JP7024699B2 - Light intensity adjustment method, light intensity adjustment device, and projection device - Google Patents

Description

The present invention relates to a light amount adjusting method, a light amount adjusting device, and a projection device that stabilize the light amount of image light projected on a projection medium such as a screen over 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 light-modulates the illumination light for each pixel based on the image data to generate the 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 amount of illumination light applied to the light modulation element by an optical sensor arranged in the vicinity of the light modulation element.

Japanese Unexamined Patent Publication No. 2012-47951

Usually, a projection device has a plurality of optical components arranged in its limited internal space. Therefore, it is practically difficult to arrange the optical sensor in the vicinity of the light modulation element. Even if the optical sensor can be placed in the vicinity of the light modulation element, the irradiation area of the illumination light must be expanded to a range that is not originally required in order for the optical sensor to detect the illumination light. As a result, the amount of light of the image light is reduced, so that the image projected on the projected medium becomes darker than the target brightness.

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

In the present invention, at the first time point, the light modulation element makes the illumination light emitted from the light source unit through the illumination optical system lower than the first display image level and the first display image level. When the illumination light and the optical modulation element photomodulate the illumination light based on the image data of the first display image level, the illumination light is optical-modulated based on the image data of the display image level of the above. The first light amount, which is the total amount of light emitted from the light modulation element and returned to the light source unit, and the illumination light and the light modulation element display the illumination light at the second display image level. When light modulation is performed based on the data, the second light amount, which is the total light amount of the return light emitted from the light modulation element and returned to the light source unit, is detected, and the light amount calculation unit detects the first and second light amounts. The first transmission rate of the illumination optical system with respect to the illumination light is calculated based on the amount of light of the above, and at the second time point after the first time point, the light modulation element transfers the illumination light to the first. Light modulation is performed based on the image data of the first and second display image levels, and the optical sensor emits the illumination light and the optical modulation element emits the illumination light based on the image data of the first display image level. A third amount of light, which is the total amount of light emitted from the optical modulation element and returned to the light source unit when modulated, and the illumination light and the light modulation element make the illumination light the second. When light modulation is performed based on the image data at the display image level, the fourth light amount, which is the total light amount of the return light emitted from the light modulation element and returned to the light source unit, is detected, and the light amount calculation unit determines the fourth light amount. The second transmission rate of the illumination optical system with respect to the illumination light is calculated based on the third and fourth light amounts, and the target at the second time point is calculated based on the first and second transmission rates. At a third time point after the light amount is calculated, the light source drive control unit controls the light amount of the illumination light based on the target light amount, and the light source drive control unit controls the light amount of the illumination light, the said The light amount calculation unit irradiates the light modulation element at the third time point with respect to the light amount of the illumination light irradiated to the light modulation element at the first time point based on the first and second transmission rates. Provided is a light amount adjusting method in which a light amount ratio, which is a ratio of the light amount of the illumination light to be generated, is calculated, and a gain adjusting unit controls driving 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 optical modulation element photomodulate the illumination light based on the image data of the first display image level at the first time point. The first light amount, which is the total amount of light emitted from the light modulation element and returned to the light source unit, and the illumination light and the light modulation element emit the illumination light from the first display image level. The second light amount, which is the total amount of light with the return light emitted from the light modulation element and returned to the light source unit, is detected when the light is light-modulated based on the image data of the second display image level, which is also low. At a second time point after the first time point, when the illumination light and the light modulation element photomodulate the illumination light based on the image data of the first display image level, the illumination light is emitted from the light modulation element. A third amount of light, which is the total amount of light that is the sum of the return light that returns 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, which is the total amount of light emitted from the light modulation element and returns to the light source unit when modulated, and the illumination based on the first and second light amounts. The first time point transmission rate of the illumination optical system with respect to light is calculated, and the second time point of the illumination optical system with respect to the illumination light is calculated based on the third and fourth light amounts. A light amount calculation unit that calculates a second transmission rate and calculates a target light amount at the second time point based on the first and second transmission rates, and a light amount of the illumination light based on the target light amount. A light amount drive control unit for controlling the light intensity and a gain adjustment unit for controlling the drive of the optical modulation element are provided, and the light amount calculation is performed at a third time point after the light source drive control unit controls the light amount of the illumination light. The unit is irradiated to the light modulation element at the third time point with respect to the amount of light of the illumination light to be applied to the light modulation element at the first time point based on the first and second transmission rates. The light amount ratio, which is the ratio of the light amount of the illumination light, is calculated, and the gain adjusting unit provides a light amount adjusting device that controls the driving of the light modulation element based on the light amount ratio.

