Patent Description:
Current technologies provide light emitting devices for projection display systems, which produce lights or different primary colors by using a semiconductor laser to generate an excitation light, to excite different wavelength conversion material segments on a wavelength conversion device. Such light emitting devices have the advantages of high efficiency and low etendue, and are rapidly gaining wide use. They have become ideal choices for light emitting devices for projection display systems. In single chip DMD (digital micromirror device) projection systems, a blue laser light is typically used as the excitation light to excite a segmented color wheel to generate a time sequence of red, green and blue lights, thereby providing the three primary color lights required for projection systems. The blue light is obtained using scattering power to remove the coherency of the laser light. The green light is obtained by exciting a green phosphor material with the blue light, and the red light is obtained by exciting an orange or yellow phosphor material with the blue light and then using a corresponding filter to filter out the shorter wavelength components.

An example of the prior art can be seen in document <CIT>. Further examples are described in documents <CIT>, <CIT> and <CIT>.

In the above light emitting devices for projection systems, the light utilization efficiencies of green and blue lights are relatively high and can achieve satisfactory brightness, but the wavelength conversion efficiency of orange or yellow phosphor materials are relatively low, and the efficiency for obtaining the red light is even lower after using the filter. Also, the color coordinates of the red light is different from the standard gamut defined by the REC. <NUM> or DCI (Digital Copyright Identifier) standards. As a result, the portion of the brightness of the red light in the total brightness of the projection system is low, and the saturation of the red light is low. In applications that require high image quality, such as playing video, laser television, which have high requirement for the brightness ratio and saturation of the red light, using the above described light emitting devices will result in low image quality.

To address the above problem, it is possible to additionally filter the red light so that its color coordinates meet the standard gamut requirement, but the brightness and light utilization efficiency of the red light will be further reduced. Thus, the brightness and color saturation for the red light are difficult to reconcile. For green fluorescent light, because the light conversion efficiency is relatively high, typically there is no problem with brightness. However, because the spectral range of green fluorescent light is relatively broad, its color saturation is low. Therefore, typically the longer wavelength portion of the spectrum needs to be filtered out so that its color coordinates can meet the REC. <NUM> and DCI standards. This causes lower utilization efficiency for the green light.

To further address the above problems, the above described light emitting device for projection system may be improved by adding laser lights, and combining the laser lights with the fluorescent lights, so that the fluorescence efficiency, brightness and color coordinates can all be improved, and the speckle of the laser light is also within acceptable ranges. This provides a feasible solution.

Take the example of red light compensation. For a transmission type color wheel, the blue laser light and the red laser light may be combined into one beam, and when the color wheel is rotated to a position where the orange phosphor segment is illuminated, the blue laser and red laser are simultaneously turned on. At this time, the blue laser light excites the orange phosphor to generate an orange fluorescent light; the red laser light also illuminates the orange phosphor, however it does not excite the phosphor, and is only scattered by it. The orange fluorescent light and the red laser light are combined based on etendue, and output from the color wheel to the collection lens to be collected. Using this design, the coating on the input side of the transmission type color wheel is required to transmit blue light and red light. This type of coating is more difficult to make compared to coatings that are only required to transmit blue light. Moreover, because the red laser light is scattered by the orange phosphor, a part of the light is back-scattered and passes through the coating and is lost. Also, a part of the orange light generated from the blue excitation light is also incident on the coating, and because of their large incident angles, the spectral characteristic curve of the coating shift, so that a part of the orange light within the desired spectral range is also lost due to transmission, which results in lower efficiency for the red light output.

For a reflection type color wheel, the blue laser light and the red laser light may be combined into one beam, passed through a partially coated filter, then collected by a collection lens and focused on the orange phosphor segment of the color wheel. The red laser light is incident on the orange phosphor, is scattered by it, and then reflected by the reflective layer at the bottom of the phosphor layer. This process causes a certain loss. Also, because the reflected light output from the color wheel has a Lambertian distribution, there is a certain loss when the light is collected by the collection lens. Moreover, when the light is passed through the partially coated filter, there is another loss at the filter. For all these reasons, the utilization efficiency of the red laser light is reduced, and the efficiency of the red phosphor is also lower. Because the cost of red laser is relatively high, its low utilization efficiency will increase the cost of the entire system. This is disadvantageous to product manufacturing and application. Therefore, because of all of the factures discussed above, there is a need for a high efficiency light combination system that combines fluorescent light and red laser light.

In light of the above, embodiments of the present invention provide a projection system, to solve the problem in the conventional technology that when the laser light and the fluorescent light are combined, the utilization efficiencies of both the laser light and the fluorescent light are low.

In one aspect, the present invention provides a projection device according to claim <NUM>.

In a second aspect, the present invention provides a projection device according to claim <NUM>.

Comparing to conventional technologies, embodiments of the present invention have the following advantages.

By combining the laser light and converted fluorescent light using time-based light combination, the utilization efficiencies of the laser light and converted light are improved. The brightness of the light emitting device as well as the projection system using the light emitting device is increased, and the cost of the light emitting device and the projection system is greatly reduced.

To more clearly describe embodiments of the present invention or the conventional technology, the drawings used in to describe the embodiments or conventional technology are briefly described below. These drawings illustrate embodiments of the present invention, and those of ordinary skill in the relevant art can construct other drawings based on the described drawings without creative work.

The first through twelfth examples described in <FIG> represent examples not according to the claimed subject-matter, but useful for understanding the invention.

The first and second embodiments described in <FIG> represent embodiments according to the claimed subject-matter.

Embodiments and examples of the present invention provide a light emitting device, including at least two light sources, and a wavelength conversion device, the at least two light sources including an excitation light source and a compensation light source, wherein:.

Embodiments and examples of the present invention also provide a light emitting device, including:.

The key principles of the invention are described above; to further explain the purpose, characteristics and advantages of the invention, specific embodiments and examples of the invention are described in detail below.

Many details are described below for a full understanding of the invention, however the invention may be implemented in other ways. Based on the described embodiments and examples, those of ordinary skill in the art can obtain other embodiments without creative work. The invention is not limited to the embodiments described below.

Further, embodiments of the present invention and examples are described in detail with reference to the drawings; when explaining the embodiments and examples, for ease of explanation, some views of the drawings that illustrate some structural components may be locally enlarged out of scale. These drawings are for illustration only, and do not limit the scope of the invention. Moreover, the actual devices are three dimensional, including length, width and depth.

Embodiments and examples of the invention are described in detail below.

This example provides a light emitting device. As shown in <FIG>, the light emitting device includes two light sources, which are respectively an excitation light source <NUM> that emits an excitation light and a compensation light source <NUM> that emits a compensation light having a spectral range different from that of the excitation light, and a wavelength conversion device <NUM>. The wavelength conversion device <NUM> is disposed on the transmission path of the excitation light emitted by the excitation light source <NUM> and the compensation light emitted by the compensation light source <NUM>. The wavelength conversion device <NUM> outputs a light sequence when alternatingly illuminated by the excitation light source <NUM> and the compensation light source <NUM>, the light sequence including at least one converted light and the compensation light. The compensation light has spectral overlap with at least one converted light of the at least one converted light.

The excitation light source <NUM> may be a blue light source, such as a blue laser device or blue light emitting diode or other solid state light emitting devices, or a solid state light emitting device array containing multiple solid state light emitting devices. The blue light source may be one that has a dominant wavelength of <NUM>.

The compensation light source <NUM> is a laser light source. The compensation light generated by the compensation light source <NUM> is related to the converted light generated by the wavelength conversion device <NUM> when illuminated by the excitation light source <NUM>, i.e., the compensation light generated by the compensation light source <NUM> has spectral overlap with at least one converted light of the at least one converted light generated by the wavelength conversion device <NUM>. For example, when the at least one converted light generated by the wavelength conversion device <NUM> when illuminated by the excitation light source <NUM> includes a sequence of green and orange lights, then the compensation light source <NUM> may be a red laser light source emitting a red laser light which has spectral overlap with the orange light, and/or the compensation light source <NUM> may be a blueish-green laser light source emitting a blueish-green laser light which has spectral overlap with the green light, etc..

