Fingertip size projector into the field of vision"

OKI digital imaging (OKI Digital Imaging, referred to as ODI) announced by the semiconductor material into a film, "EFB technology using molecular force between non identical material firmly engaged (Epi Film Bonding)", the development of the image display device. The 2 new LED display. A LED component size is reduced to less than the original production level of high density. The other is to increase the number of LED components equipped to increase the size of the display, are arranged on the glass substrate with a two-dimensional array, the luminous wavelength of 650nm red LED components. The former is a high density product, which is expected to be used in front projection projector. In the future also plans to increase the blue and green LED components, I hope to be able to create a fingertip size projector (the company).

The advantage of EFB is that it can help to reduce the size of components and reduce the cost of the same kind of material, which can be joined by the molecular force. The specific application of the molecular force engagement is to paste the epitaxial growth layer of the compound semiconductor from the bottom plate and paste it onto the silicon substrate to form a whole with IC. Punch data has begun to use the technology mass production will be LED array and driver IC set in one of the LED print head, and is equipped with the company's A4 color LED printer "C3400n".

In order to apply the EFB technology to the image display device outside the LED print head, the digital image is developing LED display. At present, it has been tested on the display of a 300 m m square, a red LED (light emitting wavelength of 765nm) assembly on the glass substrate with a spacing of 600 mu. In order to realize the bendable display, the red LED component which is arranged on the resin (PET) base plate is arranged in a two-dimensional array.

Fingertip size projector into the field of vision

The newly developed high-density LED display will be reduced to only 20 m square LED components, and the configuration space from the original m to shorten the m to 42.3 mu. At present, only the use of red LED components, if the basis of this increase in blue and green LED components, and a two-dimensional array configuration of the product used as a light source, can also produce a fingertip size projector". Ideally, the image can be displayed only by the addition of an imaging optical system on the light source. If the development of ultra small projector is expected in the mobile phone and notebook computer equipped with.

To achieve this goal, it is necessary to develop a safe and reliable technology to peel off the green LED and blue LED. EBF technology is used to design the sacrificial layer between the substrate and the epitaxial layer to realize the easy peeling of the base plate and the epitaxial layer. The sacrificial layer affects the peeling effect. When the utility model is peeled off, wet etching is carried out on the sacrificial layer, and the epitaxial layer is attached to the supporting body. After etching, the sacrificial layer is easily dissolved.

At present, it has reached the practical level is the infrared and red LED components from the bottom plate technology. In the red LED, if the print head using near infrared LED, then on the GaAs substrate epitaxial growth of AlGaAs film, if the display is red LED, epitaxial growth of InGaAlP films. On the other hand, the blue LED and green LED with different materials with red LED. Blue and green LED components are mostly grown on sapphire substrate epitaxial GaN semiconductor. Therefore, it is necessary to change the sacrificial layer on the base plate to remove the epitaxial layer with the blue LED and the green LED.

On the size of the LED display, the number of components from the original 24 x 24 to an increase of 24 x 96. The size of the LED component is 300 m square, and the configuration space is the same as that of the original, both of which are 600 m. Through the 24 rows in a row and driven by the LED, the text can be displayed rolling. Power consumption of 0.2W. Brightness below 300cd/m2. The release of the two monitors are thick with a thickness of 2 m epitaxial layer and thick 1mm glass substrate.

Source: Nikkei BP