In the present invention, a light source unit that emits illumination light, an illumination optical system in which the illumination light is incident from the light source unit and emits the illumination light, and the illumination light emitted from the illumination optical system are the first. An optical modulation element that photomodulates based on image data of a display image level 1 and a second display image level lower than the first display image level, and an illumination optical system from the light source unit at a first time point. When the illumination light and the optical modulation element light-modulated the illumination light based on the image data of the first display image level, the illumination light is emitted from the optical modulation element and returns to the light source unit. Based on the first light amount which is the total amount of light with the return light, and the image data of the second display image level where the illumination light and the light modulation element make the illumination light lower than the first display image level. When the light is modulated, the second light amount, which is the total amount of light emitted from the light modulation element and returned to the light source unit, is detected, and at the second time point after the first time point, the said The total amount of light of the illumination light and the return light emitted from the light modulation element and returned to the light source unit when the illumination light is photomodulated based on the image data of the first display image level. When the illumination light and the light modulation element photomodulate the illumination light based on the image data of the second display image level, the third light amount is emitted from the light modulation element and the light source is emitted. An optical sensor that detects a fourth amount of light, which is the sum of the amount of light returning to the unit, and the first time point of the illumination optical system with respect to the illumination light based on the first and second light amounts. The transmission rate of 1 is calculated, and the second transmission rate of the illumination optical system at the second time point with respect to the illumination light is calculated based on the third and fourth light amounts, and the first and second transmission rates are calculated. A light amount calculation unit that calculates a target light amount at the second time point based on the transmission rate of 2, a light source drive control unit that controls the light amount of the illumination light based on the target light amount, and the light modulation element. A gain adjusting unit for controlling the drive is provided, and at a third time point after the light source drive control unit controls the light amount of the illumination light, the light amount calculation unit is based on the first and second transmission rates. Then, the light amount ratio, which is the ratio of the light amount of the illumination light to be irradiated to the light modulation element at the third time point, to the light amount of the illumination light to be irradiated to the light modulation element at the first time point is calculated. The gain adjusting unit provides a projection device that controls the driving of the optical modulation element based on the light amount ratio.

According to the light amount adjusting method, the light amount adjusting device, and the projection device of the present invention, the brightness of the image projected on the projected medium such as a screen can be stabilized over time.

It is a block diagram which shows the projection apparatus of 1st to 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 which the light modulation element photomodulates the illumination light based on the image data of a white level. It is a figure which shows the state which the light modulation element photomodulates the illumination light based on the image data of a black level. It is a figure which shows the state which the light modulation element photomodulates 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 flowchart which shows the light amount adjustment method in 1st Embodiment. It is a flowchart which shows the light amount adjustment method in 1st Embodiment. It is a block diagram which shows an example of the light amount adjustment apparatus in the projection apparatus 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 to 6th Embodiment when the optical sensor is arranged at the position different from FIG.

[First Embodiment]
A configuration example of the projection device of 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 adjusting device 6. In the first embodiment, in order to distinguish from the projection device 1 and the light amount adjusting device 6 of other embodiments described later, the projection device 1 is referred to as a projection device 1a and the light amount adjusting device 6 is referred to as a light amount adjusting device 6a.

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, condensing 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 unit 21 constitute 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 a blue laser beam.

A configuration example of the phosphor section 21 will be described with reference to FIGS. 2 to 3. The phosphor unit 21 includes a phosphor wheel 22, a phosphor 23, a rotation shaft 24, and a wheel drive unit 25. The phosphor wheel 22 has, for example, a disk shape. The phosphor 23 is formed on the outer peripheral portion of the surface of the phosphor wheel 22 which is a mirror surface. When the blue laser light BL irradiates the phosphor 23, 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 while the phosphor wheel 22 is rotated, the local temperature rise generated by the irradiation of the blue laser light BL is caused by the outer peripheral portion of the phosphor wheel 22. It can be distributed throughout. As a result, the temperature rise of the phosphor 23 can be suppressed.

The condensing lenses 11 to 13 condense the blue laser light BL, which is the incident light. The split mirror 14 divides the blue laser beam 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 beam BL1 transmitted through the split mirror 14 is incident on 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, further condensed by the condenser lenses 12 and 13, and irradiated 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 unit 21 emits yellow light as yellow illumination light YLL by being irradiated with the blue laser light BL1. The yellow illumination light YLL is incident on the illumination optical system 3 via the condenser lenses 12 and 13 and the dichroic mirror 15.

The blue laser beam 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 is incident on the illumination optical system 3 as blue illumination light BLL. That is, white illumination light WLL, which is a mixed light of yellow illumination light YLL and 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 has 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 incident on the illumination optical system 3 toward the fly-eye lenses 33 and 34. The fly-eye lenses 33 and 34 constitute a uniform illumination optical system. The fly-eye lenses 33 and 34 make the illumination distribution of the illumination light WLL irradiated on the light modulation element 4 uniform.

