Image projection device and image projection method

Abstract

This image projection device has a projection lens that projects an image on a projection target surface, a drive control unit that adjusts a focus position of the projection lens, and an adaptive correction unit that moves the focus position via the drive control unit in response to a change in the focus position occurring during projection. According to adjustment intensity set by a user, the adaptive correction unit changes the movement amount of the focus position.

Description

Image projection device and image projection method

[0001] The present invention relates to an image projection device and an image projection method.

[0002] Image projection devices such as projectors generate a display image based on a video signal and light emitted from a light source, and project the generated display image onto a projection surface such as a screen. In such image projection devices, focus drift, in which the focus of the display image fluctuates during projection, can occur. This occurs because the temperature of the projection lens and the lens holder frame that holds it increases as light emitted from the light source passes through the projection lens, causing a change in the refractive index of the projection lens and thermal expansion of the lens holder frame, resulting in a shift in the focal position of the optical system. Patent Document 1 discloses a technology for appropriately correcting focus drift during projection.

[0003] JP 2009-223111 A

[0004] However, in the prior art, performing correction according to the conditions of the site where the projector is installed has not been sufficiently considered. For example, in Patent Document 1, the temperature rise of the projection lens is estimated by grasping the amount of light passing through the projection lens using the brightness of the displayed image, etc., and a correction value corresponding to the estimated temperature rise is calculated. Therefore, the actual conditions of the site where the projector is installed, such as the installation environment of the projector and individual differences between projectors, are not taken into consideration. As a result, if the projector is installed in a space with a high temperature or if the projector incorporates an optical system that is prone to temperature rise due to individual differences, the temperature may rise further than the estimated temperature, resulting in an insufficient correction value. On the other hand, if the projector is installed in a space with a low temperature or if the projector incorporates an optical system that is less prone to temperature rise due to individual differences, the temperature may not rise to the estimated temperature, resulting in an excessive correction value.

[0005] In view of the above-mentioned problems, an object of the present invention is to provide an image projection device and an image projection method that can correct focus deviations that occur during projection in accordance with the installation environment of the projector and individual differences between projectors.

[0006] One aspect of the present invention is an image projection device having a projection lens that projects an image onto a projection surface, a drive control unit that adjusts the focus position of the projection lens, and an adaptive correction unit that moves the focus position via the drive control unit in response to fluctuations in the focus position that occur during projection, wherein the adaptive correction unit changes the amount of movement of the focus position depending on an adjustment strength set by a user.

[0007] Another aspect of the present invention is an image projection method for projecting an image through a projection lens, in which the focus position is moved in response to fluctuations in the focus position of the projection lens that occur during projection, and the amount of movement of the focus position can be changed by an adjustment strength set by a user.

[0008] According to the present invention, it is possible to correct the defocus occurring during projection in accordance with the installation environment of the projector and individual differences between projectors.

[0009] 1 is an external view showing an example of an image projection system in this embodiment. FIG. 2 is a block diagram showing an example of an image projection device in this embodiment. FIG. 3 is a diagram explaining focus correction in this embodiment. FIG. 4 is a block diagram showing the configuration of a storage unit in this embodiment. FIG. 5 is a diagram showing an example of target data in this embodiment. FIG. 6 is a diagram showing an example of current data in this embodiment. FIG. 7 is a diagram showing an example of correction cycle data in this embodiment. FIG. 8 is a block diagram showing the configuration of a control unit in this embodiment. FIG. 9 is a diagram explaining processing performed by the control unit in this embodiment. FIG. 10 is a diagram showing an example of an OSD image in this embodiment. FIG. 11 is a diagram showing an example of an OSD image in this embodiment. FIG. 12 is a diagram showing an example of an OSD image in this embodiment. FIG. 13 is a flowchart showing the flow of processing performed by the image projection device in this embodiment. FIG. 14 is a flowchart showing the flow of processing performed by the image projection device in this embodiment. FIG. 15 is a diagram showing the basic configuration of an image projection device according to the present invention.

[0010] An image projection device according to an embodiment of the present invention will now be described with reference to the drawings.

[0011] 1 is an external view showing an example of an image projection system 1 according to this embodiment. As shown in FIG. 1, the image projection system 1 includes an image projection device 10, a video signal input device 20, a remote control device 30, and a projection surface 40.

[0012] The image projection device 10 is a projector that is connected to a video signal input device 20 via a wired or wireless connection and generates a display image based on a video signal received from the video signal input device 20. The image projection device 10 has an OSD (On Screen Display) device that displays setting and operation information for the device itself, generates an OSD image in response to a user's operation of a remote control device 30, and projects a display image with the OSD image superimposed onto a projection surface 40.

[0013] The video signal input device 20 is, for example, a personal computer or a smartphone, and transmits a video signal to the image projection device 10 .

[0014] As will be described in detail later, the remote control device 30 inputs to the image projection device 10 instruction information instructing whether to enable or disable the adaptive correction function for the image projection device 10, and information indicating the adjustment strength and adjustment period when the adaptive correction function is performed.

[0015] The projection surface 40 is, for example, a screen, onto which the display image with the OSD image superimposed is projected from the image projection device 10 .

[0016] Next, the configuration of the image projection device 10 according to this embodiment will be described with reference to Fig. 2. Fig. 2 is a block diagram showing an example of the image projection device 10 according to this embodiment. As shown in Fig. 2, the image projection device 10 includes an image processing unit 11, a focus position detection unit 12, a receiving unit 13, a projection unit 14, a storage unit 15, a control unit 16, and a signal line 17.

[0017] The image processing unit 11 includes a video signal processing unit 111 and an OSD processing unit 112. The video signal processing unit 111 performs video signal processing such as image quality improvement on the video signal received from the video signal input device 20, and transmits the resulting signal to the OSD processing unit 112. The OSD processing unit 112 receives a superimposition instruction, which is an instruction to generate an OSD image, from the control unit 16, and generates an OSD image signal. The OSD processing unit 112 superimposes the OSD image signal on the video signal received from the video signal processing unit 111, and transmits the superimposed signal to the projection unit 14 (optical unit 142, described later).

