Light-emitting element matrix array

Electric lamp and discharge devices: systems – Plural power supplies – Plural cathode and/or anode load device

Reexamination Certificate

Rate now

  [ 0.00 ] – not rated yet Voters 0   Comments 0

Details

C257S088000

Reexamination Certificate

active

06590347

ABSTRACT:

TECHNICAL FIELD
This invention relates to a light-emitting element matrix array, particularly to a light-emitting element matrix array in which a light up state of light-emitting element may be controlled by a small control current.
BACKGROUND ART
In an light-emitting element array used in an optical printer, it is essentially required to derive the same number of lines from light-emitting elements as that of light-emitting elements. A wire bonding method is generally used for the derivation of lines. Therefore, the following problems are caused as the density of light-emitting elements is increased.
(1) A product cost becomes larger due to the increase of an area of a wire bonding pad on a light-emitting element array chip, i.e. an area of a chip.
(2) A production cost becomes larger due to the increase of the number of wire bondings.
(3) A production becomes difficult as a pitch of wire bonding becomes smaller.
(4) A product cost is increased because driving circuits, the number thereof is equal to that of light-emitting elements, are generally required.
An area of one bonding pad is several times or more compared with an area of one light-emitting element, so that the increase of light-emitting elements density leads to the increase of chip area.
In order to avoid these problems, a light-emitting element including a shift register, a light-emitting diode (LED) matrix array, and a light-emitting thyristor matrix array have been proposed heretofore.
The LED matrix array as shown in
FIG. 1
has resolved above-described problems by providing a plurality of light-emitting diodes in one line on an insulating substrate, and constituting a matrix with an anode side and a cathode side to decrease the number of terminals derived from the array.
In
FIG. 1
, one or more of light-emitting diodes L
1
, L
2
, L
3
, . . . may be lighted up by a combination of levels of anode electrodes A
1
-A
3
and levels of cathode-selecting lines K
1
-K
4
. When an anode electrode A
i
is at a High (H) level and a cathode selecting line K
j
a Low (L) level, a light-emitting diode L
j+4(i−1)
is lighted up. However, a current flows from an anode driver (not shown) to a cathode driver (not shown) through a light-emitting diode, so that both of drivers require a large current driving capacity, resulting in the cost increase of driver ICs.
In order to resolve this problem, a light-emitting thyristor matrix array using a light-emitting thyristor of pnpn-structure in place of a light-emitting diode has been proposed.
FIG. 2
shows the light-emitting thyristor matrix array. According to this matrix array, a plurality of light-emitting thyristors T
1
, T
2
, T
3
, . . . are arrayed in one line. These thyristors are divided into groups four by four. Anodes of thyristors in each group are commonly connected to anode terminals A
1
, A
2
, A
3
, . . . , respectively, gates of thyristors in each group are separately connected to gate-selecting lines G
1
-G
4
, and cathodes of all the thyristor are commonly connected to a cathode line K. The lighting up of thyristors T
1
, T
2
, T
3
, . . . is determined by a combination of levels of gate-selecting lines G
1
-G
4
and levels of anode terminals A
1
, A
2
, A
3
, . . . . As this matrix array is a type of cathode common, when the cathode line K is at L level and an anode terminal A
i
is at H level while one gate-selecting line G
j
being at L level and the others H level, a light-emitting thyristor T
j+4(i−1)
is lighted up.
The gate-selecting lines only give trigger signals, so that the lighting up of the thyristors may be controlled by a small current driving capacity. As a result, the cost of a driving IC may be decreased. For this matrix array using a light-emitting thyristor, Japanese Patent has already been issued to the present applicant (Japanese Patent No. 2807910).
However, there is a problem such that the product cost thereof is high because such thyristor uses a pnpn-structure.
DISCLOSURE OF THE INVENTION
The object of the present invention is to provide a light-emitting element matrix array in which a function equivalent to a light-emitting thyristor may be implemented by elements different therefrom.
According to the present invention, a function of a light-emitting thyristor may be implemented by a combination of a transistor and light-emitting diode (LED). In this case, an LED may be fabricated by emitter and base layers or base and collector layers of a transistor, so that the combinational element of a transistor and an LED may be implemented from a three-layer structure of npn or pnp. Therefore, the thickness of an epitaxial film becomes thinner compared with a light-emitting thyristor of a four-layer pnpn-structure, resulting in a low cost of products.
Furthermore, a light-emitting element matrix array in which a light up state of light-emitting element may be controlled by a small control current may be implemented by integrating transistors and LEDs in the same wafer. Accordingly, the number of terminals derived from a light-emitting element matrix array chip may be decreased, thereby reducing an area of the chip. As a result, a high resolution light-emitting element matrix array may be easily provided.


REFERENCES:
patent: 5408105 (1995-04-01), Adachi et al.
patent: 5483085 (1996-01-01), Holm et al.
patent: 0335553 (1989-10-01), None
patent: 0683528 (1995-11-01), None
patent: 60-201382 (1985-10-01), None
patent: 1-178471 (1989-07-01), None
patent: 3-83377 (1991-04-01), None
patent: 4-7165 (1992-01-01), None
patent: 4-11449 (1992-01-01), None
patent: 5-131681 (1993-05-01), None
patent: 5-212905 (1993-08-01), None
patent: 6-71938 (1994-03-01), None
T. Kawase et al.; “Properties of 6-inch Semi-insulting GaAs Substrates Manufactured by Vertical Boat Method”; 1999; http://www.gaasmantech.org/digest/1999/PDF/66.pdf.
PCT International Search Report, Apr. 17, 2001.

LandOfFree

Say what you really think

Search LandOfFree.com for the USA inventors and patents. Rate them and share your experience with other people.

Rating

Light-emitting element matrix array does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Light-emitting element matrix array, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Light-emitting element matrix array will most certainly appreciate the feedback.

Rate now

     

Profile ID: LFUS-PAI-O-3049313

  Search
All data on this website is collected from public sources. Our data reflects the most accurate information available at the time of publication.