Projector, control device, and program product

Abstract

Projector, control device, and program product. Temperature drift countermeasures for a projection lens are simply performed. A projector (100) has a projection lens (41) and a control device (88) that controls focusing of the projection lens (41), and the control device (88) performs a drift canceling shift that linearly changes a focus position according to a focus change rate from a focus start point to a quasi-steady state.

Description

Technical Field

[0001] This invention relates to projectors, control devices, and software products. Background Technology

[0002] It is known that there are projectors that control the projection optical device in accordance with the measured operating time so that the projected image can be clearly displayed at both low and high temperatures (Patent Document 1).

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 2012-042780 Summary of the Invention

[0006] The problem that the invention aims to solve

[0007] In the technology of Patent Document 1, the specific control method for clearly displaying the projected image is not clear.

[0008] Methods for solving problems

[0009] One aspect of the present invention provides a projector comprising: a projection lens; and a control device that controls the focusing of the projection lens, the control device performing drift cancellation shifting that linearly changes the focusing position according to the rate of change of focus from the starting point of focusing up to a quasi-stable state.

[0010] One aspect of the control device of the present invention is a control device for controlling the focusing of the projection lens of a projector, which performs drift cancellation shifting that causes the focus position to change linearly according to the focusing change rate from the starting point of focusing to a quasi-stable state.

[0011] One aspect of the present invention is a program product for controlling the focus of the projection lens of a projector, which causes the computing device to perform the following processing: performing a drift cancellation shift that linearly changes the focus position according to the focus change rate from the focus start point to a quasi-stable state. Attached Figure Description

[0012] Figure 1 This is a top view illustrating the structure of the projector in the embodiment.

[0013] Figure 2 This is a side view illustrating an example of how a projector is in use.

[0014] Figure 3 This is a block diagram illustrating the control mechanism of the projector.

[0015] Figure 4 This is a functional block diagram of the control device.

[0016] Figure 5 It is a graph illustrating the change in the projector's focus position over time.

[0017] Figure 6 This diagram illustrates focus correction in AF mode.

[0018] Figure 7 This diagram illustrates another focus correction in AF mode.

[0019] Figure 8 This is a diagram illustrating focus correction in MF mode.

[0020] Figure 9 This diagram illustrates another focus correction in MF mode.

[0021] Figure 10 This is an example diagram illustrating the focus adjustment action of a projector.

[0022] Figure 11 This is a diagram illustrating the AF adjustment action.

[0023] Figure 12 This is a diagram illustrating the MF adjustment action.

[0024] Figure 13 This is a diagram illustrating a variation of focus correction.

[0025] Label Explanation

[0026] 2…Main body, 8a…Start-up time measurement unit, 8b…Distance acquisition unit, 8c…Focus adjustment unit, 8d…Focus correction unit, 10…Light source device, 20…Image display device, 40…Projection optical system, 41…Projection lens, 50…Optical device, 60…Optical system section, 80…Circuit device, 81…Image processing unit, 82…Display driving unit, 83…Lens driving unit, 85…Distance measuring device, 88…Control device, 91…Remote operator, 92… Receiver, 100… Projector, 882… Operation signal receiving device, 883… Communication device, 884… Input / output device, 885… Storage device, 886… Computing device, AN… Moving mechanism, D3a… Startup time database, D3b… Focus adjustment database, D3c… Focus correction database, DB3… Database, NT… Network, P3a… Startup time measurement program, P3b… Distance measurement program, P3c… AF mode program, P3d… MF mode program, PG3… Program. Detailed Implementation

[0027] [Implementation Method]

[0028] Hereinafter, the projector according to an embodiment of the present invention will be described with reference to the accompanying drawings. Figure 1This is a top view illustrating the structure of the projector 100 according to the embodiment. Figure 2 This is a side view illustrating an example of the use of the projector 100. Additionally, blue will sometimes be referred to as "color B", blue light as "light B", green as "color G", green light as "light G", red as "color R", and red light as "light R".

[0029] like Figure 1 As shown, the projector 100 includes an optical system section 60 for projecting image light ML or image light and a circuit device 80 for controlling the operation of the optical system section 60 as its main body 2. Details will be explained later, but in this embodiment, the projector 100 controls the focus position by following the time-dependent changes in the focus state caused by temperature drift. Temperature drift is an error or variation that occurs in the device due to temperature changes.

[0030] The optical system section 60 includes an image display device 20 for displaying image light ML and a screen SC for projecting image light ML onto the screen (see reference). Figure 2 The projection optical system 40 of the projector 100 is equipped with a remote operator 91. The remote operator 91 sends the command signal corresponding to the user's operation as an infrared signal to the receiver 92 of the main body 2. The circuit device 80 receives the command signal via the receiver 92.

[0031] The image display device 20 includes a light source device 10, a separate optical system 20a, an image forming unit 20b, and a prism PR. Alternatively, if the image display device 20 has a single-plate structure, other optical components may be used instead of the prism PR. Furthermore, the prism PR may be omitted.

[0032] The light source device 10 emits light, including R-light, G-light, and B-light, in a homogenized state. Although not shown in the figure, the light source device 10 includes, for example: a light emitter such as an ultra-high pressure mercury lamp; a two-stage integrating lens having multiple lens elements arranged in an array; a polarization conversion element that converts the light passing through the two-stage integrating lens into predetermined linearly polarized light; and an overlapping lens that causes the illumination light emitted from the subsequent integrating lens to overlap on the display areas of the liquid crystal panels 29R, 29G, and 29B. Alternatively, the light emitter can be replaced with a laser diode, in which case a wavelength conversion element that generates fluorescence can be arranged in the light path from the laser diode.