[0018] The focus position detection unit 12 detects the focus position of the projection lens 143, which will be described later. The focus of the projection lens 143 is changed by rotating a ring provided on the projection lens 143, which moves a group of lenses (hereinafter referred to as the focus lens group) built into the projection lens 143 along the optical axis. There is a one-to-one correspondence between the amount of rotation of the ring and the focus position. The focus position detection unit 12 detects the position of this ring. Specifically, it is detected by a potentiometer attached to the focus ring. The focus position detection unit 12 outputs information indicating the detected position to the control unit 16.

[0019] The receiving unit 13 receives control instructions for controlling the image projection device 10 from the remote control device 30, and transmits the received control instructions to the control unit 16. The receiving unit 13 receives, for example, a power activation signal, an OSD image display signal, a signal instructing whether to enable or disable the adaptive correction function, and a signal indicating the adjustment strength and adjustment period from the remote control device 30, and transmits them to the control unit 16.

[0020] The projection unit 14 projects the processed video signal output from the image processing unit 11 or the OSD image onto a projection surface. The projection unit 14 includes, for example, a light source 141, an optical unit 142, a projection lens 143, and a drive unit 144. The light source 141 is, for example, an ultra-high pressure mercury lamp, a semiconductor laser, a light-emitting diode, or a phosphor. The light source 141 receives an irradiation instruction from the control unit 16 to irradiate light and irradiates the optical unit 142 with the irradiated light. The optical unit 142 receives a video signal from the image processing unit 11. The optical unit 142 generates a display image based on the video signal and the light irradiated by the light source 141 and displays it on the display panel 142a. The display panel 142a is, for example, a digital micromirror device (DMD). The DMD is an image-forming element that spatially modulates incident light depending on the direction in which it is reflected. The display panel 142a may also be a liquid crystal panel. The projection lens 143 projects the display image generated by the optical unit 142 onto the projection surface 40. The drive unit 144 is, for example, a motor. The drive unit 144 changes the focus position of the projection lens 143 in response to a drive instruction from the drive control unit 166 of the control unit 16.

[0021] The process of adjusting the focal position will be described with reference to FIG. 3 . FIG. 3 is a diagram illustrating focus correction in this embodiment. FIG. 3 schematically illustrates how illumination light emitted from the light source 141 passes through the display panel 142 a and the projection lens 143, resulting in a display image being projected onto the projection surface 40. The control unit 16 controls the light source 141 and the display panel 142 a to project a display image based on a video signal processed by the image processing unit 11 onto the projection surface 40 via the projection lens 143. The control unit 16 controls the drive unit 144 to move the focus lens group of the projection lens 143 in the direction of the optical axis AX, thereby correcting the focal position to match the projection surface 40, for example, by focusing on a position away from the projection surface 40 or by focusing on a position closer to the projection surface 40.

[0022] In this embodiment, the control unit 16 corrects focus drift that occurs during projection. The control unit 16 calculates a reference movement amount. The reference movement amount is a reference value for the movement amount of the focus lens group to correct focus drift that occurs during projection. The control unit 16 is, for example, a microprocessor. The control unit 16 calculates the reference movement amount using light intensity data that may be a cause of focus drift. The light intensity data here includes, for example, a light source output setting value, a video signal APL (Average Picture Level), and a light source usage time. The light source output setting value is information indicating the intensity of the light emitted from the light source 141 (light emitted by the light source 141). The video signal APL is information indicating the average value of the luminance of the displayed image. The light source usage time is information indicating the degree of deterioration of the light source 141. The reference movement amount is a movement amount appropriate for correcting focus drift for a standard projector installed in a reference space such as a laboratory. Therefore, the conditions at the site where the projector is installed are not taken into consideration. For this reason, focus correction may be excessive or insufficient depending on the situation at the projector site. To address this issue, the present embodiment employs adaptive focus control (AFC), which can adjust the reference movement amount according to the situation at the projector site. Specifically, the user can adjust the reference movement amount according to the situation at the projector site. For example, the user can increase or decrease the reference movement amount by operating and setting the projector via an OSD image. This allows the user to increase the reference movement amount when the projector is installed in a high-temperature space or when the projector incorporates an optical system that is prone to temperature rise due to individual differences. On the other hand, when the projector is installed in a low-temperature space or when the projector incorporates an optical system that is less prone to temperature rise due to individual differences, the user can adjust the reference movement amount to decrease. Therefore, focus drift that occurs during projection can be appropriately corrected according to the situation at the projector site.

[0023] The projection unit 14 can be fitted with a number of different types of projection lenses 143. The amount of focus drift that occurs during projection varies depending on the type of projection lens. For this reason, in this embodiment, a reference movement amount is calculated for each type of projection lens. The type of projection lens can be acquired based on the signal value indicated by a signal line 17, which will be described later.

[0024] The signal line 17 electrically connects the projection lens 143 and the control unit 16. The signal line 17 transmits lens identification information from the projection lens 143 to the control unit 16. For example, when the projection lens 143 is attached to the projection unit 14, a specific voltage value (a voltage value indicating High corresponding to the power supply voltage, or a voltage value indicating Low corresponding to the ground voltage) is applied to a specific terminal group. The signal line 17 is connected to this specific terminal group. The control unit 16 can grasp the lens identification information based on a signal value corresponding to the voltage value applied to the signal line 17.

[0025] The storage unit 15 stores various data used by the image projection device 10. The storage unit 15 is configured by a storage medium such as a hard disk drive (HDD), flash memory, electrically erasable programmable read-only memory (EEPROM), random access read / write memory (RAM), read-only memory (ROM), or any combination of these storage media. Furthermore, the storage unit 15 may be configured by a non-volatile memory, for example.

[0026] The configuration of the storage unit 15 will now be described with reference to Figs. 4 to 7. Fig. 4 is a block diagram showing an example of the configuration of the storage unit 15 in this embodiment. Fig. 5 is a diagram showing an example of target data stored in the storage unit 15. Fig. 6 is a diagram showing an example of current data stored in the storage unit 15. Fig. 7 is a diagram showing an example of correction cycle data stored in the storage unit 15.