The wavelength conversion device <NUM> has at least two segments arranged along its movement direction, at least one segment of the at least two segments includes a first diffuser, and at least one of the remaining segments of the at least two segments includes a wavelength conversion layer. The first diffuser is formed by a roughing optical process on the surface of the wavelength conversion device. The wavelength conversion layer absorbs the excitation light and emits a converted light having a different spectral range than the excitation light. The wavelength conversion layer is a layer that contains a wavelength conversion material, the wavelength conversion material including, without limitation, a phosphor power or other materials that can generate a converted light having a different spectral range than the excitation light when excited by the excitation light.

The movement direction of the wavelength conversion device <NUM> may be a circular movement direction, a horizontal movement direction, or a vertical movement direction. When the wavelength conversion device <NUM> moves along its movement direction, the at least two segments arranged along the movement direction of the wavelength conversion device <NUM> are alternatingly disposed in the transmission path of the excitation light source <NUM> and the compensation light source <NUM>. Each of the excitation light source <NUM> and the compensation light source <NUM>, respectively, always illuminates a same respective segment of the wavelength conversion device <NUM> during the periodic movement of the wavelength conversion device <NUM>.

Preferably, at least one segment of the at least two segments of the wavelength conversion device <NUM> includes a second diffuser. The second diffuser is formed by providing an optical material having a diffusing function on the surface of the wavelength conversion device. The first diffuser, the wavelength conversion layer and the second diffuser are respectively located in different segments of the wavelength conversion device.

The wavelength conversion device <NUM> outputs a light sequence when alternatingly illuminated by the excitation light source <NUM> and the compensation light source <NUM>. Specifically, the excitation light source <NUM> is turn on during the segment of the wavelength conversion device <NUM> that has the wavelength conversion layer and the segment that has the second diffuser, and turned off during other segments; the compensation light source <NUM> is turn on during at least one segment of the wavelength conversion device <NUM> that has the first diffuser, and turned off during other segments. This way, the wavelength conversion device <NUM> outputs a light sequence when alternatingly illuminated by the excitation light source <NUM> and the compensation light source <NUM>.

Refer to <FIG> and <FIG>, each of which schematically illustrates an arrangement of the segments of the wavelength conversion device <NUM> of <FIG>. The arrangement of the segments of the wavelength conversion device <NUM> is not limited to those shown in <FIG> and <FIG>, and can be any arrangement that meets the following requirements: at least one segment has a first diffuser, and at least one segment has a wavelength conversion layer. Further, when the light emitting device is used in a projection system, preferably, the arrangement of the segments of the wavelength conversion device <NUM> may be any arrangement that meets the following requirements: at least one segment has a first diffuser, at least one segment has a wavelength conversion layer, and the output light of the light emitting device or the output light of the wavelength conversion device includes three primary color lights.

Refer to <FIG>, this wavelength conversion device <NUM> includes, along the circumferential direction, a segment <NUM> having a first diffuser and a segment <NUM> having a wavelength conversion layer. The light sequence outputted by the wavelength conversion device <NUM> when alternatingly illuminated by the excitation light source <NUM> and the compensation light source <NUM> includes are least one converted light and the compensation light. More specifically, during the segment <NUM> of the wavelength conversion device <NUM> having the wavelength conversion layer, the excitation light source <NUM> is turned on and the compensation light source <NUM> is turned off; and during the segment <NUM> having the first diffuser, the compensation light source <NUM> is turned on and the excitation light source <NUM> is turned off. Thus, the wavelength conversion device <NUM> outputs a light sequence including the converted light and the compensation light. The compensation light has spectral overlap with the converted light generated by the wavelength conversion layer on the segment <NUM>.

Refer to <FIG>, this wavelength conversion device <NUM> includes, along the circumferential direction, a segment <NUM> having a first diffuser, a segment <NUM> having a wavelength conversion layer, and a segment <NUM> having a second diffuser. The light sequence outputted by the wavelength conversion device <NUM> when alternatingly illuminated by the excitation light source <NUM> and the compensation light source <NUM> includes at least one converted light, the excitation light, and the compensation light. More specifically, during the segment <NUM> of the wavelength conversion device <NUM> having the wavelength conversion layer and the segment <NUM> having the second diffuser, the excitation light source <NUM> is turned on and the compensation light source <NUM> is turned off; and during the segment <NUM> having the first diffuser, the compensation light source <NUM> is turned on and the excitation light source <NUM> is turned off. Thus, the wavelength conversion device <NUM> outputs a light sequence including the excitation light, the converted light and the compensation light. The compensation light has spectral overlap with the converted light generated by the wavelength conversion layer on the segment <NUM>.

In this example, the wavelength conversion device <NUM> may be a transmission type wavelength conversion device, a reflection type wavelength conversion device, or a wavelength conversion device that includes both a transmission region and a reflection region. A transmission type wavelength conversion device refers to one where the direction of propagation of the output light is the same as the direction of propagation of the input light. Transmission type wavelength conversion devices may include transmission type color wheels. A reflection type wavelength conversion device refers to one where the direction of propagation of the output light is the opposite of the direction of propagation of the input light. Reflection type wavelength conversion devices may include reflection type color wheels. A wavelength conversion device that includes both a transmission region and a reflection region refers to one where the direction of propagation of a part of the output light is the same as the direction of propagation of the input light, and the direction of propagation of another part of the output light is the opposite of the direction of propagation of the input light.

Preferably, the wavelength conversion device <NUM> is a transmission type wavelength conversion device, or a wavelength conversion device that includes both a transmission region and a reflection region. When the wavelength conversion device <NUM> is wavelength conversion device that includes both a transmission region and a reflection region, the segment having the first diffuser is located in the transmission region of the wavelength conversion device <NUM>.

Refer to <FIG>, which schematically illustrates the structure of a light emitting device employing a transmission type wavelength conversion device according to an example of the present invention. The excitation light source <NUM> and the compensation light source <NUM> are disposed on the same side of the transmission type wavelength conversion device <NUM>. The light emitting device further includes a light combination device <NUM> located on the transmission paths of the excitation light generated by the excitation light source <NUM> and the compensation light generated by the compensation light source <NUM>. The light combination device <NUM> combines the excitation light generated by the excitation light source <NUM> and the compensation light generated by the compensation light source <NUM> into one light beam, which is then collected by a collection lens <NUM> to be input to the transmission type wavelength conversion device <NUM>.

Under the alternating illumination of the excitation light source <NUM> and the compensation light source <NUM>, the transmission type wavelength conversion device <NUM> outputs a light sequence having a propagates direction that is the same as the input light into the transmission type wavelength conversion device <NUM>. The process of the excitation light source <NUM> and compensation light source <NUM> alternatingly illuminating the transmission type wavelength conversion device <NUM> is as follows:
When the segment of the transmission type wavelength conversion device <NUM> having the wavelength conversion layer and the segment having the second diffuser are located on the transmission path of the combined light beam from the light combination device <NUM>, the excitation light source <NUM> is turned on and the compensation light source <NUM> is turned off. When at least one segment of the transmission type wavelength conversion device <NUM> having the first diffuser is located on the transmission path of the combined light beam from the light combination device <NUM>, the compensation light source <NUM> is turned on and the excitation light source <NUM> is turned off. Thus, the transmission type wavelength conversion device <NUM> outputs a light sequence of the converted light, the excitation light and the compensation light.