[0033] The optical separation system 20a separates the light emitted from the light source device 10 into three colors: R, G, and B. The optical separation system 20a includes a first dichroic mirror 21, a second dichroic mirror 22, relay lenses 23 and 24, mirrors 25, 26, and 27, and field lenses 28R, 28G, and 28B. The image forming unit 20b includes liquid crystal panels 29R, 29G, and 29B, which serve as light modulation elements OM.

[0034] The first dichroic mirror 21 reflects the R light incident from the light source device 10, allowing the G and B light to pass through. The R light reflected by the first dichroic mirror 21 passes through the reflector 25 and the field lens 28R and is incident on the liquid crystal panel 29R, illuminating the liquid crystal panel 29R.

[0035] The second dichroic mirror 22 reflects the G light from the first dichroic mirror 21, allowing the B light to pass through. The G light reflected by the second dichroic mirror 22 is incident on the liquid crystal panel 29G via the field lens 28G, illuminating the liquid crystal panel 29G. The B light that has passed through the second dichroic mirror 22 is incident on the liquid crystal panel 29B via relay lenses 23 and 24, reflectors 26 and 27, and the field lens 28B, illuminating the liquid crystal panel 29B.

[0036] The liquid crystal panels 29R, 29G, and 29B constituting the image forming unit 20b are transmissive spatial light modulation elements, forming images of various colors on the reduced-side conjugate surface of the projection optical system 40. Specifically, liquid crystal panel 29R modulates the illumination light (R-light) according to the image signal, thereby forming an R-color image. Liquid crystal panel 29G modulates the illumination light (G-light) according to the image signal, thereby forming a G-color image. Liquid crystal panel 29B modulates the illumination light (B-light) according to the image signal, thereby forming a B-color image.

[0037] The prism PR is, for example, a cross-shaped dichroic prism 31. The cross-shaped dichroic prism 31 is a prism used for light synthesis, which synthesizes the light modulated by each liquid crystal panel 29R, 29G, and 29B into image light ML and then incident on the projection optical system 40.

[0038] The projection optical system 40 amplifies and projects the image light ML, which is modulated by each liquid crystal panel 29R, 29G, and 29B and synthesized by the cross-shaped dichroic prism 31, onto the screen SC (see reference). Figure 2 Projection lens 41 on the ).

[0039] The circuit device 80 includes an image processing unit 81, a display driving unit 82, a lens driving unit 83, a range measuring device 85, and a control device 88 that uniformly controls the operation of these circuit parts 81, 82, 83, 85, etc.

[0040] The image processing unit 81 receives external image signals IS, such as video signals. The image processing unit 81 converts the input external image signals IS into image signals containing grayscale values ​​of various colors. Furthermore, the image processing unit 81 can also perform various image processing operations on the external image signals IS, such as distortion correction and color correction.

[0041] The display driving unit 82 drives the liquid crystal panels 29R, 29G, and 29B disposed in the optical system section 60 based on the output of the image processing unit 81. That is, the display driving unit 82 can operate the liquid crystal panels 29R, 29G, and 29B based on the image signal output from the image processing unit 81, and can make the liquid crystal panels 29R, 29G, and 29B form an image corresponding to the image signal or an image corresponding to the signal after image processing.

[0042] The lens drive unit 83 actuates the movement mechanism AN provided in the projection optical system 40 to adjust the state of the projection optical system 40. The lens drive unit 83 operates under the control of the control device 88, and the movement mechanism AN moves the projection lens 41 constituting the projection optical system 40 appropriately along the optical axis OA, thereby adjusting the focus of the projection optical system 40. The movement mechanism AN includes, for example, an actuator.

[0043] The ranging device 85 operates under the control of the control device 88, for example, by optically measuring the projection distance L from the main body 2 of the projector 100 to the screen SC or the projected image in front of it (see reference). Figure 2 Specifically, the ranging device 85 has a light-projecting part and a light-receiving part, and measures distance based on the principle of triangulation and time difference, and outputs the measurement result to the control device 88. The ranging device 85 is mainly needed during the autofocus adjustment operation described later.

[0044] Reference Figure 3 The control device 88 includes an operation signal receiving device 882, a communication device 883, an input / output device 884, a storage device 885, and a computing device 886.

[0045] Operation signal receiving device 882 receives signals from remote operator 91 (see reference 91) via receiver 92. Figure 1 (Infrared signals emitted, etc.) Therefore, the projector 100 can be controlled according to the operation or selection of the user using the remote operator 91, such as turning the projector 100 on, turning it off, adjusting its brightness, and adjusting its focus.

[0046] The communication device 883 enables the control device 88 to connect to a network NT, such as the Internet. The control device 88 communicates with external servers via the network NT to obtain update information, programs required for the operation of the projector 100, etc. The communication device 883 can also obtain information without using the network NT, via any recording medium such as a memory card or a USB (Universal Serial Bus) memory. Furthermore, the communication device 883 can also obtain information from other devices directly connected via USB or similar means. The communication device 883 includes various interfaces such as a NIC (Network Interface Card) and USB.