[0027] As shown in FIG. 4 , the storage unit 15 stores target data 151, current data 152, correction cycle data 153, projection lens identification data 154, and adjustment information setting data 155. The target data 151 is a target value in the focus adjustment process. The current data 152 is a current value targeted for focus adjustment. The correction cycle data 153 is data indicating the relationship between a reference movement amount (or an adjustment movement amount obtained by adjusting the reference movement amount by the user) and a correction cycle. The projection lens identification data 154 is lens identification information acquired by the control unit 16 via the signal line 17. The adjustment information setting data 155 is information indicating a setting value for the adjustment strength and a setting value for the adjustment cycle as adjustment information. The adjustment information setting data 155 may also include information indicating a setting value for whether adaptive focus correction is enabled or disabled as adjustment information.

[0028] As shown in Fig. 5, target data 151 is information that associates light intensity data previously acquired in a focused state with the focus position at that time. In this figure, the light intensity data includes the light source output setting value, the video signal APL, and the light source usage time. Also in this figure, the focus position F0 is associated with the light intensity data. The light source output setting value, the video signal APL, and the light source usage time are all normalized values.

[0029] As shown in Fig. 6, current data 152 is information that associates light intensity data acquired during projection (at the time of focus correction) with the focus position at that time. In this figure, the light intensity data includes the light source output setting value, the video signal APL, and the light source usage time. Also in this figure, the focus position F1 is associated with the light intensity data. The light source output setting value, the video signal APL, and the light source usage time are all normalized values.

[0030] In FIG. 7 , the horizontal axis represents the focus movement amount, and the vertical axis represents the correction period. The focus movement amount shown in FIG. 7 corresponds to the adjustment movement amount obtained by adjusting the reference movement amount by the user. For example, the focus movement amount is the absolute value of the adjustment movement amount. Thus, the correction period data is information indicating the relationship between the focus movement amount and the correction period. The larger the focus movement amount, the shorter the correction period. In this embodiment, the relationship between the focus movement amount and the correction period is preset. That is, when moving the focus position of the projection lens 143 by a distance corresponding to the focus movement amount, rather than performing a single correction to move the focus position by a distance corresponding to the focus movement amount, the focus position is repeatedly moved by a distance corresponding to a predetermined movement amount (unit movement amount) according to the correction period. In this way, by gradually moving the focus position of the projection lens 143 by a small movement amount per correction, the focus position can be properly corrected without causing discomfort or hunting, which is caused by repeated excessive correction. Hunting here refers to a phenomenon in which, when moving the focus position of the projection lens 143, the lens fluctuates back and forth between the correct focus position and is unable to stop at the correct focus position. For example, hunting occurs when the lens is moved to a position that passes the correct focus position during the first correction, and then, when returning to the position during the next correction, the focus position is moved to a position that passes the correct focus position again. In this embodiment, the unit movement amount for moving the focus position in one correction is set to the minimum distance (one gear) that the focus position can be moved, but this is not limited to this. Any movement amount that does not cause discomfort and is unlikely to cause hunting can be set as the unit movement amount.

[0031] In this embodiment, the user can adjust the correction period depending on the situation at the site. For example, the user can adjust the reference correction period to be longer or shorter by operating and setting the OSD image. FIG. 7 shows correction period data corresponding to "normal," "fast," and "slow." In this embodiment, the reference correction period is first derived using the correction period data corresponding to "normal." The reference correction period is the reference correction period. For example, if the focus movement amount is L1, the correction period CM1 corresponding to point PM1 in the correction period data corresponding to "normal" becomes the reference correction period. Assume now that the user adjusts the reference correction period to be longer. In this case, the reference correction period is adjusted to be longer using the correction period data corresponding to "slow." Specifically, if the focus movement amount is L1, the correction period CL1 corresponding to point PL1 in the correction period data corresponding to "slow" becomes the period after adjusting the reference correction period (adjusted correction period). On the other hand, assume that the user adjusts the reference correction period to be shorter. In this case, the correction period data corresponding to "fast" is used to adjust the reference correction period to be shorter. Specifically, when the focus movement amount is L1, the correction period CF1 corresponding to the point PF1 in the correction period data corresponding to "fast" becomes the period after adjustment (adjusted correction period) by adjusting the reference correction period.

[0032] In this embodiment, the user cannot adjust the unit movement amount by which the focus position is moved in one correction. If the unit movement amount were adjustable by the user, it would be expected that the movement amount by which the focus position is moved per correction would be set to be large, which would increase the likelihood of hunting occurring.

[0033] Next, the configuration of the control unit 16 will be described with reference to Figures 8 to 10. Figure 8 is a diagram showing the configuration of the control unit 16 in this embodiment. Figure 9 is a diagram explaining the processing performed by the control unit in this embodiment. Figure 10 (Figures 10A to 10D) is a diagram showing an example of an OSD image in this embodiment. The control unit 16 includes, for example, a CPU or a microprocessor, and performs overall control of the image projection device 10.

[0034] 8, the control unit 16 includes a light intensity data acquisition unit 161, a focus position acquisition unit 162, a reference value calculation unit 163, an adjustment information acquisition unit 164, an adaptive correction unit 165, and a drive control unit 166. As shown in FIG. 9, a series of correction processes in adaptive focus correction performed by the control unit 16 is executed in three phases, Phase 1 to Phase 3.

[0035] The light intensity data acquisition unit 161 acquires light intensity data in phase 1. When the user adjusts the focus and the adaptive focus correction function is enabled (ON), the light intensity data acquisition unit 161 acquires target light intensity data (A0). The light intensity data acquisition unit 161 stores the acquired target light intensity data (A0) in the storage unit 15 as a component of the target data 151. The light intensity data acquisition unit 161 acquires current light intensity data (A1) corresponding to the current data at the timing of performing correction while the display image is being projected. The light intensity data acquisition unit 161 stores the acquired current light intensity data (A1) in the storage unit 15 as a component of the current data 152.