Refer to <FIG>, which schematically illustrates the structure of a light emitting device employing a wavelength conversion device that includes both a transmission region and a reflection region according to an example of the present invention. Differences between this light emitting device and the one shown in <FIG> lie in the spatial relationship among the laser source, the compensation light source, the wavelength conversion device and the light combination device, and the structure of the light combination device. More specifically:
The excitation light source <NUM> and the compensation light source <NUM> are respectively located on different sides of the wavelength conversion device <NUM> that includes both a transmission region and a reflection region. The light emitting device further includes a light combination device <NUM> located on the optical path between the excitation light source <NUM> and the compensation light source <NUM>. The light combination device <NUM> combines the light generated by the wavelength conversion device <NUM> when illuminated by the excitation light, and the light generated by the wavelength conversion device <NUM> when illuminated by the compensation light source <NUM>, into one light beam. The light combination device <NUM> includes a spectral light splitting plate <NUM>, a collection lens <NUM> and a reflective plate <NUM>. The excitation light generated by the excitation light source <NUM> is transmitted through the spectral light splitting plate <NUM>, and then collected by the collection lens <NUM> to be input to the wavelength conversion device <NUM>. The compensation light generated by the compensation light source <NUM> is collected by the collection lens <NUM> to be input to the wavelength conversion device <NUM>. The segment of the wavelength conversion device <NUM> having the first diffuser is located in the transmission region, and the other segments are located in the reflection region.

Under the alternating illumination of the excitation light source <NUM> and the compensation light source <NUM>, the wavelength conversion device <NUM> outputs a light sequence that includes the converted light and the compensation light, or outputs a light sequence that includes the excitation light, the converted light and the compensation light. The propagation directions of the converted light and excitation light outputted from the wavelength conversion device <NUM> are opposite to the propagation direction of the excitation light inputted into the wavelength conversion device <NUM>, and the propagation direction of the compensation light outputted from the wavelength conversion device <NUM> is the same as the propagation direction of the compensation light inputted into the wavelength conversion device <NUM>. The process is as follows:
When the segment of the wavelength conversion device <NUM> having the wavelength conversion layer and the segment having the second diffuser are located on the transmission path of the excitation light, the excitation light source is turned on and the compensation light source is turned off. When the at least one segment of the wavelength conversion device <NUM> having the first diffuser is located on the transmission path of the compensation light, the compensation light source is turned on and the excitation light source is turned off. The reflection region of the wavelength conversion device <NUM> reflects the lights generated when illuminated by the excitation light, and the transmission region of the wavelength conversion device <NUM> transmits the compensation light generated by the compensation light source <NUM>. The reflected lights and the transmitted compensation light are together collected by the collection lens <NUM> onto the spectral light splitting plate <NUM>, reflected by the spectral light splitting plate <NUM> to the reflective plate <NUM>, and then reflected by the reflective plate <NUM> to be output.

In a preferred example, the light emitting device further includes a filter device (not shown in <FIG>), the filter device being located downstream of the layer structure of the wavelength conversion device that includes the first diffuser and the wavelength conversion layer, or located downstream of the layer structure of the wavelength conversion device that includes the first diffuser, the wavelength conversion layer and the second diffuser. The filter device has the same segment arrangement corresponding to the segments of the wavelength conversion device. The filter device may be a filter plate wheel disposed coaxially with and rotating synchronously with the wavelength conversion device.

In this example, of the segments of the filter plate, the segment that corresponds to the segment of the wavelength conversion device having the first diffuser, and the segment that corresponds to the segment of the wavelength conversion device having the second diffuser, are transmissive in the entire visible spectral range, and the segments that corresponds to the segments of the wavelength conversion device having the wavelength conversion layer have band-pass, high-pass or low-pass characteristics.

When the wavelength conversion device is a transmission type wavelength conversion device, the filter device and the transmission type wavelength conversion device are arranged in a <NUM> degree correspondence as shown in <FIG>, i.e., the segments of the filter device and the corresponding segments of the transmission type wavelength conversion device coincide with each other. For example:
Refer to <FIG>, the segment 131a' of the filter device corresponds with the segment 131a of the transmission type wavelength conversion device having the first diffuser, the segment 131b' of the filter device corresponds with the segment 131b of the transmission type wavelength conversion device having the second diffuser, the segment 131c' of the filter device corresponds with the segment 131c of the transmission type wavelength conversion device having a green wavelength conversion layer, and the segment 131d' of the filter device corresponds with the segment 131d of the transmission type wavelength conversion device having an orange wavelength conversion layer.

Refer to <FIG> and <FIG>, which are filter curves of the filter device of the example of <FIG>. The segments 131a' and 131b' of the filter device are transmissive, the segment 131c' is a band-pass filter as shown in <FIG>, and the segment 131d' is a high-pass filter as shown in <FIG>.

When the wavelength conversion device is one that includes both a transmission region and a reflection region, the filter device and the wavelength conversion device <NUM> that includes both a transmission region and a reflection region are arranged in a <NUM> degree correspondence as shown in <FIG>. For example:
The segment 131a' of the filter device corresponds with the segment 131a of the transmission type wavelength conversion device having the first diffuser, the segment 131b' of the filter device corresponds with the segment 131b of the transmission type wavelength conversion device having the second diffuser, the segment 131c' of the filter device corresponds with the segment 131c of the transmission type wavelength conversion device having a green wavelength conversion layer, and the segment 131d' of the filter device corresponds with the segment 131d of the transmission type wavelength conversion device having an orange wavelength conversion layer. The segments 131a' and 131b' of the filter device are transmissive, the segment 131c' is a band-pass filter as shown in <FIG>, and the segment 131d' is a high-pass filter as shown in <FIG>.

<FIG> schematically illustrates the structure of a light emitting device according to another example of the present invention. This light emitting device is based on the one shown in <FIG>, but a third light source is added, and the light combination device of <FIG> is modified correspondingly. The rest of the structure is the same as the light emitting device of <FIG>.

The third light source <NUM> emits a third light. The third light has the same color as but different spectrum than the excitation light. For example, when the excitation light is a blue light having a dominant wavelength of <NUM>, the third light may be a blue light having a dominant wavelength of <NUM>. Preferably, the third light source <NUM> is a laser light source.

Under the alternating illumination of the third light source <NUM>, the excitation light source <NUM> and the compensation light source <NUM>, the wavelength conversion device <NUM> generates a light sequence that propagates in the same direction as the excitation light. The light sequence includes the third light, at least one converted light and the compensation light.

Specifically, the third light source <NUM> is turned on when the segment of the wavelength conversion device <NUM> having the second diffuser is located on the transmission path of the third light source <NUM>, and turned off when other segments of the wavelength conversion device <NUM> are located on the transmission path of the third light source <NUM>. The excitation light source <NUM> is turned on when the segments of the wavelength conversion device <NUM> having the wavelength conversion layer are located on the transmission path of the excitation light source <NUM>, and turned off when other segments of the wavelength conversion device <NUM> are located on the transmission path of the excitation light source <NUM>. The compensation light source <NUM> is turned on when the segment of the wavelength conversion device <NUM> having the first diffuser is located on the transmission path of the compensation light source <NUM>, and turned off when other segments of the wavelength conversion device <NUM> are located on the transmission path of the compensation light source <NUM>. Thus, the wavelength conversion device <NUM> outputs the light sequence which propagates in the same direction as the excitation light and which includes the third light, the at least one converted light and the compensation light.

Specifically, the light combination device <NUM> includes a first light combination device <NUM> and a second light combination device <NUM>. The first light combination device <NUM> is located on the transmission paths of the compensation light generated by the compensation light source <NUM> and the third light generated by the third light source <NUM>, for combining the compensation light generated by the compensation light source and the third light generated by the third light source <NUM> into one light beam. The second light combination device <NUM> is located on the transmission paths of the combined light of the first light combination device <NUM> and the excitation light generated by the excitation light source <NUM>, for combining the combined light of the first light combination device <NUM> and the excitation light generated by the excitation light source <NUM> into one light beam. The combined light from the second light combination device <NUM> is collected by a collection lens <NUM> and inputted to the wavelength conversion device <NUM>. Other aspects of this example not described in detail are similar to those of the light emitting device of <FIG>.

In this example, by using the excitation light source and the third light source that emits a light having the same color but different spectrum as the excitation light, the third light emitted by the third light source can be used as one of the primary colors of the light emitting device, so that the color coordinates of the primary color lights generated by the light emitting device can be closer to the standard color coordinates of the REC. <NUM> and DCI standards.

