TWM618004U - Projector system with automatic keystone correction - Google Patents

Abstract

A projector system with automatic keystone correction includes a ranging device, a Gravity sensor, and a microprocessor, wherein the projector system is arranged to: obtaining full field of view coordinates of a projecting picture being projected to a plane by a time of flight (TOF) ranging device as a first reference picture, utilizing the Gravity sensor to calibrate TOF scanning time deviation, and constructing a motion virtual line of a fixed field of view (FOV) through calibrating its horizontal and vertical angle to implement a rectangle adjustment function.

Description

Projector system with automatic keystone correction

The model relates to a projector system, in particular to a projector system that performs automatic keystone correction without generating patterns or positioning coordinates.

With the advancement of technology, various types of projection (micro-projection) technologies have improved the flexibility and mobility of their applications in response to the evolution of technology. The large screen, high resolution, light and thin projection technology that does not limit the space and is easy to carry has become inseparable from life. The above-mentioned projection technology broadens the infinite possibilities of its application in the home and the public domain. However, its indoor and outdoor applications may be restricted by the surrounding environment or normal mobile installations and cause horizontal and vertical image deflection, resulting in trapezoidal shapes. The picture is distorted. Among them, the short-focus system is the most serious. The larger the angle of the expanded field of view (FOV), the more difficult the adjustment will become due to the delicate changes.

In addition to manual adjustment, some projectors currently have automatic correction methods. The traditional automatic correction method is to use the method of generating image positioning coordinates, obtain the rectangular offset coordinates through a separate (such as a mobile phone) camera or a camera fixed to the projector, and then calculate the four corner point correction to complete. However, this method has poor execution efficiency, is easily affected by the ambient background light, and even is limited by frame conditions or projection screen materials. The accuracy of the automatic correction is often affected by the external environment and its quality is unstable, making the positioning conditions complex and high cost. It is even more difficult for a projector with a fixed camera to be used in micro-projection technology, because it is limited by the limitation that the lens and the camera cannot be at the same FOV angle. The resolution must be improved for a relatively short angle, and cost factors make it difficult to popularize .

Based on the above-mentioned deficiencies, this creation proposes a projector with fully automatic picture correction The system is only a tiny module after design. It does not need a camera and is not limited by the installation FOV angle. It is installed on the same projector body and is not easily affected by the environment or background light sources, or uneven walls. It does not require a frame and There is no limitation of projection screen. This method combines the gravity sensor and the time of flight (TOF) distance measuring element to correct the error relative to the normal line by actuarial calculation; and after moving the fixed point, the speed of one adjustment can be completed in less than 0.3sec, dynamic Adjust slightly to the best position, and no longer need to make repeated adjustments because of the generated image obstructing the screen.

Another embodiment of the invention is an embodiment applied to an ultra-short throw projector to overcome the problem of a large error rate when the TOF distance measuring device takes the FOV line at a short distance. It uses the tilted horizontal and vertical angles in the projection The installation method of the projector maintains the horizontal and vertical angles of the fixed FOV, and enlarges the difference ratio of the diagonal, which can compensate the FOV error rate of the ultra-short throw projector in the front projection image and achieve the same accurate effect as the general focal length.

In order to achieve the purpose of vertical or full adjustment of the above FOV, the embodiment of this creation proposes a processor including a single projector, a projection plane, and a processor developed by this creation. A single projector can project images from any angle and direction. The processor developed in this creation calculates the angle between the horizontal and vertical normals of the FOV of the projector's projection screen. Take the direction of the processor and the projector based on the same vertical and horizontal rotation axis points, and detect the trapezoidal deformation of the synchronized projection imaging, so that the deformation correction after the processor adjustment can achieve the goal of a rectangular shape and maintain the original aspect ratio .

The core of this creation is to obtain the horizontal and vertical offset after the trapezoidal deformation of the field of view (FOV), which can be applied to projection technology of any focal length (including ultra-short focus) and light source type, and has a trapezoidal correction system, which can be directly combined. No need to add other positioning or reading coordinate devices, you can complete the correction of the trapezoid on a projection plane. The processor startup time is about a few seconds to complete the first positioning, and can initiate cyclic dynamic and static detection. For the projector use process, or the pre-setting steps of the installation or environmental requirements before the projector is used, no manual labor is required. Intervention can achieve the purpose of fully automatic calibration. This creation includes the implementation of a gravity sensor that can use nine axes (three-axis acceleration, three-axis angular velocity and three-axis magnetometer), including three-axis magnetic calculation method, to obtain the Euler angle (Euler angle) rate of change and angular velocity The effect of this is to construct a directional projection function that adapts to environmental changes and achieves the effect of a north arrow. It can be used in exhibition halls or mobile vehicles in conjunction with the output rotation amount on the cloud platform.