[0036] The focus position acquisition unit 162 acquires focus position data indicating the focus position of the projection lens 143. After the user adjusts the focus, the adaptive focus correction function is enabled (ON), and the focus position acquisition unit 162 acquires focus position data (target focus position data, F0) at that time. The focus position acquisition unit 162 stores the acquired target focus position data (F0) in the storage unit 15 as a component of the target data 151. Here, the light intensity data acquisition unit 161 performs calibration as necessary before acquiring target light intensity data corresponding to the target data. Calibration is a process of matching the voltage value output from the potentiometer with the actual focus position. Note that this calibration may be performed by another functional unit, such as the control unit 16. The focus position acquisition unit 162 acquires focus position data (current focus position data, F1) corresponding to the current data at the timing of correction while the display image is being projected. The focus position acquisition unit 162 stores the acquired current focus position data (F1) in the storage unit 15 as a component of the current data 152.

[0037] The reference value calculation unit 163 calculates a reference movement amount in phase 2. The reference value calculation unit 163 calculates the difference (A1-A0) between the target light intensity data (A0) and the current light intensity data (A1). The reference value calculation unit 163 calculates the difference (A1-A0), for example, by adding or weighting the differences between the light intensity data. Specifically, the reference value calculation unit 163 calculates a first difference indicating the difference between the light source output setting value in the target light intensity data (A0) and the light source output setting value in the current light intensity data (A1). The reference value calculation unit 163 calculates a second difference indicating the difference between the video signal APL in the target light intensity data (A0) and the video signal APL in the current light intensity data (A1). The reference value calculation unit 163 calculates a third difference indicating the difference between the light source usage time in the target light intensity data (A0) and the light source usage time in the current light intensity data (A1). The reference value calculation unit 163 calculates the difference (A1-A0) by adding or weighting the first, second, and third differences. This difference (A1-A0) corresponds to a change in the amount of light passing through the projection lens. The temperature change of the projection lens due to a change in the amount of light passing through the projection lens depends on the type of the projection lens. Therefore, the reference value calculation unit 163 calculates the reference movement amount by, for example, multiplying the difference (A1-A0) by a coefficient predetermined according to the type of projection lens. This coefficient is a value determined by measuring in advance the relationship between the light amount data and the degree of defocus according to the type of projection lens. The reference value calculation unit 163 calculates a larger reference movement amount if the difference (A1-A0) is larger, and a smaller reference movement amount if the difference (A1-A0) is smaller. The absolute value of the reference movement amount indicates the magnitude of the temperature change of the projection lens, and the sign of the reference movement amount indicates the direction of the focus position.

[0038] The reference value calculation unit 163 outputs the calculated reference movement amount to the adaptive correction unit 165 .

[0039] The adjustment information acquisition unit 164 acquires information indicating the adjustment intensity in Phase 2 and the adjustment cycle in Phase 3. The adjustment information acquisition unit 164 acquires information indicating the adjustment intensity and adjustment cycle set by the user, and stores the acquired information in the storage unit 15 as adjustment information setting data 155.

[0040] For example, a user uses the remote control device 30 to display an OSD image superimposed on a display image and selects adaptive focus correction parameters that are pre-installed as configurable items via the OSD image. FIG. 10A shows an example of an OSD image for setting adaptive focus correction parameters. In this figure, three parameters, "ENABLE," "INTENSITY," and "SPEED," are provided as setting items. The "ENABLE" setting item is an item for setting whether to enable or disable the adaptive focus correction function. The "INTENSITY" setting item is an item for setting the degree of adjustment of the reference movement amount in adaptive focus correction, and corresponds to the "adjustment strength" in FIG. 9 . The "SPEED" setting item is an item for setting the degree of adjustment of the reference correction period in adaptive focus correction, and corresponds to the "adjustment period" in FIG. 9 .

[0041] In the "SPEED" setting item, a word such as "PERIOD" indicating the period would be more accurate in light of the actual processing conditions, but here, to make it easier for users to understand, the word "SPEED" is used, which indicates whether the focus correction will be completed quickly or slowly.

[0042] Fig. 10B shows an example of an OSD image that is displayed when the "ENABLE" setting item in Fig. 10A is selected. In this figure, the options "OFF" and "ON" are displayed as selectable options. "OFF" is selected to disable the adaptive focus correction function. "ON" is selected to enable the adaptive focus correction function.

[0043] 10C shows an example of an OSD image that is displayed when the "INTENSITY" setting item in FIG. 10A is selected. In this figure, the options "WEAK," "MEDIUM," and "STRONG" are displayed as selectable options. "WEAK" is selected when adjusting to a movement amount smaller than the reference movement amount. "MEDIUM" is selected when using the reference movement amount as is. "STRONG" is selected when adjusting to a movement amount larger than the reference movement amount.

[0044] 10D shows an example of an OSD image that is displayed when the "SPEED" setting item in FIG. 10A is selected. In this figure, the options of "SLOW," "MEDIUM," and "FAST" are displayed as selectable options. "SLOW" is selected when adjusting to a period longer than the reference correction period. "MEDIUM" is selected when using the reference correction period as is. "FAST" is selected when adjusting to a period shorter than the reference correction period.

[0045] Adjustment information acquisition section 164 acquires, via receiving section 13 , information corresponding to an option selected by the user operating remote control device 30 , and outputs the acquired information to adaptive correction section 165 .

[0046] The adaptive correction unit 165 calculates the adjustment movement amount in phase 2, and calculates the adjustment correction period and performs adaptive focus correction in phase 3. In phase 2, the adaptive correction unit 165 calculates the adjustment movement amount by weighting the adjustment strength to the reference movement amount and adding the difference (F1-F0) between the target focus position data (F0) and the current focus position data (F1). For example, when "WEAK" is set as the adjustment strength, the adaptive correction unit 165 adjusts the reference movement amount to be smaller. For example, when "MEDIUM" is set as the adjustment strength, the adaptive correction unit 165 sets the adjustment movement amount to be the value obtained by adding the difference (F1-F0) to 90% of the reference movement amount. Alternatively, when "MEDIUM" is set as the adjustment strength, the adaptive correction unit 165 does not change the reference movement amount, but sets the adjustment movement amount to the value obtained by adding the difference (F1-F0). When "STRONG" is set as the adjustment strength, the adaptive correction unit 165 adjusts the reference movement amount to be larger. For example, the adjusted movement amount is set to a value obtained by adding the difference (F1-F0) to 110% of the reference movement amount.