The polarization conversion element 35 aligns the illumination light WLL with the polarization of either p-polarization or s-polarization. The polarization conversion element 35 aligns the illumination light WLL with, for example, s polarization. The illumination light WLL aligned to the s polarization is incident on the cross dichroic mirror 40 via the lens 36. The cross dichroic mirror 40 separates the illumination light WLL into a yellow illumination light YLL and a blue illumination light BLL.

The yellow illumination light YLL separated by the cross dichroic mirror 40 is reflected by the reflection mirror 31 and incident on the dichroic mirror 41. The dichroic mirror 41 separates the yellow illumination light YLL into a red illumination light RLL containing a red component and a 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 composed of, for example, a wire grid.

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

The red illumination light RLL transmitted through the dichroic mirror 41 is incident on the reflective polarizing plate 42R via the lens 37. The s-polarized red illumination light RLL passes through the reflective polarizing plate 42R and irradiates the light modulation element 4R. The light modulation element 4R photomodulates the red illumination light RLL for each pixel based on the image data of the red component, and generates the p-polarized red image light RML. The red image light RML is reflected by the reflective polarizing plate 42R and is incident on the projection optical system 5.

The green illumination light GLL reflected by the dichroic mirror 41 is incident on the reflective polarizing plate 42G via the lens 38. The s-polarized green illumination light GLL passes through the reflective polarizing plate 42G and irradiates the light modulation element 4G. The light modulation element 4G photomodulates 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 is incident on 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 incident on the reflective polarizing plate 42B via the lens 39. The s-polarized blue illumination light BLL passes through the reflective polarizing plate 42B and irradiates the light modulation element 4B. The light modulation element 4B photomodulates 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 is incident on the projection optical system 5.

The projection optical system 5 includes a color synthesis prism 43 and a projection lens 44. The red image light RML, the green image light GML, and the blue image light BML incident on the projection optical system 5 are combined by the color synthesis prism 43, and are displayed on a projection medium such as a screen by the projection lens 44 as a display image of a full-color image. It is magnified and projected.

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

The light amount adjusting device 6a includes a light 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 including, for example, a red component, a green component, and a blue component. Note that FIG. 1 shows only the optical sensor 7. The light amount calculation unit 51, the light source drive control unit 52, and the light source drive unit 53 may be configured by operating a program on a CPU (Central Processing Unit) mounted on the light amount adjusting device 6a, or may be partially or partially formed. All may be configured by a hardware circuit that operates in cooperation with each other. The light amount storage unit 54 is composed of a non-volatile 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 until the illumination light WLL is emitted from the light source unit 2 and is incident on the cross dichroic mirror 40. It is desirable that the optical sensor 7 is arranged in an optical path in which each color light is mixed. The optical sensor 7 is arranged, for example, in the vicinity of the polarization conversion element 35, at a position away from the optical path of the illumination light WLL, and at a position where the leakage light of the polarization conversion element 35 can be efficiently detected.

It is assumed that the correlation between the detected value detected by the optical sensor 7 and the amount of light passing through the polarization conversion element 35 has been confirmed in advance. Hereinafter, the amount of light transmitted through the polarization conversion element 35 calculated based on the detection value detected by the optical sensor 7 is defined as the amount of light detected by the optical sensor 7.

The illumination light LL1 passes through the reflective polarizing plate 42 and irradiates the light modulation element 4. The light modulation element 4 generates image light ML by photomodulating the illumination light LL1 based on the input image data.

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

The light modulation element 4 photomodulates the illumination light LL1 to generate the reflected light LL2. When the light modulation element 4 photomodulates the illumination light LL1 based on the white level image data, substantially all the s-polarized illumination light LL1 is optical-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 a screen SR. Therefore, since almost all the reflected light LL2 is reflected by the reflective polarizing plate 42, the amount of light 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 photomodulates the illumination light LL1 based on, for example, image data at a black level (second display image level) which is the minimum gradation. The illumination light LL1 incident on the illumination optical system 3 from the light source unit 2 irradiates the light modulation element 4 (4R, 4G, 4B) via the lenses 37 to 39 and the reflective polarizing plate 42 (42R, 42G, 42B). Will be done. The illumination light LL1 of FIG. 5B corresponds to the red illumination light RLL, the green illumination light GLL, and the blue illumination light BLL of FIG.

The light modulation element 4 generates reflected light LL2 without photomodulating the illumination light LL1 based on the black level image data. Almost all of the illumination light LL1 becomes reflected light LL2 with s-polarized light, and passes through the reflective polarizing plate 42 and the lenses 37 to 39. A black image will be displayed on the projection medium.

