JP2020095919A - Light amount adjusting method, light amount adjusting device, and projection device - Google Patents

Abstract

To provide a light amount adjusting method capable of stabilizing brightness of an image projected on a projection medium such as a screen over time.SOLUTION: An illumination light LL1 is optically modulated on the basis of image data of first and second display image levels. First to fourth light amounts Cwb, Cbb, Cwa, and Cba are detected. A first transmittance t2b is calculated on the basis of the first and second light amounts Cwb and Cbb. A second transmittance t2a is calculated on the basis of the third and fourth light amounts Cwa and Cba. On the basis of the first transmittance t2b and the second transmittance t2a, a light amount ratio LQR which is a ratio of a light amount L2a of the illumination light LL1 irradiated to a light modulation element 4 at a second time point to a light amount L2b of the illumination light LL1 irradiated to the light modulation element 4 at a first time point is calculated. The drive of the light modulation element 4 is controlled on the basis of the light amount ratio LQR, and therefore, the light amount of the image light ML generated by the light modulation of the illumination light LL1 is adjusted.SELECTED DRAWING: Figure 8

Description

The present invention relates to a light amount adjusting method, a light amount adjusting device, and a projection device for stabilizing the light amount of image light projected on a projection medium such as a screen with time.

The projection device emits illumination light from a light source, and irradiates, for example, a reflection type light modulation element via an illumination optical system in which a plurality of optical components are arranged. The light modulation element optically modulates the illumination light for each pixel based on the image data to generate image light. The projection device projects image light from a projection lens onto a projection medium such as a screen. Patent Document 1 describes a projection device (projector) that detects the light amount of illumination light with which a light modulation element is irradiated by an optical sensor arranged in the vicinity of the light modulation element.

JP 2012-47951 A

Usually, in the projection device, a plurality of optical components are arranged in the limited internal space. Therefore, it is practically difficult to dispose the optical sensor near the optical modulator. Even if the light sensor can be arranged in the vicinity of the light modulation element, in order for the light sensor to detect the illumination light, the irradiation area of the illumination light must be expanded to an unnecessary range. As a result, the amount of image light is reduced, and the image projected on the projection medium becomes darker than the target brightness.

An object of the present invention is to provide a light amount adjustment method, a light amount adjustment device, and a projection device capable of stabilizing the brightness of an image projected on a projection medium such as a screen over time.

According to the present invention, at the first time point, the light modulation element emits the illumination light emitted from the light source section through the illumination optical system to the first display image level and the second display image level lower than the first display image level. Light modulation based on the image data of the display image level of, the optical sensor, when the illumination light and the light modulation element optical modulation the illumination light based on the image data of the first display image level A first light amount that is a total light amount of the return light that is emitted from the light modulation element and returns to the light source unit, and the illumination light and the light modulation element that illuminate the illumination light at the second display image level image. When the light is modulated on the basis of the data, the second light quantity that is the total light quantity emitted from the light modulation element and returned to the light source section is detected, and the light quantity calculation section detects the first and second light quantities. The first transmittance of the illumination optical system with respect to the illumination light is calculated based on the light amount of the, and at a second time point after the first time point, the light modulation element outputs the illumination light to the first light beam. Optical modulation is performed based on image data of the first and second display image levels, and the optical sensor optically modulates the illumination light and the light modulation element with the illumination light based on the image data of the first display image level. A third light amount that is a total light amount of return light that is emitted from the light modulation element and returns to the light source unit when modulated, and the illumination light and the light modulation element generate the second illumination light. When light modulation is performed based on the image data of the display image level, a fourth light amount that is a total light amount emitted from the light modulation element and returns to the light source unit is detected, and the light amount calculation unit, The second transmittance of the illumination optical system with respect to the illumination light is calculated based on the third and fourth light amounts, and the light amount calculation unit calculates the second transmittance based on the first and second transmittances. The light amount ratio, which is the ratio of the light amount of the illumination light applied to the light modulation element at the second time point to the light amount of the illumination light applied to the light modulation element at the first time point, is calculated, and the gain is adjusted. A light amount adjusting method for adjusting the light amount of image light generated by light-modulating the illumination light by controlling the drive of the light modulation element based on the light amount ratio.

According to the present invention, when the illumination light emitted from the light source unit via the illumination optical system and the light modulation element optically modulate the illumination light based on the image data of the first display image level at the first time point. A first light amount that is a total light amount of return light that is emitted from the light modulation element and returns to the light source unit, and the illumination light and the light modulation element emit the illumination light from the first display image level. When the light is modulated based on the image data of the second display image level which is also low, the second light amount which is the total light amount of the return light emitted from the light modulation element and returning to the light source unit is detected, At a second time point after the first time point, when the illumination light and the light modulation element optically modulate the illumination light based on the image data of the first display image level, the light is emitted from the light modulation element. Then, the third light amount, which is the total light amount of the return light returning to the light source unit, and the illumination light and the light modulation element emit the illumination light based on the image data of the second display image level. An optical sensor that detects a fourth light amount that is a total light amount of return light that is emitted from the light modulation element and returns to the light source unit when modulated, and the illumination is based on the first and second light amounts. A first transmittance of the illumination optical system for light at the first time point is calculated, and a second transmittance of the illumination optical system for the illumination light at the second time point is calculated based on the third and fourth light amounts. Is calculated, and based on the first and second transmittances, the light modulation element at the second time point with respect to the light amount of the illumination light with which the light modulation element is irradiated at the first time point. That the illumination light is light-modulated by controlling the drive of the light modulator based on the light amount calculation unit that calculates the light amount ratio that is the ratio of the light amount of the illumination light that is irradiated to And a gain adjusting unit that adjusts the light amount of the image light generated by the light amount adjusting device.

The present invention provides a light source unit that emits illumination light, an illumination optical system that receives the illumination light from the light source unit and emits the illumination light, and an illumination light that is emitted from the illumination optical system. A light modulation element that performs light modulation based on image data of a first display image level and a second display image level lower than the first display image level; and illumination emitted from the light source unit at a first time point. A total light amount of light and return light that is emitted from the light modulation element and returns to the light source section when the light modulation element optically modulates the illumination light based on the image data of the first display image level. A certain first light amount, and when the illumination light and the light modulation element optically modulate the illumination light based on image data of the second display image level, the light source emits the light from the light modulation element. The second light amount, which is the total light amount of the return light returning to, is detected, and at a second time point after the first time point, the illumination light and the light modulation element convert the illumination light into the first light ray. A third light amount that is a total light amount of the return light that is emitted from the light modulation element and returns to the light source unit when the light is modulated based on the image data of the display image level, and the illumination light and the light modulation. A fourth light amount, which is a total light amount of return light emitted from the light modulation element and returned to the light source unit when the element optically modulates the illumination light based on the image data of the second display image level. An optical sensor for detecting the first light amount, and a first transmittance of the illumination optical system for the illumination light at the first time point based on the first and second light amounts, and the third and fourth light amounts. A second transmittance of the illumination optical system for the illumination light at the second time point based on, and the light modulation element at the first time point based on the first and second transmittance rates. A light amount calculation unit that calculates a light amount ratio that is a ratio of the light amount of the illumination light applied to the light modulation element to the light amount of the illumination light that is applied to the light modulation element; There is provided a projection apparatus including: a gain adjusting unit that adjusts a light amount of image light generated by optically modulating the illumination light by controlling driving of a light modulation element.

According to the light amount adjusting method, the light amount adjusting device, and the projection device of the present invention, it is possible to stabilize the brightness of an image projected on a projection medium such as a screen over time.

It is a block diagram which shows the projection apparatus of 1st-6th embodiment. It is a block diagram which shows an example of a light source part. It is a block diagram which shows an example of the fluorescent substance part in a light source part. It is a block diagram which shows an example of the light amount adjustment apparatus in the projection apparatus of 1st Embodiment. It is a figure which shows the state in which a light modulation element carries out the light modulation of the illumination light based on the image data of a white level. It is a figure which shows the state in which a light modulation element carries out the light modulation of the illumination light based on the image data of black level. It is a figure which shows the state which an optical modulation element carries out the optical modulation of the illumination light based on the image data of a gray level. It is a figure which shows the relationship between an illumination optical system and an optical sensor. It is a flow chart which shows the light quantity adjustment method in a 1st embodiment. It is a flow chart which shows the light quantity adjustment method in a 1st embodiment. It is a block diagram which shows an example of the light amount adjustment apparatus in the projection apparatuses of 2nd and 3rd embodiment. It is a flowchart which shows the light amount adjustment method in 2nd and 3rd embodiment. It is a block diagram which shows an example of the light amount adjustment apparatus in the projection apparatus of 4th and 5th embodiment. It is a block diagram which shows an example of a light source part. It is a block diagram which shows an example of a light source part. It is a block diagram which shows the projection apparatus of 1st-6th embodiment when an optical sensor is arrange|positioned in the position different from FIG.