[0047] In phase 3, the adaptive correction unit 165 identifies a reference correction period. Based on the correction period data, the adaptive correction unit 165 identifies a correction period corresponding to the adjustment movement amount, and sets the identified correction period as the reference correction period. The adaptive correction unit 165 calculates the adjustment correction period by weighting the reference correction period by the adjustment period. For example, in the "SPEED" setting item in FIG. 10A, if "SLOW" is selected, the adjustment correction period is longer than the reference correction period; if "MEDIUM" is selected, the adjustment correction period is the same as the reference correction period; and if "FAST" is selected, the adjustment correction period is shorter than the reference correction period.

[0048] The adaptive correction unit 165 performs adaptive focus correction in phase 3. The adaptive correction unit 165 repeatedly performs focus movement by a unit movement amount in an adjustment correction cycle, and performs adaptive focus correction by changing the focus position of the projection lens 143 by a total distance corresponding to the adjustment movement amount.

[0049] Before performing adaptive focus correction, the adaptive correction unit 165 performs an adjustment movement amount convergence determination. The adjustment movement amount convergence determination is a process for determining whether or not to actually change the focus position of the projection lens 143. The adaptive correction unit 165 determines whether or not the adjustment movement amount is equal to or greater than a threshold value, and if the adjustment movement amount is equal to or greater than the threshold value, determines to change the focus position of the projection lens 143. On the other hand, if the adjustment movement amount is less than the threshold value, determines not to change the focus position of the projection lens 143.

[0050] Furthermore, the adaptive correction unit 165 performs a focus position end determination before performing adaptive focus correction. The focus position end determination is a process for determining whether the focus position of the projection lens 143 is at a position corresponding to the end of the movable range. When moving the focus position of the projection lens 143 in a specific movement direction, if the focus position is at a position where it cannot be moved any further, driving the drive unit 144 to move the focus position may cause the drive unit 144 to malfunction. The focus position end determination is performed to avoid such a malfunction. In the focus position end determination, the adaptive correction unit 165 determines whether the focus position is located at an end of the movement direction of the focus position in adaptive focus correction, and if it is located at the end, does not perform adaptive focus correction. On the other hand, if the focus position is not located at an end of the movement direction of the focus position in adaptive focus correction, the adaptive correction unit 165 determines to perform adaptive focus correction. Here, the position corresponding to the end may include a margin. For example, the adaptive correction unit 165 may determine whether the focus position is located within a range from the end of the movement direction of the focus position in adaptive focus correction to a position corresponding to the margin, and if the focus position is located within that range, may not perform adaptive focus correction.

[0051] The adaptive correction unit 165 executes adaptive focus correction when it determines in the adjustment movement amount convergence determination that the focus position of the projection lens 143 should be moved and when it determines in the focus position terminal determination that adaptive focus correction should be executed. The adaptive correction unit 165 drives the drive unit 144 via the drive control unit 166 to move the focus position of the projection lens 143 a distance corresponding to the unit movement amount in a predetermined movement direction. The adaptive correction unit 165 repeatedly executes focus position movement by the unit movement amount in an adjustment correction cycle. The adaptive correction unit 165 executes adaptive focus correction by moving the focus position of the projection lens 143 a total distance corresponding to the adjustment movement amount.

[0052] The drive control unit 166 controls the drive unit 144 in accordance with instructions from the adaptive correction unit 165. The drive control unit 166 controls the drive unit 144 to move the focus position of the projection lens 143 in a specific direction by a distance corresponding to the unit movement amount.

[0053] Next, the operation of the image projection device 10 according to this embodiment will be described with reference to the drawings. FIG. 11 is a flowchart showing the flow of processing executed by the image projection device 10 according to this embodiment when the adaptive focus correction function is enabled. As shown in FIG. 11 , first, the control unit 16 of the image projection device 10 determines whether the calibration process has been executed (step S1). If the calibration process has been executed, the image projection device 10 acquires data in response to the adaptive focus correction function being enabled (ON) in the adjustment information setting data 155 (step S2), and stores the data in the storage unit 15 as target data 151. Specifically, data associating light intensity data (A0) with a focus position when the display image is in focus is stored in the storage unit 15. More specifically, the light intensity data acquisition unit 161 of the image projection device 10 acquires the light intensity data (A0) when the display image is in focus, and stores the data in the target data 151 as the light intensity data (A0) in the target data. The focus position acquisition unit 162 of the image projection device 10 acquires focus position data (F0) when the display image is in focus, and stores it as focus position data (F0) in the target data in the target data 151. Note that if the calibration process has not been executed in step S1, the focus position acquisition unit 162 of the image projection device 10 executes the calibration process and then executes the process shown in step S2.

[0054] 12 is a flowchart showing the flow of processing executed by the image projection device 10 in this embodiment when the projection lens 143 is replaced. The control unit 16 of the image projection device 10 determines whether the type of projection lens has changed (step S11). The control unit 16 acquires projection lens identification information for the projection lens 143 via the signal line 17 and stores it in the storage unit 15 as projection lens identification data 154. The control unit 16 reads the projection lens identification data 154 stored in the storage unit 15 and determines whether the currently read projection lens identification data 154 has changed from the previously read projection lens identification data 154. If the currently read projection lens identification data has changed from the previously read projection lens identification data 154, the control unit 16 determines that the type of projection lens has changed. On the other hand, if the currently read projection lens identification data is the same as the previously read projection lens identification data, the control unit 16 determines that the type of projection lens has not changed.