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

The light modulation element 4 photomodulates the illumination light LL1 based on the gray level image data, and generates reflected light LL2 in which p-polarization and s-polarization 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 a screen SR. The s-polarized reflected light LL2 passes through the reflective polarizing plate 42 and the lenses 37 to 39 as return light RL and returns to the light source unit 2. The light amount of the return light RL is a value obtained by subtracting the light amount of the reflected light LL2 of p-polarization from the light amount 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, 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 optical BLL is irradiated on the optical modulation elements 4R, 4G, 4B. The amount of light of the illumination light LL1 emitted from the light source unit 2 is L0, and the amount of light of the illumination light LL1 when passing through a position near the optical sensor 7 (hereinafter referred to as a light amount detection position) is applied to L1 and the optical modulation element 4. The light amount of the illumination light LL1 is L2, and the light amount of the return light RL returning from the light amount detection element 4 to the light amount detection position is L3.

The transmission rate 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 is incident on the illumination optical system 3 to the light amount detection position is T1, and the illumination light LL1 is the optical modulation element 4 from the light amount detection position. Let T2 be the transmittance of the illumination optical system 3 on the optical path to the position where the light is irradiated. The ratio of the return light RL to the reflected light LL2 is M (0 <M <1).

The light amounts L1, L2, and L3 can be represented by the formulas (1), (2), and (3), respectively.

L1 = L0 × T1 ... (1)

L2 = L1 × T2 ... (2)

L3 = L1 x T2 ² x M ... (3)

The optical sensor 7 detects the total amount of light of the illumination light LL1 and the return light RL. The light amount C detected by the light sensor 7 can be expressed by the equation (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 amount of light detected by the optical sensor 7 when the display image level is the white level is Cw, and the amount of light 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 light sensor 7 can be represented by the formulas (5) and (6), respectively.

Cw = L1 × (1 + T2 ² × Mw)… (5)

Cb = L1 × (1 + T2 ² × Mb)… (6)

From the formula (5) and the formula (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 equation (7). The higher the display image level (gradation value), the smaller the ratio M of the return light RL, 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. When 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 equation (8).

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

L2b = L1b × T2b ... (9)

L2a = L1a × T2a ... (10)

The light source unit 2 emits the illumination light WLL having the light amount L0b in the initial state, and emits the illumination light WLL having the light amount L0a after the lapse of time. In order to maintain the light amount of the image light ML emitted from the projection optical system 5 after a lapse of time 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 used. It is important that it is always constant (L2b = L2a). Assuming that 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). Can be done.

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

Therefore, the light amount calculation unit 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 equation (12) correspond to the rate of increase 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 rate of increase R in the initial state is defined as the rate of increase Rb, and the rate of increase R after the lapse of time is defined as the rate of increase Ra. That is, Rb = (Cbb-Cwb) / Cwb and Ra = (Cba-Cwa) / Cwa. The target light amount L1c can be expressed by the equation (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 light sensor 7, and further calculates the target light amount L1c by the equation (13).

The light amount Cw detected by the light sensor 7 in the white level state is substantially the same as the light amount L1 of the illumination light WLL passing in the vicinity of the light sensor 7, and is not easily affected by the return light RL (light amount L3). On the other hand, the light amount Cb detected by the light sensor 7 in the black level state is substantially the same as the total value of the light amount L1 of the illumination light WLL passing in the vicinity of the light sensor 7 and the light amount L3 of the return light RL, and returns. It is easily affected by light RL (light amount L3).

Therefore, it is preferable that the light amount calculation unit 51 calculates the light amounts L1b and L1a with reference to the light amounts Cwb and Cwa detected by the light sensor 7 in the white level state. In the display image level state other than the white level, it is preferable that the optical 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 stores the light amount Cwb and the increase rate Rb in the initial state and the white level state in the light amount storage unit 54. After the lapse of time, the light amount calculation unit 51 calculates the light amount Cwa in the white level state and the increase rate Ra, further calculates the right side of the equation (13), and calculates the target light amount after the lapse of time. In other words, the light amount calculation unit 51 calculates the target light amount 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 quantity L1c. Specifically, the light amount Cw detected by the optical sensor 7 in the white level state 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 optical sensor 7 in the white level state to the target light amount L1c. The light source driving unit 53 is controlled so as to approach. As a result, the amount of light 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 adjusting 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 adjusting method for stabilizing the light amount of the image light ML projected from the projection device 1a over time will be described with reference to the flowcharts of FIGS. 7A and 7B. In the first embodiment, the amount of 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 the lapse of time (second time point).

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

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 the light amount to the light amount calculation unit 51. In step S13, the light amount calculation unit 51 calculates the light amount L1b with reference to 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 has a light amount Cwa (third light amount) in the white level state and a black level state in step S21. 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 rate of increase Ra after the lapse of time based on the light amounts Cwa and Cba.

In step S23, the light amount calculation unit 51 reads out 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 lapse 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 lapse of time approaches the target light amount L1c, so that the illumination light LL1 emitted from the light source unit 2 is emitted. The amount of light L0 is controlled.