<FIG> schematically illustrates the structure of a light emitting device according to another example of the present invention. This light emitting device is based on the one shown in <FIG>, but a third light source is added. The light from the third light source and the light from the excitation light source <NUM> propagate along the same optical path or are combined into one beam, and then inputted into the wavelength conversion device <NUM> via the light combination device <NUM>. The rest of the structure is the same as in the light emitting device of <FIG>. Other aspects of this example not described in detail are similar to those of the light emitting device of <FIG>.

Under the alternating illumination of the third light source <NUM>, the excitation light source <NUM> and the compensation light source <NUM>, the wavelength conversion device <NUM> generates a light sequence that propagates in the opposite direction as the excitation light, which is output via the light combination device <NUM>. The light sequence includes the third light, at least one converted light and the compensation light.

Specifically, the third light source <NUM> is turned on when the segment of the wavelength conversion device <NUM> having the second diffuser is located on the transmission path of the third light source <NUM>, and turned off when other segments of the wavelength conversion device <NUM> are located on the transmission path of the third light source <NUM>. The excitation light source <NUM> is turned on when the segments of the wavelength conversion device <NUM> having the wavelength conversion layer are located on the transmission path of the excitation light source <NUM>, and turned off when other segments of the wavelength conversion device <NUM> are located on the transmission path of the excitation light source <NUM>. The compensation light source <NUM> is turned on when the segment of the wavelength conversion device <NUM> having the first diffuser is located on the transmission path of the compensation light source <NUM>, and turned off when other segments of the wavelength conversion device <NUM> are located on the transmission path of the compensation light source <NUM>. Thus, the wavelength conversion device <NUM> outputs the light sequence which propagates in the opposite direction as the excitation light. The light sequence is relayed by the collection lens <NUM> of the light combination device <NUM> onto the spectral light splitting plate <NUM>, reflected by the spectral light splitting plate <NUM> to the reflective plate <NUM>, and then reflected by the reflective plate <NUM> to be output.

The light emitting device of this example is based on the first to third examples with modifications; aspects of this example not specifically described are similar to those of the first to third examples. The compensation light source of the light emitting device of this example includes a first compensation light source emitting a first compensation light. The wavelength conversion device includes a segment having a first diffuser, a segment having a first wavelength conversion layer that generates a first converted light when illuminated by the excitation light, and a segment having the second diffuser, arranged along the circumferential direction. Under the alternating illumination of the excitation light source and the first compensation light source, the wavelength conversion device outputs a light sequence that includes the excitation light, the first converted light and the first compensation light. The first compensation light has spectral overlap with the first converted light.

The first compensation light source is turned on when the segment of the wavelength conversion device having the first diffuser is located on the transmission path of the first compensation light source, and is turned off when the other segments of the wavelength conversion device are located on the transmission path of the first compensation light source.

The excitation light source is turned on when the segment of the wavelength conversion device having the wavelength conversion layer and the segment having the second diffuser are located on the transmission path of the excitation light source, and is turned off when the other segments of the wavelength conversion device are located on the transmission path of the excitation light source.

Preferably, the light emitting device further includes a third light source emitting a third light; under the alternating illumination of the third light source, the excitation light source and the first compensation light source, the wavelength conversion device outputs a light sequence that includes the third light, the first converted light and the first compensation light. The third light has the same color as but different spectrum than the excitation light. The third light source is similar to the third light source in the second or third example, and will not be described in detail here.

Preferable, the first compensation light source is a red laser source, and the first wavelength conversion layer is an orange wavelength conversion layer; or, the first compensation light source is a blueish-green laser source, and the first wavelength conversion layer is a green wavelength conversion layer. More preferably, the wavelength conversion device includes a segment having the orange wavelength conversion layer and a segment having the green wavelength conversion layer.

<FIG> schematically illustrates the arrangement of segments of the wavelength conversion device used in the fourth example above. The first wavelength conversion layer is the orange wavelength conversion layer or the green wavelength conversion layer.

The wavelength conversion device includes four segments arranged along the circumferential direction, which are respectively a segment having the second diffuser (the blue segment B in <FIG>), a segment having the green wavelength conversion layer (the green segment G in <FIG>), a segment having the orange wavelength conversion layer (the orange segment O in <FIG>), and the segment having the first diffuser (the diffuser segment in <FIG>). The segment having the second diffuser scatters the light incident on it, for example, it scatters the excitation light incident on it. The segment having the green wavelength conversion layer convers the light incident on it to a green light, for example, it convers the excitation light incident on it to the green light. The segment having the orange wavelength conversion layer convers the light incident on it to a orange light, for example, it convers the excitation light incident on it to the orange light. The segment having the first diffuser scatters the light incident on it, for example, it scatters the compensation light incident on it.

In one example, the arrangement of segments of the wavelength conversion device is as shown in <FIG>, and the light emitting device includes the excitation light source and the first compensation light source, where the excitation light source is a blue light source emitting a blue light B1, and the compensation light source is a red laser light source emitting a red laser light R. Refer to <FIG>, which illustrates a timing of the turning on and off of the excitation light source and the red laser source, the arrangement of the segments of the wavelength conversion device, and the light sequence of the output light of the wavelength conversion device. The wavelength conversion device is alternatingly illuminated by the blue light source and the red laser source. The blue light source is turn on when the segment of the wavelength conversion device having the second diffuser (the blue segment B in <FIG>), the segment having the green wavelength conversion layer (the green segment G in <FIG>), and the segment having the orange wavelength conversion layer (the orange segment O in <FIG>) are located on the transmission path of the blue light generated by the blue light source, and is turned off when other segments of the wavelength conversion device are located on the transmission path of the blue light generated by the blue light source. The red laser source is turn on when the segment having the first diffuser (the diffuser segment in <FIG>) is located on the transmission path of the red laser source, and is turned off when other segments of the wavelength conversion device are located on the transmission path of the red laser source. Thus, the light sequence output by the wavelength conversion device includes the blue light B1, green light G, orange light O and red laser light R. The red laser light of the compensation light has spectral overlap with the orange light O of the converted light.

In another example, the excitation light source is a blue light source emitting a blue light, and the compensation light source is a blueish-green laser light source emitting a blueish-green laser light. The wavelength conversion device is alternatingly illuminated by the blue light source and the blueish-green laser source. The blue light source is turn on when the segment of the wavelength conversion device having the second diffuser (the blue segment B in <FIG>), the segment having the green wavelength conversion layer (the green segment G in <FIG>), and the segment having the orange wavelength conversion layer (the orange segment O in <FIG>) are located on the transmission path of the blue light source, and is turned off when other segments of the wavelength conversion device are located on the transmission path of the blue light source. The blueish-green laser source is turn on when the segment having the first diffuser (the diffuser segment in <FIG>) is located on the transmission path of the blueish-green laser source, and is turned off when other segments of the wavelength conversion device are located on the transmission path of the blueish-green laser source. Thus, the light sequence output by the wavelength conversion device includes the blue light B1, green light G, orange light O and blueish-green laser light C. The blueish-green laser light C has spectral overlap with the green light G of the converted light.

In another example, the light emitting device includes the excitation light source, the first compensation light source and the third light source, where the excitation light source is a blue light source emitting a blue light B1, the first compensation light source is a red laser light source emitting a red laser light R, and the third light source is a blue light source emitting a blue light B2. Refer to <FIG>, which illustrates a timing of the turning on and off of the excitation light source, the third light source and the red laser source, the arrangement of the segments of the wavelength conversion device, and the light sequence of the output light of the wavelength conversion device.