[First Embodiment]
A configuration example of the projection apparatus according to the first embodiment will be described with reference to FIG. The projection device 1 includes a light source unit 2, an illumination optical system 3, a light modulation element 4, a projection optical system 5, and a light amount adjustment device 6. In the first embodiment, the projection device 1 is referred to as the projection device 1a, and the light amount adjustment device 6 is referred to as the light amount adjustment device 6a in order to distinguish it from the projection device 1 and the light amount adjustment device 6 of other embodiments described later.

A configuration example of the light source unit 2 will be described with reference to FIG. The light source unit 2 includes a light source 10, condenser lenses 11, 12, and 13, a split mirror 14, a dichroic mirror 15 (first dichroic mirror), lenses 16 and 17, and mirrors 18, 19, and 20. And a phosphor portion 21.

The light source 10 and the phosphor part 21 form an illumination light source. The light source 10 is composed of, for example, a laser array in which a plurality of blue laser elements BE are arranged. The light source 10 emits blue laser light.

A configuration example of the phosphor unit 21 will be described with reference to FIGS. The phosphor unit 21 includes a phosphor wheel 22, a phosphor 23, a rotating shaft 24, and a wheel driving unit 25. The phosphor wheel 22 has, for example, a disc shape. The phosphor 23 is formed on the outer periphery of the surface of the phosphor wheel 22 which is a mirror surface. When the phosphor 23 is irradiated with the blue laser light BL, the phosphor 23 is excited and emits yellow light containing a red component and a green component.

The wheel drive unit 25 rotates the phosphor wheel 22 around the rotation shaft 24. By irradiating the phosphor 23 with the blue laser light BL in a state where the phosphor wheel 22 is rotated, a local temperature rise caused by the irradiation of the blue laser light BL is prevented. It can be dispersed throughout. Thereby, the temperature rise of the phosphor 23 can be suppressed.

The condenser lenses 11 to 13 condense the incident blue laser light BL. The split mirror 14 splits the blue laser light BL which is the incident light. Specifically, the split mirror 14 reflects a part of the incident blue laser light BL and transmits the rest. The blue laser light BL transmitted through the split mirror 14 is referred to as blue laser light BL1 (first blue laser light), and the blue laser light BL reflected by the split mirror 14 is referred to as blue laser light BL2 (second blue laser light). ..

The blue laser light BL1 transmitted through the split mirror 14 enters the dichroic mirror 15. The dichroic mirror 15 reflects blue light containing a blue component and transmits yellow light containing a red component and a green component. The blue laser light BL1 is reflected by the dichroic mirror 15, is further condensed by the condenser lenses 12 and 13, and is applied to the phosphor 23.

The phosphor 23 is excited by the blue laser light BL1 and emits yellow light containing a red component and a green component. The phosphor part 21 emits yellow light as yellow illumination light YLL by being irradiated with the blue laser light BL1. The yellow illumination light YLL enters the illumination optical system 3 via the condenser lenses 12 and 13 and the dichroic mirror 15.

The blue laser light BL2 reflected by the split mirror 14 is applied to the dichroic mirror 15 via a relay optical system having lenses 16 and 17 and mirrors 18 to 20. The blue laser light BL2 is reflected by the dichroic mirror 15 and enters the illumination optical system 3 as blue illumination light BLL. That is, the white illumination light WLL, which is a mixed light of the yellow illumination light YLL and the blue illumination light BLL, is incident on the illumination optical system 3 from the light source unit 2.

The light source unit 2 is not limited to the above configuration, and may be any light source that emits white illumination light WLL. For example, a white LED light source or a white lamp light source may be used as the light source unit 2.

As shown in FIG. 1, the illumination optical system 3 includes reflection mirrors 30 to 32, fly-eye lenses 33 and 34, a polarization conversion element 35, and lenses 36 to 39. Further, the illumination optical system 3 includes a cross dichroic mirror 40 (second dichroic mirror), a dichroic mirror 41 (third dichroic mirror), and a reflective polarizing plate 42.

The reflection mirror 30 reflects the illumination light WLL that has entered the illumination optical system 3 toward the fly-eye lenses 33 and 34. The fly-eye lenses 33 and 34 form a uniform illumination optical system. The fly-eye lenses 33 and 34 uniformize the illumination distribution of the illumination light WLL with which the light modulation element 4 is irradiated.

The polarization conversion element 35 aligns the illumination light WLL into one of p-polarized light and s-polarized light. The polarization conversion element 35 aligns the illumination light WLL into, for example, s-polarized light. The illumination light WLL that has been made s-polarized enters the cross dichroic mirror 40 via the lens 36. The cross dichroic mirror 40 separates the illumination light WLL into yellow illumination light YLL and blue illumination light BLL.

The yellow illumination light YLL separated by the cross dichroic mirror 40 is reflected by the reflection mirror 31 and enters the dichroic mirror 41. The dichroic mirror 41 separates the yellow illumination light YLL into red illumination light RLL containing a red component and green illumination light GLL containing a green component. The dichroic mirror 41 transmits the red illumination light RLL and reflects the green illumination light GLL. The reflective polarizing plate 42 transmits one of p-polarized light and s-polarized light and reflects the other. The reflective polarizing plate 42 transmits, for example, s-polarized light and reflects p-polarized light. The reflective polarizing plate 42 can be configured by, for example, a wire grid.

In order to distinguish the light modulation element 4 and the reflection type polarization plate 42 for each color, the light modulation element 4 and the reflection type polarization plate 42 to which the red illumination light RLL is irradiated are referred to as a light modulation element 4R and a reflection type polarization plate 42R. .. The light modulation element 4 and the reflection type polarization plate 42 to which the green illumination light GLL is irradiated are referred to as the light modulation element 4G and the reflection type polarization plate 42G. The light modulation element 4 and the reflection type polarization plate 42 to which the blue illumination light BLL is irradiated are referred to as the light modulation element 4B and the reflection type polarization plate 42B.

The red illumination light RLL that has passed through the dichroic mirror 41 enters the reflective polarizing plate 42R via the lens 37. The s-polarized red illumination light RLL passes through the reflective polarizing plate 42R and is applied to the light modulation element 4R. The light modulation element 4R optically modulates the red illumination light RLL for each pixel based on the image data of the red component to generate p-polarized red image light RML. The red image light RML is reflected by the reflective polarizing plate 42R and enters the projection optical system 5.

The green illumination light GLL reflected by the dichroic mirror 41 enters the reflective polarizing plate 42G via the lens 38. The s-polarized green illumination light GLL passes through the reflective polarizing plate 42G and is applied to the light modulation element 4G. The light modulation element 4G optically modulates the green illumination light GLL for each pixel based on the image data of the green component, and generates the p-polarized green image light GML. The green image light GML is reflected by the reflective polarizing plate 42G and enters the projection optical system 5.

The blue illumination light BLL separated by the cross dichroic mirror 40 is reflected by the reflection mirror 32 and enters the reflection type polarizing plate 42B via the lens 39. The s-polarized blue illumination light BLL passes through the reflective polarizing plate 42B and is applied to the light modulation element 4B. The light modulation element 4B optically modulates the blue illumination light BLL for each pixel based on the image data of the blue component, and generates the p-polarized blue image light BML. The blue image light BML is reflected by the reflective polarizing plate 42B and enters the projection optical system 5.

The projection optical system 5 has a color combining prism 43 and a projection lens 44. The red image light RML, the green image light GML, and the blue image light BML that have entered the projection optical system 5 are combined by the color combining prism 43, and are projected by the projection lens 44 as a display image of a full-color image onto a projection medium such as a screen. It is enlarged and projected.