[0047] Information for processing by the arithmetic unit 886 is input to the input / output device 884. Additionally, the input / output device 884 outputs the results of the processing performed by the arithmetic unit 886. Instead of the remote operator 91, user-performed operations or selections can also be performed via the input / output device 884. The input / output device 884 includes various input and output devices, such as operation keys and indicators. Furthermore, the projected image projected by the projector 100 can also be part of the input / output device 884. Additionally, the remote operator 91 (see...) Figure 1 The receiver 92 can also be a generalized input / output device 884. The display driver 82 and the lens driver 83 can also be generalized input / output devices 884.

[0048] Storage device 885 stores a program PG3, a database DB3, etc., containing various data and commands for the control device 88 to perform the processes described later. Storage device 885 serves as a non-transitory tangible storage medium for storing program PG3, database DB3, etc. Storage device 885 is a semiconductor storage device including RAM, ROM, flash memory, etc. Program PG3 can be provided, for example, as a program product downloadable from a server, or as a program product stored on a recording medium such as a USB flash drive.

[0049] Program PG3 includes (1) Startup time measurement program P3a, (2) Distance measurement program P3b, (3) Autofocus mode program (AF mode program) P3c, and (4) Manual focus mode program (MF mode program) P3d. Startup time measurement program P3a measures the startup time of the projector 100. Distance measurement program P3b measures the distance between the projector 100 and the projection surface or projected image, i.e., the projection distance L (refer to...). Figure 2The AF mode program P3c performs focus adjustment and tracking correction in AF mode. The MF mode program P3d performs focus adjustment and tracking correction in MF mode. That is, both the AF mode program P3c and the MF mode program P3d include correction programs for focus position. Alternatively, program PG3 can also have its own correction program independently of the AF mode program P3c and the MF mode program P3d.

[0050] Database DB3 includes (1) startup time database D3a, (2) focus adjustment database D3b, and (3) focus correction database D3c. Startup time database D3a stores the startup time of projector 100. Focus adjustment database D3b stores the startup time of the projector 100 relative to the projection distance L (reference). Figure 2 The focus step count (quasi-stabilized focus position) and the time to reach the quasi-stabilized state are corresponding to the quasi-stabilized focus state. The focus correction database D3c stores various parameters used for focus correction.

[0051] The quasi-stable focus state refers to the stable operation of the projector 100. During startup and movement, the projector 100 may experience focus instability due to temperature drift. Therefore, a set focus adjustment position (focus step count or focus position) and the time to reach the quasi-stable state are defined after a specified time elapsed from startup. The quasi-stable focus state varies depending on the projector 100 model, projection distance L, and operating environment. The quasi-stable focus state is the state where the focus position is essentially stable; it can be considered a stable focus state, but because it is used in focus correction in AF and MF modes, it is described as a quasi-stable focus state.

[0052] The arithmetic unit 886 reads from the storage device 885 and executes a program PG3 containing at least a portion of commands and data for performing the processing described later. The arithmetic unit 886 performs drift cancellation shifting, which linearly changes the focus position according to the rate of focus change from the focus start point to a quasi-stable state. The arithmetic unit 886 includes a central processing unit (CPU).

[0053] Figure 4 This is a functional block diagram of control device 88. Control device 88... Figure 3 The arithmetic unit 886 shown reads and executes program PG3, realizing the startup time measurement unit 8a, distance acquisition unit 8b, focus adjustment unit 8c, and focus correction unit 8d. The startup time measurement unit 8a measures the startup time of the projector 100 and stores it in the startup time database D3a. The distance acquisition unit 8b measures the projection distance L of the projector 100 (refer to...). Figure 2The data is then sent to the focus adjustment unit 8c, focus correction unit 8d, etc. The focus adjustment unit 8c adjusts the focus based on the selected AF or MF mode, referring to the focus adjustment database D3b. The focus correction unit 8d dynamically corrects the focus position offset by referring to both the focus adjustment database D3b and the focus correction database D3c. The focus adjustment unit 8c performs focus adjustment based on either the AF or MF mode. During the AF adjustment operation, the focus adjustment unit 8c obtains a quasi-stable focus position corresponding to the projection distance L. During the AF adjustment operation, the focus adjustment unit 8c changes the focus position according to a drift control method from the deviation position (which is the starting point of the focus offset from the quasi-stable focus position) to the quasi-stable state. During the MF adjustment operation, the focus adjustment unit 8c changes the focus position according to a drift control method from the manual focus position (which is the starting point of the manually set focus) to the quasi-stable state. The focus correction unit 8d determines the drift control method for offsetting the drift shift and the deviation position (which is the starting point of the focus offset).

[0054] The projector 100 experiences focus drift or temperature drift due to internal temperature changes and the characteristics of the projection lens 41, causing the focus state to change over time. The projector 100 in this embodiment controls the focus state by automatically tracking the changes in focus state.

[0055] In recent years, autofocus has become the mainstream method for focusing, especially with the increasing use of sensors. In sensor-based autofocus, the focus position corresponding to a reference distance needs to be stored during the assembly process. At this time, the focus position is adjusted when the internal temperature of the projector 100 is stable or close to saturation. That is, autofocus stores the focus position when the drift is stable and the change converges over time.

[0056] Normally, when the projector 100 is activated, automatic focus adjustment is performed immediately after startup, initiating the focusing process. At this time, whether automatic or manual adjustment is used, the internal temperature of the projector 100 is relatively low immediately after startup, leading to defocusing over time. Consequently, the projector 100 is used with an out-of-focus state for several tens of minutes after startup. To avoid this, the projector 100 in this embodiment performs automatic focus control corresponding to changes over time.

