Incremental printing of symbolic information – Light or beam marking apparatus or processes – Scan of light
Reexamination Certificate
1999-05-21
2003-09-23
Pham, Hai (Department: 2861)
Incremental printing of symbolic information
Light or beam marking apparatus or processes
Scan of light
C347S247000
Reexamination Certificate
active
06624838
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a control apparatus for controlling a semiconductor chip such as an LED array used as a recording light-emitting element, moreover to an image recording apparatus for forming a visible image on a recording medium through an electrophotographic recording system by using the semiconductor chip.
2. Related Background Art
A self-scanning LED array (hereafter referred to as SLED) has been used so far as a recording light-emitting element.
The self-scanning LED array is disclosed in Japanese Patent Application Laid-Open Nos. 1-238962, 2-208067, 2-212170, 3-20457, 3-194978, 4-5872, 4-23367, 4-296579, and 5-84971, JAPAN HARD COPY, proposal of optical-printer light-emitting array constituted by integrating 91 (A-17) driving circuit, and proposal of self-scanning light-emitting element (SLED) using the PNPN thyristor structure of IEICE (Institute of Electronics, Information and Communication Engineers), Mar. 5, 1990, and noticed as a recording light-emitting element. The configuration of an SLED array head will be described below.
FIG. 8
shows a schematic configuration of the SLED array head.
Symbol
211
denotes an SLED semiconductor chip. Symbol
212
denotes a base substrate for mounting the SLED semiconductor chip
211
, which is configured by a printed circuit board made of glass epoxy or ceramic. Symbol
214
denotes a driver IC for receiving a control signal from an external unit to generate a driving signal for the SLED semiconductor chip
211
.
Symbol
215
denotes a bonding wire for connecting output signals supplied from the driver IC
214
(&phgr;
1
, &phgr;
2
, &phgr;S, and &phgr;I) and a negative-electrode-side power-supply input (GND as for this embodiment) to the SLED semiconductor chip
211
respectively. Symbol
216
denotes a positive-electrode (+) power-supply pattern extended to the base substrate
212
(+5V as for this embodiment). Symbol
217
denotes silver paste for electrically connecting and bonding the positive-electrode-side power-supply pattern
216
extended to the base substrate
212
with the back-face electrode of the SLED semiconductor chip
211
to fix them.
The SLED semiconductor chip
211
frequently uses a method of using the substrate of a chip as an anode because anodes of a light-emission thyristor and a transfer thyristor both serve as a common line and thereby, serve a maximum operating-current route and due to electrical characteristics of P and N of a semiconductor (generally, GaAs semiconductor is used) and problems on fabrication process.
When using a method of using the substrate of a semiconductor chip as a power-supply input unit and connecting the back-face electrode of the semiconductor chip with the power-supply pattern of a base substrate by a conductive adhesive and fixing them, it is inevitable to use a material containing positive (+) metal ions (e.g. silver paste) in order to select a low-resistance material of a predetermined level as the conductive adhesive.
As for the SLED semiconductor chip
211
described above, however, a substrate normally serves as a positive electrode. The substrate is electrically connected with the power-supply pattern
216
of the base substrate
212
by the silver paste
217
through a back-face electrode or the like.
Therefore, an electric-field configuration is formed in which positive ions in the substrate-side silver paste
217
(conductive adhesive) are attracted to the epitaxial-layer side through a chip-side face or the like at a portion serving as a negative electrode in the signal input unit of the epitaxial-layer-side face of the SLED semiconductor chip
211
configuring as a circuit opposite to the substrate-side face of the SLED semiconductor chip
211
. The distance between the signal input unit on the epitaxial-layer-side face and the silver paste
217
at the substrate side is approximately 600 &mgr;m.
The attracted positive ions are deposited through reaction with other impurity ions. Therefore, if the deposition reaction continuously occurs, a short circuit is formed between the epitaxial-layer and the substrate due to reasonable elapse of time and thereby, the original operation of an SLED can not be performed.
Therefore, it is an object of the present invention to provide a high-reliability driving controller and image recording apparatus capable of preventing the probability of short circuits formed between electrodes.
SUMMARY OF THE INVENTION
It is an object of the present invention to solve the above problems.
That is, the present invention provides a control apparatus for controlling a semiconductor chip provided with an electrode on its back face and other faces and having a recording element to drive the recording element by connecting the electrode on the back face of the semiconductor chip to a base substrate by a conductive adhesive and inputting a power supply and a control signal to the semiconductor chip from the electrodes on the back face and other faces of the semiconductor chip, which comprises means for controlling portions between the electrode on the back face and the electrodes on the other faces of the semiconductor chip to a high impedance or the same potential in a predetermined period in which the recording element is not driven.
Moreover, the present invention provides a control apparatus for controlling a semiconductor chip provided with an electrode on its back face and other faces by connecting the electrode on the back face of the semiconductor chip to a base substrate by a conductive adhesive and inputting a power supply and a control signal to the semiconductor chip from the electrodes on the back face and other faces of the semiconductor chip, which comprises means for setting portions between the electrode on the back face and the electrodes on the other faces of the semiconductor chip to a high impedance or the same potential in a predetermined period in which the semiconductor chip is not driven.
Furthermore, the present invention provides an image recording apparatus for controlling a semiconductor chip provided with an electrode on its back face and other faces and having a recording element and recording an image on a recording medium to drive the recording element by connecting the electrode on the back face of the semiconductor chip to a base substrate by a conductive adhesive and inputting a power supply and a control signal to the semiconductor chip from the electrodes on the back face and other faces of the semiconductor chip, which comprises means for controlling portions between the electrode on the back face and the electrodes on the other faces of the semiconductor chip to a high impedance or the same potential in a predetermined period in which the recording element is not driven.
Furthermore, the present invention provides a control method for controlling a semiconductor chip provided with an electrode on its back face and other faces and having a recording element to drive the recording element by connecting the electrode on the back face of the semiconductor chip to a base substrate by a conductive adhesive and inputting a power supply and a control signal to the semiconductor chip from the electrodes on the back face and other faces of the semiconductor chip, which comprises the step of controlling portions between the electrode on the back face and the electrodes on the other faces of the semiconductor chip to a high impedance or the same potential in a predetermined period in which the recording element is not driven.
Furthermore, the present invention provides a control method for controlling a semiconductor chip provided with an electrode on its back face and other faces by connecting the electrode on the back face of the semiconductor chip to a base substrate by a conductive adhesive and inputting a power supply and a control signal to the semiconductor chip from the electrodes on the back face and other faces of the semiconductor chip, which comprises the step of setting portions between the electrode on the back face and
Sekiya Toshiyuki
Shiraishi Mitsuo
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