In the light amount adjusting method, the light amount adjusting device 6a, and the projection device 1a of the first embodiment, the optical sensor 7 is illuminated in a range until the illumination light WLL is emitted from the light source unit 2 and is incident on the cross dichroic mirror 40. It is arranged near the optical path of the optical WLL and at a position that does not affect the optical 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 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 a lapse of time are based on the white level state in which the influence of the return light RL is small. The rate Ra is calculated, and further, the target light amount after the lapse of time is calculated based on the light amounts L1b and the increase rates Rb and Ra, in other words, based on the transmittances T2b and T2a. According to the light amount adjusting method, the light amount adjusting 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 lapse 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 of the second embodiment will be described with reference to FIG. In order to make the explanation easy to understand, 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 adjusting device 6 of other embodiments, the projection device 1 is referred to as a projection device 1b, and the light amount adjusting device 6 is referred to as a light amount adjusting device 6b. The projection device 1b of the second embodiment has a different configuration of the light amount adjusting device 6b as compared with the projection device 1a of the first embodiment, and the other configurations are the same.

FIG. 8 shows a configuration example of the light amount adjusting device 6b in the projection device 1b of the second embodiment. The reflective polarizing plate 42 of FIG. 8 is a simplified representation 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, 42B). The light modulation element 4 of FIG. 8 is a simplified representation of the light modulation element 4 (4R, 4G, 4B) of FIG. The projection optical system 5 of FIG. 8 is a simplified representation of the projection optical system 5 of FIG.

The light amount adjusting device 6b includes a light 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 adjusting device 6b includes an image processing unit 60, a gain adjusting unit 61, an element driving 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 on the CPU mounted on the light amount adjustment device 6b. It may be configured, or may be partially or wholly configured by a hardware circuit that operates in cooperation with each other.

The gain storage unit 63 is composed of a non-volatile memory such as 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 illumination light WLL having a predetermined light amount L0 at the time of shipment from the factory or at the time of system setting, the light amount calculation unit 51 makes the projected image (image light ML) have a predetermined brightness. Calculate the gain value like this. Further, the light amount calculation unit 51 stores the calculated gain value as the initial gain value Gref in the gain storage unit 63. Since the brightness of the image data and the projected image are not necessarily in a linear relationship, it is desirable to determine the initial gain value Gref in consideration of the gamma characteristics of the light modulation element 4.

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

The light amount calculation unit 51 reads out the light amount L1b and the increase rate Rb in the initial state stored in the light amount storage unit 54. The light amount calculation unit 51 calculates the light amount L2a after the 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 amount L2a and the light amount L2b can be calculated from the formulas (15) and (16), respectively.

From the equation (17), the light amount calculation unit 51 determines the ratio of the light amount L2a of the illumination light LL1 irradiated to the light modulation element 4 after the lapse of time to the light amount L2b of the illumination light LL1 irradiated to the light modulation element 4 in the initial state. The light amount ratio LQR is calculated. In other words, the light amount calculation unit 51 calculates the light amount 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 the gain adjustment value Ad 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 in frame units 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 the image data to the gain adjustment unit 61.

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

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

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

Therefore, the gain adjusting unit 61 serves as a light amount adjusting unit that adjusts the amount of light 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, for example, a value within the range of 0 <Gref ≦ 1.0. 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. , The brightness of the projected image can be made constant.

The smaller the initial gain value Gref, the larger the range in which the gain is increased with respect to the image data. Therefore, when it is assumed that the amount of light 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.

Using the flowchart of FIG. 9, an example of a light amount adjusting method for stabilizing the light amount of the image light ML projected from the projection device 1b over time will be described. In the second embodiment, the gain of the image data is adjusted so that the brightness of the projected image becomes constant, and the drive of the light modulation element 4 is controlled based on the gain-adjusted image data.

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

In step S33, the light amount calculation unit 51 reads out 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 the 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 amount L2a and the light amount L2b. In other words, the light amount calculation unit 51 calculates the light amount ratio LQR based on the transmittances T2b and T2a.

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

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 compared to the case of doing so.

In the light amount adjusting method, the light amount adjusting device 6b, and the projection device 1b of the second embodiment, the optical sensor 7 illuminates a range until the illumination light WLL is emitted from the light source unit 2 and is incident on the cross dichroic mirror 40. It is arranged near the optical path of the optical WLL and at a position that does not affect the optical 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 of the second embodiment, the increase rate Rb and Ra or the transmittance T2b and T2a are used as a reference based on the white level state in which the influence of the return light RL is small. The light amount ratio LQR is calculated. In the light amount adjusting method, the light amount adjusting 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 further based on the image data Ga gain-adjusted by the gain adjustment value Ad. It controls the drive of the light modulation element 4. This makes it possible to stabilize the brightness of the projected image over 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 amount of red light, the amount of green light, and the amount of blue light is used. It differs in that. 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 amount of light of the red component, the amount of light of the green component, and the amount of light of the blue component 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) of the red component based on the light amount ratio LQR (R), and calculates the gain adjustment value Ad (G) of 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 amount 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 adjusting unit 61 adjusts the gain of the image data of the red component by the initial gain value Gref and the gain adjusting value Ad (R). The gain adjusting unit 61 adjusts the gain of the image data of the green component by the initial gain value Gref and the gain adjusting value Ad (G). The gain adjusting unit 61 adjusts the gain of the image data of the blue component by the initial gain value Gref and the gain adjusting value Ad (B). Each gain is a gain for the image data of the red component, the green component, and the 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 value common to 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 compared to the case.