100: Projector system

101: Projection screen

103: The first imaging field of view

105: Second imaging field of view

211, 212, 213, 214, 215: sampling line

310, 310a, 311a, 312a, 310b, 311b, 312b: exercise intensity change line

420: Microcontroller

422: Potential conversion device

424: TOF sensor

426: Gravity Sensor

428: Voltage Regulator

500: flow chart

501, 503, 505, 506, 507, 509, 511, 513, 517: steps

Figure 1 shows the dynamic offset system diagram of this creation.

Figure 2 shows a schematic diagram of the dynamic correction principle proposed by this author.

Figure 3 shows a schematic diagram of the principle of de-jitter proposed in this creation.

Figure 4 shows the functional block diagram of the hardware system of this creation.

Figure 5 shows the program flow chart of the authoring system.

Here, this creation will be described in detail with respect to specific embodiments and viewpoints. Such descriptions are used to explain the structure or step flow of this creation, and are for illustrative purposes rather than limiting the scope of patent application of this creation. Therefore, in addition to the specific embodiments and preferred implementations in the specification, this creation can also be widely implemented in other different embodiments. The following specific examples illustrate the implementation of this creation, and those familiar with this technology can easily understand the efficacy and advantages of this creation based on the content disclosed in this specification. In addition, this creation can also be applied and implemented by other specific embodiments. The details described in this specification can also be applied based on different needs, and various modifications or changes can be made without departing from the spirit of this creation.

Figure 1 shows the dynamic offset system diagram of this creation. The processor fixing device of this creation is on the projection imaging system of the projector. The projection imaging system of the projector is equipped with the hardware required for projection such as light source, mirror and other optical systems and gravity. The sensor (which has integrated accelerometer and gyroscope Gyro) and related control circuits. Therefore, when the processor of the system is fixedly installed on the projection imaging system of the projector, it is integrated into a projector system 100, which has the same regional coordinate system ( local coordinate system), the coordinate system can define three-axis directions (X, Y, Z directions) and pitch angles (Pitch), yaw angles (Yaw) and roll angles (Roll) according to the orientation of the gravity sensor. The projection system includes a projector, a processor, and a plane that can be imaged. The plane that can be imaged can be a wall, a projection screen, a convex wallpaper/decoration material, or Other flat surfaces suitable for viewing the projection screen 101. The first consideration here is how the projector system should correct the horizontal and vertical image deflection due to tilt and vibration, resulting in trapezoidal image distortion. Correction methods including static, static to dynamic, and dynamic to static are proposed here, using a combination of gravity sensor and time of flight (TOF) ranging elements to correct the error relative to the normal line by actuarial calculation; After moving the fixed point, the speed of one adjustment is completed in less than 0.3sec, and the dynamic adjustment is slightly adjusted to the best position. The generated image no longer obscures the screen, and needs to be adjusted repeatedly. The first imaging field of view (FOV) 103 of the projector system (processor) is expressed as the previous dynamic or static FOV, and the four-side measurement length is sampled (that is, the four-side measurement line at the origin noted in the figure) ) The angle between horizontal and vertical is available; the second imaging field of view (FOV) 105 of the projector system (processor) represents the latter dynamically or statically obtained FOV, where the dynamically obtained FOV is sensed by gravity (including three-axis acceleration and Three-axis angular velocity) Calculate Euler angle (Euler angle) change rate and attitude quaternion to construct a new measurement line, and then TOF distance measuring element continues to measure points to obtain four-sided measurement length and FOV fixed included angle, in continuous dynamic behavior Repeatedly, in a preferred embodiment, the TOF ranging element may be a scanning multi-point TOF ranging element. In a preferred embodiment, the projector system of the present invention can be combined with any type of projector, for example, a laser projector, a digital optical processing projector, a short throw projector or other types of projectors. Other equipment with planar imaging or positioning can also be applied to the projector system of this creation. For the application of the projector, the creative projector system is usually equipped with a single processor. If a larger projection coverage is required or when the ultra-short throw projector needs more precise fine-tuning, multiple processors can be installed. In a preferred embodiment, the processor of this invention can be a computer central processing device, a microprocessor, a logic operation unit (FPGA), or it can be integrated into a projector, such as a built-in Scalar with embedded micro-processing micro-processing Processing unit. In a preferred embodiment, any reasonable projector technology or hardware that integrates a gravity sensor combined with a TOF distance measuring element, and related equivalent changes belong to the scope of the projector system disclosed in this creation.