[0057] Figure 5 This is a graph illustrating the time-varying focus position of the projector 100. Figure 5 In the diagram, the vertical axis represents the focus adjustment position, and the horizontal axis represents the elapsed time t after startup. The focus adjustment position corresponds to the focus step count (the amount of change in the focus position) or the focus position. Figure 5The dashed line L1 represents the ideal focus position. The ideal focus position is the one that compensates for thermal fluctuations in the focus position and is the most accurate focus position. The dashed line L2, passing through point D0, represents the AF drive position based on the initial rangefinding. The dashed line L2 corresponds to the quasi-stable focus position when thermally stabilized. The dashed line L3, passing through point DU, represents the manual focus position based on user operation. The dashed line L4 is the focus position dynamically shifted to the quasi-stable state, an approximation line following thermal fluctuations. The symbol Ts indicates the time to reach the quasi-stable state.

[0058] like Figure 5 As shown by the dashed line L2, with thermal stability as the baseline, the focusing error relative to the dashed line L1 is larger immediately after startup, but gradually decreases. Additionally, as... Figure 5 As shown by the single-dotted line L3, when the manual setting is used as a reference, the focus error relative to the dashed line L1 is smaller at the beginning of the operation, but gradually increases.

[0059] The projector 100 starts projection from different temperature states: cold start, pause, and warm start. Here, cold start refers to the projector 100 turning on when the temperature is below a specified level or when it is temporarily off. Pause refers to the projector 100 turning on from standby mode. Warm start refers to the projector 100 turning on again when the temperature is above a specified level or when it has just been turned on. Figure 5 The dashed line L1 shown is different for cold starts, pauses, and warm starts. As mentioned above, Figure 5 The dashed line L1 changes according to temperature disturbances. Therefore, the projector 100 of this embodiment is calibrated for easy and simple control, and focus control is performed along the dashed line L4, which has been sparsed to deal with temperature disturbances.

[0060] Based on the above, such as Figure 5 As shown by the dashed line L4, in this embodiment, the projector 100 linearly changes the focus position in the offset focus state after shifting from the quasi-stable focus position, so that the focus error is relatively small within the depth of field before the quasi-stable state reaches time Ts. Thus, the projector 100 corrects the focus position through simple linearly changing focus tracking control. Furthermore, in this embodiment, a linear function or drift control formula is set to minimize the focus error during the pause when the projector 100 starts from the standby state.

[0061] Figure 5 The focus position in the dashed line L4 shown, up to the quasi-stable state, is represented by the following first-order equation. That is, the following equation is the drift control equation (1).

[0062] y = at + b … (1)

[0063] Where y: focus setting value (focus position)

[0064] a: Slope coefficient (drift coefficient or focus change rate)

[0065] t: Elapsed time since projector 100 was started

[0066] b: Starting focus position (focus position at startup or at 0 minutes)

[0067] The focus setting value y is an indicator of the number of steps used for focus control. The focus setting value y is varied until it reaches a quasi-steady state. By aligning the focus position with the focus setting value y corresponding to the elapsed time t, the focus can be achieved.

[0068] The elapsed time t from the start of projector 100 is counted, for example, from 0 minutes to 20 minutes. 20 minutes is the assumed time to reach a quasi-steady state with stable focus (quasi-steady state arrival time Ts). The quasi-steady state arrival time Ts can be appropriately changed according to the projector model, operating environment, etc.

[0069] The slope coefficient 'a' is, for example, the change in step size per minute. In other words, the slope coefficient 'a' is the rate of change in focus or the change in focus time up to the quasi-steady state at time Ts. The value of the slope coefficient 'a' varies depending on the projector model 100.

[0070] The starting focus position b is the focus position at startup (0 minutes). The starting focus position b is determined when executing AF or MF mode. The starting focus position b is based on the projection distance L (refer to...). Figure 2 The changing value is the starting focus position b, which is updated during operation or switching between AF and MF modes. Further details will be explained later, but the starting focus position b can also be used without drift control, and therefore does not necessarily need to be calculated.

[0071] The projector 100 is controlled in the following manner: upon startup, the focus position is shifted to a side or closer to the front than the quasi-stable focus position; with respect to time t, the focus position changes linearly to the far side or inward side; and at time Ts, the quasi-stable focus position is reached. In this way, the focus position shifted from the quasi-stable state upon startup changes linearly with respect to time t at a predetermined slope to return to the original focus position. Therefore, the effects of temperature drift in the projector 100 can be reduced through simple control.

[0072] The projector 100 can adjust focus using AF mode and MF mode. AF mode drives the projection lens 41 to the target lens position corresponding to the ranging value. MF mode drives the projection lens 41 to the focus position operated by the user.

[0073] Focus tracking control applies to both AF and MF modes. In AF mode, a control pattern is generated and executed to guide the focus towards a pre-set autofocus position, i.e., a quasi-stabilized focus position. In MF mode, a control pattern is generated and executed using direct focusing to focus on the user's target position.

[0074] The following explains the focus control in AF mode.

[0075] The quasi-stable focus position of autofocus (AF) is a predetermined value determined by the ranging value. In AF mode, the projection lens 41 is driven in accordance with the quasi-stable focus position immediately after startup. Therefore, the projector 100 is in defocus from the initial startup and the defocus is eliminated in the quasi-stable state. The initial position of focus tracking control in AF mode is an offset position D1 or an initial offset position (refer to) after offsetting the initial autofocus (AF) position D0 corresponding to the quasi-stable focus position. Figure 6 (etc.). The offset position D1 is the focus starting point for drift cancellation shift.

