JPH0922268A - Optical device using self-scanning type light emitting element array - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical device using a light emitting element array having a self-scanning function. SOLUTION: The light emitting element array of a tight contact type image sensor which has an optical sensor formed on a glass substrate A1, is provided with a window A8 in the central part of the optical sensor and makes the light of the light emitting element array incident on the window via a rod lens A9, is the self-scanning type light emitting element array formed by one- dimensionally arranging the many light emitting elements electrically controllable in threshold voltages or threshold currents, connecting electrodes for electrically controlling the threshold voltages or threshold currents of the respective light emitting elements to each other by electrical means and connecting clock lines for impressing the voltages or currents from outside to the respective light emitting elements.

Description

Detailed Description of the Invention

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an optical device using a light emitting element array in which light emitting elements are integrated on the same substrate.

[0002]

2. Description of the Related Art As a typical light emitting element, an LED is used.
(Light Emitting Diode) and LD (Laser Diode) are known.

An LED is a compound semiconductor (GaAs, Ga
A PN or PIN junction (P, GaAlAs, etc.) is formed, a carrier is injected into the junction by applying a forward voltage to the junction, and a light emission phenomenon generated in the process of recombination is used.

The LD has a structure in which a waveguide is provided inside the LED. When a current higher than a certain threshold current is passed, the number of injected electron-hole pairs increases to form a population inversion state, photon multiplication (gain) occurs by stimulated emission, and parallel reflection using a cleavage plane or the like. The light generated by the mirror is returned to the active layer again, and laser oscillation occurs. Then, the laser light is emitted from the end face of the waveguide.

As a light emitting element having the same light emitting mechanism as these LEDs and LDs, a negative resistance element (light emitting thyristor, laser thyristor, etc.) having a light emitting function is also known. The light-emitting thyristor is a compound semiconductor having a PNPN structure as described above, and has been put into practical use as a thyristor in silicon (see “Light-Emitting Diode” Industrial Research Committee, edited by Shoji Aoki, pp. 167 to 169).

FIGS. 22 and 23 show the basic structure and current-voltage characteristics of a negative resistance element having this light emitting function (herein referred to as a light emitting thyristor). The structure shown in FIG. 22 is obtained by forming a PNPN structure on an N-type GaAs substrate, and has exactly the same structure as a thyristor. FIG. 23 similarly shows the same S-shaped negative resistance as the thyristor. As the thyristor, not only the two terminals shown in FIG. 22 but also a three terminal thyristor shown in FIG. 24 is known. The gate of the three-terminal thyristor has a function of controlling the ON voltage, and the ON voltage is a voltage obtained by adding a diffusion potential to the gate voltage. After being turned on, the gate electrode becomes substantially equal to the cathode voltage. If the cathode electrode is grounded, the gate electrode will be at zero volts. Further, it is known that the threshold voltage of the light emitting thyristor is lowered when light is incident from the outside.

Further, a laser thyristor can be formed by providing a waveguide in the light-emitting thyristor and using the same principle as that of the LD (Tashiro et al., 1987 Autumn Applied Physics Conference,
No. 18p-ZG-10).

[0008] A large number of such light-emitting elements, particularly LEDs, are produced on a compound semiconductor substrate, cut, packaged and sold as individual light-emitting elements. The LED used as the light source for the contact image sensor and the printer is a LE with multiple LEDs arranged on one chip.
Sold as D-array.

[0009]

On the other hand, in a contact type image sensor, an LED printer, and the like, a scanning function (light scanning function) of a light emitting point by these light emitting elements is required in order to designate a reading point and a writing point.

However, in order to perform optical scanning using these conventional light emitting elements, each LED made in the LED array is connected to a driving IC by a technique such as wire bonding. It was necessary to drive each LED by an IC. For this reason, when the number of LEDs is large, the same number of wire bondings are required, and a large number of drive ICs are required, resulting in high costs. In addition, it is necessary to secure a space for installing the drive IC, which causes a disadvantage that it is difficult to reduce the size. Also, the pitch at which the LEDs are arranged is determined by the wire bonding technique, and there is a disadvantage that it is difficult to reduce the pitch.

An object of the present invention is to provide a contact-type image sensor, an optical printer, and a light-emitting device array using a light-emitting device array (hereinafter referred to as a self-scanning light-emitting device array) in which such drawbacks are improved.
An object of the present invention is to provide an optical device such as a display.

[0012]

According to the present invention, an optical sensor is formed on a glass substrate, a window is provided at the center of the optical sensor, and a light emitting element array is incident on this window through a rod lens. In the contact-type image sensor, the light-emitting element array has a plurality of light-emitting elements whose threshold voltage or threshold current can be externally controlled by light and is arranged one-dimensionally, and at least one of the light emitted from each light-emitting element is arranged. Is a self-scanning light-emitting element array in which a clock line for applying a voltage or current from the outside is connected to each light-emitting element. Alternatively, in the light emitting element array, a large number of light emitting elements whose threshold voltage or threshold current can be electrically controlled from the outside are arranged one-dimensionally,
A self-scanning light-emitting element array in which electrodes for controlling a threshold voltage or a threshold current of each light-emitting element are connected to each other by electric means, and a clock line for externally applying a voltage or current is connected to each light-emitting element. It is characterized by being.

Further, the present invention is an optical printer in which light is emitted from a light emitting element array to a photosensitive drum via a rod lens array. In the light emitting element array, a threshold voltage or a threshold current can be externally controlled by light. A large number of light emitting elements are arranged in a one-dimensional manner, and at least a part of light emitted from each light emitting element is configured to be incident on another light emitting element near each light emitting element. A self-scanning light-emitting element array connected to a clock line for applying a voltage or current, or the light-emitting element array is a light-emitting element whose threshold voltage or threshold current can be electrically controlled from the outside. A large number of elements are arranged one-dimensionally, and the electrodes for controlling the threshold voltage or the threshold current of each light emitting element are connected to each other by electrical means, and each light emitting element is connected. Characterized in that the external is a self-scanning type light-emitting element array are connected to clock lines for applying a voltage or current.