The light amount adjusting device 6a will be described with reference to FIG. 4 and FIGS. 5A to 5C. FIG. 4 shows a configuration example of the light amount adjustment device 6a in the projection device 1a of the first embodiment. The reflective polarizing plate 42 in FIG. 4 is a simplified representation of the reflective polarizing plate 42 (42R, 42G, and 42B) in FIG. Reference numeral LL1 shown in FIG. 4 indicates each color light (RLL, GLL, BLL) incident on each reflective polarization plate 42 (42R, 42G, and 42B). The light modulation element 4 of FIG. 4 is a simplified illustration of the light modulation element 4 (4R, 4G, 4B) of FIG. The projection optical system 5 in FIG. 4 is a simplified illustration of the projection optical system 5 in FIG.

The light amount adjustment device 6a includes an optical sensor 7, a light amount calculation unit 51, a light source drive control unit 52, a light source drive unit 53, and a light amount storage unit 54. The optical sensor 7 is a sensor that detects the amount of white light that includes, for example, a red component, a green component, and a blue component. Note that only the optical sensor 7 is shown in FIG. The light amount calculation unit 51, the light source drive control unit 52, and the light source drive unit 53 may be configured by a program operating on a CPU (Central Processing Unit) mounted in the light amount adjustment device 6a, or part or All may be configured by hardware circuits that operate in cooperation with each other. The light amount storage unit 54 is composed of a nonvolatile memory such as a RAM, and stores the result calculated by the light amount calculation unit 51.

The optical sensor 7 is arranged in the vicinity of the optical path in the range in which the illumination light WLL is emitted from the light source unit 2 and is incident on the cross dichroic mirror 40. The optical sensor 7 is preferably arranged in the optical path where the color lights are mixed. The optical sensor 7 is arranged, for example, in the vicinity of the polarization conversion element 35, and is arranged at a position away from the optical path of the illumination light WLL and at a position where the leaked light of the polarization conversion element 35 can be efficiently detected.

It is assumed that the detection value detected by the optical sensor 7 and the amount of light passing through the polarization conversion element 35 have been previously confirmed to have a correlation. Hereinafter, the amount of light transmitted through the polarization conversion element 35 calculated based on the detection value detected by the optical sensor 7 will be referred to as the amount of light detected by the optical sensor 7.

The illumination light LL1 passes through the reflective polarizing plate 42 and is applied to the light modulation element 4. The light modulator 4 optically modulates the illumination light LL1 based on the input image data to generate the image light ML.

FIG. 5A shows a state in which the light modulation element 4 optically modulates the illumination light LL1 based on image data of the white level (first display image level) which is the maximum gradation. The illumination light LL1 that has entered the illumination optical system 3 from the light source unit 2 is applied to the light modulation element 4 (4R, 4G, 4B) via the lenses 37 to 39 and the reflective polarizing plate 42 (42R, 42G, 42B). To be done. The illumination light LL1 in FIG. 5A corresponds to the red illumination light RLL, the green illumination light GLL, and the blue illumination light BLL in FIG.

The light modulation element 4 optically modulates the illumination light LL1 to generate reflected light LL2. When the light modulation element 4 optically modulates the illumination light LL1 based on the white level image data, almost all the s-polarized illumination light LL1 is optically modulated to the p-polarized image light ML. Therefore, almost all the reflected light LL2 is reflected by the reflective polarizing plate 42 and is emitted to the projection optical system 5 as p-polarized image light ML. As shown in FIG. 4, the image light ML emitted from the projection optical system 5 is projected as a white image on a projection medium such as the screen SR. Therefore, since almost all the reflected light LL2 is reflected by the reflective polarizing plate 42, the amount of the return light RL that passes through the reflective polarizing plate 42 and returns to the light source unit 2 is minimized.

FIG. 5B shows a state in which the light modulation element 4 optically modulates the illumination light LL1 based on image data of the black level (second display image level) which is the minimum gradation. The illumination light LL1 that has entered the illumination optical system 3 from the light source unit 2 is applied to the light modulation element 4 (4R, 4G, 4B) via the lenses 37 to 39 and the reflective polarizing plate 42 (42R, 42G, 42B). To be done. The illumination light LL1 in FIG. 5B corresponds to the red illumination light RLL, the green illumination light GLL, and the blue illumination light BLL in FIG.

The light modulator 4 generates the reflected light LL2 without optically modulating the illumination light LL1 based on the black level image data. Almost all of the illumination light LL1 becomes s-polarized light as reflected light LL2 and passes through the reflective polarizing plate 42 and the lenses 37 to 39. Therefore, the amount of return light RL returning to the light source unit 2 becomes the maximum, and the screen SR or the like is covered. A black image will be displayed on the projection medium.

FIG. 5C shows a state in which the light modulation element 4 optically modulates the illumination light LL1 based on gray level (intermediate gradation) image data. The illumination light LL1 that has entered the illumination optical system 3 from the light source unit 2 is applied to the light modulation element 4 (4R, 4G, 4B) via the lenses 37 to 39 and the reflective polarizing plate 42 (42R, 42G, 42B). To be done. The illumination light LL1 in FIG. 5C corresponds to the red illumination light RLL, the green illumination light GLL, and the blue illumination light BLL in FIG.

The light modulation element 4 optically modulates the illumination light LL1 based on the gray level image data, and generates the reflected light LL2 in which the p-polarized light and the s-polarized light are mixed according to the gradation value of the image data. The p-polarized reflected light LL2 is emitted to the projection optical system 5 as p-polarized image light ML. As shown in FIG. 4, the image light ML emitted from the projection optical system 5 is projected as a gray image on a projection medium such as the screen SR. The s-polarized reflected light LL2 passes through the reflective polarizing plate 42 and the lenses 37 to 39 as the return light RL and returns to the light source unit 2. The light quantity of the return light RL is approximately a value obtained by subtracting the light quantity of the p-polarized reflected light LL2 from the light quantity of the illumination light LL1.

A method of calculating the transmittance of the illumination optical system 3 will be described with reference to FIG. Specifically, in the illumination optical system 3, the transmittance of the illumination optical system 3 refers to the red illumination light RLL, the green illumination light GLL, and the blue illumination from the incident position of the illumination light WLL emitted from the light source unit 2 in the illumination optical system 3. It is the transmittance in the range up to the position where the light BLL is irradiated to the light modulation elements 4R, 4G, 4B. The light amount of the illumination light LL1 emitted from the light source unit 2 is L0, and the light amount of the illumination light LL1 when passing through a position near the optical sensor 7 (hereinafter, light amount detection position) is L1, and the light modulation element 4 is irradiated. The light quantity of the illumination light LL1 is L2, and the light quantity of the return light RL returning from the light modulation element 4 to the light quantity detection position is L3.

The transmittance of the illumination optical system 3 on the optical path from the position where the illumination light WLL emitted from the light source unit 2 enters the illumination optical system 3 to the light amount detection position is T1, and the illumination light LL1 from the light amount detection position is the light modulation element 4. Let T2 be the transmittance of the illumination optical system 3 on the optical path up to the position where the light is illuminated. The ratio of the return light RL to the reflected light LL2 is M (0<M<1).

The light quantities L1, L2, and L3 can be expressed by Equation (1), Equation (2), and Equation (3), respectively.

L1=L0×T1 (1)

L2=L1×T2 (2)

L3=L1×T2 ² ×M (3)

The optical sensor 7 detects the total light amount of the illumination light LL1 and the return light RL. The light amount C detected by the optical sensor 7 can be expressed by Expression (4).

C = L1 + L3 = L1 × (1 + T2 2 × M) ... (4)

The ratio M changes according to the display image level (for example, gradation value) of the image data. The light amount detected by the optical sensor 7 when the display image level is the white level is Cw, and the light amount detected by the optical sensor 7 when the display image level is the black level is Cb (Cw<Cb). The ratio of the return light RL to the reflected light LL2 when the display image level is the white level is Mw, and the ratio of the return light RL to the reflected light LL2 when the display image level is the black level is Mb.

The light amounts Cw and Cb detected by the optical sensor 7 can be expressed by equations (5) and (6), respectively.

Cw = L1 × (1 + T2 2 × Mw) ... (5)

Cb=L1×(1+T2 ² ×Mb) (6)

From the formulas (5) and (6), the transmittance T2 can be expressed by the formula (7). That is, the transmittance T2 can be calculated from the light amounts Cw and Cb and the ratios Mw and Mb.