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

With the passage of time, 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. Therefore, not only the brightness but also the color balance of the projected image may change with the passage of time. Therefore, not only the brightness but also the color balance of the projected image may change with the passage of time. According to the light amount adjusting method, the light amount adjusting 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 a range until the illumination light LL1 is emitted from the light source unit 2 and is incident on the cross dichroic mirror 40. It is arranged near the optical path of the optical LL1 and at a position that does not affect the optical 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 of the fourth embodiment will be described with reference to FIG. For the sake of clarity, the same components as those of the projection devices 1a and 1b of the first and second embodiments are designated by the same reference numerals. In the fourth embodiment, in order to distinguish from the projection device 1 and the light amount adjusting device 6 of other embodiments, the projection device 1 is referred to as a projection device 1c, and the light amount adjusting device 6 is referred to as a light amount adjusting device 6c.

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

FIG. 10 shows a configuration example of the light amount adjusting device 6c in the projection device 1c of the fourth embodiment. The reflective polarizing plate 42 of FIG. 10 is a simplified representation 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, 42B). The light modulation element 4 of FIG. 10 is a simplified representation of the light modulation element 4 (4R, 4G, 4B) of FIG. The projection optical system 5 of FIG. 10 is a simplified representation of the projection optical system 5 of 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 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 amount of light detected by the optical sensor 7 with the target amount of light 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 in order to set the target light amount L1c is within a predetermined range. The configuration may be adjusted when it exceeds the limit. For example, if the adjustment amount exceeds 10%, it is adjusted, and if it is less than 10%, it is not adjusted.

At the third time point after the light source drive control unit 52 controls the light amount of the illumination light WLL, the light amount calculation unit 51 of the projection device 1c follows 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 at the third time point to the light amount L2b of the illumination light LL1 irradiated to the light modulation element 4, is calculated. The gain adjusting 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.

In general, the larger the amount of gain adjustment for 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 fourth embodiment, the brightness of the projected image is adjusted by the light amount of the illumination light WLL emitted from the light source unit 2, and the pixels of the projected image. The value can be adjusted by the gain adjustment value Ad. Therefore, since the amount of adjustment by the gain adjustment value Ad can be reduced, a projected image having higher gradation performance can be displayed.

In the light amount adjusting method, the light amount adjusting device 6c, and the projection device 1c of the fourth embodiment, the optical sensor 7 illuminates in a range until the illumination light LL1 is emitted from the light source unit 2 and is incident on the cross dichroic mirror 40. It is arranged near the optical path of the optical LL1 and at a position that does not affect the optical 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 adjusting method, the light amount adjusting 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 based on the gain-adjusted image data Ga. It controls the drive of the modulation element 4. This makes it possible to stabilize the brightness of the projected image over time.

According to the light amount adjusting method, the light amount adjusting 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 for increasing the gain of the image data. Therefore, it is not necessary to set the initial gain value Gref to a small value, and 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. For example, 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), so that it is brighter. The image can be projected onto a projection medium such as a screen. When an image having a predetermined brightness is projected onto a projection medium, the amount of light 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 be reduced. 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 amount of red light, the amount of green light, and the amount of blue light is used. It differs in that. 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 amount of light of the red component, the amount of light of the green component, and the amount of light of the blue component 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 by the same procedure as the projection device 1a of the first embodiment. In this case, the light amount C is the sum of the light amounts of the light components of each color component detected by the light sensor 7. The total light amount C of the illumination light LL1 and the return light RL can be expressed by the equation (18).

C = IR x CR + IG x CG + IB x CB ... (18)

CR, CG, and CB are the detected 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 detected 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 the equation (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 amount of light detected by the optical sensor 7 with the target amount of light 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 in order to set the target light amount L1c exceeds a predetermined range. The configuration may be adjusted in case of such cases. For example, if the adjustment amount exceeds 10%, it is adjusted, and if it is less than 10%, it is not adjusted.

The projection device 1c of the fifth embodiment controls the light source by the same procedure as that of the first embodiment, and then adjusts the gain of each image data by the same procedure as that of the projection device 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.

In general, the larger the amount of gain adjustment for 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 for each color component, so that the brightness of the projected image is emitted from the light source unit 2. It can be adjusted by the amount of light of the illumination light LL1 and the color balance of the projected image can be adjusted by the gain adjustment value Ad for each color component. Therefore, by detecting the amount of light for each color component, the amount of adjustment by the gain adjustment value Ad can be reduced, so that a projected image having higher gradation performance can be displayed.