Further, according to the present invention, a large number of light emitting elements whose threshold voltage or threshold current can be externally controlled by light are arranged one-dimensionally, and at least a part of the light emitted from each light emitting element is A display in which a plurality of self-scanning light-emitting element arrays, which are configured to be incident on other light-emitting elements in the vicinity of the light-emitting element and which are connected to a clock line for externally applying a voltage or current to each light-emitting element, are arranged in a plane. Alternatively, a number of light-emitting elements whose threshold voltage or threshold current can be electrically controlled from the outside are arranged one-dimensionally, and electrodes for controlling the threshold voltage or threshold current of each light-emitting element are arranged. A self-scanning light-emitting element array in which each light-emitting element is connected to each other by an electric means and a clock line for applying a voltage or a current from the outside is connected to each light-emitting element,
It is a display in which a plurality is arranged in a plane.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS First, various examples of a self-scanning light emitting element array used in the optical device of the present invention will be described.

Example A The self-scanning light emitting element array of Example A described herein utilizes light as a medium for interaction.

Example A-1 FIG. 1 shows an equivalent circuit diagram of the principle of the self-scanning light emitting element array of Example A-1. This shows the case where the most standard three-terminal light-emitting thyristor is used as an example of a light-emitting element whose light-emitting threshold voltage and current can be externally controlled.

The light-emitting thyristors T _{(-2) to} T ₍₊₂₎ are arranged in a line. Three transfer clock lines (φ ₁ , φ ₂ , φ
₃ ) are connected every third element (as repeated). As described in the conventional example, the light-emitting thyristor has a characteristic that the turn-on voltage is reduced when light is sensed. When the light-emitting thyristors are configured so that light emitted from the light-emitting thyristors is incident on each other, the turn-on voltage of an element that is close to the light-emitting element in a distance or an element that is arranged so as to be exposed to light is reduced.

The operation of the equivalent circuit diagram of FIG. 1 will be described. Now, assume that the high level pulse voltage is applied to the transfer clock line φ ₃ and the light emitting thyristor T ₍₀₎ is in the ON state. Light emitted from the light emitting thyristor T ₍₀₎ is incident on the adjacent light emitting thyristors T _(-1) and T ₍₊₁₎ , and the ON voltage of these light emitting thyristors is lowered. Light-emitting thyristors T _(-2) , T _(+
2) is farther than the light emitting thyristors T _(-1) and T ₍₊₁₎ , so that the incident light is weak and the ON voltage does not decrease so much. In this state, then applies a high-level pulse voltage to the clock line phi _1. The light-emitting thyristor T ₍₊₁₎ of the ON voltage light-emitting thyristor T _{(- 2)} Due to the decrease in the influence of light than the ON voltage of the light-emitting thyristor T ₍₊₁₎ ON voltage of the light-emitting thyristor T _{(-2 If} the high-level voltage of the transfer clock is set to a voltage between the ON voltages of _{(1) and (2)} , only the light-emitting thyristor T ₍₊₁₎ can be turned on and the light-emitting thyristor T _(-2) cannot be turned on. Therefore, the light emitting thyristors T ₍₊₁₎ and T ₍₀₎
Are turned on at the same time. Then, when the clock line φ ₃ is dropped to a low level voltage, the light emitting thyristor T
₍₀₎ is turned off, and only the light emitting thyristor T _{(+1 )} is turned on. Thus, the transfer in the ON state has been performed.

From the principle described above, if the high level voltages of the transfer clocks φ ₁ , φ ₂ , and φ ₃ are set so as to overlap each other in order, the ON states of the light emitting elements are sequentially transferred. . That is, the light emitting points are sequentially transferred.

According to this example, it is possible to realize a self-scanning type light-emitting element array which has not been conventionally possible.

<Example A-2> In Example A-1, an equivalent circuit of the self-scanning light emitting element array was shown and described. In Example A-2, the light emitting element array of Example A-1 was integrated. The configuration will be described.

FIG. 2 shows a conceptual diagram of the structure of this embodiment. A p-type semiconductor layer (23) on a grounded n-type GaAs substrate (1),
Each layer of an n-type semiconductor layer (22) and a p-type semiconductor layer (21) is formed. Then, the individual light emitting elements T ₍ −2 _{) to} T ₍₊₁₎ are separated by photolithography and etching. The electrode (40) is in ohmic contact with the p-type semiconductor layer (21), and the insulating layer (30) acts as a protective film for preventing a short circuit between the element and the wiring and at the same time preventing characteristic deterioration. Here, the insulating layer (30) is made of a material through which light having the emission wavelength of the light emitting thyristor passes.

The p-type semiconductor layer (21) is the anode of the thyristor, and the n-type GaAs substrate (1) is the cathode. Three transfer clock lines (φ ₁ , φ ₂ , φ ₃ ) are connected to the anode electrode (40) of each single light emitting element, respectively.
Connected every other element.

It is generally known that the ON voltage of the light emitting thyristor changes depending on the amount of light incident on the element.
Therefore, if a part of the light of the ON light emitting thyristor is configured to be incident on the adjacent light emitting thyristor, the ON voltage of the light emitting thyristor close to the ON light emitting thyristor is reduced as compared with the case where there is no light.

In the structure shown in FIG. 2, since the insulating layer (30) is formed of a film transparent to the emission wavelength, light can easily enter an adjacent element and lower its ON voltage.

The operation of the light emitting element array is exactly the same as the operation described in Example A-1.

From the above-described principle, if the high level voltages of the transfer clocks φ ₁ , φ ₂ , φ ₃ are set so as to slightly overlap each other in order, the ON state of the light emitting thyristor is sequentially transferred. . That is, the light emitting points are sequentially transferred. According to this example, it is possible to realize a self-scanning light-emitting element array by integrated optical coupling, which has not been conventionally possible.