The wavelength conversion device is alternatingly illuminated by the blue light source, the third light source and the red laser source. The third light source is turned on when the segment of the wavelength conversion device having the second diffuser (the blue segment B in <FIG>) is located on the transmission path of the third light source, and is turned off when other segments of the wavelength conversion device are located on the transmission path of the third light source. The blue light source is turn on when the segment having the green wavelength conversion layer (the green segment G in <FIG>) and the segment having the orange wavelength conversion layer (the orange segment O in <FIG>) are located on the transmission path of the blue light source, and is turned off when other segments of the wavelength conversion device are located on the transmission path of the blue light source. The red laser source is turn on when the segment having the first diffuser (the diffuser segment in <FIG>) is located on the transmission path of the red laser source, and is turned off when other segments of the wavelength conversion device are located on the transmission path of the red laser source. Thus, the light sequence output by the wavelength conversion device includes the blue light B2, green light G, orange light O and red laser light R. The red laser light R has spectral overlap with the orange light O of the converted light.

In this example, the orange converted light and the red laser light are combined by time-based light combination to form the red primary color light, or the green converted light and the blueish-green laser light are combined by time-based light combination to form the green primary color light. Compared to the conventional technology which obtains the red primary color light by directly filtering the orange light, and the conventional technology which obtains the green primary color light by directly filtering the green light generated by the green wavelength conversion layer, the light emitting device of this example of the invention can increase the brightness of the red primary color and the green primary color. Further, the orange light and the red laser light are combined by time-based light combination to form the red primary color light, i.e., the present example obtains the red primary color light by adding the red laser light to the orange light; compared to the conventional technology which directly filters the orange light to form the red primary color light, the present example can adjust the ratio of the added red laser light to adjust the color coordinates of the red primary color light to make it closer to the standard color coordinates, or similarly can adjust the ratio of the added blueish-green laser light to adjust the color coordinates of the green primary color light to make it closer to the standard color coordinates. This reduces the amount of filtered-out orange light or green light, thereby reducing the brightness loss when obtaining the red primary color light or green primary color light. Further, because the orange light and the red light are combined by time-based light combination, or the green light and the blueish-green light are combined using time-based light combination, compared to wavelength-based light combination, the example improves the light utilization efficiency of the red laser light or the blueish-green laser light. Through experiments, it was shown that according to examples of the present invention, by time-based light combination of the red laser light and orange light, it can be achieved that when the color coordinates of the red primary color light are (<NUM>, <NUM>), at most <NUM>% of the brightness is lost. In conventional technology where the orange light is directly filtered to obtain the red primary color light, in order to achieve the color coordinates of the red primary color light of (<NUM>, <NUM>), <NUM>% of the brightness will be lost. Based on calculation and experiments, when the red laser light has a dominant wavelength of <NUM> and color coordinates of (<NUM>, <NUM>), if the ratio of the optical powers of the orange light and the red laser light is <NUM>:<NUM>, and the brightness ratio of the orange light and the red laser light is <NUM>:<NUM>, then the color coordinates of the red primary color light obtained by time-based light combination of the orange light and red laser light are (<NUM>, <NUM>), which meets the requirements of the REC. <NUM> standard. In this case, the brightness of the red primary color light is three times of that obtained by conventional technology which directly uses the orange light with a filter plate.

<FIG> schematically illustrates the arrangement of segments of a wavelength conversion device used in the above fourth example, according to another example of the present invention. The first wavelength conversion layer is an orange wavelength conversion layer or a green wavelength conversion layer.

The wavelength conversion device includes six segments arranged along the circumferential direction, which are respectively a segment having the second diffuser (the blue segment B in <FIG>), a segment having the green wavelength conversion layer (the green segment G in <FIG>), a segment having the orange wavelength conversion layer (the orange segment O in <FIG>), another segment having the second diffuser (the other blue segment B in <FIG>), another segment having the green wavelength conversion layer (the other green segment G in <FIG>), and the segment having the first diffuser (the diffuser segment in <FIG>).

In one example, the arrangement of segments of the wavelength conversion device is as shown in <FIG>, the excitation light source is a blue light source emitting a blue light B1, and the compensation light source is a red laser light source emitting a red laser light R. Refer to <FIG>, which illustrates a timing of the turning on and off of the excitation light source and the red laser source, the arrangement of the segments of the wavelength conversion device, and the light sequence of the output light of the wavelength conversion device. The wavelength conversion device is alternatingly illuminated by the blue light source and the red laser source. The blue light source is turn on when the segments of the wavelength conversion device having the second diffuser (the two blue segments B in <FIG>), the segments having the green wavelength conversion layer (the two green segments G in <FIG>), and the segment having the orange wavelength conversion layer (the orange segment O in <FIG>) are located on the transmission path of the blue light source, and is turned off when other segments of the wavelength conversion device are located on the transmission path of the blue light source. The red laser source is turn on when the segment having the first diffuser (the diffuser segment in <FIG>) is located on the transmission path of the red laser source, and is turned off when other segments of the wavelength conversion device are located on the transmission path of the red laser source. Thus, the light sequence output by the wavelength conversion device includes the blue light B1, green light G, orange light O, blue light B, green light G, and red laser light R. The red laser light of the compensation light has spectral overlap with the orange light O of the converted light.

In this example, the sequence of the light sequence output by the wavelength conversion device is B1GOBGR, so the projection system employing this light emitting device can directly use currently available control program of DDP (DLP data processor) to control the spatial modulator component of the projection system. Thus, it can pass the RGB image data of the source image to be displayed, which is obtained by decoding the Digital Visual Interface (DVI) data, directly to the DDP without requiring any signal conversion.

<FIG> schematically illustrates the arrangement of segments of a wavelength conversion device used in the above four examples according to another example of the present invention. The first wavelength conversion layer is an orange wavelength conversion layer or a green wavelength conversion layer.

The wavelength conversion device includes five segments arranged along the circumferential direction, which are respectively a segment having the second diffuser (the blue segment B in <FIG>), a segment having a green wavelength conversion layer (the green segment G in <FIG>), a segment having a yellow wavelength conversion layer (the yellow segment Y in <FIG>), a segment having an orange wavelength conversion layer (the orange segment O in <FIG>), and the segment having the first diffuser (the diffuser segment in <FIG>).

In one example, the arrangement of segments of the wavelength conversion device is as shown in <FIG>, the excitation light source is a blue light source emitting a blue light B1, and the compensation light source is a red laser light source emitting a red laser light R. Refer to <FIG>, which illustrates a timing of the turning on and off of the excitation light source and the red laser source, the arrangement of the segments of the wavelength conversion device, and the light sequence of the output light of the wavelength conversion device. The wavelength conversion device is alternatingly illuminated by the blue light source and the red laser source. The blue light source is turn on when the segment of the wavelength conversion device having the second diffuser (the blue segment B in <FIG>), the segment having the green wavelength conversion layer (the green segment G in <FIG>), the segment having the yellow wavelength conversion layer (the yellow segment Y in <FIG>), and the segment having the orange wavelength conversion layer (the orange segment O in <FIG>) are located on the transmission path of the blue light source, and is turned off when other segments of the wavelength conversion device are located on the transmission path of the blue light source. The red laser source is turn on when the segment having the first diffuser (the diffuser segment in <FIG>) is located on the transmission path of the red laser source, and is turned off when other segments of the wavelength conversion device are located on the transmission path of the red laser source. Thus, the light sequence output by the wavelength conversion device includes the blue light B1, green light G, yellow light Y, orange light O, and red laser light R.

In this example, because the wavelength conversion device additionally includes the segment having the yellow wavelength conversion layer, the brightness of the light emitting device is increased; also, the yellow light may be used directly or after further processing as one of the primary color lights of the light emitting device, so that the light emitting device can achieve a four-sided color gamut, which enlarges the color gamut and also increases the saturation of the yellow color.

The wavelength conversion device includes eight segments arranged along the circumferential direction, which are respectively a segment having the second diffuser (the blue segment B in <FIG>), a segment having a green wavelength conversion layer (the green segment G in <FIG>), a segment having a yellow wavelength conversion layer (the yellow segment Y in <FIG>), a segment having an orange wavelength conversion layer (the orange segment O in <FIG>), another segment having the second diffuser (the other blue segment B in <FIG>), another segment having the green wavelength conversion layer (the other green segment G in <FIG>), another segment having the yellow wavelength conversion layer (the other yellow segment G in <FIG>), and the segment having the first diffuser (the diffuser segment in <FIG>).