[0076] In AF mode, the starting focus position b in drift control formula (1) is represented by the following formula (2). The quasi-stabilized focus setting value (quasi-stabilized focus position) y1 in the quasi-stabilized state arrival time Ts is the quasi-stabilized focus position determined in AF mode.

[0077] b = y1 - a × Ts … (2)

[0078] The drift control formula (1) is converted into the control formula (3).

[0079] y = y1 - a(Ts - t) …(3)

[0080] Figure 6 This diagram illustrates focus correction in AF mode. Figure 6 The focus correction shown is based on the condition when the projector 100 is started. The value Pa0 is relative to the projection distance L at startup (refer to...). Figure 2 The initial AF position D0 corresponds to the quasi-stabilized focus position. The quasi-stabilized focus position Pa0 corresponds to the quasi-stabilized focus setting value y1.

[0081] When the projector 100 is started, the focus correction unit 8d of the control device 88 obtains the quasi-stable focus position Pa0 (quasi-stable focus setting value y1), the quasi-stable state arrival time Ts, and the slope coefficient a. The focus correction unit 8d calculates the starting focus position b using equation (2) based on the quasi-stable focus setting value y1, the quasi-stable state arrival time Ts, and the slope coefficient a, and determines the above control equation (1). In addition, the focus correction unit 8d determines the offset position D1 using control equation (1). The focus adjustment unit 8c of the control device 88 performs offset shift OS1 according to control equation (1), and performs dynamic offset processing (OS1+DS) from the start of AF Ta. Thus, the focus adjustment unit 8c performs focus adjustment at the offset position D1 at the start of AF Ta. Afterwards, the focus adjustment unit 8c performs drift cancellation shift DS according to control equation (1) until the quasi-stable state arrival time Ts. The ideal tracking position shown by the dashed line L5 is the most accurate focusing position, while the actual tracking position shown by the solid line L6 is also the focusing position within the depth of field. In addition, the focus correction unit 8d can also determine the control formula (3) without calculating the starting focus position b of formula (2).

[0082] Figure 7 This is a diagram illustrating another focus correction in AF mode. Figure 7 The focus correction shown is based on the case when the projector 100's AF is updated. AF updates are performed when the projector 100 has moved, etc. The value Pa1 is relative to the projection distance L at the time of update (refer to...). Figure 2 The initial AF position D0 corresponds to the quasi-stabilized focus position. The quasi-stabilized focus position Pa1 corresponds to the quasi-stabilized focus setting value y1.

[0083] When the projector 100 is updated, the focus correction unit 8d of the control device 88 obtains the quasi-stable focus position Pa1 (quasi-stable focus setting value y1), the quasi-stable state arrival time Ts, and the slope coefficient a. The focus correction unit 8d calculates the starting focus position b using equation (2) based on the quasi-stable focus setting value y1, the quasi-stable state arrival time Ts, and the slope coefficient a, and determines the above control equation (1). In addition, the focus correction unit 8d determines the offset position D2 using control equation (1). The focus adjustment unit 8c of the control device 88 performs offset shift OS2 according to control equation (1), and performs dynamic offset processing (OS2+DS) from the AF update time Tb. Thus, the focus adjustment unit 8c performs focus adjustment at the offset position D2 at the AF update time Tb. Afterwards, the focus adjustment unit 8c performs drift cancellation shift DS according to control equation (1) until the quasi-stable state arrival time Ts.

[0084] The following explains the focus control in MF mode.

[0085] The semi-stabilized focus position in manual (MF) mode is a value determined at the end of the user's manual focus adjustment. The user's focus adjustment is, for example, using motorized focus operation via the remote controller 91. In MF mode, upon initial activation, the projection lens 41 is driven to the semi-stabilized focus position via initial autofocus, but then the user manually adjusts the focus. Therefore, in MF mode, the focus shifts continuously over time. Alternatively, the initial AF adjustment can be omitted in MF mode. The initial position of focus tracking control in MF mode is the manual focus position set by the user. The manual focus position is the starting point for drift compensation.

[0086] In MF mode, the starting focus position b in drift control formula (1) is represented by the following formula (4). The value y0 is the MF setting value (manual focus position), which is the focus setting value determined in MF mode. The value Tm is the MF setting time, which is the elapsed time from the start when the MF setting value y0 is determined.

[0087] b = y0 - a × Tm … (4)

[0088] The drift control mode is converted to control mode (5). In control mode (5), the quasi-stabilized focus setting value y1 obtained based on the projection distance L is not required as in AF mode.

[0089] y = y0 + a(t - Tm) …(5)

[0090] =y0+aΔt

[0091] Here, Δt = t - Tm

[0092] Furthermore, the control equation (5) can also be expressed as the condition equation (3).

[0093] y = y1 - a(Ts - t) …(3)

[0094] Here, the value y1 in MF mode is the quasi-stabilized focus setting or quasi-stabilized focus position in MF mode. The quasi-stabilized focus setting y1 is not the quasi-stabilized focus setting corresponding to the projection distance L, but is obtained according to the following formula reflecting the manual setting state.

[0095] y1 = y0 + a(Ts - Tm)

[0096] Figure 8 This diagram illustrates focus correction in MF mode. Figure 8The focus correction shown is based on the first MF setting Tm1. The value Pm1 is the quasi-stabilized focus position of Tm1 in the first MF setting. The quasi-stabilized focus position Pm1 corresponds to the quasi-stabilized focus setting value y1 in MF mode. The value Pm is the set focus position at the manual focus position DU, which corresponds to the manual focus (MF) setting value y0.