<Example A-3> This example shows the actual structure of Example A-2.

FIG. 3 is a plan view of this embodiment, and FIGS. 4 and 5 are sectional views taken along lines XX 'and YY' of FIG. 3, respectively. Between each of the light emitting elements T _{(-2) to} T ₍₊₁₎ , there is a light emitting element separation groove (50), and light from the light emitting element is located in a part of the separation groove (50). A light barrier (61) for preventing the light from entering other elements is provided.

In this example, the field (60) is used as a light barrier.
Although the protrusion is used, another substance may be used and the shape may be another shape. Contact holes C ₁ to the electrode of the light emitting element is provided, is electrically connected to the electrode (40). Contact holes C ₂ are electrodes (40) and the transfer clock lines phi _1, phi _2, a through hole for connection to the phi _3.

The transfer clock line φ ₁ is connected to the light emitting element T ₍₋₂₎
And T ₍₊₁₎ , the transfer clock line φ ₂ is connected to the light emitting element T ₍₋₁₎ , and the transfer clock line φ ₃ is connected to the light emitting element T
Connected to ₍₀₎ .

FIG. 4 is a sectional view taken along line XX 'of FIG. This is a line cut in the arrangement direction of the light emitting element array, and it can be seen that each light emitting element is arranged. An insulating film (30) for preventing a short circuit between the light emitting element and the electrode (40) and an interlayer insulating film (31) for preventing a short circuit between the electrode (40) and the transfer clock line are provided in the separation groove (50) of the light emitting element. ). These insulating films (30) and (31) are made of a translucent insulating film so as not to prevent optical coupling between elements. Alternatively, an insulating film which appropriately absorbs light so that optical coupling between elements can be adjusted may be used. Furthermore, an insulating film that appropriately absorbs light and a translucent insulating film may be used by adjusting their film thicknesses appropriately. With such a configuration, optical coupling between elements becomes possible, and transfer operation (optical scanning operation) can be performed.

FIG. 5 is a sectional view taken along the line YY 'of FIG. This is a line cut perpendicularly to the arrangement direction of the light emitting element array, and the connection status of wiring and electrodes can be seen. The extraction contact hole C ₁ and the upper electrode of the light emitting element provided in the insulating film (30), taken out by the electrode (40). And is connected through a transfer clock lines phi ₃ and the through hole in the field.

Manufacturing steps for realizing the self-scanning light emitting element array include the following steps.

First, n-type GaAs is formed on an n ^{+ -type} GaAs substrate.
Layer (24b), n-type AlGaAs layer (24a), p-type G
aAs layer (23), n-type GaAs layer (22), p-type Al
A GaAs layer (21b) and a p-type GaAs layer (21a) are sequentially stacked to form a film (epitaxial growth). Next, an isolation groove (50) is formed using a photo-etching method. Thereafter, an insulating film (30) is formed and a contact hole (C ₁ ) is formed.
Is formed using a photo-etching method. Next, a metal for an electrode is formed by a vapor deposition method or a sputtering method, and an electrode (40) is formed by a photoetching method. Further an interlayer insulating film (31), a through hole is formed (C ₂₎ using a photoetching method. Then, a wiring metal is formed by vapor deposition or sputtering, and transfer clock lines (φ ₁ , φ ₂ , φ ₃ ) are formed by photoetching.
Through the above steps, the structure of this example is completed.

Although not particularly described in the present embodiment, a light-transmitting protective film may be provided on the transfer clock line, and the thickness of the insulating film is increased, the light transmittance is deteriorated, and the amount of light that can be extracted to the outside is reduced. If dislike, part or all of the upper insulating film of the light emitting element may be removed by a method such as a photoetching method.

According to this example, an integrated self-scanning light emitting device array can be manufactured.

<Example A-4> Examples A-2 and A-3 are examples in which a light emitting thyristor is considered as a light emitting element. However, the present invention is not limited to this, and other types of light emitting elements may be used. Is also good.

As an example, this embodiment describes a case where a laser thyristor is used.

FIG. 6 is a sectional view showing a configuration in which a laser thyristor is used as a light emitting element. Each light emitting element (laser thyristor) T _{(-1) to} T ₍₊₁₎ is formed with the following configuration. On an n-type GaAs substrate (1), an n-type AlGaAs (2
5), p-type AlGaAs (24), I-type (non-doped)
GaAs (23), n-type AlGaAs (22), p-type A
1GaAs (21) is sequentially laminated, and n-type Al
The layers of GaAs (21) and p-type AlGaAs (22) are processed as shown. This is the same as the shape of a laser diode having a stripe shape. This n-type AlGaAs
The width of (21) and a part of the p-type AlGaAs (22) were set to 10 μm or less. Other parts are the same as those in FIGS.

The operation of the laser thyristor is the same as that of a normal light emitting thyristor until the laser oscillation current is reached, and light emission by a current component equal to or smaller than the laser oscillation current is emitted. The laser beam exits perpendicularly to the plane of FIG. Therefore, laser light does not contribute to optical coupling, and only light emission by a current component equal to or less than the laser oscillation current contributes to optical coupling. The other mechanism of the transfer operation is the same as in Example A-2.

According to this embodiment, a self-scanning semiconductor laser array can be constructed.