In one example, the arrangement of segments of the wavelength conversion device is as shown in <FIG>, the excitation light source is a blue light source emitting a blue light B1, and the compensation light source is a red laser light source emitting a red laser light R. Refer to <FIG>, which illustrates a timing of the turning on and off of the excitation light source and the red laser source, the arrangement of the segments of the wavelength conversion device, and the light sequence of the output light of the wavelength conversion device. The wavelength conversion device is alternatingly illuminated by the blue light source and the red laser source. The blue light source is turn on when the segments of the wavelength conversion device having the second diffuser (the two blue segments B in <FIG>), the segments having the green wavelength conversion layer (the two green segments G in <FIG>), the segments having the yellow wavelength conversion layer (the two yellow segment Y in <FIG>), and the segment having the orange wavelength conversion layer (the orange segment O in <FIG>) are located on the transmission path of the blue light source, and is turned off when other segments of the wavelength conversion device are located on the transmission path of the blue light source. The red laser source is turn on when the segment having the first diffuser (the diffuser segment in <FIG>) is located on the transmission path of the red laser source, and is turned off when other segments of the wavelength conversion device are located on the transmission path of the red laser source. Thus, the light sequence output by the wavelength conversion device includes the blue light B1, green light G, yellow light Y, orange light O, blue light B, green light G, yellow light Y, and red laser light R.

In this example, the sequence of the light sequence output by the wavelength conversion device is B1GYOBGYR, so that the projection system employing this light emitting device can directly use currently available control program of DDP to control the spatial modulator component. Thus, it can pass the RGB image data of the source image to be displayed, obtained by decoding the DVI data, directly to the DDP without requiring any signal conversion. Further, because the wavelength conversion device additionally includes segments having the yellow wavelength conversion layer, the brightness of the light emitting device is increased; also, a four-sided color gamut can be achieved, which enlarges the color gamut and also increases the saturation of the yellow color.

The light emitting device of this example is based on the fourth example with modifications; aspects of this example not specifically described are similar to those of the fourth example. The compensation light source of the light emitting device of this example further includes a second compensation light source emitting a second compensation light which has a different spectral range than the first compensation light. The wavelength conversion device includes, arranged along the circumferential direction, at least two segments each having a first diffuser, a segment having a first wavelength conversion layer that generates a first converted light when illuminated by the excitation light, a segment having the second diffuser, and a segment having a second wavelength conversion layer that generates a second converted light when illuminated by the excitation light. Under the alternating illumination of the excitation light source, the first compensation light source and the second compensation light source, the wavelength conversion device outputs a light sequence that includes the excitation light, the first converted light, the first compensation light, the second converted light and the second compensation light. The first compensation light has spectral overlap with the first converted light, and the second compensation light has spectral overlap with the second converted light.

The first compensation light source is turned on when the at least one segment of the wavelength conversion device having the first diffuser is located on the transmission path of the first compensation light source, and is turned off when the other segments of the wavelength conversion device are located on the transmission path of the first compensation light source.

The second compensation light source is turned on when the at least one segment of the wavelength conversion device having the first diffuser is located on the transmission path of the second compensation light source, and is turned off when the other segments of the wavelength conversion device are located on the transmission path of the second compensation light source. The first compensation light source and the second compensation light source are turned on during different segments.

The excitation light source is turned on when the segments of the wavelength conversion device having the wavelength conversion layer and the segment of the wavelength conversion device having the second diffuser are located on the transmission path of the excitation light source, and is turned off when the segment of the wavelength conversion device having the first diffuser is located on the transmission path of the excitation light source.

Preferably, the light emitting device further includes a third light source emitting a third light; under the alternating illumination of the third light source, the excitation light source, the first compensation light source and the second compensation light source, the wavelength conversion device outputs a light sequence that includes the third light, the first converted light, the first compensation light, the second converted light and the second compensation light. The third light has the same color as but different spectrum than the excitation light. The third light source is similar to the third light source in the second or third example, and will not be described in detail here.

Preferable, the first compensation light source is a red laser source, the first wavelength conversion layer is an orange wavelength conversion layer, the second compensation light source is a blueish-green laser source, and the second wavelength conversion layer is a green wavelength conversion layer.

<FIG> schematically illustrates the arrangement of segments of the wavelength conversion device according to the above ninth example. The wavelength conversion device includes six segments arranged along the circumferential direction, which are respectively a segment having the second diffuser (the blue segment B in <FIG>), a segment having the green wavelength conversion layer (the green segment G in <FIG>), a segment having the first diffuser (the diffuser segment in <FIG>), another segment having the second diffuser (the other blue segment B in <FIG>), a segment having the orange wavelength conversion layer (the orange segment O in <FIG>), and a segment having the first diffuser (the other diffuser segment in <FIG>).

In one example, the arrangement of segments of the wavelength conversion device is as shown in <FIG>, and the light emitting device includes the excitation light source, the first compensation light source and the second compensation light source, where the excitation light source is a blue light source emitting a blue light B1, the first compensation light source is a red laser light source emitting a red laser light R, and the second compensation light source is a blueish-green laser light source emitting a blueish-green laser light. Refer to <FIG>, which illustrates a timing of the turning on and off of the excitation light source, the red laser source and the blueish-green laser source, the arrangement of the segments of the wavelength conversion device, and the light sequence of the output light of the wavelength conversion device.

The wavelength conversion device is alternatingly illuminated by the blue light source, the red laser source and the blueish-green laser source. The blue light source is turn on when the segments of the wavelength conversion device having the second diffuser (the two blue segments B in <FIG>), the segment having the green wavelength conversion layer (the green segment G in <FIG>), and the segment having the orange wavelength conversion layer (the orange segment O in <FIG>) are located on the transmission path of the blue light source, and is turned off when other segments of the wavelength conversion device are located on the transmission path of the blue light source. The red laser source is turn on when one of the segments having the first diffuser (one of the diffuser segments in <FIG>) is located on the transmission path of the red laser source, and is turned off when other segments of the wavelength conversion device are located on the transmission path of the red laser source. The blueish-green laser source is turn on when another segment having the first diffuser (the other diffuser segments in <FIG>) is located on the transmission path of the blueish-green laser source, and is turned off when other segments of the wavelength conversion device are located on the transmission path of the blueish-green laser source. Thus, the light sequence output by the wavelength conversion device includes the blue light B1, orange light O, blueish-green light C, blue light B1, green light G, and red laser light R. The red laser light R has spectral overlap with the orange light O of the converted light, and the blueish-green laser light C has spectral overlap with the green light G of the converted light.

In another example, the light emitting device includes the third light source, the excitation light source, the first compensation light source and the second compensation light source, where the third light source is a blue light source emitting a blue light B2, the excitation light source is a blue light source emitting a blue light B1, the first compensation light source is a red laser light source emitting a red laser light R, and the second compensation light source is a blueish-green laser light source emitting a blueish-green laser light. The wavelength conversion device is alternatingly illuminated by the third light source, the blue light source, the red laser light source and the blueish-green laser light source. The third light source is turned on when the segments of the wavelength conversion device having the second diffuser (the two blue segment B in <FIG>) is located on the transmission path of the third light source, and is turned off when other segments of the wavelength conversion device are located on the transmission path of the third light source. The blue light source is turn on when the segment having the green wavelength conversion layer (the green segment G in <FIG>) and the segment having the orange wavelength conversion layer (the orange segment O in <FIG>) are located on the transmission path of the blue light source, and is turned off when other segments of the wavelength conversion device are located on the transmission path of the blue light source. The red laser source is turn on when one of the segments having the first diffuser (one of the diffuser segments in <FIG>) is located on the transmission path of the red laser source, and is turned off when other segments of the wavelength conversion device are located on the transmission path of the red laser source. The blueish-green laser source is turn on when another segment having the first diffuser (the other diffuser segment in <FIG>) is located on the transmission path of the blueish-green laser source, and is turned off when other segments of the wavelength conversion device are located on the transmission path of the blueish-green laser source. Thus, the light sequence output by the wavelength conversion device includes the blue light B2, orange light O, blueish-green light C, blue light B1, green light G, and red laser light R. The red laser light R of the compensation light has spectral overlap with the orange light O of the converted light, and the blueish-green laser light C of the compensation light has spectral overlap with the green light G of the converted light.

