Patent Description:
At present, many vehicles are equipped with puddle lamps as auxiliary illumination sources, whereby people who get in or out of the vehicles can pay attention to ground conditions and can be protected from accidentally treading on dangerous ground or dirt. For aesthetic purposes or indication functions, some light beams emitted from the puddle lamps may form a pattern or an image on the ground. According to the related art, if the same puddle lamp is installed on different models of vehicles, such as a sedan, a sports car, a truck, and so on, due to the height difference of different vehicle models, the pattern projected by the puddle lamp that is farther from the ground is of greater size but smaller brightness, and the pattern projected by the puddle lamp that is closer to the ground is of smaller size but greater brightness. In other words, the projection image is changed in response to different heights of the chassis of the vehicles, and thus uniformity and image quality of the projection image cannot stay consistent.

The information disclosed in this Background section is only for enhancement of understanding of the background of the described technology and therefore it may contain information that does not form the prior art that is already known to a person of ordinary skill in the art. Further, the information disclosed in the Background section does not mean that one or more problems to be resolved by one or more embodiments of the invention were acknowledged by a person of ordinary skill in the art.

<CIT> discloses a mobile image projection system including a wireless network interface configured to communicate with at least one remote computing device and an optical projection device communicatively coupled with the wireless network interface and configured to be mounted on a vehicle and project an image on a surface of a vehicle body. The system includes a processor and a memory configured to store at least one image file and instructions that, when executed, cause the processor to receive, using the wireless network interface an image file from the at least one remote computing device and display an image from the received image file on the surface of the vehicle. <CIT> discloses a laser projection adaptive intelligent headlight, comprising a first cylinder, a fixed end of the first cylinder is connected to a second cylinder, the inner wall of second cylinder is slidably connected with a lens barrel, and one side of the inner wall of the first cylinder is fixedly connected with a control device, and a fixing plate is fixedly connected to an inner wall of the first cylinder body near the control device. <CIT> discloses a greeting lamp, and the greeting lamp includes a transparent electronic display, a controller configured to control the electronic display to display an image, and a light source disposed on a first side of the electronic display and configured to emit light to the electronic display for projecting a display image of the electronic display. It is further referred to <CIT>, <CIT>, <CIT> and <CIT>.

The invention provides a projection device and a control method thereof capable of adjusting a projection image according to a projection distance, so as to maintain stable brightness and size of the projection image.

The invention provides a projection device adapted to be disposed on a vehicle and comprising a storage device, a projection module, a distance detection device, and a control device, wherein the storage device is configured to store image data of at least one projection image, the distance detection device is configured to measure a projection distance from the distance detection device to a projection plane, and the control device is electrically connected to the storage device, the projection module, and the distance detection device, wherein the control device is configured to enable the projection module to project the at least one projection image and to control a brightness and/or a size of the at least one projection image according to the corresponding projection distance, and wherein the control device is configured to calculate an estimated size of the at least one projection image according to the projection distance and a throw ratio of the projection module, and wherein the control device is configured to calculate an estimated brightness of the at least one projection image according to the estimated size, and when the estimated brightness is greater than a first brightness threshold value, the brightness of the at least one projection image projected by the projection module is controlled not to be greater than the first brightness threshold value by the control device.

The invention further provides a control method of a projection device, wherein the projection device is adapted to be disposed on a vehicle and at least comprises a distance detection device, a control device, and a projection module, and the control method comprises: measuring a projection distance from the distance detection device to a projection plane by the distance detection device; calculating an estimated size of the at least one projection image according to the projection distance and a throw ratio of the projection module; calculating an estimated brightness of the at least one projection image according to the estimated size, wherein when the estimated brightness is greater than a first brightness threshold value, the brightness of the at least one projection image projected by the projection module is controlled not to be greater than the first brightness threshold value by the control device, projecting at least one projection image through the projection module, wherein the control device controls the brightness and/or a size of the at least one projection image according to the corresponding projection distance.

Preferably, the control device may control the projection module to change the size of the at least one projection image from the estimated size to a desired size through digital zooming or optical zooming, so that the size of the at least one projection image stays at the desired size.

Preferably, the brightness of the at least one projection image projected by the projection module may be controlled to be not less than a second brightness threshold by the control device.

In some or more embodiments, the projection device may further comprise a driving circuit electrically connected to the control device and an illumination light source in the projection module and configured to provide a driving current to the illumination light source.

In some or more embodiments, the control device may adjust a current value or a pulse duty ratio of the driving current through the driving circuit according to the projection distance.

The control device controls The control device controls the projection module to ensure the brightness of the at least one projection image not to exceed a first brightness threshold value.