<Example A-5> FIGS. 7 and 8 show Example A-5. This shows a more realistic structure of the self-scanning semiconductor laser array of Example A-4. FIG. 7 is a plan view, and FIG. 8 is a sectional view taken along line XX 'in FIG. The manufacturing method of this example will be outlined. n-type G
n-type AlGaAs (25), p-type AlGaAs (24), I-type (non-doped) GaAs on an aAs substrate (1)
(23), n-type AlGaAs (22), p-type AlGaAs
s (21) and the upper electrode (20) are sequentially laminated (p-type A
In some cases, a p-type GaAs layer is interposed between the lGaAs (21) and the upper electrode (20) to improve ohmic contact. ). Next, the upper electrode (20) is formed by photoetching.
Is processed into a rectangle having the same width as the width of the n-type AlGaAs layer (25) in FIG.
The layer of s (21) to n-type AlGaAs (25) is etched. At this time, an isolation groove (50) between the elements is formed. Next, the same upper electrode (20) is further etched by photoetching to form a stripe having a width of 10 μm or less, and using this as a mask, p-type AlGaAs (2
1) Etch the n-type AlGaAs (22) layer. The n-type AlGaAs (22) is not removed completely but partially left. An insulating film (30) is deposited to form a through-hole (C ₂₎ by photoetching. Thereafter, a wiring metal for a transfer clock line is formed by vapor deposition or sputtering, and transfer clock lines (φ ₁ , φ ₂ , φ ₃ ) are formed by photoetching. Finally, the end face on the laser beam output side is formed with good parallelism by a method such as cleavage, and the structure of this example is completed.

A conventional integrated light emitting element array has a P
N-junction diodes are independently formed on the same substrate, taken out one by one using wire bonding, etc., and operated by applying a voltage with a driving IC, which makes assembly of wire bonding etc. troublesome. The cost was high. On the other hand, in the self-scanning light emitting element array of this embodiment, only three terminals of the transfer clock need to be taken out to the outside, and the assembly is considerably simplified. At the same time, a space for providing the drive IC is not required, and a more compact self-scanning light emitting element array can be manufactured as a whole. Further, the pitch at which the light emitting elements are arranged is conventionally determined from the bonding technique. However, according to Examples A-1 to A-5 described above, the regulation is eliminated, and a light emitting element array with a smaller pitch can be produced, and the resolution can be reduced. Applicable to very high equipment.

In the above Examples A-1 to A-5, the transfer clock
Φ₁ , Φ_Two , Φ _Three Assuming three phases
However, when a more stable transfer operation is required, this is set to four phases.
It may be increased to five phases. Light emitting thyristor T₍₀₎ of
Light emitting thyristor T_(-1)More light emitting thyristor T₍₊₁₎
To the two-phase clock
It is also possible to operate.

In the above example, the light-emitting thyristor has the simplest structure. However, a more complicated structure and layer structure can be introduced to increase the light-emitting efficiency. A specific example thereof is the adoption of a double hetero structure. An example is shown in FIG. 21 (Tashiro et al., Lecture by the Society of Applied Physics, Spring 1987, number 28p-ZE-8). In this method, an n-type GaAs layer (0.5 μm) is stacked on an n-type GaAs substrate, and an n-type AlGaAs having a wide band gap is formed thereon.
(1 μm), p-type GaAs layer (5 nm), n-type GaAs
Layer (1 μm), wide bandgap p-type AlGaAs
(1 μm) and a p-type GaAs layer (0.15 μm) for ohmic contact with the extraction electrode. The light-emitting layer is sandwiched between n-type (1 μm) G
aAs layer. This is because the injected electrons and holes are confined in the GaAs layer with a narrow band gap, and recombine in this region to emit light.

The light emitting element does not need to be a light emitting thyristor, and is not particularly limited as long as the light emitting element changes its turn-on voltage by light. The laser thyristor described above may be used.

In the above example, a PNPN thyristor configuration has been described as an example. However, a configuration in which a threshold voltage is reduced by this light and a transfer operation is performed using the threshold voltage is as follows.
The element is not limited to the PNPN configuration, and is not particularly limited as long as it is an element that can achieve the function. For example, a similar effect can be expected with a configuration of six or more layers instead of a PNPN four-layer configuration.
It is possible to achieve exactly the same self-scanning function.
The same is true even when a thyristor called an electrostatic induction (SI) thyristor or an electric field control thyristor (FCT) is used. This SI thyristor or FCT has a structure in which a central p-type semiconductor layer serving as a current block is replaced by a depletion layer (SM Sze, Phys.
ics of Semiconductor Physs
ics, 2nd Edition pp. 238-24
0).

Further, in the above-mentioned Examples A-1 to A-5, the light emitting elements are arranged in a line, but the arrangement is not required to be linear and may be meandered depending on the application, or may be increased to two or more rows from the middle. It is also possible.

The self-scanning light-emitting element array described above
The light emitting element may be constituted by a single individual component, or may be realized by integration by some method.

Example B Example B of the self-scanning light emitting element array described here utilizes a potential as a medium for interaction.

<Example B-1> Example A shown in FIGS.
-1 to A-5 relate to the case where the coupling by light is used, but in this example, the coupling by electric potential is used.

As a specific example, FIG. 9 shows an equivalent circuit diagram of Example B-1. The feature of this example is Example A-1, that is, FIG.
And a resistance network.

As an example of the light emitting element, a light emitting thyristor T
_{Using (-2) to} T ₍₊₂₎ , the light emitting thyristors T _{(-2) to} T ₍₊₂₎ are provided with gate electrodes G _{-2 to} G ₊₂ , respectively. A power supply voltage V _GK is applied to each gate electrode via a load resistor _RL . Further, the respective gate electrodes G _{-2 to} G ₊₂ are electrically connected to each other through a resistor R _I to make an interaction. Resistor network with resistor R _L and resistor R _I is formed. Also, three transfer clock lines (φ ₁ , φ ₂ , φ ₃ ) are connected to the anode electrode of each single light emitting element every three elements (in a repetitive manner).