Figure 2 shows a schematic diagram of the dynamic correction principle proposed by this creation, which reveals that this creation is dealing with changes in the movement curve. The schematic diagram of the dynamic correction principle is based on the creation of the projector system (processor and projector) fixed on the same three axes On the normal line, the FOV rectangle of the projection screen is changed by the same amount, so it is depicted on the same imaging surface. The focus of this creation is to start and complete the first imaging positioning, the projector or device displacement operation, after the anti-shake calculation to eliminate the misoperation, real-time dynamic calculation, ranging line sampling, and compensation for the time difference to achieve the effect of real-time correction, and install it Accurate correction after stabilizing the projection angle, Obtain the absolute distance between the peripheral line and the center point through TOF, calculate the accurate angle correction of the full expansion, the center point to the four-point expansion within the fixed angle difference, and obtain the horizontal and vertical angle between the processor of the projector system and the projection surface. The related anti-jitter operation will be detailed in Figure 3.

In FIG. 2, the horizontal and vertical movement of the projector system 100 is represented as the offset from the first imaging field of view 103 to the second imaging field of view 105. The figure shows five sampling lines measured horizontally and vertically at a fixed time. (211, 212, 213, 214, 215), and respectively calculate the Euler angle (Euler angle) rate of change to obtain the pitch angle (Pitch) and yaw angle (Yaw) direction of rotation angle, taking the first imaging angle of view as the origin , Dynamically change the horizontal and vertical changes of each sampling line. The sampling line is a continuous time action, and the end-time action is extended, and there is no limitation on the number of sampling lines. As shown in Figure 1 and Figure 2, the main technical point of this creation is the presentation of a FOV angle correction system that is first static and then dynamic and is automatically complemented by endless loops. The static-to-dynamic detection is based on a gravity sensor (G sensor). Mainly, it can make up for the unreliability of the accuracy distortion caused by the movement measurement of the TOF distance measuring element; the dynamic recovery of the static FOV imaging of the real time projection surface is corrected by the TOF distance measuring element measuring the four sides and the center line The final angle between the horizontal and vertical directions is finally de-trapezoidal and maintains the projection aspect ratio. Any method that uses a reasonable transformation of the Euler angle rate of change to achieve the relationship between the accumulation of the angle between the horizontal and the vertical and the angle correction is within the scope of this creation.

