Patent Description:
Recently, in the field of display technology, display devices having excellent characteristics, such as thinness and flexibility, have been developed. Meanwhile, currently commercialized major displays are represented by a liquid crystal display (LCD) and an organic light-emitting diode (OLED).

However, the LCD has problems in which the response time is slow and it is difficult to realize flexibility, and the OLED has problems in which the lifespan thereof is short and the production yield thereof is low.

Meanwhile, a light-emitting diode (LED), which is a well-known semiconductor light-emitting element that converts current into light, has been used as a light source for displaying an image in electronic devices including information communication devices together with a GaP:N-based green LED, starting with commercialization of a red LED using a GaAsP compound semiconductor in <NUM>. Therefore, a method of solving the above-described problems by implementing a display using the semiconductor light-emitting element may be proposed. Such a light-emitting diode has various advantages, such as a long lifespan, low power consumption, excellent initial driving characteristics, and high vibration resistance, compared to a filament-based light-emitting element.

Meanwhile, when a light-emitting module in which light-emitting elements are arranged in one dimension is rotated and driven at a high speed according to the angle thereof, various letters, graphics, and videos may be recognized by a human due to an afterimage effect.

In general, when still images are continuously displayed at a rate of <NUM> or more sheets per second, a viewer recognizes the same as a video. A conventional image display device, such as a CRT, an LCD, or a PDP, displays still images at a rate of <NUM> to <NUM> frames per second, so a viewer is capable of recognizing the same as a video. As the number of still images displayed per second increases, a viewer may experience smoother video, and as the number of still images displayed per second decreases, it becomes difficult to implement smooth video.

A general rotatable display device is structured such that a lower side of a light source module is connected to a driving shaft of a motor so as to be rotated thereby. Because the light source module is supported by a single shaft, vibration occurs due to the insufficient stiffness of a rotary shaft during rotation thereof at high speed, leading to screen shaking.

A rotatable display device is applicable to end products including image display devices, such as artificial intelligence speakers and small display apparatuses. In the case of a general product having a single-shaft support structure, when the product is dropped or when an external impact is applied thereto, the shaft may be deformed, or the product may be damaged due to the insufficient stiffness of the shaft.

Meanwhile, a rotatable display device using an afterimage displays one image sheet for each rotation thereof. When the rotational speed thereof is low, screen flickering occurs. For example, when it is necessary to output a <NUM> image, a rotatable display device provided with a single light source module (panel) needs to be rotated at <NUM> rpm.

In order to reduce the number of rotations per minute, the number of light source modules (panels) may be increased. However, increasing the number of light source modules decreases transparency (see-through) and increases costs. Therefore, it is necessary to select an appropriate number of light source modules and an appropriate rotational speed thereof.

In the case of a motor-powered rotatable device, the operational speed thereof is selected so as to avoid a critical speed in order to reduce vibration and noise and to increase the lifespan of the device. In general, the operational speed is designed to be outside of a range of the critical speed ±<NUM>%.

Here, the critical speed may be measured on the basis of a natural frequency of a system, or may be calculated based on a simulation such as finite element analysis. In a rotary body, a natural frequency is an eigenvalue determined by the moment of inertia and the stiffness of a structure.

As a result of analyzing vibration simulation for a rotatable display device that is composed of a light source module including two panels and has a single-shaft support structure (that is, a structure in which only a driving shaft of a motor is connected to a rotary portion), it can be seen that a primary natural frequency is <NUM>, and at this time, the rotatable display device performs rotating movement in a tilted state. That is, when the rotational speed is about <NUM> rpm, the light source module is rotated in a tilted state by exciting force, such as eccentricity. This rotational speed is similar to the rotational speed of an actual rotatable display.

At this time, vibration, noise, and image shaking may occur, which may significantly degrade the quality of the product.

Therefore, there is a need for a method of eliminating vibration and noise phenomena. <CIT> relates to an invisible transparent display. <CIT> relates to a rotary scan type color display device. <CIT> relates to a display device having a plurality of moving light sources. <CIT> relates to a means for all-around display of a picture.

A technical task of the present disclosure is to provide a rotatable display device using a semiconductor light-emitting element, which is capable of reducing the occurrence of vibration and noise of the rotatable display device.

In addition, the present disclosure provides a rotatable display device using a semiconductor light-emitting element, which is capable of setting a frequency corresponding to the rotational speed of a display to be very different from a rotational natural frequency.