[0097] At the first MF setting time Tm1, the focus correction unit 8d of the control device 88 obtains the set focus position Pm (MF setting value y0), the elapsed time of MF setting time Tm1, and the slope coefficient a. Based on the MF setting value y0, the elapsed time of MF setting time Tm1, and the slope coefficient a, the focus correction unit 8d calculates the starting focus position b using equation (4) and determines the aforementioned control equation (1). The focus adjustment unit 8c of the control device 88 performs dynamic offset processing from the first MF setting time Tm1 using control equation (1). Afterwards, the focus adjustment unit 8c performs drift cancellation shift DS according to control equation (1) until the quasi-stable state reaches time Ts. Alternatively, the focus correction unit 8d may determine control equation (5) without calculating the starting focus position b of equation (4). Furthermore, the focus correction unit 8d may also obtain the quasi-stable focus position Pm1 (quasi-stable focus setting value y1), the quasi-stable state reaches time Ts, and the slope coefficient a. At this time, the focus adjustment unit 8c performs drift cancellation shift DS according to control formula (3). Figure 9 This diagram illustrates another focus correction in MF mode. Figure 9 The focus correction shown is based on the second MF setting time Tm2. The second MF setting time Tm2 is a timing different from the first MF setting time Tm1, based on the startup time. The value Pm2 is the quasi-stabilized focus position at the second MF setting time Tm2. The quasi-stabilized focus position Pm2 corresponds to the quasi-stabilized focus setting value y1 in MF mode. The value Pm is the set focus position at the manual focus position DU, corresponding to the MF setting value y0.

[0098] At the second MF setting time Tm2, ​​the focus correction unit 8d of the control device 88 obtains the set focus position Pm (MF setting value y0), the elapsed time of MF setting time Tm2, ​​and the slope coefficient a. Based on the MF setting value y0, the elapsed time of MF setting time Tm2, ​​and the slope coefficient a, the focus correction unit 8d calculates the starting focus position b using equation (4) and determines the aforementioned control equation (1). The focus adjustment unit 8c of the control device 88 performs dynamic offset processing from the second MF setting time Tm2 using control equation (1). Afterward, the focus adjustment unit 8c performs drift cancellation shift DS according to control equation (1) until the quasi-stable state reaches time Ts.

[0099] Reference Figure 10An example of the focus adjustment operation of the projector 100 will be described. When the projector 100 is started, the arithmetic unit 886 reads the program PG3, which controls the focus adjustment of the projector 100, from the storage device 885 and executes it. When the program PG3 is executed, the arithmetic unit 886 repeats... Figure 10 The processing shown.

[0100] In addition, the projector 100 can automatically perform autofocus by executing program PG3 immediately after startup or after movement, without disabling autofocus. AF mode and MF mode can also be switched at any time before, immediately after, or during startup of the projector 100 via the operation buttons on the main body 2 of the projector 100, the remote operator 91, etc.

[0101] First, the control device 88 confirms whether it is the initial setting for autofocus (step S11). If it is not the initial setting, it is an update based on the interruption of AF mode operation or MF mode operation.

[0102] In the initial autofocus setting (step S11), the control device 88, acting as the focus adjustment unit 8c, activates the lens drive unit 83 to perform AF adjustment (step S12). At this time, the control device 88, acting as the focus correction unit 8d, appropriately performs focus tracking control.

[0103] If the focus adjustment operation ends (yes in step S13), the control device 88 terminates the focus adjustment operation. If the operation continues (no in step S13), the process returns to step S11.

[0104] In step S11, if it is not the initial setting for autofocus (No in step S11), the control device 88 confirms the operating mode (step S14). If it is in AF mode (AF in step S14), proceed to step S12. If it is in MF mode (MF in step S14), the control device 88, acting as the focus adjustment unit 8c, handles the MF adjustment action (step S15). At this time, the control device 88, acting as the focus correction unit 8d, appropriately performs focus tracking control. Then, proceed to step S13.

[0105] exist Figure 10In this process, the control device 88 can also periodically perform interrupt processing to confirm whether it is an AF mode setting, an MF mode setting, or a drift update timing. When the AF mode is set, the starting focus position b of the control formula (1) is determined based on the distance measurement value and an offset shift is performed. When the MF mode is set, the focus is adjusted according to the user's instructions and the starting focus position b of the control formula (1) is determined. When the drift update timing is performed, the starting focus position b of the control formula (1) is determined, the elapsed time t of the control formula (1) is input or updated, the value of the focus setting y is updated, and a drift cancellation shift is performed.

[0106] Reference Figure 11 ,right Figure 10 The AF adjustment action in step S12 shown will be explained.

[0107] First, the control device 88 confirms whether the projector 100 is in a quasi-stable state (step S21). Specifically, if the startup time of the projector 100, as measured by the startup time measuring unit 8a, is longer than a predetermined time, the control device 88 determines that it is in a quasi-stable state. The predetermined time is set to, for example, 20 minutes from the start of startup. Furthermore, it is preferable to reconfirm the quasi-stable state if the state of the projector 100 changes due to movement or other reasons during the predetermined time from startup. Alternatively, the quasi-stable state can also be determined by the internal temperature of the projector 100.