Further, by detecting the amount of light for each color component, the initial gain value Gref can be made a large value. As a result, a bright image can be displayed on a projection medium such as a screen SR. When an image having a predetermined brightness is projected onto a projection medium, the amount of light L0 of the illumination light LL1 emitted from the light source unit 2 can be further reduced by detecting the amount of light 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 adjusting method, the light amount adjusting device 6c, and the projection device 1c of the fifth embodiment, the optical sensor 7 illuminates in a range until the illumination light LL1 is emitted from the light source unit 2 and is incident on the cross dichroic mirror 40. It is arranged near the optical path of the optical LL1 and at a position that does not affect the optical 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 adjusting method, the light amount adjusting 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 based on the gain-adjusted image data Ga. It controls the drive of the modulation element 4. This makes it possible to stabilize the brightness of the projected image over time.

According to the light amount adjusting method, the light amount adjusting 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. can. As a result, the image can be projected onto a projection medium such as a screen while maintaining high gradation performance.

According to the light amount adjusting method, the light amount adjusting 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 for increasing the gain of the image data. Therefore, it is not necessary to set the initial gain value Gref to a small value, and 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. For example, 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), so that it is brighter. The image can be projected onto a projection medium such as a screen. When an image having a predetermined brightness is projected onto a projection medium, the amount of light 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 be reduced. The life can be extended.

[Sixth Embodiment]
In the first embodiment, as the illumination light source, the amount of illumination light emitted from one light source 10 is controlled. On the other hand, the projection device 1a of the sixth embodiment has a plurality of light sources having different color components of the illumination light as the illumination light source. The light source drive control unit 52 controls the light source drive unit 53 to independently control the amount of illumination light emitted from each light source for 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 emits the amount of red illumination light emitted from the red light source 2R, the amount of green illumination light emitted from the green light source 2G, and the amount of green illumination light emitted from the blue light source 2B. The amount of green illumination light 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 reflects the dichroic mirror 71 and passes through the dichroic mirror 72. The blue illumination light emitted from the blue light source 2B reflects 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 amount of red light, the amount of green light, and the amount of blue light may be used. When a color sensor is used as the optical sensor 7 in the projection device 1a of the sixth embodiment, the optical sensor 7 determines the amount of light of the red component, the amount of light of the green component, and the amount of light of the blue component of the illumination light WLL and the return light RL. To detect.

The projection device 1a of the sixth 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 amount calculation unit 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. do. The light source drive control unit 52 controls each light source so that the amount of light of each color component becomes the target amount of light.

(Modification example)
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 do not have to be independent. FIG. 12 shows a case where the light source unit 2 has a yellow light source 2Y and a blue light source 2B as a modification. The yellow light source 2Y emits yellow illumination light containing 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 passes through the dichroic mirror 74, and the blue illumination light emitted from the blue light source 2B reflects 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 an optical system deteriorates, the transmittance of blue light tends to deteriorate. Therefore, there is no problem in practical use by configuring the configuration so that only the blue illumination light can be controlled independently.

FIG. 1 shows a case where the optical sensor 7 is arranged in the vicinity of the polarization conversion element 35. The optical sensor 7 is arranged near the optical path of the illumination light LL1 in the range until 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 optical modulation element 4. It suffices if it has been done. For example, as shown in FIG. 13, the optical sensor 7 may be arranged closer to the light source unit 2 (for example, in the vicinity of the reflection mirror 30) than the fly-eye lens 33.

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

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

1,1a, 1b, 1c Projection device 2 Light source unit 3 Illumination optical system 4, 4R, 4G, 4B Light modulation element 7 Optical sensor 51 Light intensity calculation unit 52 Light source drive control unit (light intensity adjustment unit)
61 Gain adjustment unit (light intensity adjustment unit)
Cba light intensity (fourth 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 (4)