In addition, the present disclosure provides a rotatable display device using a semiconductor light-emitting element, which enables a rotary portion to rotate at an appropriate speed by stably supporting the rotation of the rotary portion without a change, for example, without using a lightweight and high-stiffness material.

In accordance with a first aspect for accomplishing the above objects, a rotatable display device using a light-emitting element of the present disclosure may include a fixed portion including a motor, a rotary portion located on the fixed portion and including a first side coupled to the motor and a second side rotatably coupled to a rotation coupling portion so as to be rotated, the second side being opposite the first side, and a light source module mounted to the rotary portion and including one or more panels disposed at respective positions on a rotational circumference of the rotary unit, and light-emitting element arrays including individual pixels disposed along a longitudinal length of the one or more panels.

In addition, a casing which encases the fixed portion, the rotary portion, and the light source module, may be further included.

In addition, the rotation coupling portion may be connected to the casing.

In addition, the casing may include an opaque portion positioned to correspond to the fixed portion, a transparent portion positioned to correspond to the light source module, and a cover portion located on the transparent portion.

In addition, the rotation coupling portion may be positioned to correspond to the center of the cover portion.

In addition, the rotation coupling portion may include a rotary shaft inserted into the second side of the rotary portion.

In addition, the second side of the rotary portion may include a shaft-coupling portion into which the rotary shaft is inserted.

In addition, a shaft support portion may be located between the rotary shaft and the shaft-coupling portion so as to facilitate coupling and rotation between the rotary shaft and the shaft-coupling portion.

In addition, the longitudinal length of the one or more panels of the light source module may extend between the first side and the second side of the rotary portion.

In addition, the rotation coupling portion may be connected to the fixed portion.

In addition, the rotation coupling portion may be coupled to a vertical frame connected to the fixed portion.

In addition, the fixed portion may include a frame structure, and the vertical frame may be coupled to the frame structure.

In accordance with a second aspect for accomplishing the above objects, a rotatable display device using a light-emitting element of the present disclosure may include a fixed portion including a motor, a rotary portion located on the fixed portion and including a first side fixedly coupled to the motor and a second side provided with a shaft-coupling portion so as to be rotated by operation of the motor, the second side being opposite the first side, a light source module mounted to the rotary portion and including one or more panels disposed along an imaginary cylindrical outer circumferential surface and light-emitting element arrays including individual pixels disposed on the panels in a longitudinal direction of the panels, and a rotation coupling portion coupled to the shaft-coupling portion to support rotational movement of the rotary portion.

According to an embodiment of the present disclosure, there are the following effects.

First, according to the present disclosure, it can be confirmed that, when the configuration of the rotatable display device is changed from a single-shaft support structure to a double-ended support structure of the present disclosure, a natural frequency can be increased twofold or greater, i.e. to <NUM> or greater.

Accordingly, since the primary natural frequency is distant from the rotational frequency band of the rotatable display device, vibration and noise may be greatly reduced.

Therefore, it may be possible to enable the rotary portion to rotate at an appropriate speed by stably supporting the rotation of the rotary portion without a change, for example, without using a lightweight and high-stiffness material, thereby preventing the occurrence of vibration and noise of the light source module and an image shaking phenomenon.

Further, according to the present disclosure, there are additional technical effects not mentioned herein, and those skilled in the art can understand the effects through the specification and the drawings.

Reference will now be made in detail to embodiments of the present disclosure, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts, and a redundant description thereof will be omitted. As used herein, the suffixes "module" and "unit" are added or used interchangeably to facilitate preparation of this specification, and are not intended to suggest distinct meanings or functions. In describing embodiments disclosed in this specification, relevant well-known technologies may not be described in detail in order to avoid obscuring the subject matter of the embodiments disclosed in this specification. In addition, it should be noted that the accompanying drawings are only for easy understanding of the embodiments disclosed in the present specification.

Furthermore, although the drawings are separately described for simplicity, embodiments implemented by combining two or more drawings are also within the scope of the present disclosure.

In addition, when an element such as a layer, a region, or a substrate is described as being "on" another element, it is to be understood that the element may be directly on the other element, or there may be an intermediate element between them.

The display device described herein conceptually includes all display devices that display information with a unit pixel or a set of unit pixels. Therefore, the term "display device" may be applied not only to finished products but also to parts. For example, a panel corresponding to a part of a digital TV also independently corresponds to the display device in the present specification. Such finished products include a mobile phone, a smartphone, a laptop computer, a digital broadcasting terminal, a personal digital assistant (PDA), a portable multimedia player (PMP), a navigation system, a slate PC, a tablet PC, an Ultrabook, a digital TV, a desktop computer, and the like.