The operation will be described. First, the transfer clock φ_Three 
Becomes high level, and the light emitting element T_{(0 )} Is ON
I do. At this time, due to the characteristics of the three-terminal thyristor,
Pole G ₀ Is reduced to near zero volts (silicon
In the case of an iristor, it is about 1 volt). Power supply voltage V_GKTo
Assuming 5V, the load resistance R_L , Resistance R_I Network
The gate voltage of each light emitting thyristor is determined from the peak. Soshi
Light emitting element T₍₀₎ The gate voltage of the element close to
And then T₍₀₎ Gate voltage increases as the distance from
I will do it. This can be expressed as:

V _G0 <V _G1 = V _G−1 <V _G2 = V _G−2 (1) The difference between these voltages is set by appropriately selecting the values of the load resistances R _L and R _I. be able to.

It is known that the turn-on voltage V _ON on the anode side of the three-terminal thyristor is higher than the gate voltage by the diffusion potential V _df .

V _ON ≈V _G + V _df (2) Therefore, the voltage applied to the anode is the turn-on voltage V _ON.
If it is set higher, the light emitting thyristor is turned on.

By the way, this T₍₀₎ When is ON, next
Transfer clock pulse φ₁ High-level voltage V_H Apply
I do. This clock pulse φ₁ Is the light emitting element T₍₊₁₎And T
_(-2)At the same time, but the high level voltage V_H The value of
When set in the range, the light emitting element T ₍₊₁₎Only turn on
Can be.

V _G−2 + V _df > V _H > V _{G + 1} + V _df (3) The light emitting elements T ₍₀₎ and T ₍₊₁₎ are simultaneously turned on. And would turn off the high-level voltage of the clock pulse phi ₃ light-emitting element T ₍₀₎ is able to OFF, the ON state transfers.

As described above, in this embodiment, the light emitting element can have a transfer function by connecting the gate electrodes of the respective light emitting thyristors by the resistance network.

From the above-described principle, if the high-level voltages of the transfer clocks φ ₁ , φ ₂ , φ ₃ are set so as to slightly overlap each other in order, the ON state of the light emitting elements is sequentially transferred. . That is, the light emitting points are sequentially transferred. According to this example, it is possible to realize a self-scanning type light-emitting element array that has not been conventionally possible.

<Example B-2> Although the equivalent circuit is shown and described in the example B-1, the structure in the case where the self-scanning light emitting element array of the example B-1 is formed by integration is described in the example B-2. Things.

FIG. 10 shows a schematic diagram of the structure of the self-scanning light-emitting element array of this example. An N-type semiconductor layer (24) and a P-type semiconductor layer (2) are formed on a grounded N-type GaAs substrate (1).
3), N-type semiconductor layer (22) and P-type semiconductor layer (21) are formed. Then, the individual light emitting elements T _{(-1) to} T ₍₊₁₎ are separated by photolithography and etching (separation groove (50)). The anode electrode (40) has ohmic contact with the P-type semiconductor layer (21), and the gate electrode (41) has ohmic contact with the n-type semiconductor layer (22). The insulating layer (30) is a protective film for preventing a short circuit between the element and the wiring and, at the same time, preventing characteristic deterioration. Insulation layer (3
For 0), it is desirable to use a material through which light having the emission wavelength of the light-emitting thyristor passes well. The N-type GaAs substrate (1) is the cathode of this thyristor. Three transfer clock lines (φ ₁ , φ) are connected to the anode electrode (40) of each single light emitting element.
₂ and φ ₃ ) are connected every third element. Further, a resistance network composed of a load resistance R _L and an interaction resistance R _I is connected to the gate electrode.

Here, if the optical coupling as described in Example A occurs, it is considered that the transfer operation of this example is affected. Therefore, a part of the gate electrode is inserted into the separation groove between the light emitting elements. , To prevent optical coupling.

The configuration of this example is exactly the same as the equivalent circuit shown in Example B-1 (FIG. 9), and operates exactly the same. Therefore, if the high-level voltages of the transfer clocks φ ₁ , φ ₂ , φ ₃ are set so as to slightly overlap each other in order, the ON state of the light emitting thyristor is sequentially transferred. That is, the light emitting points are sequentially transferred.

<Example B-3> The self-scanning light emitting element array of Example B-3 is shown in FIGS. This example shows a practical structure of the self-scanning light-emitting element array of Example B-2. FIG. 11 is a plan view of this example, and FIG.
FIG. 13 is a cross-sectional view taken along line XX ′ and YY ′ in FIG.

Each of the light emitting elements T _{(-1) to} T ₍₊₁₎ , the separation groove (50) of the light emitting element, the field (60) and the like are the same as those in the above-described example. The resistance (63) forms a resistance network connecting the respective gate electrodes. Further, the light from the light emitting element is prevented from entering the resistor (63) by the light absorbing block (62). In this example, a part of the field 60 is used as a light barrier, but another material may be used, and the shape may be different. The upper electrode of the light emitting element, through extraction contact hole C _1, is taken out by the electrode (40). Electrode (40) and the transfer clock lines φ _1, φ _2, connected to the phi ₃ is performed using a through hole C _2. Clock line φ ₁ is light emitting element T _(-2)
And T ₍₊₁₎ , the clock line φ ₂ is connected to the light emitting element T ₍₋₁₎ , and the clock line φ ₃ is connected to the light emitting element T ₍₀₎ . Resistance (63) is extracted to the outside using the contact hole C _3.

FIG. 12 is a sectional view taken along line XX 'of FIG. This is a line cut in the arrangement direction of the light emitting element array, and it can be seen that each light emitting element is arranged. Light-emitting element separation groove (50), light-emitting element and electrode (40) (4
There is an insulating film (30) for preventing short circuit with 1), and an electrode (4)
The interlayer insulating film (31) for preventing short-circuit between 0) and the transfer clock line and the like are the same as in the above-described example. These insulating films (30) and (31) need to be translucent insulating films so that light can be effectively extracted to the outside. In this case, it is effective to insert the gate electrode (41) in the separation groove to block the light in order to eliminate the influence of the optical coupling on the transfer operation as described above.