[0055] If the type of projection lens has not changed, the control unit 16 determines whether or not the calibration process has been performed (step S12). After confirming that the calibration process has been performed, the reference value calculation unit 163 reads and acquires the target data 151 from the storage unit 15 (step S13). If it is determined in step S11 that the type of projection lens has changed, or if it is determined in step S12 that the calibration process has not been performed, the focus position acquisition unit 162 of the image projection device 10 executes the calibration process (step S14). When the adaptive focus correction function is enabled (ON) (step S15), the control unit 16 reacquires target data corresponding to the changed projection lens 143, and stores the acquired data as target data 151 in the storage unit 15 (step S16).

[0056] 13 is a flowchart showing the flow of adaptive focus correction processing performed by the image projection device 10 of this embodiment. The reference value calculation unit 163 of the image projection device 10 reads and acquires target data from the storage unit 15 (step S21). The reference value calculation unit 163 also reads and acquires current data from the storage unit 15 (step S22). The reference value calculation unit 163 calculates a reference movement amount based on the difference (A1-A0) between the target light intensity data (A0) of the acquired target data and the current light intensity data (A1) of the current data, and the projection lens coefficient (step S23).

[0057] The adjustment information acquisition unit 164 of the image projection device 10 acquires the setting value of the adjustment strength (step S24). The adjustment information acquisition unit 164 acquires the setting value of the adjustment strength by reading it from the adjustment information setting data 155 in the storage unit 15. The adaptive correction unit 165 of the image projection device 10 weights the reference movement amount by the adjustment strength, and then adds the difference between the target focus position data (F0) and the current focus position data (F1) to calculate the adjustment movement amount (step S25). The adaptive correction unit 165 acquires a reference correction period corresponding to the adjustment movement amount using the correction period data 153 (step S26). The adjustment information acquisition unit 164 acquires the setting value of the adjustment period (step S27). The adjustment information acquisition unit 164 acquires the setting value of the adjustment period by reading it from the adjustment information setting data 155 in the storage unit 15. The adaptive correction unit 165 calculates the adjustment correction period by weighting the reference correction period by the adjustment period (step S28).

[0058] The adaptive correction unit 165 determines whether the adjustment movement amount is less than a threshold value as an adjustment movement amount convergence determination (step S29). The adaptive correction unit 165 determines whether the focus position is at the end position as a focus position end determination (step S30). The adaptive correction unit 165 also determines whether the adaptive correction function is enabled (ON) (step S31). The adaptive correction unit 165 acquires the enable / disable setting value of the adaptive correction function by reading the enable / disable setting value of the adaptive correction function from the adjustment information setting data 155 in the storage unit 15. If the adjustment movement amount during the adjustment / correction cycle is not less than the threshold value in step S29, the focus position is not at the end position in step S30, and the adaptive correction function is enabled in step S31, the adaptive correction unit 165 performs adaptive focus correction and moves the focus position of the projection lens 143 by a distance corresponding to the unit movement amount (step S32). The adaptive correction unit 165 determines whether or not a time corresponding to the adjustment correction cycle has elapsed since the focus position of the projection lens 143 was moved in step S32 (step S33), and if a time corresponding to the adjustment correction cycle has elapsed, returns to step S22 and acquires the current data (current light intensity data A1 and current focus position data F1) to be used for the next correction.

[0059] Although the embodiments of the present invention have been described above in detail with reference to the drawings, the specific configuration is not limited to this embodiment and includes designs within the scope of the present invention. For example, while the above-described embodiment illustrates an example in which adjustment information is acquired via the remote control device 30, the present invention is not limited to this. A configuration in which an OSD image is superimposed on a display image by a user operating an operation panel provided on the image projection device 10 may also be used. In this case, the receiving unit 13 receives an operation signal operated on the operation panel. Alternatively, a configuration in which an option displayed on the OSD image is selected by a user operating the operation panel may also be used. Furthermore, the above-described embodiment illustrates an example in which three pieces of data, namely, the light source output setting value, the video signal APL, and the light source usage time, are used as light intensity data. However, the present invention is not limited to this. It is sufficient for the light intensity data to be a characteristic related to at least one of the light source 141 and the display image. In other words, the light intensity data may be any physical quantity from which the amount of light passing through the projection lens can be estimated.

[0060] As described above, the image projection device 10 according to this embodiment includes the projection unit 14, the drive control unit 166, the reference value calculation unit 163 (calculation unit), the adjustment information acquisition unit 164 (acquisition unit), and the adaptive correction unit 165 (correction unit). The projection unit 14 generates a display image based on the light emitted from the light source and the video signal from the video source, and projects the generated display image onto the projection surface 40 after enlarging it using the projection lens 143. The drive control unit 166 adjusts the focus by controlling the drive of the motor (drive unit 144) that moves the projection lens 143 along the optical axis of the emitted light. The reference value calculation unit 163 calculates a reference movement amount. The reference movement amount is a reference value for the amount of movement of the projection lens 143 to correct the focus in response to fluctuations in the focus position (focus drift) that occur during projection. The adjustment information acquisition unit 164 acquires an adjustment strength indicating the degree to which the reference movement amount is adjusted. The adaptive correction unit 165 performs adaptive focus correction. As adaptive focus correction, the adaptive correction unit 165 moves the projection lens 143 to a position according to an adjustment amount obtained by weighting the reference amount of movement with the adjustment strength via the drive control unit 166. This allows the image projection device 10 according to this embodiment to make adjustments by increasing or decreasing the reference amount of movement, and to appropriately correct the focal position according to the conditions of the site where the image projection device 10 is installed.

[0061] Furthermore, in the image projection device 10 according to this embodiment, the adjustment information acquisition unit 164 acquires the adjustment strength set by the user, which allows the user to adjust the focus movement amount and correct the focus position according to the situation on site.

[0062] The image projection device 10 according to this embodiment further includes an OSD processing unit 112. The OSD processing unit 112 displays an OSD image for setting the adjustment intensity, superimposed on the display image. The adjustment information acquisition unit 164 acquires information indicating the adjustment intensity selected in response to a user operation from multiple setting values ​​displayed in the OSD image. This allows the image projection device 10 according to this embodiment to acquire the adjustment intensity set by the user via the OSD image, and allows the user to easily set the adjustment intensity using existing OSD functions without adding a dedicated function.