However, it will be readily apparent to those skilled in the art that the configuration according to the embodiments described herein is also applicable to new products to be developed later as display devices.

In addition, the term "semiconductor light-emitting element" mentioned in this specification conceptually includes an LED, a micro LED, and the like, and may be used interchangeably therewith.

<FIG> is an external perspective view of a rotatable display device according to a first embodiment of the present disclosure. In addition, <FIG> is a cross-sectional view taken along line C-C in <FIG>.

<FIG> illustrates a cylindrical-shaped rotatable display device in which light-emitting element arrays <NUM> and <NUM> (refer to <FIG>) are respectively provided on one or more panels <NUM> and <NUM>, which are disposed along an imaginary cylindrical outer circumferential surface, in the longitudinal direction of each of the panels.

Such a rotatable display device may broadly include a fixed portion <NUM>, which includes a motor <NUM>, a rotary portion <NUM>, which is located on the fixed portion <NUM> and is rotated by the motor <NUM>, and a light source module <NUM>, which is coupled to the rotary portion <NUM> and includes the light-emitting element arrays <NUM> mounted on the panels <NUM> and <NUM> so as to implement a display by creating an afterimage resulting from rotation.

In this case, the light source module <NUM> may include the light-emitting element arrays <NUM> and <NUM>, which are mounted on one or more bar-shaped panels <NUM> and <NUM>, which are arranged at regular intervals on the outer circumferential surface of the cylinder, in the longitudinal direction of each of the panels.

Referring to <FIG> and <FIG>, the light source module <NUM> may include two panels <NUM> and <NUM>, on which the light-emitting element arrays <NUM> and <NUM> are provided. However, this is given merely by way of example, and the light source module <NUM> may include one or more panels.

In the light-emitting element arrays <NUM>, individual pixels may be disposed on the panels <NUM> and <NUM> in the longitudinal direction of each of the panels. A detailed description of the operation of the light-emitting element arrays <NUM> and <NUM> provided in the light source module <NUM> will be omitted.

Each of the panels <NUM> and <NUM> constituting the light source module <NUM> may be configured as a printed circuit board (PCB). That is, each of the panels <NUM> and <NUM> may have the function of a printed circuit board. Each of the light-emitting element arrays <NUM> and <NUM> may implement an individual unit pixel, and may be disposed on a corresponding one of the panels <NUM> and <NUM> in the longitudinal direction of the corresponding panel.

The panels provided with the light-emitting element arrays <NUM> and <NUM> may implement a display using an afterimage created by rotation thereof. Implementation of an afterimage display will be described later in brief.

As described above, the light source module <NUM> may be constituted by a plurality of panels <NUM> and <NUM>. However, the light source module <NUM> may be constituted by a single panel provided with a light-emitting element array. When the light source module <NUM> is constituted by two panels <NUM> and <NUM>, as illustrated in <FIG>, the plurality of panels may realize one frame image in a shared manner, and may thus be rotated at a lower speed than when realizing a given frame image using a single panel.

Meanwhile, the fixed portion <NUM> may include frame structures <NUM>, <NUM>, and <NUM>. That is, the fixed portion <NUM> may include a lower frame <NUM>, an upper frame <NUM>, and a connection frame <NUM>, which connects the lower frame <NUM> and the upper frame <NUM> to each other.

These frame structures <NUM>, <NUM>, and <NUM> may provide a space in which to mount the motor <NUM>, and may further provide a space in which to mount a power supply <NUM> and an RF module <NUM>.

In addition, a weight (not shown) may be mounted to the fixed portion <NUM> in order to reduce the influence of high-speed rotation of the rotary portion <NUM>.

Similarly, the rotary portion <NUM> may include frame structures <NUM>, <NUM>, and <NUM>. That is, the rotary portion <NUM> may include a lower frame <NUM>, an upper frame <NUM>, and a connection frame <NUM>, which connects the lower frame <NUM> and the upper frame <NUM> to each other.

These frame structures <NUM>, <NUM>, and <NUM> may provide a space in which a driving circuit <NUM> for driving the light-emitting element arrays <NUM> and <NUM> in order to implement a display is mounted.

In this case, a driving shaft <NUM> of the motor <NUM> may be coupled to a first side of the rotary portion <NUM>. Here, the first side of the rotary portion <NUM> may be the lower frame <NUM>, which is located at a lower side of the rotary portion <NUM>. The following description will be made with reference to the case in which the lower side (the first side) of the rotary portion <NUM>, which is coupled to the motor <NUM>, is the lower frame <NUM>. However, the present disclosure is not limited thereto.