Figure 3 is a schematic diagram of the principle of debouncing proposed by the creation. It is illustrated in a spherical limited time motion space (phase space). The content mainly shows the concept of using the Euler angular velocity of gravity sensing to calculate the three-axis motion (ie X , Y, Z direction movement) within a period of time (periof of time) around the core of the movement, the sensor is stimulated by external force to produce changes in displacement, forming changes in acceleration and gravity values, and then calculate the pitch angle (Pitch), The yaw angle (Yaw) and the roll angle (Roll) are three movement angles (where Pitch corresponds to θ, Yaw corresponds to φ, and Roll corresponds to Φ in the coordinate system) and intensity. Figure 3(A) illustrates the three-axis motion intensity and the corresponding coordinate system. The figure shows the pitch angle (Pitch), yaw angle (Yaw) and roll angle (Roll) of the three motion angles and the three-axis Correspondence; among them, the origin represents the core of motion, the Euler angle of vertical motion indicates the rate of change in the pitch direction (Pitch) angle, the Euler angle of horizontal motion indicates the rate of change in the yaw direction (Yaw) angle, and the Euler angle of lateral rotation The angle represents the rate of change of the angle of the rolling direction (Roll); the outside of the sphere boundary represents the invalid jitter range in the limited time motion space, that is, the outside of the sphere boundary is effective motion. Figure 3(B) shows an explanation of the evolution of uniaxial exercise intensity over time, taking horizontal exercise as an example (partial The rate of change of Yaw angle), where the dashed concentric circles extending outward from the moving core represent the displacement increment △r with a fixed time scale △t outward from the initial time axis to, and △t is related to the sense of gravity The response time and frequency of the detector settings are related. The exercise intensity change line 310 in the figure shows that when the horizontal exercise is at the end of the longest time axis (same as the time-space boundary shown in Figure 3(A)), it is not greater than the maximum exercise intensity, and the axis accumulated to this point is reset to zero during calculation. . In addition, consider that the normal movement has continuity and the monotonic increasing/decreasing (monotonic increasing/decreasing) characteristics in the three-axis directions (X, Y, Z directions), and the jittering movement has the characteristics of the three-axis direction. (X, Y, Z directions) each presents the characteristics of repetitive non-monotonic function, and the influence of gravity is integrated into the calculation to obtain the positive and negative offset of the three directions of movement in a period of time Function, which can more reliably distinguish the difference between jitter and motion, and prevent misoperation. Please refer to Figure 3(C)-(D) for the judgment method. Figure 3(C) is the judgment for jitter. Figure 3(C) draws the exercise intensity change line of horizontal movement, lateral movement and vertical movement ( Respectively represented as 310a, 311a, 312a), using Euler's anti-shake-three-axis fusion algorithm to start measurement when the horizontal movement is not zero; the lateral movement is not zero when the initial calculation reaches the second order, Add to the time measurement; then the vertical motion is not zero when the initial calculation reaches the fourth step, and add it to the time measurement; when the time axis dynamic intensity marking line is reached, the three motion directions start to reverse, and the cycle ends. The fusion calculation returns to zero. Figure 3(D) is the judgment for exercise. Figure 3(D) draws the exercise intensity change lines of horizontal movement, lateral movement and vertical movement (represented as 310b, 311b, 312b), using Euler (Euler) Anti-shake-the three-axis fusion algorithm starts to measure when the lateral movement is not zero; when the initial calculation reaches the second level, the horizontal movement is not zero, and it is added to the time measurement; then when the initial calculation reaches the fourth level, it is vertical Movement is not zero, add it to the time measurement; the level of excessive movement increases steadily (exercise intensity change line 310b), re-set the vertical movement as the starting point, increase the second-level simulation level from the second level; the horizontal movement reaches the stable increase condition, this cycle Interpretation is effective. The description of the above discrimination method can be summarized as the use of Euler angular velocity to perform environmental transformation calculations within a period of time, and the pitch angle (Pitch), yaw angle (Yaw) and roll angle (Roll) rotation changes calculated by determining the environmental transformation The intensity threshold of anti-shake can be preset as the result of several evolutions within the time period to achieve the purpose of anti-shake. The performance of this calculation method in terms of stability and reliability is far more accurate than the traditional bias value estimated by setting a threshold on a gravity sensor, gyroscope, or accelerometer, and does not produce The accumulated error of a single (or several) data caused by being excluded from the calculation because it is below the threshold. The use of six-axis (three-axis acceleration, three-axis gyroscope) and nine-axis gravity sensor (nine-axis is the original six-axis plus three-axis magnetometer) must have the above-mentioned jitter identification performance, the processor of this creation can clearly Expose this category.

Figure 4 is a functional block diagram of the hardware system created. The main arithmetic unit is a programmable logic microcontroller 420, which uses the I2C standard protocol via a potential conversion device 422, a TOF sensor (ranging element) 424 and gravity in parallel The sensor (G sensor) 426, the power supply is designed by a low dropout linear regulator (LDO) 428 to provide the core voltage of the sensor (the sensor is designed for low-voltage drive, after LDO voltage regulation and post-filtering, Cleaner power supply and suppression of electrical noise and ripple give the sensor a stable working environment). For the communication of the projector or other application equipment, this creation uses RS232 and reserved RS485. RS232 is a commonly used internal and external communication interface for projectors, which is convenient for system integration and product development efficiency. RS485 is half-duplex. The industrial differential signal is suitable for large-scale theater platforms, and can support long-distance installation and use in projector external devices.