The light amount calculation unit 51 calculates the transmittance T2 by the formula (7). The higher the display image level (gradation value), the smaller the proportion M of the return light RL becomes, and ideally zero at the white level (maximum gradation). The ratio Mw of the return light RL at the white level (maximum gradation) is very small compared to the ratio Mb of the return light RL at the black level (minimum gradation), and the ratio Mw/Mb of the ratio Mw to the ratio Mb is almost 0. If it can be regarded as, the transmittance T2 can be expressed by the equation (8). When the ratio Mw/Mb can be regarded as almost 0, the light amount calculation unit 51 calculates the transmittance T2 by the formula (8).

A method of adjusting the light amount of the illumination light WLL emitted from the light source unit 2 will be described. The transmittance T2, the light amounts L0 to L3, and the light amounts Cw and Cb may change due to a lapse of time from an initial state such as at the time of factory shipment or system adjustment due to aging or environmental change. For example, the light amounts L0, L1, L2, and L3 at the first time point in the initial state are set as light amounts L0b, L1b, L2b, and L3b, respectively. The light quantities L0, L1, L2, and L3 at the second time point after the first time point are set as light quantities L0a, L1a, L2a, and L3a, respectively. The transmittance T2 in the initial state (first time point) is called transmittance T2b (first transmittance), and the transmittance T2 after a lapse of time (second time point) is called transmittance T2a (second transmittance). .. The light quantity L2b and the light quantity L2a can be expressed by Equations (9) and (10), respectively.

L2b=L1b×T2b (9)

L2a=L1a×T2a (10)

The light source unit 2 emits the illumination light WLL with the light amount L0b in the initial state, and emits the illumination light WLL with the light amount L0a after a lapse of time. In order to maintain the light amount of the image light ML emitted from the projection optical system 5 after the passage of time so as to be the same as the light amount in the initial state, the light amount L2 of the illumination light LL1 applied to the light modulation element 4 is set to It is important that it is always constant (L2b=L2a). When the target light amount of the light amount L1a for L2b=L2a is L1c, the target light amount L1c of the light amount L1a is expressed by the formula (11) by setting L2b=L2a in the formulas (9) and (10). You can

The light amounts Cw and Cb in the initial state are referred to as light amounts Cwb and Cbb, respectively, and the light amounts Cw and Cb after the passage of time are referred to as light amounts Cwa and Cba, respectively. The target light amount L1c can be expressed by Expression (12). The light amount calculation unit 51 calculates the target light amount L1c by the formula (12).

Therefore, the light amount calculator 51 calculates the transmittance T2b based on the light amounts Cwb and Cbb, and calculates the transmittance T2a based on the light amounts Cwa and Cba.

The relational expressions (Cbb-Cwb)/Cwb and (Cba-Cwa)/Cwa in the expression (12) correspond to the increasing rate of the light amount Cb in the black level state when the light amount Cw in the white level state is used as a reference. .. The increase rate R in the initial state is an increase rate Rb, and the increase rate R after the passage of time is an increase rate Ra. That is, Rb=(Cbb-Cwb)/Cwb and Ra=(Cba-Cwa)/Cwa. The target light amount L1c can be expressed by Expression (13). The light amount calculation unit 51 calculates the increase rates Rb and Ra based on the light amounts Cbb, Cwb, Cba, and Cwa detected by the optical sensor 7, and further calculates the target light amount L1c by the equation (13).

The light amount Cw detected by the optical sensor 7 in the white level state is almost the same as the light amount L1 of the illumination light WLL passing near the optical sensor 7, and is hardly affected by the return light RL (light amount L3). On the other hand, the light amount Cb detected by the optical sensor 7 in the black level state is almost the same as the sum of the light amount L1 of the illumination light WLL and the light amount L3 of the return light RL that pass near the optical sensor 7, and It is easily affected by the light RL (light amount L3).

Therefore, it is preferable that the light amount calculation unit 51 calculates the light amounts L1b and L1a based on the light amounts Cwb and Cwa detected by the optical sensor 7 in the white level state. In the display image level state other than the white level, it is preferable that the light sensor 7 detects the light amounts Cwb and Cwa and the light amount calculation unit 51 calculates the light amounts L1b and L1a in the same display image level state.

The light amount calculation unit 51 causes the light amount storage unit 54 to store the light amount Cwb and the increase rate Rb in the initial state and in the white level state. The light amount calculation unit 51 calculates the light amount Cwa in the white level state and the increase rate Ra after the passage of time, further calculates the right side of the equation (13), and calculates the target light amount after the passage of time. In other words, the light quantity calculation unit 51 calculates the target light quantity L1c based on the transmittances T2b and T2a.

The light amount calculation unit 51 outputs the target light amount L1c to the light source drive control unit 52. The light source drive control unit 52 controls the light source drive unit 53 based on the target light amount L1c. Specifically, in the white level state, the light amount Cw detected by the light sensor 7 is considered to be substantially equal to the light amount L1, and the light source drive control unit 52 sets the light amount Cw detected by the light sensor 7 in the white level state to the target light amount L1c. The light source drive unit 53 is controlled so as to approach. As a result, the light amount L0 of the illumination light LL1 emitted from the light source unit 2 is controlled.

Therefore, the light source drive control unit 52 functions as a light amount adjustment unit that adjusts the light amount of the image light ML emitted from the projection optical system 5 by controlling the light amount L0 of the illumination light WLL based on the target light amount L1c.

An example of a light amount adjustment method for stabilizing the light amount of the image light ML projected from the projection device 1a with time will be described with reference to the flowcharts of FIGS. 7A and 7B. In the first embodiment, the light amount of the illumination light WLL emitted from the light source unit 2 is adjusted so that the brightness of the projected image becomes constant. FIG. 7A shows a flowchart in the initial state (first time point), and FIG. 7B shows a flowchart after a lapse of time (second time point).

In FIG. 7A, in step S11, the light source drive control unit 52 controls the light source drive unit 53 so that the projection image (image light ML) has the target brightness, and emits the illumination light WLL from the light source unit 2. Let

In step S12, the optical sensor 7 detects the light amount Cwb (first light amount) in the white level state and the light amount Cbb (second light amount) in the black level state, and outputs it to the light amount calculation unit 51. In step S13, the light amount calculation unit 51 calculates the light amount L1b based on the light amount Cwb, and calculates the increase rate Rb based on the light amounts Cwb and Cbb. Further, the light amount calculation unit 51 stores the light amount L1b and the increase rate Rb in the initial state in the light amount storage unit 54.

After a lapse of time, in FIG. 7B, in a state where the illumination light WLL is emitted from the light source unit 2, the optical sensor 7 determines in step S21 the light amount Cwa (third light amount) in the white level state and the black level state. The light amount Cba (fourth light amount) is detected and output to the light amount calculation unit 51. In step S22, the light amount calculation unit 51 calculates the increase rate Ra after the passage of time based on the light amounts Cwa and Cba.

In step S23, the light amount calculation unit 51 reads the light amount L1b and the increase rate Rb stored in the light amount storage unit 54. Further, the light amount calculation unit 51 calculates the target light amount L1c after the elapse of time based on the light amount L1b and the increase rates Rb and Ra. In other words, the light amount calculation unit 51 calculates the target light amount L1c based on the transmittances T2b and T2a. In step S24, the light source drive control unit 52 controls the light source drive unit 53 so that the light amount L1a in the white level state after the elapse of time approaches the target light amount L1c, so that the illumination light LL1 emitted from the light source unit 2 is obtained. The light amount L0 of the light is controlled.

In the light amount adjusting method, the light amount adjusting device 6a, and the projection device 1a according to the first embodiment, the optical sensor 7 illuminates the illumination light WLL in the range from the light source unit 2 to the cross dichroic mirror 40. It is arranged in the vicinity of the optical path of the light WLL and at a position that does not affect the light modulation element 4. Therefore, the light modulation element 4 can be irradiated with the illumination light WLL having a uniform illumination distribution.

In the light amount adjustment method, the light amount adjustment device 6a, and the projection device 1a of the first embodiment, the light amount L1b and the increase rate Rb in the initial state and the increase after the elapse of time are set on the basis of the white level state in which the return light RL is less affected. The ratio Ra is calculated, and the target light amount after a lapse of time is calculated based on the light amount L1b and the increase ratios Rb and Ra, in other words, the transmittances T2b and T2a. According to the light amount adjustment method, the light amount adjustment device 6a, and the projection device 1a of the first embodiment, the light amount L0 of the illumination light WLL is controlled so that the light amount L1a in the white level state after the elapse of time becomes the target light amount. The brightness of the projected image can be stabilized over time.