More specifically, the driving shaft <NUM> of the motor <NUM> may be fixed to a shaft-fixing portion <NUM> formed at the lower frame <NUM>. In this way, the driving shaft <NUM> of the motor <NUM> and the center of rotation of the rotary portion <NUM> may be coaxially located. Accordingly, the lower side of the rotary portion <NUM> may be coupled to the driving shaft <NUM> of the motor <NUM>.

Referring to <FIG>, a second side (that is, an upper side) of the rotary portion <NUM>, which is opposite the first side thereof, may be rotatably coupled to a rotation coupling portion <NUM>. That is, the rotary portion <NUM> is capable of rotating because the first side thereof is coupled to the motor <NUM> and the second side, which is opposite the first side, is rotatably coupled to the rotation coupling portion <NUM>.

In this way, since both the upper side and the lower side of the rotary portion <NUM> are supported, the rotary portion <NUM> may stably rotate without positional deviation of the center of rotation thereof. This will be described later in detail.

The light source module <NUM> may be fixedly mounted to an upper side of the upper frame <NUM> of the rotary portion <NUM>.

A cover frame <NUM>, which corresponds to the second side of the rotary portion <NUM>, may be located on the panels <NUM> and <NUM> constituting the light source module <NUM>.

<FIG> is an enlarged view showing an example of portion B in <FIG>. Referring to <FIG> and <FIG>, the cover frame <NUM> may be provided with a shaft-coupling portion <NUM>, which has an insertion hole formed therein to allow the rotation coupling portion <NUM> to be fitted thereinto.

In this case, the rotation coupling portion <NUM> may include a rotary shaft <NUM>, which is inserted into the second side of the rotary portion <NUM>, i.e. the shaft-coupling portion <NUM>. That is, the rotation coupling portion <NUM> may be formed in the shape of a rotary shaft.

Alternatively, the rotation coupling portion <NUM> may be formed in the shape of an insertion hole, and the second side of the rotary portion <NUM> may be formed in the shape of a shaft so as to be inserted into the insertion hole. That is, the rotation coupling portion <NUM> may be formed in the shape of a rotary shaft, or may be formed in the shape of an insertion hole into which a rotary shaft is inserted, so long as the same is capable of rotatably supporting the second side of the rotary portion <NUM> (refer to <FIG>).

A shaft support portion <NUM> is located between the rotary shaft <NUM> and the shaft-coupling portion <NUM> so as to be coupled thereto. This shaft support portion <NUM> serves to support the rotary shaft <NUM> and the shaft-coupling portion <NUM> so that the rotary shaft <NUM> and the shaft-coupling portion <NUM> are rotatably coupled to each other and are capable of smoothly rotating relative to each other. The shaft support portion <NUM> may include, for example, a bearing <NUM>.

In addition, the shaft support portion <NUM> further includes a shock-absorbing member <NUM>, which is located between the bearing <NUM> and the shaft-coupling portion <NUM>.

The shaft support portion <NUM>, which includes the bearing <NUM> and the shock-absorbing member <NUM>, may help the rotary shaft <NUM> and the shaft-coupling portion <NUM> rotate smoothly without vibrating.

<FIG> is an enlarged view showing another example of portion B in <FIG>. As shown in <FIG>, the shaft support portion <NUM> may include only a bearing <NUM>. That is, the bearing <NUM> may be mounted between the shaft-coupling portion <NUM> and the rotary shaft <NUM> so as to be in contact therewith.

In this way, the panels <NUM> and <NUM> of the light source module <NUM> may be mounted between the first side (the upper frame <NUM>) of the rotary portion <NUM> and the second side (the cover frame <NUM>) of the rotary portion <NUM> in the longitudinal direction thereof. In this case, the first side may be coupled to the driving shaft <NUM> of the motor <NUM>, and the second side may be coupled to the rotation coupling portion (the rotary shaft) <NUM>. Accordingly, the rotary portion <NUM> is capable of smoothly rotating, with the two opposite sides thereof supported.

Meanwhile, referring to <FIG> and <FIG>, there may be provided a casing <NUM>, which is located outside the fixed portion <NUM>, the rotary portion <NUM>, and the light source module <NUM>.