Preferably, the number of the at least one projection image may be plural, or the image data are video data.

Preferably, the at least one projection image may be a still image.

Preferably, the method may comprise detecting an opening of a door of the vehicle to activate the projection device activate.

The invention also provides a vehicle comprising a door, a power module and the projection device, wherein the projection device as defined above is disposed in the door of the vehicle to project the image to floor under the door, when the door is opened.

However, the projection device might be also disposed at a different part of the vehicle to project an image to a projection plane outside the vehicle.

Based on the above, one or more embodiments of the invention provide a projection device and a control method thereof. The projection device has the distance detection device to measure the projection distance, and the control device controls the brightness or the size of the at least one projection image generated by the projection module according to the corresponding projection distance. As such, when the projection distance is short, the projection image generated by the projection device having the high luminous flux may be prevented from being excessively bright, thus protecting human eyes from fatigue and achieving energy saving effects. Besides, through the control of the size of the projection image, the overall brightness and the size of the projection image can remain consistent.

Other objectives, features and advantages of the invention will be further understood from the further technological features disclosed by the embodiments of the invention wherein there are shown and described preferred embodiments of this invention, simply by way of illustration of modes best suited to carry out the invention.

It is to be understood that other embodiment may be utilized and structural changes may be made without departing from the scope of the invention. Also, it is to be understood that the phraseology and terminology used herein are for the purpose of description and should not be regarded as limiting. Unless limited otherwise, the terms "connected," "coupled," and "mounted," and variations thereof herein are used broadly and encompass direct and indirect connections, couplings, and mountings.

<FIG> is a schematic diagram illustrating activation of a projection device when a door of a vehicle is opened according to an embodiment of the invention. With reference to <FIG>, a projection device <NUM> is adapted to be disposed on a vehicle <NUM>, for instance, on a door of the vehicle <NUM> (as shown in <FIG>), at a rear-view mirror mounted on the door (or an A-pillar), or at a position below the front and rear fenders, which should however not be construed as limitations to the invention. When the door is opened (or when there is another activation device, such as a sensor key or the like), the projection device <NUM> starts to perform the illumination function and projects an image on a projection plane G, thus not only providing illumination for passengers or the driver to pay attention to the ground conditions but also rendering light and shadow effects. In <FIG>, the projection plane G is the ground.

<FIG> is a schematic diagram illustrating the appearance of a projection device according to an embodiment of the invention, and <FIG> is a block diagram of a projection device according to an embodiment of the invention. With reference to <FIG>, and <FIG>, the projection device <NUM> includes at least one projection module <NUM>, a distance detection device <NUM>, a control device <NUM>, and a storage device <NUM>. The projection module <NUM> is configured to generate at least one projection image on the projection plane G. The distance detection device <NUM> is configured to measure a projection distance D from the distance detection device <NUM> to the projection plane G. The projection module <NUM> and the distance detection device <NUM> may be disposed together in the projection device <NUM>, and an image beam projected by the projection module <NUM> passes through a surface S facing the projection plane G to present an image on the projection plane G. The distance detection device <NUM> projects a detection beam or sound wave from the surface S, such that the projection distance D measured by the distance detection device <NUM> is also the distance between the projection module <NUM> and the projection plane G. The storage device <NUM> is configured to store image data corresponding to the projection image. The control device <NUM> is electrically connected to the storage device <NUM>, the projection module <NUM>, and the distance detection device <NUM>. The control device <NUM> is configured to enable the projection module <NUM> to project at least one projection image and control a brightness or a size of the at least one projection image according to the corresponding projection distance D. Here, the image data in the storage device <NUM> are, for instance, video data or a plurality of pictures, and the projection device <NUM> may project one or more projection images of different contents, such as a trademark or an advertisement picture. In an embodiment, the projection device <NUM> may project a video clip.

In the present embodiment, the projection device <NUM> may be activated by opening the door of the vehicle <NUM>, and power VDD of the projection device <NUM> comes from the vehicle <NUM>. The control device <NUM> is electrically connected to a door detector <NUM> on the vehicle <NUM>, and the control device <NUM> may activate the projection device <NUM> according to a door-opening signal provided by the door detector <NUM>. When the door of the vehicle <NUM> is opened, the projection device <NUM> automatically projects an image. The door detector <NUM> is, for instance, a mechanical switch or an optical shielding detector for detecting whether the door of the vehicle <NUM> is opened.

