavelength band, the second wavelength band, and the third wavelength band. One of the first wavelength bands is from 457.5 nm to 460 nm, the second wavelength band is from 460 nm to 462.5 nm, and the third band is from 462.5 nm to 465 nm. The flat display device of claim 1, wherein the backlight module has a light mixing unit disposed on the frame and located in front of the light source, wherein the light mixing unit is configured to use the first color light beam. The light is mixed to form a backlight that provides the display panel. The flat display device of claim 2, wherein the light mixing unit generates a second color light beam and a third color light beam when the light is mixed, such that the first color light beam is further associated with the second color light. The light beam and the third color light beam are mixed; the wavelength of the second color light beam is from 500 nm to 590 nm, and the wavelength of the third color light beam is from 570 nm to 760 nm. The flat display device of claim 2, wherein the light mixing unit mixes the first color beam with a second color beam and a third color beam The wavelength of the second color beam ranges from 500 nm to 580 nm, and the wavelength of the third color beam ranges from 570 nm to 760 nm. A backlight generating method is applied to a flat display device, the flat display device includes a display panel and a backlight module, wherein the backlight module is configured to provide backlight of the display panel, and the method comprises the following steps: A light source of the module generates a first color light beam at one of a range of emission wavelengths; wherein the emission wavelength range is from 457.5 nanometers (nm) to 465 nanometers, the emission wavelength range having a first wavelength band, a second wavelength band and a third wavelength band, wherein the wavelength of the first color light beam falls in one of the first wavelength band, the second wavelength band, and the third wavelength band; wherein the first wavelength band is from 457.5 nm to At 460 nm, the second band is from 460 nm to 462.5 nm, and the third band is from 462.5 nm to 465 nm. The backlight generating method of claim 5, wherein the backlight module has a light mixing unit disposed in front of the light source, wherein the light mixing unit is configured to mix the first color light beam to form Providing a backlight of the display panel. The backlight generating method of claim 6, wherein the light mixing unit generates a second color light beam and a third color light beam when the light is mixed, so that the first color light beam is further combined with the second color light. The light beam and the third color light beam are mixed; the wavelength of the second color light beam is from 500 nm to 590 nm, and the wavelength of the third color light beam is from 570 nm to 760 nm. The backlight generating method of claim 6, wherein the light mixing unit mixes the first color light beam with a second color light beam and a third color light beam; and the wavelength of the second color light beam The range is from 500 nm to 580 nm, and the wavelength of the third color beam is from 570 nm to 760 nm.