[Second Embodiment]
A configuration example of the projection device according to the second embodiment will be described with reference to FIG. For easy understanding of the description, the same components as those of the projection device 1a of the first embodiment are designated by the same reference numerals. In the second embodiment, in order to distinguish from the projection device 1 and the light amount adjustment device 6 of the other embodiments, the projection device 1 will be referred to as the projection device 1b, and the light amount adjustment device 6 will be referred to as the light amount adjustment device 6b. The projection device 1b of the second embodiment is different from the projection device 1a of the first embodiment in the configuration of the light amount adjustment device 6b, and the other configurations are the same.

FIG. 8 shows a configuration example of the light amount adjustment device 6b in the projection device 1b of the second embodiment. The reflective polarizing plate 42 of FIG. 8 is a simplified illustration of the reflective polarizing plate 42 (42R, 42G, and 42B) of FIG. Reference numeral LL1 shown in FIG. 8 indicates each color light (RLL, GLL, BLL) incident on each reflective polarizing plate 42 (42R, 42G, and 42B). The light modulation element 4 of FIG. 8 is a simplified illustration of the light modulation element 4 (4R, 4G, 4B) of FIG. The projection optical system 5 in FIG. 8 is a simplified illustration of the projection optical system 5 in FIG.

The light amount adjustment device 6b includes an optical sensor 7, a light amount calculation unit 51, a light source drive control unit 52, a light source drive unit 53, and a light amount storage unit 54. Further, the light amount adjustment device 6b includes an image processing unit 60, a gain adjustment unit 61, an element drive unit 62, and a gain storage unit 63. The light amount calculation unit 51, the light source drive control unit 52, the light source drive unit 53, the image processing unit 60, the gain adjustment unit 61, and the element drive unit 62 are operated by a program running on the CPU installed in the light amount adjustment device 6b. They may be configured, or part or all may be configured by hardware circuits that operate in cooperation with each other.

The gain storage unit 63 is composed of a nonvolatile memory such as a RAM, and stores the initial gain value Gref used in the calculation of the gain adjustment unit 61. For example, when the light source unit 2 emits the illumination light WLL with a predetermined light amount L0 at the time of factory shipment or system setting, the light amount calculation unit 51 causes the projection image (image light ML) to have a predetermined brightness. Such a gain value is calculated. Further, the light amount calculation unit 51 stores the calculated gain value in the gain storage unit 63 as the initial gain value Gref. Since the image data and the brightness of the projected image do not necessarily have a linear relationship, it is desirable to determine the initial gain value Gref in consideration of the gamma characteristic of the light modulation element 4.

The light amount calculation unit 51 calculates the increase rate Ra after the passage of time based on the light amounts Cba and Cwa after the passage of time detected by the optical sensor 7 with the white level state as a reference. The light amount calculation unit 51 calculates the transmittance T2a after a lapse of time from Expression (14) based on the increase rate Ra and the ratio Mb of the return light RL.

The light amount calculation unit 51 reads the light amount L1b and the increase rate Rb in the initial state stored in the light amount storage unit 54. The light amount calculator 51 calculates the light amount L2a after a lapse of time and the light amount L2b in the initial state from the transmittance T2a, the light amount Cba, the light amount L1b, and the increase rate Rb. The light quantity L2a and the light quantity L2b can be calculated from the equations (15) and (16), respectively.

From the formula (17), the light quantity calculation unit 51 calculates the ratio of the light quantity L2a of the illumination light LL1 to the light modulation element 4 after a lapse of time with respect to the light quantity L2b of the illumination light LL1 to the light modulation element 4 in the initial state. The light quantity ratio LQR is calculated. In other words, the light quantity calculation unit 51 calculates the light quantity ratio LQR based on the transmittances T2b and T2a.

The light amount calculation unit 51 calculates a gain adjustment value Ad for adjusting the gain when driving the light modulation element 4 based on the light amount ratio LQR, and outputs it to the gain adjustment unit 61. The input image data includes, for example, data of pixels of each color of R, G, and B, and is input to the image processing unit 60 frame by frame at a predetermined frame rate. The image processing unit 60 executes predetermined image processing such as gamma correction processing on the input image data and outputs it as image data to the gain adjusting unit 61.

The gain adjusting unit 61 adjusts the gain of the image data based on the initial gain value Gref and the gain adjusting value Ad read from the gain storage unit 63. The gain is a gain for image data when the element driving unit 62 drives the light modulation element 4. The gain adjusting unit 61 can adjust the brightness of the projection image based on the image data, for example, by multiplying the gradation value of each pixel in the image data by the initial gain value Gref and the gain adjustment value Ad. The gain adjusting unit 61 adds or subtracts the initial gain value Gref and the gain adjustment value Ad to or from the gradation value of each pixel in the image data to adjust the brightness of the projection image based on the image data. Good.

A case where the gain adjusting unit 61 multiplies the gradation value of each pixel in the image data by the initial gain value Gref and the gain adjusting value Ad will be described. In this case, the gain adjustment value Ad may be determined by multiplying the gain adjustment value Ad so that the brightness becomes 1/LQR which is the reciprocal of the light quantity ratio LQR calculated by the equation (17).

The gain adjustment unit 61 multiplies the gradation value of each pixel in the image data by the initial gain value Gref and the gain adjustment value Ad to adjust the gain of the image data. The gain adjusting unit 61 outputs the gain-adjusted image data Ga to the element driving unit 62. The element driving unit 62 controls driving of the light modulation element 4 based on the gain-adjusted image data Ga.

Therefore, the gain adjusting unit 61 is a light amount adjusting unit that adjusts the light amount of the image light ML emitted from the projection optical system 5 by adjusting the gain of the image data based on the light amount ratio LQR (gain adjustment value Ad). Function.

The initial gain value Gref stored in the gain storage unit 63 is set to a value within the range of 0<Gref≦1.0, for example. When the initial gain value Gref is set to a value within the range of 0<Gref<1.0, even when the light source unit 2 deteriorates or the transmittance T1 or T2 of the optical path of the illumination light LL1 decreases. , It is possible to make the brightness of the projected image constant.

The smaller the initial gain value Gref, the larger the range in which the gain is increased for the image data. Therefore, when it is assumed that the light amount L0 of the illumination light LL1 emitted from the light source unit 2 or the degree of decrease in the transmittance T2 is large, the initial gain value Gref is set to a small value (a value closer to 0 than 1.0). ) Is preferable.

An example of a light amount adjustment method for stabilizing the light amount of the image light ML projected from the projection device 1b with time will be described with reference to the flowchart of FIG. In the second embodiment, the gain of the image data is adjusted so that the brightness of the projected image is constant, and the drive of the light modulation element 4 is controlled based on the image data whose gain has been adjusted.

9, in step S31, the light amount calculation unit 51 calculates the increase rate Ra after the passage of time based on the light amounts Cba and Cwa after the passage of time detected by the optical sensor 7 with the white level state as a reference. In step S32, the light amount calculation unit 51 calculates the transmittance T2a after the elapse of time based on the increase rate Ra and the ratio Mb of the return light RL.

In step S33, the light amount calculation unit 51 reads the light amount L1b and the increase rate Rb in the initial state stored in the light amount storage unit 54. Further, the light amount calculation unit 51 calculates the light amount L2a after a lapse of time based on the light amount L1a and the transmittance T2a, and calculates the light amount L2b in the initial state based on the light amount L1b and the transmittance T2b. In step S34, the light amount calculation unit 51 calculates the light amount ratio LQR based on the light amounts L2a and L2b. In other words, the light quantity calculation unit 51 calculates the light quantity ratio LQR based on the transmittances T2b and T2a.

In step S35, the light amount calculation unit 51 calculates the gain adjustment value Ad based on the light amount ratio LQR. In step S36, the image processing unit 60 executes predetermined image processing on the input image data and outputs it as image data to the gain adjusting unit 61. In step S37, the gain adjusting unit 61 adjusts the gain of the image data with the initial gain value Gref and the gain adjusting value Ad. Further, the gain adjusting unit 61 outputs the image data Ga whose gain has been adjusted to the element driving unit 62. In step S38, the element driving section 62 controls the driving of the light modulation element 4 based on the image data Ga.

Since the light amount adjusting method, the light amount adjusting device 6b, and the projection device 1b of the second embodiment do not require light source control, a light source that cannot finely adjust the light amount can be used. Therefore, a light source that finely adjusts the light amount is used. The cost can be kept low as compared with the case of performing.