At the first point,
The light modulation element emits the illumination light emitted from the light source unit through the illumination optical system based on the image data of the first display image level and the second display image level lower than the first display image level. Optically modulated
When the optical sensor photomodulates the illumination light and the illumination light based on the image data of the first display image level, it emits light from the optical modulation element and returns to the light source unit. The first light amount, which is the total amount of light with the light, and the light modulation element when the illumination light and the light modulation element light-modulate the illumination light based on the image data of the second display image level. The second amount of light, which is the total amount of light emitted and returned to the light source unit, is detected.
The light amount calculation unit calculates the first transmittance of the illumination optical system with respect to the illumination light based on the first and second light amounts.
At the second time point after the first time point,
The light modulation element photomodulates the illumination light based on the image data of the first and second display image levels.
When the illumination light and the optical modulation element photomodulate the illumination light based on the image data of the first display image level, the optical sensor emits light from the optical modulation element and returns to the light source unit. The third light amount, which is the total amount of light with the return light, and the light modulation element when the illumination light and the light modulation element photomodulate the illumination light based on the image data of the second display image level. The fourth light amount, which is the total amount of light with the return light emitted from the light source and returned to the light source unit, is detected.
The light amount calculation unit calculates the second transmittance of the illumination optical system with respect to the illumination light based on the third and fourth light amounts, and based on the first and second transmittances, the said Calculate the target light intensity at the second time point,
The light source drive control unit controls the amount of illumination light based on the target amount of light.
At a third time point after the light source drive control unit controls the amount of illumination light,
Based on the first and second transmittances, the light amount calculation unit attaches to the light modulation element at the third time point with respect to the light amount of the illumination light applied to the light modulation element at the first time point. The light amount ratio, which is the ratio of the light amount of the illumination light to be irradiated, is calculated.
A light amount adjusting method in which a gain adjusting unit controls driving of the light modulation element based on the light amount ratio. The optical 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 amount of illumination light based on the total amount of light of the red component, the green component, and the blue component.
The light amount calculation unit calculates the light amount ratio of the red component, the green component, and the blue component of the illumination light.
The light amount adjusting method according to claim 1, wherein the gain adjusting 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. At the first time point, when the illumination light emitted from the light source unit via the illumination optical system and the optical modulation element photomodulate the illumination light based on the image data of the first display image level, the optical modulation element. The first light amount, which is the total amount of light emitted from the light source and the return light returning to the light source unit, and the second, in which the illumination light and the light modulation element make the illumination light lower than the first display image level. When light modulation is performed based on the image data of the display image level of, the second light amount, which is the total light amount of the return light emitted from the light modulation element and returned to the light source unit, is detected, and the first time point is described. At a later second time point, when the illumination light and the light modulation element photomodulate the illumination light based on the image data of the first display image level, the illumination light is emitted from the light modulation element to the light source. When the third light amount, which is the total light amount of the return light returning to the unit, and the illumination light and the light modulation element light-modulate the illumination light based on the image data of the second display image level. An optical sensor that detects a fourth amount of light, which is the total amount of light emitted from the optical modulation element and returned to the light source unit.
The first transmittance of the illumination optical system at the first time point with respect to the illumination light is calculated based on the first and second light amounts, and the illumination is based on the third and fourth light amounts. With a light amount calculation unit that calculates the second transmittance of the illumination optical system for light at the second time point and calculates the target light amount at the second time point based on the first and second transmittances. ,
A light source drive control unit that controls the amount of illumination light based on the target amount of light,
A gain adjustment unit that controls the drive of the light modulation element, and
Equipped with
At a third time point after the light source drive control unit controls the amount of illumination light,
Based on the first and second transmittances, the light amount calculation unit applies to the light modulation element at the third time point with respect to the light amount of the illumination light applied to the light modulation element at the first time point. The light amount ratio, which is the ratio of the light amount of the illumination light to be irradiated, is calculated.
The gain adjusting unit is a light amount adjusting device that controls driving of the light modulation element based on the light amount ratio. A light source that emits illumination light and
An illumination optical system in which the illumination light is incident from the light source unit and emits the illumination light.
An optical modulation element that photomodulates 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 via the illumination optical system and the optical modulation element photomodulate the illumination light based on the image data of the first display image level. The first light amount, which is the total amount of light emitted from the light modulation element and returned to the light source unit, and the illumination light and the light modulation element emit the illumination light from the first display image level. The second light amount, which is the total amount of light with the return light emitted from the light modulation element and returned to the light source unit, is detected when the light is light-modulated based on the image data of the second display image level, which is also low. At a second time point after the first time point, when the illumination light and the light modulation element photomodulate the illumination light based on the image data of the first display image level, the illumination light is emitted from the light modulation element. A third amount of light, which is the total amount of light that is the sum of the return light that returns 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 amount of light, which is the total amount of light emitted from the optical modulation element and returned to the light source unit when modulated.
The first transmittance of the illumination optical system at the first time point with respect to the illumination light is calculated based on the first and second light amounts, and the illumination is based on the third and fourth light amounts. With a light amount calculation unit that calculates the second transmittance of the illumination optical system for light at the second time point and calculates the target light amount at the second time point based on the first and second transmittances. ,
A light source drive control unit that controls the amount of illumination light based on the target amount of light,
A gain adjustment unit that controls the drive of the light modulation element, and
Equipped with
At a third time point after the light source drive control unit controls the amount of illumination light,
Based on the first and second transmittances, the light amount calculation unit applies to the light modulation element at the third time point with respect to the light amount of the illumination light applied to the light modulation element at the first time point. The light amount ratio, which is the ratio of the light amount of the illumination light to be irradiated, is calculated.
The gain adjusting unit is a projection device that controls the drive of the light modulation element based on the light amount ratio.

Images