Figure 5 is a flow chart 500 of the system program created. The first program (step 501) is the automatic completion of the automatic calibration of the gravity sensor (G sensor auto-calibration) as the first program (step 501), the initialization of the Euler angle change rate (Step 503) and start the pre-anti-shake loop detection of origin detection (steps 505→506→507). When the condition of eliminating jitter is established, it is judged as the effective Euler angle change rate (step 509), and the fusion three is performed The original calculation of the axis angle offset (step 511), and take the center line after offset from the origin to the projector's reasonable radius of gyration, and convert the maximum and minimum reasonable range of the offset angle (the cumulative time tolerance of the center line value) In the anti-shake detection calculation cut-off point) (step 513), if it is determined to be the ideal offset angle (step 514), then accumulate the three-axis offset to the new coordinate position (step 515), and then continue the loop Anti-shake detection (step 507). If not, it is judged to be an excessive deviation angle, which may be caused by the machine falling, being carried, transferring to the field, or other factors affecting the environment change, reset the posture quaternion and recheck whether it is moving ( Step 517), lies in the repositioning of the new positioning point. The system of this creation is designed by closely integrating the operation method of the level affected by the Euler angle change rate. Any reasonable dynamic, static or environmental conversion using the Euler angle change rate on the projector is designed to be disclosed in this creation. category.

In summary, this creation describes a system combined with a projector, which is more efficient than traditional manual methods or coordinate positioning methods. In addition to the processor of this creation, there is no need to add other devices with positioning sensing, and the calibration process Does not produce any patterns that obscure the screen. The projector does not need to be equipped with a camera, and there is no need to set up before use or install any scanning/positioning device due to changes in the environment. Amplitude or very slight dynamic adjustment, and the projection of the adjustment process The images and frames displayed on the screen conform to the predetermined projection range.

The above embodiments are only used to illustrate the technical solutions of this creation, but not to limit them; although the creation and its benefits are described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still compare the foregoing embodiments. The recorded modification or equivalent replacement of some of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solution to deviate from the scope of the creation claims.

100: Projector system

101: Projection screen

103: The first imaging field of view

105: Second imaging field of view

Claims (10)

A projector system with automatic keystone correction. The system includes: a microprocessor; a distance measuring element and a gravity sensing element, wherein the microprocessor couples the distance measuring element and the gravity through a potential conversion device A sensing element; wherein the distance measuring element obtains the horizontal and vertical included angle of the first static field of view projected by the projector system to a plane for static positioning; the gravity sensing element obtains the first static field of view horizontal and After the vertical angle, any motion detection and displacement estimation in the horizontal and vertical directions are calculated by calculating Euler's angle change rate and attitude quaternion to construct a new measurement line to obtain a real-time projection image; and The method of fixing the angle of the field of view uses the distance measuring element to measure the four sides and the center line of the real-time projection image to correct the final angle between the horizontal and vertical directions. The projector system according to claim 1, wherein the above-mentioned ranging element is a multi-point scanning time-of-flight (TOF) ranging element. The projector system according to claim 1, wherein the above-mentioned gravity sensing element is a six-axis gravity sensing element integrating an accelerometer and a gyroscope. The projector system according to claim 3, which further includes a magnetic sensing element. The projector system according to claim 1, further comprising using Euler angular velocity to perform environmental transformation calculation within a period of time, and the pitch angle (Pitch), yaw angle (Yaw) and roll angle ( Roll) The amount of change in rotation can be preset as the result of several evolutions of the anti-shake intensity threshold within the time period to achieve the purpose of anti-shake. The projector system according to claim 1, wherein the above-mentioned microprocessor serves as a main arithmetic unit, and the microprocessor is coupled to the distance measuring element and the gravity sensing element via a potential conversion device according to the I2C standard protocol. The projector system according to claim 6, wherein the above-mentioned distance measuring element is connected in parallel with the gravity sensing element and is controlled by the microcontroller. The projector system according to claim 6, wherein the microprocessor, the distance measuring element and the gravity sensor are powered by a low-voltage linear regulator. The projector system according to claim 1, wherein the above-mentioned microprocessor includes a computer central processing unit, a microprocessor, a logic operation unit (FPGA), a built-in Scalar and an embedded microprocessor micro-operation processing unit. The projector system according to claim 1, which further includes the following steps: booting to perform automatic calibration of the gravity sensor; initializing the Euler angle change rate; front anti-shake loop detection; performing fusion three-axis angle Offset the original calculation, and take the offset centerline from the origin to the projector's reasonable radius of gyration; if it is determined to be the ideal offset angle, accumulate the three-axis offset to the new coordinate position.

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