In this example, two segments of the wavelength conversion device are provided with the first diffuser, and two compensation light sources are provided and each corresponding to a respective diffuser. The two compensation lights are respectively combined using time-based light combination with the two converted lights generated by the two wavelength conversion layers of the wavelength conversion device. This further increases the brightness of the light emitting device.

<FIG> schematically illustrates the structure of a light emitting device according to another example of the present invention. This light emitting device is based on the light emitting device of the ninth example with modifications, and the wavelength conversion device is a transmission type wavelength conversion device. The first compensation light source <NUM> and the second compensation light source <NUM> are on the same optical path; for example, the first compensation light source <NUM> and the second compensation light source <NUM> are disposed side by side. The light combination device <NUM> combines the excitation light emitted by the excitation light source <NUM>, the first compensation light emitted by the first compensation light source <NUM> and the second compensation light emitted by the second compensation light source <NUM> into one light beam. The combined light beam is collected by the collection lens <NUM> to be input to the wavelength conversion device <NUM>.

Under the alternating illumination of the excitation light source <NUM>, the first compensation light source <NUM> and the second compensation light source <NUM>, the transmission type wavelength conversion device <NUM> outputs a light sequence propagating in the same direction as the light input into the transmission type wavelength conversion device <NUM>. The process of the excitation light source <NUM>, the first compensation light source <NUM> and the second compensation light source <NUM> alternatingly illuminating the transmission type wavelength conversion device <NUM> is as follows:
When the segment of the wavelength conversion device <NUM> having the wavelength conversion layer and the segment having the second diffuser are located on the transmission path of the combined light from the light combination device <NUM>, the excitation light source <NUM> is turned on, and the first compensation light source <NUM> and the second compensation light source <NUM> are turned off. When at least one of the segments of the wavelength conversion device <NUM> having the first diffuser is located on the transmission path of the combined light from the light combination device <NUM>, the first compensation light source <NUM> is turned on, and the excitation light source <NUM> and the second compensation light source <NUM> are turned off. When at least another segment of the wavelength conversion device <NUM> having the first diffuser is located on the transmission path of the combined light from the light combination device <NUM>, the second compensation light source <NUM> is turned on, and the excitation light source <NUM> and the first compensation light source <NUM> are turned off.

In this example, the light emitting device includes the excitation light source, the first compensation light source and the second compensation light source. Or, it includes the third light source, the excitation light source, the first compensation light source and the second compensation light source. Under the alternating illumination of the excitation light source, the first compensation light source and the second compensation light source, the wavelength conversion device outputs a light sequence that includes the excitation light, at least two converted lights, the first compensation light and the second compensation light. Or, under the alternating illumination of the third light source, the excitation light source, the first compensation light source and the second compensation light source, the wavelength conversion device outputs a light sequence that includes the third light, at least two converted lights, the first compensation light and the second compensation light. The first compensation light is combined with one of the converted lights using time-based light combination to form one primary color light, and the second compensation light is combined with the other converted light using time-based light combination to form another primary color light. This can simultaneously increase the utilization efficiencies of the two different converted lights, and increase the brightness of the light emitting device.

<FIG> schematically illustrates the structure of a light emitting device according to another example of the present invention. This light emitting device is based on the light emitting device of the ninth example with modifications, and the wavelength conversion device is one that includes both a transmission region and a reflection region. The first compensation light source <NUM> and the second compensation light source <NUM> are on the same optical path; for example, the first compensation light source <NUM> and the second compensation light source <NUM> are disposed side by side. The light combination device <NUM> combines the light generated by the wavelength conversion device <NUM> under illumination of the excitation light source <NUM>, and the light generated by the wavelength conversion device <NUM> under illumination of the first compensation light source <NUM>, into one light beam. The light combination device <NUM> includes a spectral light splitting plate <NUM>, a collection lens <NUM> and a reflective plate <NUM>. The excitation light emitted by the excitation light source <NUM> is transmitted through the spectral light splitting plate <NUM>, collected by the collection lens <NUM>, and then input to the wavelength conversion device <NUM>. The compensation light emitted by the compensation light source <NUM> is collected by the collection lens <NUM> and input to the wavelength conversion device <NUM>. The segment of the wavelength conversion device <NUM> having the first diffuser is located in the transmission region, and the other segments are located in the reflection region.

Under the alternating illumination of the excitation light source <NUM>, the first compensation light source <NUM> and the second compensation light source <NUM>, the wavelength conversion device <NUM> outputs a light sequence propagating in a direction opposite to the excitation light. More specifically:
When the segment of the wavelength conversion device <NUM> having the wavelength conversion layer and the segment having the second diffuser are located on the transmission path of the excitation light, the excitation light source <NUM> is turned on, and the first compensation light source <NUM> and the second compensation light source <NUM> are turned off. When at least one of the segments of the wavelength conversion device <NUM> having the first diffuser is located on the transmission path of the first compensation light, the first compensation light source <NUM> is turned on, and the excitation light source <NUM> and the second compensation light source <NUM> are turned off. When at least another segment of the wavelength conversion device <NUM> having the first diffuser is located on the transmission path of the second compensation light, the second compensation light source <NUM> is turned on, and the excitation light source <NUM> and the first compensation light source <NUM> are turned off. The reflection region of the wavelength conversion device <NUM> reflects the lights that are generated under illumination of the excitation light. The transmission region of the wavelength conversion device <NUM> transmits the first compensation light emitted by the first compensation light source <NUM> and the second compensation light emitted by the second compensation light source <NUM>. The reflected light beam and the transmitted first compensation light and second compensation light from the wavelength conversion device <NUM> are together collected by the collection lens <NUM> and input onto the spectral light splitting plate <NUM>, reflected by the spectral light splitting plate <NUM> to the reflective plate <NUM>, and then reflected by the reflective plate <NUM> to be output.

<FIG> schematically illustrates the structure of a light emitting device according to the embodiment of the present invention. The light emitting device includes two light sources, which are an excitation light source <NUM> emitting and excitation light and a compensation light source <NUM> emitting a compensation light which has a different spectrum than that of the excitation light, and a wavelength conversion device <NUM>.

The wavelength conversion device <NUM> is disposed on the transmission paths of the excitation light emitted by the excitation light source <NUM> and the compensation light emitted by the compensation light source <NUM>. It includes at least two segments arranged in the circumferential direction, where at least one of the at least two segments has a wavelength conversion layer. When the excitation light source <NUM> and compensation light source <NUM> simultaneously illuminate different segments of the wavelength conversion device <NUM>, the wavelength conversion device <NUM> outputs a combined light of the compensation light and a converted light. The compensation light has spectral overlap with the converted light. The wavelength conversion device <NUM> is a reflection type wavelength conversion device.

At least one segment of the at least two segments has a second diffuser.

When the excitation light source <NUM> and compensation light source <NUM> simultaneously illuminate different segments of the wavelength conversion device <NUM>, the process of generating the combined light of the compensation light and a converted light is as follows:
The excitation light source <NUM> is continuously turned on. The compensation light source <NUM> is turned on when the segment of the wavelength conversion device <NUM> having the wavelength conversion layer is in the transmission path of the excitation light source <NUM>, and turned off during other segments. Thus, the wavelength conversion device outputs a combined light of the compensation light and the converted light.