In this case, the casing <NUM> may include an opaque portion <NUM>, which is located outside the fixed portion <NUM>, a transparent portion <NUM>, which is located outside the light source module <NUM>, and a cover portion <NUM>, which is located on the transparent portion <NUM> to cover the upper surface thereof.

In this configuration, the rotation coupling portion <NUM> may be connected to the casing <NUM>. More specifically, the rotation coupling portion <NUM> may be connected to the cover portion <NUM> of the casing <NUM>.

That is, the rotation coupling portion <NUM> may be located at the center of the cover portion <NUM>. The rotation coupling portion <NUM> may be integrally formed with the cover portion <NUM>. The rotation coupling portion <NUM> may stably support one side of the light source module <NUM> via the casing <NUM>.

Meanwhile, the fixed portion <NUM> and the rotary portion <NUM> may transfer power therebetween in a wireless power transfer manner. To this end, a transmission coil <NUM> for transferring wireless power may be mounted to an upper portion of the fixed portion <NUM>, and a reception coil <NUM> may be mounted to a lower portion of the rotary portion <NUM> so as to be located at a position facing the transmission coil <NUM>.

<FIG> is a perspective view showing the front surface of the light source module according to the present disclosure, and <FIG> is a perspective view showing the rear surface of the light source module according to the present disclosure.

Although <FIG> and <FIG> illustrate the first panel <NUM> of the first embodiment as an example, the configuration illustrated in <FIG> and <FIG> may be identically applied not only to the other panel <NUM> but also to the panels <NUM> and <NUM> of the second embodiment, which will be described later. That is, the light source module of the first embodiment and the light source module of the second embodiment may have the same configuration.

<FIG> illustrates one panel <NUM> forming the light source module <NUM>. As mentioned above, the panel <NUM> may be a printed circuit board (PCB). A plurality of light-emitting elements <NUM> (refer to <FIG>) may be mounted on the panel <NUM> so as to be disposed in one direction to form pixels, thereby constituting the light-emitting element array <NUM>. Here, a light-emitting diode (LED) may be used as the light-emitting element.

That is, the light-emitting elements <NUM> are disposed in one direction on one panel <NUM> to form individual pixels, with the result that the light-emitting element array <NUM> may be provided so as to be linearly mounted.

<FIG> illustrates the rear surface of the panel <NUM>. Drivers <NUM> for driving the light-emitting elements <NUM> may be mounted on the rear surface of the panel <NUM>, which constitutes the light source module.

Since the drivers <NUM> are mounted on the rear surface of the panel <NUM>, as described above, the drivers <NUM> may not interfere with a light-emitting surface, the influence on light emission from the light sources (the light-emitting elements) <NUM> due to interference may be minimized, and the area of the panel <NUM> may be minimized. The panel <NUM>, having a small area, may improve the transparency of the display.

Meanwhile, the front surface of the panel <NUM>, on which the light-emitting element array <NUM> is mounted, may be processed into a dark color (e.g. black) in order to improve the contrast ratio and the color expression of the display, thereby maximizing the effect of the light sources.

<FIG> is an enlarged view of portion A in <FIG>, and <FIG> is a cross-sectional view of the light source module according to the present disclosure.

Referring to <FIG>, it can be seen that the individual light-emitting elements <NUM> are mounted linearly in one direction (the longitudinal direction of the panel). In this case, a protective portion <NUM> may be located outside the light-emitting elements <NUM> in order to protect the light-emitting elements <NUM>.

Red, green, and blue light-emitting elements <NUM> may form one pixel in order to realize natural colors, and the individual pixels may be mounted in one direction on the panel <NUM>.

Referring to <FIG>, the light-emitting elements <NUM> may be protected by the protective portion <NUM>. Further, as described above, the drivers <NUM> may be mounted on the rear surface of the panel <NUM>, and may drive the light-emitting elements <NUM> in units of pixels or subpixels. In this case, one driver <NUM> may individually drive at least one pixel.

<FIG> is a block diagram of the rotatable display device according to the present disclosure.

Hereinafter, a configuration for driving the rotatable display device will be described briefly with reference to <FIG>. Although this configuration will be described with reference to the first embodiment described above, the same may also be identically applied to the second embodiment.

First, a driving circuit <NUM> may be mounted to the fixed portion <NUM>. The driving circuit <NUM> may include a power supply. The driving circuit <NUM> may include a wireless power transmitter <NUM>, a DC-DC converter <NUM>, and a voltage generator <NUM> for supplying individual voltages.

External power may be supplied to the driving circuit <NUM> and the motor <NUM>.