[0108] When the projector is in a quasi-stable state (as in step S21), the control device 88, acting as the distance acquisition unit 8b, acquires the projection distance L of the projector 100 (step S22). This reveals the quasi-stable focus position corresponding to the projection distance L. Alternatively, step S22 can be omitted if the projection distance L acquired during projector 100 startup or update does not change. Afterward, the control device 88, acting as the focus adjustment unit 8c, adjusts the focus position to achieve the quasi-stable focus position (step S23).

[0109] If the state is not quasi-stable in step S21 (no in step S21), the control device 88, as the distance acquisition unit 8b, acquires the projection distance L of the projector 100 (step S122). Alternatively, if the projection distance L acquired when the projector 100 is started or updated does not change, step S122 can be omitted.

[0110] After step S122, the control device 88, acting as the focus correction unit 8d, determines the drift control mode (step S24). At this time, the focus correction unit 8d confirms the elapsed time and determines the offset position.

[0111] After step S24, the control device 88 performs offset shifting as the focus adjustment unit 8c (step S25). Specifically, the focus adjustment unit 8c actuates the lens drive unit 83, driving it stepwise to the offset position obtained in step S24.

[0112] After step S25, the control device 88 performs drift cancellation shift as the focus adjustment unit 8c (step S26). Specifically, the focus adjustment unit 8c uses the drift control formula obtained in step S24 to perform focus tracking control starting from the offset position.

[0113] Then, the control device 88 confirms whether a quasi-stable state has been reached (step S27). If the quasi-stable state is reached (yes in step S27), the control device 88 stops the shift (step S28).

[0114] If the situation is not quasi-stable (No in step S27), the control device 88 checks for interruptions (step S29). An interruption refers to processing requests related to user instructions, such as key operations related to focus, or the end of device operation.

[0115] If there is an interruption (yes in step S29), proceed to step S28. If there is no interruption (no in step S29), return to step S27.

[0116] Reference Figure 12 ,right Figure 10 The MF adjustment action in step S15 shown will be explained.

[0117] First, the control device 88 confirms whether the projector 100 is in a quasi-stable state (step S31).

[0118] When in a quasi-stable state (as in step S31), the control device 88 accepts a manual focus adjustment based on user operation (step S32).

[0119] If the state is not quasi-stable in step S31 (No in step S31), the control device 88 accepts a manual focus adjustment based on user operation (step S132).

[0120] After step S132, the control device 88, acting as the focus correction unit 8d, determines the drift control mode (step S33).

[0121] After step S33, the control device 88 performs drift cancellation shift as the focus adjustment unit 8c (step S34). Specifically, the focus adjustment unit 8c uses the drift control method obtained in step S33 to perform focus tracking control starting from the manual focus position.

[0122] Then, the control device 88 confirms whether a quasi-stable state has been reached (step S35). If the quasi-stable state is reached (yes in step S35), the control device 88 stops the shift (step S36).

[0123] If the condition is not quasi-steady (No in step S35), the control device 88 checks for interruption (step S37).

[0124] If there is an interruption (yes in step S37), proceed to step S36. If there is no interruption (no in step S37), return to step S35.

[0125] The projector 100 described above has a projection lens 41 and a control device 88 for controlling the focus of the projection lens 41. The control device 88 performs drift cancellation shifting that linearly changes the focus position from the starting point of focus to a quasi-stable state according to the rate of change of focus.

[0126] In the projector 100 described above, by using simple focus control to linearly change the focus position according to the rate of change of focus from the starting point of focus to the quasi-stable state, a good projected image can be projected by minimizing the focus error before the quasi-stable state.

[0127] [Other matters]

[0128] The above description is an example; various changes can be made within the scope of achieving the same function.

[0129] For example, the structure of the projector 100 can be modified appropriately. For example, the object magnified and projected by the projection optical system 40 is not limited to the image formed by the liquid crystal panels 29R, 29G, and 29B, but can magnify and project images formed by light modulation elements such as digital micromirror devices.

[0130] In the above embodiment, the focus correction unit 8d of the control device 88 is set to a drift control mode in order to minimize the focus error when paused, but it can also be set to a drift control mode in order to minimize the focus error during cold start and hot start.

[0131] The control device 88 can also change the slope coefficient 'a' (focus change rate) and the quasi-steady state arrival time Ts of the drift control formula based on the internal temperature of the projector 100 at startup. For example, the control device 88 changes the drift control formula based on the state of the projector 100, such as cold start, pause, and warm start. In this case, the projector 100 has a temperature measuring device such as a temperature sensor. By making the drift control formula temperature-dependent, the calibration accuracy can be improved.

[0132] Figure 13 This diagram illustrates an example of temperature-dependent focus correction. For example... Figure 13As shown, the slope coefficient a (focus change rate) of the drift control mode indicated by the double-dotted line L7 during cold start is greater than the slope coefficient a indicated by the dashed line L4 during pause.

[0133] [Summary of this disclosure]

[0134] The following is a summary published in this note.

[0135] (Note 1)

[0136] A projector includes: a projection lens; and a control device that controls the focusing of the projection lens, the control device performing drift cancellation shifting that linearly changes the focus position according to the rate of change of focus from the starting point of focusing to a quasi-stable state.

[0137] By using simple focus control to linearly change the focus position according to the rate of focus change from the starting point of focus until the quasi-stable state, a good projected image can be projected while minimizing focus error before the quasi-stable state.

[0138] (Note 2)

[0139] In the projector described in Appendix 1, the control device includes: a focus adjustment unit that adjusts the focus according to the selection of either an autofocus mode or a manual focus mode; and a focus correction unit that dynamically corrects the offset of the focus position.