[0063] Furthermore, in the image projection device 10 according to this embodiment, the adaptive correction unit 165 performs adaptive focus correction by moving the focus position of the projection lens 143 by a unit movement amount at a reference correction period according to the adjustment movement amount. As a result, in the image projection device 10 according to this embodiment, even when the adjustment movement amount is large, the focus position of the projection lens 143 can be moved little by little, and the focus position can be corrected so as to prevent discomfort to the user viewing the displayed image and to prevent hunting from occurring.

[0064] In the image projection device 10 according to this embodiment, the adjustment information acquisition unit 164 acquires an adjustment period. The adjustment period is a setting value indicating the degree to which the reference correction period is adjusted. The adaptive correction unit 165 performs adaptive focus correction by moving the focus position of the projection lens 143 by a unit movement amount at an adjustment correction period obtained by weighting the reference correction period by the adjustment period. As a result, the image projection device 10 according to this embodiment can adjust the reference correction period by increasing or decreasing it. Depending on the conditions at the site where the image projection device 10 is installed, the focus position of the projection lens 143 can be moved more frequently than the reference frequency (reference correction period) to quickly return to the appropriate focus position, or the focus position of the projection lens 143 can be moved more slowly than the reference frequency (reference correction period) to slowly return to the appropriate focus position.

[0065] Furthermore, in the image projection device 10 according to this embodiment, the adjustment information acquisition unit 164 acquires the adjustment period set by the user. This allows the user to adjust the correction period in the image projection device 10 according to this embodiment, and to correct the focal position with a focus movement amount that suits the situation at the site. The focus position of the projection lens 143 can be moved at a frequency that suits the situation at the site.

[0066] The image projection device 10 according to this embodiment also includes an OSD processing unit 112. The OSD processing unit 112 displays an OSD image for setting the adjustment period superimposed on the display image. The adjustment information acquisition unit 164 acquires the adjustment period selected in response to a user operation from multiple setting values ​​displayed in the OSD image. This allows the image projection device 10 according to this embodiment to easily allow the user to set the adjustment period by utilizing existing OSD functions without adding a dedicated function.

[0067] Furthermore, in the image projection device 10 according to this embodiment, the adaptive correction unit 165 sets, as the unit movement amount, a value less than a predetermined threshold value as the amount of movement of the focus position at which the user can perceive the movement of the focus. This makes it difficult for the user to perceive the movement of the focus position of the projection lens 143 in the image projection device 10 according to this embodiment, and allows the user to adjust the focus position naturally without feeling uncomfortable.

[0068] The image projection device 10 according to this embodiment further includes a storage unit 15. The storage unit 15 stores correction cycle data 153 that associates the amount of movement of the focus position of the projection lens 143 with a correction cycle. The adaptive correction unit 165 reads the correction cycle data 153 from the storage unit 15 and obtains a reference correction cycle corresponding to the amount of adjustment movement from the read correction cycle data 153. As a result, the image projection device 10 according to this embodiment can easily obtain a reference correction cycle corresponding to the amount of adjustment movement using the correction cycle data 153.

[0069] Furthermore, in the image projection device 10 according to this embodiment, the reference value calculation unit 163 calculates the reference movement amount using the relationship between the light characteristics (light intensity data), which are characteristics of at least one of the light source and the displayed image, and information (position data) indicating the focus position of the projection lens. As a result, in the image projection device 10 according to this embodiment, the focus position of the projection lens can be estimated according to the light passing through the projection lens 143, and the movement amount of the focus position according to the focus deviation (focus drift) caused by temperature fluctuations can be accurately calculated.

[0070] Furthermore, in the image projection device 10 according to this embodiment, the reference value calculation unit 163 uses the respective characteristics of the intensity of the irradiated light (light source output setting value), the brightness of the displayed image (video signal APL), and the degree of degradation of the light source (light source usage time) as light quantity data. The reference value calculation unit 163 calculates the reference movement amount using the relationship between the light quantity data and the focus position data. This makes it possible to achieve the same effect as described above.

[0071] Furthermore, the image projection device 10 according to this embodiment calculates a reference movement amount based on the difference (A1-A0) between the target light intensity data A0 and the current light intensity data A1. The target data includes light intensity data (A0) and focus position data (F0) acquired when focusing. The current data A1 includes light intensity data (A1) and focus position data (F1) acquired at the timing of performing adaptive focus correction. As a result, the image projection device 10 according to this embodiment can estimate fluctuations in the focus position of the projection lens 143 in accordance with fluctuations in the light passing through the projection lens 143, thereby achieving the same effects as those described above.

[0072] Furthermore, in the image projection device 10 according to this embodiment, the projection unit 14 can be interchangeably mounted with a plurality of different types of projection lenses 143. The reference value calculation unit 163 acquires target data (target light intensity data A0 and target focus position data F0) for each type of mounted projection lens 143. The reference value calculation unit 163 calculates a reference movement amount based on the difference (A1-A0) between the target light intensity data A0 and the current light intensity data A1 corresponding to the same type of projection lens 143. As a result, the image projection device 10 according to this embodiment can move the focus position to a focus position corresponding to the focus deviation depending on the type of projection lens 143, thereby enabling appropriate correction.

[0073] The image projection device 10 according to this embodiment further includes an OSD processing unit 112. The OSD processing unit 112 displays an OSD image, which sets whether adaptive focus correction is enabled or disabled, superimposed on the display image. The adjustment information acquisition unit 164 acquires information indicating whether adaptive focus correction is enabled (ON) or disabled (OFF) from the OSD image, selected in response to a user operation. The adaptive correction unit 165 performs adaptive focus correction when the adjustment information acquisition unit 164 acquires information indicating that adaptive focus correction is enabled. As a result, the image projection device 10 according to this embodiment can easily enable or disable adaptive focus correction by utilizing existing OSD functions without adding any dedicated functions.