FIG. 13 is a sectional view taken along line YY 'of FIG.
The figure is shown. This is perpendicular to the light emitting element array direction.
This indicates the connection status of wiring and electrodes. Departure
Contact hole C for taking out from upper electrode of optical element₁ Abstain
Provided on the rim membrane (30) and taken out with the electrode (40)
You. Then, on the field 60, the transfer clock line φ
_Three And through a through hole. Also resistance net
In this example, as a resistance for the work, an n-type semiconductor layer (2
2) is used. Of course, this is another layer
In addition, without using a semiconductor layer, another species
A similar type of film may be formed.

The gate electrode (41) is designed to enter the separation groove so that light from the light emitting element does not affect the resistance value of the resistor (63).

The following steps can be cited as manufacturing steps for realizing this embodiment.

First, n⁺ N-type G on GaAs substrate (1)
aAs layer (24b), n-type AlGaAs layer (24a),
p-type GaAs layer (23), n-type GaAs layer (22), p-type
-Type AlGaAs layer (21b), p-type GaAs layer (21b)
a) are sequentially laminated to form a film (epitaxial growth).
Next, an isolation groove (50) is formed using a photo-etching method.
I do. And by photo-etching using another mask,
A part of the light emitting element and a p-type GaAs layer (21
a) The p-type AlGaAs layer (21b) is removed. this
Thereafter, an insulating film (30) is formed, and the contact hole (C₁ ),
(C_Three ) Is formed using a photo-etching method. next,
A metal for electrodes is deposited by vapor deposition or sputtering, and
The electrodes (40), (41) and (42) are formed by etching.
Form. Further, an interlayer insulating film (31) is formed,
Through holes (C _Two ) Is formed.
Then, a metal for wiring is formed by vapor deposition or sputtering.
Then, the transfer clock line (φ
₁ , Φ_Two , Φ_Three ) Is formed. With the above steps, this example
The structure of the self-scanning light-emitting element array is completed.

Although not particularly described in the present embodiment, a light-transmitting protective film may be provided on the transfer clock line, and the thickness of the insulating film may be increased to reduce the light transmittance and reduce the amount of light that can be extracted to the outside. If dislike, part or all of the upper insulating film of the light emitting element may be removed by a method such as a photoetching method.

<Example B-4> Examples B-2 and B-3 are examples in which a light-emitting thyristor is considered as a light-emitting element. However, the present invention is not limited to this. Is also good. In this example, a case where a laser thyristor is used will be described as an example.

FIG. 14 shows the self-scanning light-emitting element array of Example B-4. FIG. 14 shows a plan view, and FIG.
3 is a sectional view taken along line XX ′ of FIG.

Single light emitting element (laser thyristor) T _(-1)
Numbers such as ~ T ₍₊₁₎ are the same as in the above example. A method for manufacturing the self-scanning light-emitting element array in FIG. 14 will be outlined. n-type GaAs
n-type AlGaAs (25), p-type Al on s substrate (1)
GaAs (24), I-type (non-doop) GaAs (2
3), n-type AlGaAs (22), p-type AlGaAs
(21), upper electrode (20) is sequentially laminated (p-type Al
A p-type GaAs layer may be interposed between the GaAs (21) and the upper electrode (20) in order to improve the ohmic contact. Next, the upper electrode (20) is processed into a rectangle having the same width as the n-type AlGaAs (25) layer in the figure by photoetching, and using this as a mask, the p-type AlGaAs is formed.
(21) to n-type AlGaAs (25) layers are etched. At this time, an isolation groove (50) between the elements is formed.
Next, the same upper electrode (20) is further etched by photoetching to form a stripe having a width of 10 μm or less, and using this as a mask, p-type AlGaAs (2
1) Etch the n-type AlGaAs (22) layer. The n-type AlGaAs (22) layer is not removed completely but partially left. Further, the insulating films (30c) (30b) (3
0a) is formed. Here, the three types of insulating films are composed of an insulating film (30c) (30a) and a light shielding film (3).
0b), which has two functions of insulation and light shielding. This is because when an SiO ₂ film is used as the insulating film, the emission wavelength of GaAs is 870 nm.
This may cause optical coupling due to the transmission of light, and a light-shielding film (30b) made of a light-absorbing material such as amorphous silicon must be provided between them. Needless to say, if a substance having both functions of insulation and light shielding is used, only one layer is required. Next, a contact hole (C ₁ ) is provided by photoetching, a resistor (63) is formed thereon, and photoetching is performed. Further an interlayer insulating film (31), the through-holes (C ₂₎ is formed by photoetching. At this time, the through-hole on the resistor (63) may be removed only by the insulating film (31), but the through-hole on the upper electrode (20) is removed simultaneously with the insulating film (31).
c) Care must be taken because (30b) and (30a) also need to be removed. Thereafter, a wiring metal for the transfer clock line is formed by vapor deposition or sputtering, and the transfer clock lines (φ ₁ , φ ₂ , φ ₃ ) and the power supply _VGK line are formed by photoetching. Finally, the end face on the laser light output side is formed with good parallelism by a method such as cleavage, and the structure of this example is completed.

The light emitting element arrays of the above examples B-1 to B-4 also have the self-scanning function which the conventional light emitting element array does not have, as in the case of the example A, and the effects such as the assembling efficiency, downsizing, and high pitch can be obtained. Have.

In the above Examples B-1 to B-4, three phases φ ₁ , φ ₂ , and φ ₃ are assumed as transfer clock pulses.
As in the case of Example A, when a more stable transfer operation is required, the transfer operation may be increased to four phases or five phases.

Further, in each example of the self-scanning light-emitting element array, the light-emitting elements are arranged in a line. However, as in the case of Example A, the arrangement does not need to be linear, and may be meandering depending on the application, or may be two-way from the middle. It is possible to have more than columns.

The light-emitting element does not need to be a light-emitting thyristor, and is not particularly limited as long as its light-emitting element changes its turn-on voltage by an external potential, and may be a laser thyristor as described above.