In addition, an RF module <NUM> may be provided at the fixed portion <NUM>, so that the display may be driven in response to a signal transmitted from the outside.

Meanwhile, a means for sensing rotation of the rotary portion <NUM> may be provided at the fixed portion <NUM>. Infrared radiation may be used to sense rotation. Accordingly, an IR emitter <NUM> may be mounted to the fixed portion <NUM>, and an IR receiver <NUM> may be mounted to the rotary portion <NUM> at a position corresponding to the IR emitter <NUM>.

In addition, a controller <NUM> may be provided at the fixed portion <NUM> in order to control the driving circuit <NUM>, the motor <NUM>, the IR emitter <NUM>, and the RF module <NUM>.

Meanwhile, the rotary portion <NUM> may include a wireless power receiver <NUM> for receiving a signal from the wireless power transmitter <NUM>, a DC-DC converter <NUM>, and a voltage generator (LDO) <NUM> for supplying individual voltages.

The rotary portion <NUM> may be provided with an image processor <NUM> in order to realize an image through the light-emitting element array using RGB data of an image to be displayed. The signal processed by the image processor <NUM> may be transmitted to the drivers <NUM> of the light source module, and thus an image may be realized.

In addition, a controller <NUM> may be mounted to the rotary portion <NUM> in order to control the wireless power receiver <NUM>, the DC-DC converter <NUM>, the voltage generator (LDO) <NUM>, the IR receiver <NUM>, and the image processor <NUM>.

The image processor <NUM> may generate a signal for controlling light emission from the light sources of the light source module based on data of an image to be output. At this time, the data for light emission from the light source module may be internal data or external data.

The data stored in the internal device (the rotary portion <NUM>) may be image data pre-stored in a storage device, such as a memory (an SD-card) mounted together with the image processor <NUM>. The image processor <NUM> may generate a light emission control signal based on the internal data.

The image processor <NUM> may transmit control signals to the drivers <NUM> so that light-emitting element arrays <NUM> and <NUM> display image data of a specific frame in a delayed manner.

Further, the image processor <NUM> may transmit control signals to the drivers <NUM> so that the light-emitting element arrays <NUM> and <NUM> are sequentially driven.

Meanwhile, the image processor <NUM> may receive image data from the fixed portion <NUM>. At this time, external data may be output through an optical data transmission device, such as a photo coupler, or an RF-type data transmission device, such as a Bluetooth or Wi-Fi device.

In this case, as mentioned above, a means for sensing rotation of the rotary portion <NUM> may be provided. That is, the IR emitter <NUM> and the IR receiver <NUM> may be provided as a means for detecting the rotational position (speed) of the rotary portion <NUM>, such as an absolute rotational position or a relative rotational position, in order to output light source data suitable for each rotational position (speed) during rotation of the rotary portion <NUM>. Alternatively, this function may also be achieved using an encoder, a resolver, or a Hall sensor.

Meanwhile, data required to drive the display may be transmitted as a signal in an optical manner at low cost using the principle of a photo coupler. That is, if the fixed portion <NUM> and the rotary portion <NUM> are provided with a light emitter and a light receiver, reception of data is continuously possible even when the rotary portion <NUM> rotates. Here, the IR emitter <NUM> and the IR receiver <NUM> described above may be used to transmit data.

As described above, power may be transferred between the fixed portion <NUM> and the rotary portion <NUM> in a wireless power transfer (WPT) manner.

Wireless power transfer enables the supply of power without connection of a wire using a resonance phenomenon of a coil.

To this end, the wireless power transmitter <NUM> may convert power into an RF signal of a specific frequency, and a magnetic field generated by current flowing through the transmission coil <NUM> may generate an induced current in the reception coil <NUM>.

At this time, the natural frequency of the coil and the transmission frequency for transferring actual energy may differ from each other (a magnetic induction method).

Meanwhile, the resonant frequencies of the transmission coil <NUM> and the reception coil <NUM> may be the same (a magnetic resonance method).

The wireless power receiver <NUM> may convert the RF signal input from the reception coil <NUM> into direct current, and may transmit required power to a load.

<FIG> is an external perspective view of a rotatable display device according to a second embodiment of the present disclosure. In addition, <FIG> is a cross-sectional view of the rotatable display device according to the second embodiment of the present disclosure.

There may be provided a casing <NUM>, which is located outside the fixed portion <NUM>, the rotary portion <NUM>, and the light source module <NUM>.