In the light amount adjusting method, the light amount adjusting device 6b, and the projection device 1b according to the second embodiment, the optical sensor 7 illuminates the illumination light WLL in the range from the light source unit 2 to the cross dichroic mirror 40. It is arranged in the vicinity of the optical path of the light WLL and at a position that does not affect the light modulation element 4. Therefore, the light modulation element 4 can be irradiated with the illumination light WLL having a uniform illumination distribution.

In the light amount adjusting method, the light amount adjusting device 6b, and the projection device 1b according to the second embodiment, based on the increase rates Rb and Ra or the transmittances T2b and T2a with reference to the white level state in which the influence of the return light RL is small. The light quantity ratio LQR is calculated. In the light amount adjustment method, the light amount adjustment device 6b, and the projection device 1b of the second embodiment, the gain adjustment value Ad is calculated based on the light amount ratio LQR, and based on the image data Ga that is gain adjusted by the gain adjustment value Ad. The drive of the light modulation element 4 is controlled. This makes it possible to stabilize the brightness of the projected image with time.

[Third Embodiment]
In the third embodiment, as compared with the second embodiment, as the optical sensor 7 in the projection device 1b, a color sensor that separately detects the light amount of red light, the light amount of green light, and the light amount of blue light is used. Differences in points. When a color sensor is used as the optical sensor 7 in the projection device 1b of the third embodiment, the optical sensor 7 determines the red component light amount, the green component light amount, and the blue component light amount of the illumination light WLL and the return light RL. To detect.

The light amount calculation unit 51 calculates the light amount ratio LQR(R) of the red component, the light amount ratio LQR(G) of the green component, and the light amount ratio LQR(B) of the blue component. The light amount calculation unit 51 calculates the gain adjustment value Ad(R) for the red component based on the light amount ratio LQR(R), and calculates the gain adjustment value Ad(G) for the green component based on the light amount ratio LQR(G). Then, the gain adjustment value Ad(B) of the blue component is calculated based on the light quantity ratio LQR(B). Further, the light amount calculation unit 51 outputs the gain adjustment values Ad(R), Ad(G), and Ad(B) to the gain adjustment unit 61.

The gain adjustment unit 61 adjusts the gain of the image data of the red component based on the initial gain value Gref and the gain adjustment value Ad(R). The gain adjustment unit 61 adjusts the gain of the image data of the green component based on the initial gain value Gref and the gain adjustment value Ad(G). The gain adjustment unit 61 adjusts the gain of the image data of the blue component based on the initial gain value Gref and the gain adjustment value Ad(B). Each gain is a gain for image data of a red component, a green component, and a blue component when the element driving unit 62 drives the light modulation elements 4R, 4G, and 4B. The initial gain value Gref may be set to a common value for each color component, or may be set to a different value for each color component.

Since the light amount adjusting method, the light amount adjusting device 6b, and the projection device 1b of the third embodiment do not require light source control, a light source that cannot finely adjust the light amount can be used. Therefore, a light source that finely adjusts the light amount is used. The cost can be kept low as compared with the case.

The gain adjusting unit 61 can adjust the gain of the image data for each color component. Accordingly, the projection devices 1b and 1c can adjust the brightness of the projected image for each color component.

The emission spectrum of the illumination light LL1 emitted from the light source unit 2 or the spectral transmittance of the illumination light LL1 on the optical path may change over time. Therefore, the projected image may change not only in brightness but also in color balance over time. Therefore, the projected image may change not only in brightness but also in color balance over time. According to the light amount adjustment method, the light amount adjustment device 6b, and the projection device 1b of the third embodiment, the brightness of the projected image can be adjusted for each color component by detecting the light amount for each color component by the optical sensor 7. As a result, not only the brightness of the projected image but also the color balance can be stabilized over time.

In the light amount adjusting method, the light amount adjusting device 6b, and the projection device 1b of the third embodiment, the optical sensor 7 illuminates in the range from the illumination light LL1 emitted from the light source unit 2 to the incidence on the cross dichroic mirror 40. It is arranged in the vicinity of the optical path of the light LL1 and at a position that does not affect the light modulation element 4. Therefore, the light modulation element 4 can be irradiated with the illumination light LL1 having a uniform illumination distribution.

[Fourth Embodiment]
A configuration example of the projection device according to the fourth embodiment will be described with reference to FIG. 10. In order to make the description easy to understand, the same components as those of the projection devices 1a and 1b of the first and second embodiments are denoted by the same reference numerals. In the fourth embodiment, in order to distinguish from the projection device 1 and the light amount adjustment device 6 of the other embodiments, the projection device 1 will be referred to as the projection device 1c, and the light amount adjustment device 6 will be referred to as the light amount adjustment device 6c.

The projection apparatus 1c of the fourth embodiment has a configuration in which the configuration of the projection apparatus 1a of the first embodiment and the configuration of the projection apparatus 1b of the second embodiment are combined. Specifically, the projection device 1c according to the fourth embodiment has the same configuration as the projection device 1b according to the second embodiment, and the light amount calculation unit 51 passes the same time as the projection device 1a according to the first embodiment. The subsequent target light amount is calculated and output to the light source drive control unit 52.

FIG. 10 shows a configuration example of the light amount adjustment device 6c in the projection device 1c of the fourth embodiment. The reflective polarizing plate 42 of FIG. 10 is a simplified illustration of the reflective polarizing plate 42 (42R, 42G, and 42B) of FIG. Reference numeral LL1 shown in FIG. 10 indicates each color light (RLL, GLL, BLL) incident on each reflective polarizing plate 42 (42R, 42G, and 42B). The light modulation element 4 in FIG. 10 is a simplified illustration of the light modulation element 4 (4R, 4G, 4B) in FIG. The projection optical system 5 in FIG. 10 is a simplified illustration of the projection optical system 5 in FIG.

The projection device 1c of the fourth embodiment controls the light amount L0 of the illumination light WLL emitted from the light source unit 2 in the same procedure as the projection device 1a of the first embodiment. The light source drive control unit 52 does not need to match the light amount detected by the optical sensor 7 with the target light amount L1c. That is, the light source drive control unit 52 does not need to finely control the light amount of the illumination light WLL emitted from the light source unit 2, and the adjustment amount for adjusting the light amount of the illumination light WLL to obtain the target light amount L1c falls within a predetermined range. The configuration may be adjusted when the value exceeds the limit. For example, if the adjustment amount exceeds 10%, the adjustment is performed, and if it is less than 10%, the adjustment is not performed.

At the third time point after the light source drive control section 52 controls the light quantity of the illumination light WLL, the light quantity calculation section 51 of the projection device 1c performs the same procedure as the projection device 1b of the second embodiment at the first time point. In, the light amount ratio LQR, which is the ratio of the light amount L2a of the illumination light LL1 irradiated to the light modulation element 4 to the light amount L2b of the illumination light LL1 irradiated to the light modulation element 4, is calculated. The gain adjustment unit 61 adjusts the gain of the image data based on the light amount ratio LQR, and controls the drive of the light modulation element 4 (4R, 4G, 4B) based on the gain-adjusted image data Ga. In the projection device 1c of the fourth embodiment, the light source drive control unit 52 and the gain adjustment unit 61 function as a light amount adjustment unit.

Generally, the larger the adjustment amount of the gain with respect to the image data, the lower the gradation performance of the projected image. According to the light amount adjustment method, the light amount adjustment device 6c, and the projection device 1c of the fourth embodiment, the brightness of the projection image is adjusted by the light amount of the illumination light WLL emitted from the light source unit 2, and the pixels of the projection image are adjusted. The value can be adjusted with the gain adjustment value Ad. Therefore, since the amount of adjustment by the gain adjustment value Ad can be reduced, it is possible to display a projection image having higher gradation performance.

In the light amount adjustment method, the light amount adjustment device 6c, and the projection device 1c of the fourth embodiment, the light sensor 7 illuminates the illumination light LL1 from the light source unit 2 until it reaches the cross dichroic mirror 40. It is arranged in the vicinity of the optical path of the light LL1 and at a position that does not affect the light modulation element 4. Therefore, the light modulation element 4 can be irradiated with the illumination light LL1 having a uniform illumination distribution.

In the light amount adjustment method, the light amount adjustment device 6c, and the projection device 1c of the fourth embodiment, the light amount L0 of the illumination light LL1 is controlled, the gain of the image data is further adjusted, and the light is adjusted based on the gain-adjusted image data Ga. The drive of the modulation element 4 is controlled. This makes it possible to stabilize the brightness of the projected image with time.