In this embodiment, the light emitting device further includes a light combination device <NUM>. The light combination device <NUM> includes a first light combination plate <NUM>, a collection lens <NUM> and a second light combination plate <NUM>. The excitation light emitted by the excitation light source <NUM> is transmitted through the first light combination plate <NUM>, and collected by the collection lens <NUM> to be input to the wavelength conversion device <NUM>. The compensation light source <NUM> is transmitted through the second light combination plate <NUM> to be input to the wavelength conversion device <NUM>. The output light of the wavelength conversion device <NUM> is collected by the collection lens <NUM> onto the first light combination plate <NUM>, reflected by the first light combination plate <NUM> to the second light combination plate <NUM>, and then reflected by the second light combination plate <NUM> where it is combined with the compensation light that is transmitted through the second light combination plate <NUM> to form one light beam. The first light combination plate <NUM> may be a partially coated filter, which includes a transmission portion and a reflection portion. The transmission portion transmits the excitation light emitted by the excitation light source, and the reflection portion reflects the light beam output from the wavelength conversion device. To reduce light loss, the size of the transmission portion is smaller than the size of the reflection portion.

To avoid having the compensation light directly output by the wavelength conversion device, which causes speckle, and also to reduce light loss, in a preferred embodiment, a scattering device <NUM> and a collection lens <NUM> are provided on the optical path between the compensation light emitted by the compensation light source <NUM> and the wavelength conversion device. The scattering device <NUM> has a first diffuser, for scattering the compensation light. The collection lens <NUM> collects the compensation light scattered by the scattering device <NUM>, and relays it to the wavelength conversion device <NUM>. This way, the second light combination plate <NUM> may also be a partially coated filter, which includes a transmission portion and a reflection portion. The transmission portion transmits the compensation light, which has been scattered by the scattering device <NUM> and collected by the collection lens <NUM>, to the wavelength conversion device <NUM>. The reflection portion reflects the light beam from the first light combination plate <NUM> to the wavelength conversion device <NUM>.

Refer to <FIG>, which schematically illustrates the arrangement of segments of the wavelength conversion device <NUM> shown in <FIG> according to an embodiment of the present invention. The arrangement of the segments of the wavelength conversion device <NUM> is not limited to that shown in <FIG>.

The wavelength conversion device <NUM> includes, arranged along the circumferential direction, a segment having the second diffuser (the blue segment B in <FIG>), a segment having the green wavelength conversion layer (the green segment G in <FIG>), and a segment having the orange wavelength conversion layer (the orange segment O in <FIG>).

In one example, the excitation light source <NUM> is a blue light source, such as a blue laser or blue LED, and the compensation light source <NUM> is a red laser source. The excitation light source <NUM> is continuously turned on. The compensation light source <NUM> is turned on when the segment of the wavelength conversion device <NUM> having the orange wavelength conversion layer is in the transmission path of the excitation light source <NUM>, and turned off during other times. Thus, the wavelength conversion device <NUM> outputs a combined light of the red laser light and the orange light, which increases the utilization efficiency of the orange light and brightness.

In another example, the excitation light source <NUM> is a blue light source, such as a blue laser or blue LED, and the compensation light source <NUM> is a green laser source, such as a laser having a dominant wavelength of <NUM> to <NUM>. The excitation light source <NUM> is continuously turned on. The compensation light source <NUM> is turned on when the segment of the wavelength conversion device <NUM> having the green wavelength conversion layer is in the transmission path of the excitation light source <NUM>, and turned off during other times. Thus, the wavelength conversion device <NUM> outputs a combined light of the green laser light and the green light, which increases the utilization efficiency of the green light and brightness.

In another embodiment, the light emitting device further includes a third light source (not shown in <FIG>). The third light source emits a third light. The third light has a different spectrum than the compensation light. The third light has the same color as but different spectrum than the excitation light. For example, the excitation light is a blue laser light of <NUM>, the third light is a blue laser light of <NUM>. The third light emitted by the third light source is combined with the excitation light, and input to the wavelength conversion device via the light combination device.

In this embodiment, which is not according to the claimed subject-matter, the excitation light source is turned on during the segments having the wavelength conversion layers, and turned off during other segments. The compensation light source is turned on when the segment of the wavelength conversion device having the first wavelength conversion layer is located on the transmission path of the excitation light source, and turned off during other segments. The third light source is turned on during the segment having the second diffuser, and turned off during other segments. Thus, the wavelength conversion device outputs a light sequence that includes the third light, the converted light and the compensation light, so that the third light may be used as one of the primary color lights output by the light emitting device.

<FIG> schematically illustrates the structure of a projection system according to an embodiment of the present invention. The projection system includes a light emitting device <NUM> as those described in earlier embodiments and examples, and a first image forming assembly <NUM>. The first image forming assembly <NUM> includes a light relay <NUM>, a TIR prism <NUM>, a spatial light modulator <NUM>, and a projection lens <NUM>. The light relay <NUM> may include a light rod, relay lens, etc. The spatial light modulator <NUM> includes a digital micromirror device (DMD). The light relay <NUM> relays the light outputted by the light emitting device <NUM> to the TIR prism <NUM>; the TIR prism <NUM> guides this light to the DMD, and guides the image light outputted by the DMD to the projection lens <NUM>.

<FIG> schematically illustrates the structure of a projection system according to another example of the present invention. The projection system includes a light emitting device <NUM> as those described in earlier examples, and a second image forming assembly <NUM>. The second image forming assembly <NUM> includes a light relay <NUM>, a TIR prism <NUM>, a light separation and combination prism <NUM>, a spatial light modulator including first DMD 340a and second DMD 340b, and a projection lens <NUM>. The light relay <NUM> may include a light rod, relay lens, etc. The light separation and combination prism <NUM> includes a first prism and a second prism, and a light splitting coating because the first prism and the second prism. The light splitting coating is a low-pass light splitting coating or a bandpass light splitting coating.

The light relay <NUM> relays the light outputted by the light emitting device <NUM> to the TIR prism <NUM>. The TIR prism <NUM> guides the light from the light relay <NUM> to the light separation and combination prism <NUM>. The light separation and combination prism <NUM> splits the light from the TIR prism <NUM> into a light traveling along a first optical path and a light traveling along a second optical path. The first DMD 340a modulates the light traveling along the first optical path to obtain a first image light, and the second DMD 340b modulates the light traveling along the second optical path to obtain a second image light. The light separation and combination prism <NUM> combines the first image light and the second image light, and the TIR prism <NUM> guides the combined light to the projection lens <NUM>.

Claim 1:
A projection device, comprising a light emitting device (<NUM>) and a first image forming assembly (<NUM>) including a light relay (<NUM>), a TIR prism (<NUM>), a spatial light modulator (<NUM>), and a projection lens (<NUM>),
wherein the light relay (<NUM>) relays the light outputted by the light emitting device (<NUM>) to the TIR prism (<NUM>), the TIR prism (<NUM>) guides this light to the spatial light modulator (<NUM>), and guides the image light outputted by the spatial light modulator (<NUM>) to the projection lens (<NUM>);
wherein
the light emitting device (<NUM>) comprises:
an excitation light source (<NUM>) for generating an excitation light;
a compensation light source (<NUM>) for generating a compensation light having a spectral range different from a spectral range of the excitation light;
a wavelength conversion device (<NUM>) disposed on transmission paths of the excitation light and the compensation light, the wavelength conversion device (<NUM>) including a segment having a second diffuser, a segment having a green wavelength conversion layer, and a segment having an orange wavelength conversion layer, arranged along a circumferential direction;
wherein when the excitation light source (<NUM>) and the compensation light source (<NUM>) simultaneously illuminate different segments of the wavelength conversion device, the wavelength conversion device (<NUM>) outputs a combined light of the compensation light and a converted light, wherein the compensation light has spectral overlap with the converted light;
wherein the excitation light source (<NUM>) is continuously turned on, wherein the compensation light source (<NUM>) is turned on when the segment of the wavelength conversion device (<NUM>) having the first wavelength conversion layer is located on a transmission path of the excitation light source (<NUM>), and is turned off when other segments are located on the transmission path of the excitation light source (<NUM>), wherein the first wavelength conversion layer converts the excitation light to a converted light that has spectral overlap with the compensation light.