Hereinafter, the second embodiment of the present disclosure will be described in detail. The following description of the second embodiment will focus on differences from the first embodiment. Thus, with regard to any aspect of the second embodiment that is not described herein, reference may be made to the description of the configuration of the first embodiment.

Referring to <FIG> and <FIG>, the light source module <NUM> may include the light-emitting element arrays <NUM> and <NUM>, which are mounted on one or more bar-shaped panels <NUM> and <NUM>, which are arranged at regular intervals on the outer circumferential surface of the cylinder, in the longitudinal direction of each of the panels.

In the light-emitting element arrays <NUM>, individual pixels may be disposed on the panels <NUM> and <NUM> in the longitudinal direction. A detailed description of the operation of the light-emitting element arrays <NUM> and <NUM> provided in the light source module <NUM> will be omitted.

More specifically, the driving shaft <NUM> of the motor <NUM> may be fixed to a shaft-fixing portion <NUM> formed at the lower frame <NUM>. In this way, the driving shaft of the motor <NUM> and the center of rotation of the rotary portion <NUM> may be coaxially located. Accordingly, the lower side of the rotary portion <NUM> may be coupled to the driving shaft <NUM> of the motor <NUM>.

In this case, the rotation coupling portion <NUM> may be connected to the fixed portion <NUM>. More specifically, the rotation coupling portion <NUM> may be coupled to vertical frames <NUM> and <NUM>, which are connected to the fixed portion <NUM>. The rotation coupling potion <NUM> may have a hole <NUM> formed therein. The hole <NUM> may function to reduce weight and to improve assemblability.

In addition, as described above, the fixed portion <NUM> may include frame structures <NUM>, <NUM>, and <NUM>, and the vertical frames <NUM> and <NUM> may be coupled to the frame structures <NUM>, <NUM>, and <NUM>.

That is, referring to <FIG>, the vertical frames <NUM> and <NUM> may be connected to end portions of the lower frame <NUM> and the upper frame <NUM>.

In this way, the rotation coupling portion <NUM> may be formed in the shape of a rotary shaft that extends inwards from the cover portion <NUM>. The cover portion <NUM> may be connected to the fixed portion <NUM> via the vertical frames <NUM> and <NUM>.

In this case, the rotation coupling portion <NUM> may be located at the center of the cover portion <NUM>. The rotation coupling portion <NUM> may be integrally formed with the cover portion <NUM>. The rotation coupling portion <NUM> may stably support one side of the light source module <NUM> via the vertical frames <NUM> and <NUM>.

In this way, since both the upper side and the lower side of the rotary portion <NUM> are supported, the rotary portion <NUM> may stably rotate without positional deviation of the center of rotation thereof.

The cover frame <NUM> may be provided with a shaft-coupling portion <NUM>, which has an insertion hole formed therein to allow the rotation coupling portion <NUM> to be fitted thereinto.

Alternatively, as shown in <FIG>, the cover frame <NUM>, which corresponds to the second side of the rotary portion <NUM>, may be provided with a shaft portion <NUM>, which protrudes upwards, and the cover portion <NUM> may have formed therein an insertion hole <NUM> into which the shaft portion <NUM> is inserted.

In this case, a shaft support portion <NUM> may be located between the shaft portion <NUM> and the insertion hole <NUM> so as to be coupled thereto. This shaft support portion <NUM> serves to support the shaft portion <NUM> and the insertion hole <NUM> so that the shaft portion <NUM> and the insertion hole <NUM> are rotatably coupled to each other and are capable of smoothly rotating relative to each other. The shaft support portion <NUM> may include, for example, a bearing <NUM>.

In this case, the shaft support portion <NUM> may further include a shock-absorbing member (refer to <FIG>), in addition to the bearing <NUM>.

The shaft support portion <NUM>, which includes the bearing <NUM>, may help the rotary shaft <NUM> and the shaft-coupling portion <NUM> rotate smoothly without vibrating.

Because it is difficult to observe changes in the interior of a product when the product is dropped, it is necessary to analyze the same through simulation. <FIG> is a simulation diagram showing changes in the interior of a rotatable display device having a single-shaft support structure when the same is dropped.

It can be seen from <FIG> that, when a rotatable display device having a single-shaft support structure is dropped, a rotary frame and an inner frame collide with each other and stress is concentrated on a shaft of a motor.

That is, describing the same in the context of the above-described embodiment, portion D in <FIG>, on which stress is primarily concentrated, corresponds to the cover frame <NUM> of the rotary portion <NUM>, and portion E corresponds to the upper frame <NUM> of the rotary portion <NUM>. In addition, portion H corresponds to the driving shaft <NUM> of the motor <NUM>.

