Sphere Led Screen P4 Globe Indoor Advertising LED Display with 360° Viewing Angle

Sphere LED Display Designing and Characteristics of P4 Indoor Globe Screen

   Sphere led display is introduced to the LED display market in recent years. There are three types of sphere led display. The designing and manufacturing of the three types of sphere led screen had been applied for patent in the related led companies. Some people even applied for PCT international patent.

Types of Sphere LED Display

I. Watermelon peel Sphere LED Display

   Watermelon-peel sphere led display appeared the earliest. It looks like pieces of watermelon peels. So we call it “Watermelon-peel Sphere LED Display”. Watermelon-peel sphere led display is made up of peel-like led modules. It looks displayed directly, and the types of PCBs are not too many. However, it has vital disadvantage that the south and north poles ( North of the northern latitude 45°& South of the southern latitude 45°) can’t display and the images showed on deformed seriously. Currently, all the pixels on the images are assigned in rows; but the pixels on both the North Pole and the South Pole are not assigned in rows; on the contrary, they are assigned in circle. Consequently, the pixels can’t be showed there.

II. Triangle Sphere LED Display

   Triangle sphere led display is made up of triangle modules. It looks like a football, so we also call it “Football Sphere Led Display”. It hits off the disadvantage that the South Pole and the North Pole can’t display images. Image occupation rate greatly increases. Disadvantages are that types of PCB are too many, pixel pitch can’t be too small and software programming is too complicated.

III. Hexahedron Sphere LED Display

   Appearing recently, hexahedron sphere led display is made up of quadrangle PCB. Its manufacturing is simple. Now we make an example with a 1.5m-diameters sphere screen:

1. Divide the sphere into 6 same surfaces;

2. Divide each surface into 4 same unit panels, totally there will be 24 panels;

3. Each unit panel is made up of 16 pieces of led modules;

4. At last, install them together into a complete hexahedron sphere led display;

   PCB types of hexahedron sphere led display are less than triangle sphere led display. The assignment of the pixel is as similar as surface led display. So the images and video sources that can be display on surface led display can also be display on the hexahedron sphere led display. Compared with watermelon-peel display and triangle display, the visual effect of hexahedron sphere led display is better than the above two types.

   The hexahedron sphere led display is made up with 6 same size and same shape surfaces; each surface is made up of 4 same size and same shape panels. So they can be put into flight case conveniently. Installation and dismantling become so easy. So it is commodious for rental business. In broadcasting, it can show one video source as a whole, such as the tellurion (the globe). It can also show 6 different or same video sources with the 6 surfaces; it can even show single video source or show union surfaces via software. This is pretty important for those spheres that have the diameters of more than 2 meters, as one person only can enjoy 1/6 of the whole sphere.

IV. Outdoor Sphere LED Display

   Outdoor sphere led display has the same theory as indoor sphere led display. The differences are that outdoor sphere led display not only needs waterproof function, but also it needs air-conditioner to decrease the inside temperature.

Characteristics of Sphere LED Screen

   The appearance of sphere led display is the result of development of people’s abnormal aesthetic. People were surprised when a giant TV --- a larger-sized surface led display appeared on the square in the earlier years. Now giant TV can’t meet people’s curiosities. Imaging that one day a 5m-diameter sphere led display appears on the public square, people will gather and it will become a hot-sell product. So, it will be an avant-garde and person-gathering product. The video sources that can be displayed on surface screens will be deformed when they are displayed on the sphere led display and all the flaws will be tolerated. It will be accepted by the people just as those images take by wide-angle lens or fish-eye camera will deform.

Broadcasting of Sphere LED Display

   Almost all the video sources in the world are surface video sources. It is nearly impossible to put surface video sources to the sphere led display without processing. As the sphere display is round, any audience can’t see all the details on the ball. He can only enjoy a small part of the ball. It is related to the diameter of the ball. If the ball was larger enough, it was about 1/6 of the ball surface area that people can notice (because of viewing angle). The left 5/6 of the ball surface area couldn’t seen by the person. The left parts are direct back, direct left and right, and direct roof and bottom.

Then, there will be several broadcasting methods:

1. six different of video sources can be broadcast on the 6 different parts;

2. three different of video sources can be broadcast on three different parts (the left and back; the roof and right; the front and bottom);

3. two different of video sources can be broadcast on the 2 different parts (the back, the right and the front; the roof, the left and the bottom);

4. Surely, one video source can be displayed on the whole area of the ball, just like watermelon-peel sphere led display.
 

Imaging Theory of Sphere LED Display

   The resolution of sphere led display is the same as surface led screen. It is closely related to the viewing distance. General speaking, if the display is P2.5, the best viewing distance is 2.5m and beyond; it is P6, the best viewing distance is 6m and beyond; if it is P20 outdoor led display, the best viewing distance will be 20m and beyond. It is the same in the reality world. It is a pretty fuzzy choice and it is qualitative rather than quantitative. The theory is in the following:

   Just like computer screen, the images showed by led display are made up of pixels. Each pixel includes red, green, and blue pixels. There will be distance between two nearest neighboring pixels. We call it “Pixel Pitch”. We set a resolution of 1024 x 768 to the computer, so there will be 1024 pixels on the horizontal directions and 768 pixels on the vertical directions. Then it is enough to express an image with full details.

   If the dimension of the vertical direct of the computer is 300mm, then the pixel pitch of the computer is: P=300/768=0.39mm; Pixel pitch is an important parameter to any digital displays.
 

   We test that the distance between one’s eyes and the screen of the computer is D=450mm, so the angle θ that between two neighboring pixels will be:

θ=Arctg0.39/450
 

   If we put the computer to a distance beyond 30, 000mm, and turn the computer into common led screen or sphere led display, then the distance that people see is 30, 000mm. As a result, in order to keep the resolution unchangeable (θ will not change), we have to change the pixel pitch.

   Since θ=Arctg0.39/450=ArctgPh/(30, 000+450), we conclude that PH=26.39. If the pixel pitch of the sphere led display was 15 to 20 mm, the sphere will be clear enough to show any detailed images. The visual effect of seeing a sphere led display in a 30m distance is the same as we see it on a HD computer. If the distance between people and sphere led display changes, we can calculate it out owing to the above method.
 

   For more details about sphere led display, please email us: info@ocolour.com.

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