Specifically, the projection module <NUM> is, for instance, a projection module having a light valve, and the light valve is, for instance, a reflective liquid crystal on silicon (LCOS) device or a digital micro-mirror device (DMD), or a transmissive transparent liquid crystal panel. The distance detection device <NUM> is, for instance, a proximity sensor and can perform distance detection through infrared ray, laser, ultrasonic waves, sound waves, photoelectric sensing, and the like. The control device <NUM> is, for instance, a device with computation capabilities, such as a central processing unit (CPU), a microprocessor, or a combination thereof. The storage device <NUM> is, for instance, any type of fixed or movable random access memory (RAM), read-Only memory (ROM), flash memory, hard disk, any other similar device, or a combination thereof. In addition to storing the image data, the storage device <NUM> may also store various programs, parameters, or threshold values required for the operation of the projection device <NUM>.

In this embodiment, the control device <NUM> may calculate an estimated size of the projection image according to the projection distance D, an image aspect ratio, and a throw ratio of the projection module <NUM>. The throw ratio is a ratio of the projection distance D to a width W of the projection image, and the image aspect ratio is a ratio of the width W to the height H of the projection image. In detail, since doors of different vehicle models have different height designs, the projection distance D may change depending on the model of the vehicle <NUM> where the projection device <NUM> is disposed or depending on the terrain where the vehicle <NUM> is parked. As the projection distance D changes, the control device <NUM> may estimate the estimated size of the projection image at different projection distances D according to the preset/default image aspect ratio and the throw ratio of the projection module <NUM>.

<FIG> is a schematic diagram illustrating an estimated size and a projection distance of a projection image according to an embodiment of the invention. As shown in <FIG>, generally speaking, the farther the projection distance D is, the larger the estimated size is.

Specifically, the control device <NUM> of the projection device <NUM> controls the projection module <NUM> to change the size of the projection image from the estimated size to a desired size through digital zooming or optical zooming, so that the size of the projection image may substantially stay at the desired size. Here, the desired size has a predetermined and constant value that does not change with the projection distance D. As such, if the projection device <NUM> projects a LOGO, regardless of the model of the vehicle <NUM> where the projection device <NUM> is disposed or the terrain where the passengers or the driver gets out of the vehicle <NUM>, the LOGO projected by the projection device <NUM> has substantially the same size which is not changed with the projection distance D. Here, the digital zooming is to change the size of the projection image by means of software or hardware and application programs, and the optical zooming is to change the size of the projection image by adjusting positions of a plurality of physical lenses.

In addition, the control device <NUM> also calculates an estimated brightness of the projection image based on the estimated size. When the estimated brightness is greater than a first brightness threshold value, the brightness of the projection image projected by the projection module <NUM> is controlled to be not greater than the first brightness threshold value by the control device <NUM>. In an embodiment, the control device <NUM> also controls the brightness of the projection image projected by the projection module <NUM> to be not less than a second brightness threshold. That is, after the control device <NUM> calculates the estimated brightness and the estimated size corresponding to the projection distance D, the luminous flux emitted by the projection module <NUM> is adjusted according to the estimated brightness by the control device <NUM> to prevent the brightness of the projection image from being overly bright or overly dark.

Specifically, the projection module <NUM> of the projection device <NUM> further includes a driving circuit <NUM>, an illumination light source <NUM>, and an optical engine module <NUM>. The control device <NUM> is electrically connected to the driving circuit <NUM>, and the driving circuit <NUM> is electrically connected to the illumination light source <NUM> and configured to provide a driving current to the illumination light source <NUM>. The driving circuit <NUM> is, for instance, a light source driving circuit, and the illumination light source <NUM> is, for instance, a solid-state light source (e.g., a light emitting diode, a laser diode) or a lamp. The control device <NUM> is electrically connected to the optical engine module <NUM> and configured to provide image data to the optical engine module <NUM> to generate the image beam described above. The optical engine module <NUM> includes, for instance, a light valve of a reflective type or a transmissive type. The reflective light valve is, for instance, an LCOS device or a DMD, and the transmissive light valve is, for instance, a transparent liquid crystal panel.

The control device <NUM> adjusts a pulse duty ratio or a current value of the driving current through the driving circuit <NUM> according to the projection distance D, so as to adjust the brightness of the image projected by the projection module <NUM> on the projection plane G.

In an embodiment, the throw ratio of the projection module <NUM> is set as <NUM>, and the image aspect ratio is preset as <NUM>:<NUM>. The control device <NUM> aims at keeping the size and the brightness of the projection image projected by the projection module <NUM>. The diagonal size of the projection image is intended to be fixed at around <NUM>, and the brightness is intended to be kept at around <NUM> nits. The first brightness threshold value is set as <NUM> nits, and the second brightness threshold is set as <NUM> nits. Table <NUM> records the estimated size and the estimated brightness while the projection distances D are different and the actual size and the actual brightness of the projection image on the projection plane G adjusted by the control device <NUM>.