According to the light amount adjustment method, the light amount adjustment device 6c, and the projection device 1c of the fourth embodiment, the gain adjustment amount can be reduced, so that it is not necessary to widen the range in which the gain of the image data is increased. Therefore, it is not necessary to make the initial gain value Gref small, so that the setting range of the initial gain value Gref can be widened. Generally, the closer the gain value is to 1.0 (100%), the higher the gradation display performance of the light modulation element. Therefore, the light amount adjustment method, the light amount adjustment device 6c, and the projection device 1c according to the fourth embodiment may be used. If so, the gradation performance of the projected image can be further improved as compared with the first embodiment.

According to the light amount adjusting method, the light amount adjusting device 6c, and the projection device 1c of the fourth embodiment, the initial gain value Gref can be set to a large value (a value closer to 1.0 than 0), and thus brighter. An image can be projected on a projection medium such as a screen. When projecting an image of a predetermined brightness on the projection medium, the light amount L0 of the illumination light LL1 emitted from the light source unit 2 can be reduced, so that the power consumption of the light source 10 can be reduced or the light source 10 can emit light. The life can be extended.

[Fifth Embodiment]
In the fifth embodiment, as compared with the fourth embodiment, as the optical sensor 7 in the projection device 1c, a color sensor that separately detects the light amount of red light, the light amount of green light, and the light amount of blue light is used. Differences in points. When a color sensor is used as the optical sensor 7 in the projection device 1c of the fifth embodiment, the optical sensor 7 determines the red component light amount, the green component light amount, and the blue component light amount of the illumination light WLL and the return light RL. To detect.

The projection device 1c of the fifth embodiment controls the light amount L0 of the illumination light LL1 emitted from the light source unit 2 in the same procedure as the projection device 1a of the first embodiment. In this case, the light amount C is the total light amount of the light components of the respective color components detected by the optical sensor 7. The total light amount C of the illumination light LL1 and the return light RL can be expressed by Expression (18).

C=IR×CR+IG×CG+IB×CB (18)

CR, CG, and CB are detection values of the red component, the green component, and the blue component detected by the optical sensor 7. IR, IG, and IB are coefficients for converting the detection values CR, CG, and CB into the light amounts of the red component, the green component, and the blue component, and satisfy the condition of IR+IG+IB=1. In the projection device 1c of the fifth embodiment, the light amount calculation unit 51 calculates the total light amount C from Expression (18) and outputs it to the light source drive control unit 52.

The projection device 1c of the fifth embodiment controls the light amount L0 of the illumination light WLL emitted from the light source unit 2 by the same procedure as the projection device 1a of the first embodiment. The light source drive control unit 52 does not need to match the light amount detected by the optical sensor 7 with the target light amount L1c. That is, the light source drive control unit 52 does not need to finely control the light amount of the illumination light WLL emitted from the light source unit 2, and the adjustment amount for adjusting the light amount of the illumination light WLL to reach the target light amount L1c exceeds a predetermined range. It may be configured to adjust when there is a problem. For example, if the adjustment amount exceeds 10%, the adjustment is performed, and if it is less than 10%, the adjustment is not performed.

The projection apparatus 1c of the fifth embodiment performs light source control in the same procedure as that of the first embodiment, and then adjusts the gain of each image data by the same procedure as the projection apparatus 1b of the third embodiment. The drive of each light modulation element 4 (4R, 4G, 4B) is controlled based on the adjusted image data Ga.

Generally, the larger the adjustment amount of the gain with respect to the image data, the lower the gradation performance of the projected image. According to the light amount adjusting method, the light amount adjusting device 6c, and the projection device 1c of the fifth embodiment, the light sensor 7 detects the light amount of each color component, and the brightness of the projected image is emitted from the light source unit 2. It is possible to adjust the light amount of the illumination light LL1 and adjust the color balance of the projected image with the gain adjustment value Ad for each color component. Therefore, by detecting the light amount for each color component, the adjustment amount by the gain adjustment value Ad can be reduced, so that it is possible to display a projection image having higher gradation performance.

Further, the initial gain value Gref can be set to a large value by detecting the light amount for each color component. Thereby, a bright image can be displayed on the projection medium such as the screen SR. When an image having a predetermined brightness is projected on the projection medium, the light amount L0 of the illumination light LL1 emitted from the light source unit 2 can be further reduced by detecting the light amount for each color component. Therefore, the power consumption of the light source 10 can be further reduced and the life of the light source 10 can be extended.

In the light amount adjustment method, the light amount adjustment device 6c, and the projection device 1c of the fifth embodiment, the optical sensor 7 illuminates in a range from the illumination light LL1 emitted from the light source unit 2 to the incidence on the cross dichroic mirror 40. It is arranged near the optical path of the light LL1 and at a position that does not affect the light modulation element 4. Therefore, the light modulation element 4 can be irradiated with the illumination light LL1 having a uniform illumination distribution.

In the light amount adjustment method, the light amount adjustment device 6c, and the projection device 1c of the fifth embodiment, the light amount L0 of the illumination light LL1 is controlled, the gain of the image data is further adjusted, and the light is adjusted based on the gain-adjusted image data Ga. The drive of the modulation element 4 is controlled. This makes it possible to stabilize the brightness of the projected image with time.

According to the light amount adjustment method, the light amount adjustment device 6c, and the projection device 1c of the fifth embodiment, the gain adjustment amount of the image data by the gain adjustment value Ad can be reduced by controlling the light amount L0 of the illumination light LL1. it can. As a result, the image can be projected onto the projection medium such as a screen while maintaining high gradation performance.

According to the light amount adjustment method, the light amount adjustment device 6c, and the projection device 1c of the fifth embodiment, the gain adjustment amount can be reduced, so that it is not necessary to widen the range in which the gain of the image data is increased. Therefore, it is not necessary to make the initial gain value Gref small, so that the setting range of the initial gain value Gref can be widened. In general, the closer the gain value is to 1.0 (100%), the higher the gradation display performance of the light modulation element. Therefore, the light amount adjustment method, the light amount adjustment device 6c, and the projection device 1c according to the fifth embodiment may be used. If so, the gradation performance of the projected image can be further improved as compared with the first embodiment.

According to the light amount adjusting method, the light amount adjusting device 6c, and the projection device 1c of the fifth embodiment, the initial gain value Gref can be set to a large value (a value closer to 1.0 than 0), and thus brighter. An image can be projected on a projection medium such as a screen. When projecting an image of a predetermined brightness on the projection medium, the light amount L0 of the illumination light LL1 emitted from the light source unit 2 can be reduced, so that the power consumption of the light source 10 can be reduced or the light source 10 can emit light. The life can be extended.

[Sixth Embodiment]
In the first embodiment, as the illumination light source, the light amount of the illumination light emitted from one light source 10 is controlled. On the other hand, the projection apparatus 1a according to the sixth embodiment has a plurality of light sources having different color components of illumination light as illumination light sources. By controlling the light source drive unit 53, the light source drive control unit 52 independently controls the light amount of the illumination light emitted from each light source.

FIG. 11 shows a configuration example of the light source unit 2. The light source unit 2 includes a red light source 2R, a green light source 2G, a blue light source 2B, dichroic mirrors 71 and 72, and a condenser lens 73. By controlling the light source drive unit 53, the light source drive control unit 52 controls the light amount of the red illumination light emitted from the red light source 2R, the light amount of the green illumination light emitted from the green light source 2G, and the blue light source 2B. The amount of green illumination light that is generated is independently controlled.

The dichroic mirror 71 transmits red light and reflects green light. The dichroic mirror 72 transmits red light and green light and reflects blue light. The red illumination light emitted from the red light source 2R passes through the dichroic mirrors 71 and 72. The green illumination light emitted from the green light source 2G is reflected by the dichroic mirror 71 and transmitted through the dichroic mirror 72. The blue illumination light emitted from the blue light source 2B is reflected by the dichroic mirror 72. The illumination light of each color becomes mixed light, passes through the condenser lens 73, and is emitted as white illumination light WLL.

In the sixth embodiment, as the optical sensor 7, a color sensor that separately detects the light amount of red light, the light amount of green light, and the light amount of blue light may be used. When a color sensor is used as the optical sensor 7 in the projection device 1a according to the sixth embodiment, the optical sensor 7 determines the red component light amount, the green component light amount, and the blue component light amount of the illumination light WLL and the return light RL. To detect.