The self-scanning light-emitting element array may be constituted by forming the light-emitting elements by a single individual component, or may be realized by integrating them by some method.

As described in Example A, the structure of the light emitting thyristor may be a structure in which a more complicated structure or layer structure is introduced, or may be an arbitrary structure such as a structure having six or more layers.

The series of examples A and B of the self-scanning light-emitting element array use a semiconductor substrate as a substrate and set the potential to zero volt (ground). However, the present invention is not limited to this. May be used. The closest example is semi-insulating GaAs doped with chromium (Cr).
An n-type GaAs layer may be formed on a substrate, and the structure described in the above example may be formed thereon. Alternatively, for example, a semiconductor film may be formed on an insulating substrate made of glass, alumina, or the like, and the structure of the above example may be formed using the semiconductor.

The structure of the laser is not limited to this structure. For example, TJS type, BH type, CSP type, VSIS
It is of course possible to use a shape or the like (SM Sze, Ph.
ysics of Semiconductor Ph
ysics, 2nd Edition pp. 724
730). Although the description has been made mainly of AlGaAs as a material, other materials (for example, AlGaInP,
nGaAsP, ZnSe, GaP, etc.).

In the above Examples A and B, the light emitting element which is emitting light has the most influence on the adjacent light emitting element, and the adjacent light emitting element is the next driving light emitting element. However, the present invention is not limited to this. For example, every other light-emitting element may be configured to have the influence, and transfer driving to every other light-emitting element may be possible.

Example C Example C described here relates to a method of driving the self-scanning light-emitting element array constituted by Examples A and B described above.

An explanatory diagram of Example C is shown in FIG. FIG. 16 shows an equivalent circuit diagram illustrating the driving principle and a pulse waveform applied to each terminal.

In this example, the transfer clock pulse φ₁ , Φ_Two , Φ
_Three Current source I in parallel with₁ , I _Two , I_Three Side by side,
The amount of current is represented by the emission signal φ_I Configured to be controlled by
It is a thing.

The operation will be described. First, the light emitting element T ₍₀₎ is turned on by the start pulse φ _S. Then, by sequentially applying transfer pulses φ ₁ , φ ₂ , φ ₃ , O
An N state transfer is performed. Examples A, B for this mechanism
As described above.

Now, when it is desired to make the position of the light emitting element T ₍₃₎ emit light more strongly, the light emitting signal φ _{I is set} to the high level in consideration of the time when the light emitting point comes to T ₍₃₎ . At this time, current flows from the current sources I ₁ , I ₂ and I ₃ in synchronization with φ _I. However, the anode of T ₍₃₎ that is ON absorbs the current from the current source, but the other light-emitting elements cannot absorb the current because of the OFF state, and the current that flows in is the drive circuit that outputs the transfer clock pulse. It flows out to the side. Therefore, the anode current of the light emitting element that is ON increases, and the light emission intensity also increases.

The graph of the light emission intensity L is also shown at the same time.
_It can be seen that only the emission intensity of ₍₃₎ is increased. By using this driving method, it is possible to increase the light emission intensity at an arbitrary place, and it is possible to perform spatial optical writing.

In the case where a laser thyristor is used as the light emitting element of this embodiment, if the anode current by the transfer clock is set to be equal to or less than the threshold current of laser oscillation, no laser light is emitted in the normal transfer state, and a light emission signal is emitted. Only laser light can be emitted.

Hereinafter, an embodiment of an optical device using the above-described self-scanning light emitting element array will be described.

[0096]

Embodiment 1 FIG. 17 shows a principle diagram of a contact type image sensor according to a first embodiment of the present invention. This is equivalent to a case where the function of shifting the light emitting point can be realized by the self-scanning light emitting element array, and this is applied to location scanning.

In FIG. 17, an optical sensor made of amorphous Si is formed on a glass substrate (A1). Conventionally, a method has been adopted in which this optical sensor is separated into pixels of about 100 μm, which are scanned by a reading IC and taken out. The lighting was uniformly performed by the LED. In the method shown here, the optical sensor using amorphous Si is not separated into pixels, but is instead scanned by illumination.

In FIG. 17, an electrode (A2) also serving as a light shield, an amorphous Si (A3),
A transparent electrode (A4) and an electrode (A5) are formed. In this configuration, the electric conductivity of the amorphous Si (A3) is increased by light, so that the electrodes (A2) and (A5)
It utilizes the phenomenon that the resistance decreases with light exposure. A transparent protective layer (A6) is provided on these, and the original (A7) comes in close contact with the transparent protective layer (A6).

Now, the self-scanning light emitting element array (A1
No. 0) is provided on the opposite side of the glass substrate (A1), and its light passes through a rod lens array (A9) and passes through a window (A8) for introducing light provided at the center of the optical sensor, and the original ( A7) It is configured to form an image on it.

The self-scanning light emitting element array (A10)
The light emitting point has a function of sequentially moving, and accordingly, the image forming point on the document also sequentially moves. Now, if there is shading due to characters or the like on the document, the reflected light from the document changes accordingly. This is read by an optical sensor made of amorphous Si.

When a laser thyristor is used as this light emitting element array, a light emitting element array with a large amount of light can be obtained due to its high quantum efficiency, and low power consumption or high speed reading can be performed.

[0102]

Embodiment 2 As a second embodiment of the present invention, an optical printer to which a self-scanning light emitting element array is applied will be described.
2. Description of the Related Art Conventionally, there is known an example in which a module in which a driving IC is connected to each pixel of an LED array is applied to an optical printer. FIG. 18 shows the principle of the optical printer. First, a photoconductive material (photoconductor) such as amorphous Si is formed on the surface of a cylindrical photosensitive drum (B1). This drum rotates at the speed of the print. First, the charger (B7)
To uniformly charge the photoreceptor surface. Then, light of a dot image to be printed by the light emitting element array optical print head (B8) is irradiated onto the photoreceptor to neutralize the charging at the place where the light is applied. Next, according to the charged state on the photoconductor in the developing unit,
Apply toner on photoreceptor. The transfer unit (B2) transfers the toner onto the sheet (B9) sent from the cassette (B11). And the paper is a fixing device (B3)
The heat is applied to fix the toner. On the other hand, the drum on which the transfer has been completed is neutralized over the entire surface by the erase lamp (B5), and the remaining toner is removed by the cleaner (B6).