When the projection distance D is <NUM>, the estimated size of the projection image calculated by the control device <NUM> is <NUM> (the diagonal length), which is similar to the desired size, but the estimated brightness reaches <NUM> nits. The control device <NUM> may not adjust the size of the image but controls the driving circuit <NUM> to decrease the driving current, so that the brightness of the projection image on the projection plane G conforms to the desired brightness of <NUM> nits and less than the first brightness threshold value. When the projection distance D is <NUM>, the estimated size of the projection image calculated by the control device <NUM> is <NUM> (diagonal length), and the estimated brightness is <NUM> nits. The control device <NUM> may adjust the size of the projection image through scaler zooming, so that the actual size of the projection image finally projected on the projection plane G is <NUM>, which is substantially fixed at the desired size. The control device <NUM> may also reduce the brightness of the projection image on the projection plane G by controlling the driving circuit <NUM>, so that the actual brightness of the projection image is <NUM> nits, which is less than the first brightness threshold value. When the projection distance D is <NUM>, the estimated size of the projection image calculated by the control device <NUM> is <NUM> (diagonal length), and the estimated brightness is <NUM> nits. The control device <NUM> may change the size of the projection image from <NUM> to <NUM> through digital zooming or optical zooming without changing the luminous flux of the illumination light source <NUM>. When the projection distance D is <NUM>, the estimated size of the projection image calculated by the control device <NUM> is <NUM> (diagonal length), and the estimated brightness is <NUM> nits, which is less than the second brightness threshold. The control device <NUM> may control the driving circuit <NUM> to increase the driving current, such that the brightness of the projection image projected on the projection plane G is greater than or equal to the second brightness threshold but still less than the first brightness threshold value. The adjusted actual brightness is <NUM> nits. In another embodiment, the control device <NUM> may also decide not to increase the driving current.

In the present embodiment, the projection device <NUM> may measure the projection distance D by means of the distance detection device <NUM>, and the control device <NUM> calculates the corresponding estimated size and the corresponding estimated brightness according to the projection distance D. Given the illumination light source <NUM> provides the same luminous flux, the smaller the projection distance D is, the smaller the estimated size, and the greater the corresponding estimated brightness is. Therefore, when the projection distance D is less than a distance threshold value, the control device <NUM> may control the projection module <NUM> to ensure that the brightness of the projection image does not exceed the first brightness threshold value, thus achieving the energy saving effect. According to Table <NUM>, the distance threshold value provided in this embodiment may be <NUM>.

<FIG> is a flowchart illustrating a control method of a projection device according to an embodiment of the invention. The projection device illustrated in <FIG> is adapted to be disposed on the vehicle, e.g., at the door or the rear-view mirror. Hence, the control method provided may be applicable to the embodiments illustrated in <FIG>.

With reference to <FIG>, according to the embodiment, in step S510, a door of a vehicle is opened to activate a projection device, and power of the projection device comes from the vehicle. In step S520, when the door is opened and the projection device is activated, a projection distance from a distance detection device to a projection plane is measured by the distance detection device. Next, in step S530, at least one projection image is projected by a projection module, wherein a control device controls a brightness or a size of the at least one projection image according to the corresponding projection distance. Since people skilled in the art can obtain sufficient suggestions, teachings, or explanations according to the above embodiments, details will not further described hereinafter.

Claim 1:
A projection device adapted to be disposed on a vehicle and comprising a storage device (<NUM>), a projection module (<NUM>), a distance detection device (<NUM>), and a control device (<NUM>),
wherein the storage device (<NUM>) is configured to store image data of at least one projection image,
the distance detection device (<NUM>) is configured to measure a projection distance (D) from the distance detection device (<NUM>) to a projection plane (G), and
the control device (<NUM>) is electrically connected to the storage device (<NUM>), the projection module (<NUM>), and the distance detection device (<NUM>),
wherein the control device (<NUM>) is configured to enable the projection module (<NUM>) to project the at least one projection image and to control a brightness and/or a size of the at least one projection image according to the corresponding projection distance (D), and
wherein the control device (<NUM>) is configured to calculate an estimated size of the at least one projection image according to the projection distance (D) and a throw ratio of the projection module (<NUM>), and wherein the control device (<NUM>) is configured to calculate an estimated brightness of the at least one projection image according to the estimated size, and when the estimated brightness is greater than a first brightness threshold value, the brightness of the at least one projection image projected by the projection module (<NUM>) is controlled not to be greater than the first brightness threshold value by the control device (<NUM>).