The projection apparatus 1a of the sixth embodiment controls the light amount L0 of the illumination light WLL emitted from the light source unit 2 in the same procedure as the projection apparatus 1a of the first embodiment. The light amount calculator 51 calculates the transmittance of the optical system of each color component based on the light amount of each color component of red light, green light, and blue light, and calculates the target light amount of each color component based on the calculated transmittance. To do. The light source drive control unit 52 controls each light source so that the light amount of each color component becomes the target light amount.

(Modification)
In the light source unit 2, all the color light sources of the red light source 2R, the green light source 2G, and the blue light source 2B may not be independent. FIG. 12 shows, as a modified example, a case where the light source unit 2 has a yellow light source 2Y and a blue light source 2B. The yellow light source 2Y emits yellow illumination light including a red component and a green component. The dichroic mirror 74 transmits yellow light and reflects blue light. The yellow illumination light emitted from the yellow light source 2Y is transmitted through the dichroic mirror 74, and the blue illumination light emitted from the blue light source 2B is reflected by the dichroic mirror 74.

The yellow illumination light and the blue illumination light become mixed light, pass through the condenser lens 73, and are emitted as white illumination light WLL. In general, when the transmittance of the optical system deteriorates, the transmittance of blue light tends to deteriorate. Therefore, if only the blue illumination light can be controlled independently, there is no practical problem.

FIG. 1 shows a case where the optical sensor 7 is arranged near the polarization conversion element 35. The optical sensor 7 is arranged in the vicinity of the optical path of the illumination light LL1 in the range from when the illumination light LL1 is emitted from the light source unit 2 and is incident on the cross dichroic mirror 40, and at a position that does not affect the light modulation element 4. It should have been done. For example, as shown in FIG. 13, the optical sensor 7 may be arranged closer to the light source unit 2 than the fly-eye lens 33 (for example, near the reflection mirror 30).

When the light sensor 7 is arranged closer to the light source unit 2 side than the fly-eye lens 33, even if the light sensor 7 is arranged at a position that affects the illumination light LL1, the fly-eye lenses 33 and 34 perform light modulation. The illumination distribution of the yellow illumination light YLL and the blue illumination light BLL with which the element 4 is irradiated can be made uniform.

The present invention is not limited to the above-described first to sixth embodiments, and various modifications can be made without departing from the gist of the present invention.

1, 1a, 1b, 1c Projection device 2 Light source section 3 Illumination optical system 4, 4R, 4G, 4B Light modulation element 7 Optical sensor 51 Light quantity calculation section 61 Gain adjustment section (light quantity adjustment section)
Cba light intensity (4th light intensity)
Cbb light intensity (second light intensity)
Cwa light intensity (third light intensity)
Cwb light intensity (first light intensity)
LL1 illumination light ML image light T2a transmittance (second transmittance)
T2b transmittance (first transmittance)

Claims (5)

At the first time,
Based on image data of a first display image level and a second display image level lower than the first display image level, the light modulation element emits illumination light emitted from the light source unit through the illumination optical system. Light modulated,
A light sensor emits light from the light modulator and returns to the light source unit when the light and the light modulator optically modulate the light on the basis of image data of the first display image level. A first light amount that is a total light amount of light, and when the illumination light and the light modulation element optically modulate the illumination light based on image data of the second display image level, The second light amount, which is the total light amount with the return light that is emitted and returns to the light source unit, is detected,
A light amount calculation unit calculates a first transmittance of the illumination optical system with respect to the illumination light, based on the first and second light amounts,
At a second time point after the first time point,
The light modulation element optically modulates the illumination light based on the image data of the first and second display image levels,
When the light sensor optically modulates the illumination light and the light modulation element based on the image data of the first display image level, the light sensor emits the light and returns to the light source unit. The third light amount that is the total light amount with the return light, and the light modulation device when the illumination light and the light modulation device optically modulate the illumination light based on the image data of the second display image level. A fourth light amount that is a total light amount with the return light that is emitted from and returns to the light source unit,
The light amount calculation unit calculates a second transmittance of the illumination optical system with respect to the illumination light based on the third and fourth light amounts,
The light amount calculation unit, based on the first and second transmittances, sets the light modulation element to the light modulation element at the second time point with respect to the light quantity of the illumination light with which the light modulation element is irradiated at the first time point. Calculate the light amount ratio that is the ratio of the light amount of the illumination light that is irradiated,
A light quantity adjusting method in which a gain adjusting section adjusts a light quantity of image light generated by light-modulating the illumination light by controlling driving of the light modulation element based on the light quantity ratio. The light sensor detects the light amount of the red component, the light amount of the green component, and the light amount of the blue component of the illumination light and the return light,
The light source drive control unit controls the light amount of the illumination light based on the total light amount of the red component, the green component, and the blue component,
The light amount calculation unit calculates the light amount ratio in the red component, the green component, and the blue component of the illumination light,
The light amount adjustment method according to claim 1, wherein the gain adjustment unit controls driving of the light modulation element based on the light amount ratio of at least one of the red component, the green component, and the blue component. The light amount adjusting method according to claim 1, wherein the first display image level is a white level. When the illumination light emitted from the light source unit via the illumination optical system and the light modulation element optically modulate the illumination light based on the image data of the first display image level at the first time point, the light modulation element. From a first light amount that is a total light amount of the return light that is emitted from the light source unit and returns to the light source unit, and a second light amount that is lower than the first display image level by the illumination light and the light modulation element. When the light is modulated based on the image data of the display image level, the second light amount, which is the total light amount of the return light emitted from the light modulation element and returning to the light source section, is detected, and the first time point is detected. At a second time point after that, when the illumination light and the light modulation element optically modulate the illumination light based on the image data of the first display image level, the light is emitted from the light modulation element and the light source. When the third light amount that is the total light amount of the return light returning to the unit and the illumination light and the light modulation element optically modulate the illumination light based on the image data of the second display image level. An optical sensor that detects a fourth light amount that is a total light amount with return light that is emitted from the light modulation element and returns to the light source unit;
The first transmittance of the illumination optical system for the illumination light at the first time point is calculated based on the first and second light amounts, and the first transmittance for the illumination light is calculated based on the third and fourth light amounts. The second transmittance of the illumination optical system at the second time point is calculated, and the illumination light emitted to the light modulation element at the first time point is calculated based on the first and second transmittance rates. A light amount calculation unit that calculates a light amount ratio that is a ratio of the light amount of the illumination light with which the light modulation element is irradiated at the second time point to the light amount of
By controlling the drive of the light modulation element based on the light quantity ratio, a gain adjusting section that adjusts the light quantity of the image light generated by the light modulation of the illumination light,
A light quantity adjusting device. A light source unit that emits illumination light,
An illumination optical system that receives the illumination light from the light source unit and emits the illumination light,
A light modulation element for optically modulating the illumination light emitted from the illumination optical system based on image data of a first display image level and a second display image level lower than the first display image level;
At the first time point, when the illumination light emitted from the light source unit and the light modulation element optically modulate the illumination light based on the image data of the first display image level, the light is emitted from the light modulation element. The first light amount which is the total light amount of the return light returning to the light source unit, and the illumination light and the light modulation element optically modulate the illumination light based on the image data of the second display image level. Then, a second light amount, which is a total light amount of the return light emitted from the light modulation element and returning to the light source unit, is detected, and the illumination light is detected at a second time point after the first time point. And the return light emitted from the light modulation element and returned to the light source section when the light modulation element optically modulates the illumination light based on the image data of the first display image level. A third light amount, and when the illumination light and the light modulation element optically modulate the illumination light based on image data of the second display image level, the light is emitted from the light modulation element to the light source section. And an optical sensor for detecting a fourth light amount that is a total light amount of the return light,
The first transmittance of the illumination optical system for the illumination light at the first time point is calculated based on the first and second light amounts, and the first transmittance for the illumination light is calculated based on the third and fourth light amounts. The second transmittance of the illumination optical system at the second time point is calculated, and the illumination light emitted to the light modulation element at the first time point is calculated based on the first and second transmittance rates. A light amount calculation unit that calculates a light amount ratio that is a ratio of the light amount of the illumination light with which the light modulation element is irradiated at the second time point to the light amount of
By controlling the drive of the light modulator based on the light amount ratio, a gain adjusting unit that adjusts the light amount of the image light generated by the light modulation of the illumination light,
A projection device.

Images