Here, the critical speed may be measured on the basis of a natural frequency of a system, or may be calculated based on a simulation such as finite element analysis. In a rotary body, a natural frequency is an eigenvalue determined by the moment of inertia and the stiffness of a structure, and may be increased using a lightweight and high-stiffness material.

However, the present disclosure is capable of solving the above-described problems without needing to change materials. This will be described below in detail.

As a result of analyzing vibration simulation for a rotatable display device that is composed of a light source module including the two panels of the present disclosure and has a single-shaft support structure (that is, a structure in which only a driving shaft of a motor is connected to a rotary portion), it can be seen that a primary natural frequency is <NUM>, and at this time, the rotatable display device performs rotating movement in a tilted state.

That is, when the rotational speed is about <NUM> rpm, the light source module is rotated in a tilted state by exciting force, such as eccentricity, and at this time, vibration, noise, and image shaking occur, which may significantly degrade the quality of the product.

Therefore, there is a need for a structure having a high natural frequency with respect to the required number of rotations per minute. It may be possible to increase the stiffness of a shaft system and thus to increase the natural frequency by employing the above-described double-ended support structure in which the rotary portion <NUM> is rotated, with both the first side and the second side thereof supported.

<FIG> is a graph showing the frequency response characteristics of a general rotatable display device having a single-shaft support structure. In addition, <FIG> is a graph showing the frequency response characteristics of the rotatable display device according to the embodiment of the present disclosure.

Referring to <FIG>, it can be seen that the rotatable display device having a single-shaft support structure has a primary natural frequency of <NUM> (G1). In addition, a secondary natural frequency thereof is about <NUM>.

When a <NUM> image is realized using the light source module including two panels <NUM> and <NUM> (<NUM>), the rotational frequency is <NUM>. In addition, when a <NUM> image is realized (<NUM> rpm), the rotational frequency is <NUM>.

Accordingly, in the case of a rotatable display device having a single-shaft support structure, the primary natural frequency overlaps or is similar to the rotational frequency band of the rotatable display device, and accordingly, vibration and noise may be increased due to a resonance phenomenon. As a result, the quality of the product may be significantly deteriorated due to the occurrence of image shaking.

Meanwhile, referring to <FIG>, it can be seen that the rotatable display device according to the embodiment of the present disclosure has a primary natural frequency of <NUM> (G2). In addition, although not shown in <FIG>, a secondary natural frequency thereof is about <NUM>.

That is, it can be confirmed that, when the configuration of the rotatable display device is changed from the single-shaft support structure to the double-ended support structure of the present disclosure, the natural frequency can be increased twofold or greater, i.e. to <NUM> or greater.

Therefore, embodiments disclosed in the present disclosure are not intended to limit the technical idea of the present disclosure, but to describe the same, and the scope of the technical idea of the present disclosure is not limited by such embodiments.

The scope of protection of the present disclosure should be interpreted by the claims below, and all technical ideas within the scope equivalent thereto should be construed as being included in the scope of the present disclosure.

Claim 1:
A rotatable display device using a light-emitting element, the rotatable display device comprising:
a fixed portion (<NUM>) comprising a motor (<NUM>);
a rotary portion (<NUM>) located on the fixed portion (<NUM>) and comprising a first side coupled to the motor (<NUM>) and a second side rotatably coupled to a rotation coupling portion (<NUM>) so as to be rotated, the second side being opposite the first side; and
a light source module (<NUM>) mounted to the rotary portion (<NUM>) and comprising:
one or more panels (<NUM>, <NUM>) disposed at respective positions on a rotational circumference of the rotary portion (<NUM>); and
light-emitting element arrays (<NUM>, <NUM>) comprising individual pixels disposed along a longitudinal length of the one or more panels (<NUM>, <NUM>),
wherein the rotation coupling portion (<NUM>) comprises a rotary shaft (<NUM>) inserted into the second side of the rotary portion (<NUM>),
wherein the second side of the rotary portion (<NUM>) comprises a shaft-coupling portion (<NUM>) into which the rotary shaft (<NUM>) is inserted, and
wherein a shaft support portion (<NUM>) is located between the rotary shaft (<NUM>) and the shaft-coupling portion (<NUM>), the shaft support portion (<NUM>) including a bearing (<NUM>), and
wherein a shock-absorbing member (<NUM>) is located between the bearing (<NUM>) and the shaft-coupling portion (<NUM>).