[0074] The adaptive focus correction process in the above-described embodiment may be implemented by a computer. In this case, a program for implementing this function may be recorded on a computer-readable recording medium, and the program may be loaded into a computer system and executed. Note that the term "computer system" as used herein includes hardware such as an OS and peripheral devices. Furthermore, the term "computer-readable recording medium" refers to portable media such as flexible disks, optical magnetic disks, ROMs, and CD-ROMs, as well as storage devices such as hard disks built into a computer system. Furthermore, the term "computer-readable recording medium" may also include media that dynamically store programs for a short period of time, such as communication lines used when transmitting programs via networks such as the Internet or telephone lines, or media that store programs for a fixed period of time, such as volatile memory within a computer system that serves as a server or client. The program may be a program that implements part of the above-described functions, or may be a program that can implement the above-described functions in combination with a program already stored in the computer system, or may be implemented using a programmable logic device such as an FPGA (Field Programmable Gate Array).

[0075] Furthermore, an image projection device with a minimum configuration according to an embodiment of the present invention will be described with reference to FIG. 13 . FIG. 13 is a diagram showing an image projection device with a minimum configuration according to an embodiment of the present invention. The image projection device 50 may include at least a projection unit 51, a drive control unit 52, a reference value calculation unit 53, an adjustment information acquisition unit 54, and an adaptive correction unit 55. The projection unit 51 generates a display image based on light emitted from a light source and a video signal from an image source, and enlarges and projects the generated display image onto a projection surface using a projection lens. The drive control unit 52 adjusts the focus position by controlling the drive of a motor that moves the focus position of the projection lens. The reference value calculation unit 53 calculates a reference movement amount by which the focus position of the projection lens is moved in response to fluctuations in the focus position that occur during projection. The adjustment information acquisition unit 54 acquires an adjustment strength indicating the degree to which the reference movement amount is adjusted. The adaptive correction unit 55 performs adaptive focus correction via the drive control unit 52 to move the focus position of the projection lens to a position according to an adjusted movement amount obtained by weighting the reference movement amount with the adjustment strength.

[0076] REFERENCE SIGNS LIST 1 Image projection system 10 Image projection device 11 Image processing unit 112 OSD processing unit 12 Focus position detection unit 13 Receiving unit 14 Projection unit 143 Projection lens 15 Storage unit 16 Control unit 161 Light intensity data acquisition unit 162 Focus position acquisition unit 163 Reference value calculation unit 164 Adjustment information acquisition unit 165 Adaptive correction unit 166 Drive control unit 17 Signal line 20 Video signal input device 30 Remote control device 40 Projection surface 50 Image projection device 51 Projection unit 52 Drive control unit 53 Reference value calculation unit 54 Adjustment information acquisition unit 55 Adaptive correction unit

Claims

1. An image projection device comprising: a projection lens that projects an image onto a projection surface; a drive control unit that adjusts the focus position of the projection lens; and an adaptive correction unit that moves the focus position via the drive control unit in response to fluctuations in the focus position that occur during projection, wherein the adaptive correction unit changes the amount of movement of the focus position depending on the adjustment strength set by a user.

2. The image projection device according to claim 1, further comprising an adjustment information acquisition unit that acquires the adjustment strength.

3. An image projection device as described in claim 2, further comprising an OSD processing unit that superimposes an OSD image that sets the adjustment intensity on the image, and the adjustment information acquisition unit acquires the adjustment intensity selected in response to user operation from multiple setting values ​​displayed in the OSD image.

4. The image projection device according to claim 2, wherein the adaptive correction section moves the focus position by moving the focus position by a unit movement amount.

5. The image projection device according to claim 2, wherein the adjustment information acquisition unit acquires an adjustment period, which is a weighting amount of a reference correction period that serves as a reference, and the focus position moves at an adjustment correction period that is the reference correction period weighted by the adjustment period.

6. The image projection device according to claim 5, wherein the adjustment period is set by a user.

7. An image projection device as described in claim 6, further comprising an OSD processing unit that superimposes an OSD image that sets the adjustment period on the image, and the adjustment information acquisition unit acquires the adjustment period selected in response to a user operation from a plurality of setting values ​​displayed on the OSD image.

8. The image projection device according to claim 4, wherein the adaptive correction section sets, as the unit movement amount, a value less than a predetermined threshold value as the amount of movement of the focus position at which a user can recognize a movement of the focus.

9. The image projection device according to claim 5, wherein the adjustment correction period is longer as the movement amount of the focus position is smaller.

10. An image projection device as described in claim 1, further comprising a reference value calculation unit that calculates a reference movement amount, which is the amount by which the focus position moves in response to fluctuations in the focus position that occur during projection, and the reference value calculation unit calculates the reference movement amount from light quantity data, which is a physical quantity that can be used to estimate the amount of light passing through the projection lens.

11. The image projection device according to claim 10, wherein the light quantity data is all or part of the intensity of the light source, the degree of deterioration of the light source, and the luminance of the displayed image.

12. The image projection device according to claim 10, wherein the reference value calculation section calculates the reference movement amount based on the difference between the light intensity data acquired in advance and the light intensity data acquired at the timing of correction.

13. The image projection device according to claim 10, wherein the image projection device is capable of mounting a plurality of projection lenses of different types by changing them, and the reference value calculation unit calculates the reference movement amount for each type of the mounted projection lens.

14. An image projection device as described in claim 2, further comprising an OSD processing unit that superimposes an OSD image on the image to enable or disable the adaptive correction unit, wherein the adjustment information acquisition unit acquires information from the OSD image indicating whether the adaptive correction unit is enabled or disabled, selected in accordance with user operation, and the adaptive correction unit changes the amount of movement of the focus position when the adjustment information acquisition unit acquires information indicating that the adaptive correction unit is enabled.

15. An image projection method for projecting an image through a projection lens, the focus position is moved in response to fluctuations in the focus position of the projection lens that occur during projection, and the amount of movement of the focus position can be changed by an adjustment strength set by a user.

16. The image projection method according to claim 15, wherein the period for moving the focus position can be changed according to an adjustment period set by a user.

17. The image projection method according to claim 15, wherein the cycle of moving the focus position is shorter as the amount of movement of the focus position is greater.

Images