[0140] Both autofocus and manual focus modes can handle focus correction.

[0141] (Note 3)

[0142] In the projector described in Appendix 1 or 2, the drift cancellation shift is performed according to the following drift control formula.

[0143] y = y1 - a(Ts - t)

[0144] Where y: the focus position

[0145] y1: Quasi-stable focus position in the quasi-stable state

[0146] a: The rate of change in focus

[0147] Ts: The time from startup to the arrival of the quasi-steady state.

[0148] t: Elapsed time since startup

[0149] Especially effective control during autofocus adjustment.

[0150] (Note 4)

[0151] In the projector described in Appendix 1 or Appendix 2, the drift cancellation shift is performed according to the following drift control formula.

[0152] y = y0 + a(t - Tm)

[0153] Where y: the focus position

[0154] y0: Manual focus position

[0155] a: The rate of change in focus

[0156] Tm: The elapsed time from the start of the operation when the manual focus position is determined.

[0157] t: Elapsed time since startup

[0158] This is a control used during manual focus adjustment. A rangefinder is not needed when only manual focus adjustment is being performed.

[0159] (Note 5)

[0160] In the projector described in Appendix 3, the control device includes: a focus adjustment unit that performs an automatic focus adjustment operation; and a focus correction unit that determines the drift control formula and an offset position as the focus starting point offset from the quasi-stable focus position. In the automatic focus adjustment operation, the focus adjustment unit changes the focus position according to the drift control formula from the offset position to the quasi-stable state.

[0161] (Note 6)

[0162] In the projector described in Appendix 5, a distance measuring device is provided to measure the projection distance, and the focus adjustment unit obtains the quasi-stable focus position corresponding to the projection distance during the automatic focus adjustment operation.

[0163] (Note 7)

[0164] In the projector described in any of Appendices 3 to 6, the control device includes: a focus adjustment unit that performs a manual focus adjustment operation; and a focus correction unit that determines the drift control formula. In the manual focus adjustment operation, the focus adjustment unit changes the focus position according to the drift control formula from a manual focus position, which is a manually set focus start point, to the quasi-stable state.

[0165] (Postscript 8)

[0166] A control device for controlling the focusing of a projection lens of a projector, wherein the control device performs drift cancellation shifting that causes the focus position to change linearly according to the rate of change of focus from the starting point of focusing to a quasi-stable state.

[0167] By using simple focus control to linearly change the focus position based on the rate of change of focus from the starting point of focus until the quasi-steady state, focus error can be minimized before the quasi-steady state is reached.

[0168] (Note 9)

[0169] A program product that controls the focusing of a projection lens of a projector, wherein the program product causes a computing device to perform the following processing: performing a drift cancellation shift that linearly changes the focus position according to the rate of change of focus from the starting point of focus to a quasi-stable state.

[0170] By using simple focus control to linearly change the focus position based on the rate of change of focus from the starting point of focus until the quasi-steady state, focus error can be minimized before the quasi-steady state is reached.

Claims

1. A projector, wherein, The projector has the following features: Projection lens; and A control device that controls the focusing of the projection lens. The control device performs drift cancellation shifting from the starting point of focusing until the quasi-stable state, based on the rate of change of focus, to linearly change the focus position and offset the shift.

2. The projector according to claim 1, wherein, The control device has: The focus adjustment unit adjusts the focus based on the selection of either autofocus mode or manual focus mode; and The focus correction unit dynamically corrects the shift in the focus position.

3. The projector according to claim 1, wherein, The drift cancellation shift is performed according to the following drift control formula. y = y1 - a(Ts - t) Where y: the focus position y1: Quasi-stable focus position in the quasi-stable state a: The rate of change in focus Ts: The time from startup to the arrival of the quasi-steady state. t: Time elapsed since startup.

4. The projector according to claim 1, wherein, The drift cancellation shift is performed according to the following drift control formula. y = y0 + a(t - Tm) Where y: the focus position y0: Manual focus position a: The rate of change in focus Tm: The elapsed time from the start of the operation when the manual focus position is determined. t: Time elapsed since startup.

5. The projector according to claim 3, wherein, The control device has: The focus adjustment unit performs automatic focus adjustment. as well as The focus correction unit determines the drift control formula and the offset position as the focus starting point offset from the quasi-stable focus position. During the autofocus adjustment operation, the focus adjustment unit changes the focus position according to the drift control formula from the offset position to the quasi-stable state.

6. The projector according to claim 5, wherein, The projector is equipped with a ranging device for measuring the projection distance. During the autofocus adjustment operation, the focus adjustment unit obtains the quasi-stable focus position corresponding to the projection distance.

7. The projector according to any one of claims 3 to 6, wherein, The control device has: The focus adjustment unit performs manual focus adjustment. as well as The focus correction unit determines the drift control formula. During the manual focus adjustment operation, the focus adjustment unit changes the focus position according to the drift control method from the manual focus starting point (which is manually set) to the quasi-stable state.

8. A control device that controls the focusing of a projection lens of a projector, wherein, The control device performs drift cancellation shifting from the starting point of focusing until the quasi-stable state, based on the rate of change of focus, to linearly change the focus position and offset the shift.

9. A program product that controls the focusing of a projection lens of a projector, wherein, The program product causes the computing device to perform the following processing: perform drift cancellation shifting that linearly changes the focus position from the starting point of focus to the quasi-stable state according to the rate of focus change.

Images