Now, a self-scanning light-emitting element array is used as an example C-
The device operated by the driving method shown in 1 is applied to the light emitting element array optical print head (B8). FIG. 19 shows the structure of the optical print head. It is composed of a self-scanning light emitting element array (B12) and a rod lens array (B13), and the lens focuses on the photosensitive drum (B1). When the driving method shown in Example C-1 is used, in the self-scanning light emitting element array, the light emission intensity can be increased at the position where light is to be written while the ON state is being transferred, so that image information can be written on the photosensitive drum. .

When a laser thyristor is used as the self-scanning light-emitting element array, a light-emitting element array with a large amount of light can be obtained because of its high quantum efficiency, and low power consumption or high-speed writing or printing can be performed. .

[0105]

Embodiment 3 A light emitting element array for an optical printer has a configuration in which the light emitting element arrays are arranged in a line in a one-dimensional direction. A display can be made by arranging the one-dimensional light emitting element arrays in a plane. This configuration is shown in FIG. Assuming that N arrays are arranged, video signals may be written from φ ₁ (1) to φ _I (N). A high-density display element can be manufactured by using an integrated light-emitting element array, and a large-area display can be manufactured by combining single light-emitting elements.

[0106]

As described above, the self-scanning light-emitting element array having a self-scanning function can be applied to a contact image sensor, an optical printer, a display, and the like.
It can be expected to be widely applied to facsimile machines, bar code readers, copiers, etc., and can greatly contribute to improving the performance and reducing the price of these devices.

[Brief description of drawings]

FIG. 1 is a circuit diagram schematically showing a self-scanning light-emitting element array using light described in Example A-1.

FIG. 2 is a sectional view schematically showing a self-scanning light emitting element array using light described in Example A-2.

FIG. 3 is a plan view schematically showing a self-scanning light-emitting element array using light described in Example A-3.

FIG. 4 is a cross-sectional view schematically showing a self-scanning light-emitting element array using light described in Example A-3.

FIG. 5 is a cross-sectional view schematically illustrating a self-scanning light-emitting element array using light described in Example A-3.

FIG. 6 is a cross-sectional view schematically showing a self-scanning light-emitting element array using light described in Example A-4.

FIG. 7 is a plan view schematically showing a self-scanning light-emitting element array using light described in Example A-5.

FIG. 8 is a cross-sectional view schematically showing a self-scanning light-emitting element array using light described in Example A-5.

FIG. 9 is a circuit diagram schematically illustrating a self-scanning light-emitting element array using the potential described in Example B-1.

FIG. 10 is a sectional view schematically showing a self-scanning light-emitting element array using the potential described in Example B-2.

FIG. 11 is a plan view schematically showing a self-scanning light-emitting element array using the potential described in Example B-3.

FIG. 12 is a sectional view schematically showing a self-scanning light-emitting element array using the potential described in Example B-3.

FIG. 13 is a sectional view schematically showing a self-scanning light-emitting element array using the potential described in Example B-3.

FIG. 14 is a plan view schematically showing a self-scanning light-emitting element array using the potential described in Example B-4.

FIG. 15 is a cross-sectional view schematically showing a self-scanning light-emitting element array using the potential described in Example B-4.

FIG. 16 is a circuit diagram schematically illustrating a method of driving the self-scanning light emitting element array described in Example C, and a diagram illustrating waveforms of respective pulses.

FIG. 17 is a cross-sectional view schematically illustrating the contact image sensor described in the first embodiment.

FIG. 18 is a cross-sectional view schematically illustrating the optical printer described in the second embodiment.

FIG. 19 is a side view schematically illustrating the optical printer head described in the second embodiment.

FIG. 20 is a plan view schematically illustrating the optical display described in the third embodiment.

FIG. 21 is a sectional view schematically showing a light emitting thyristor having a double hetero structure.

FIG. 22 is a sectional view showing a schematic structure of a light emitting thyristor.

FIG. 23 is a diagram showing current-voltage characteristics of a light-emitting thyristor.

FIG. 24 is a sectional view showing a schematic structure of a three-terminal thyristor.

[Explanation of symbols]

 A1 Glass substrate A2, A5 electrode A3 Amorphous Si A4 Transparent electrode A6 Transparent protective film A8 Window A9 Rod lens array A10 Light emitting element array B1 Photosensitive drum B12 Light emitting element array B13 Rod lens array

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Internal reference number FI Technical indication location H04N 1/036 1/04 101 (72) Inventor Shuhei Tanaka 3-chome, Doshomachi, Chuo-ku, Osaka-shi, Osaka 5th-11th Nippon Sheet Glass Co., Ltd.

Claims (6)

[Claims] 1. A contact type image sensor in which an optical sensor is formed on a glass substrate, a window is provided at the center of the optical sensor, and a light emitting element array is incident on the window through a rod lens. In the element array, a large number of light emitting elements whose threshold voltage or threshold current can be externally controlled by light are arranged one-dimensionally, and at least a part of the light generated from each light emitting element A contact-type image sensor, which is a self-scanning light-emitting element array configured so as to be incident on another light-emitting element, and each light-emitting element being connected to a clock line for applying a voltage or a current from the outside. 2. A contact type image sensor in which an optical sensor is formed on a glass substrate, a window is provided in the center of the optical sensor, and a light emitting element array is incident on the window through a rod lens. The element array is a one-dimensional array of a number of light-emitting elements whose threshold voltage or threshold current can be electrically controlled from the outside, and the electrodes for controlling the threshold voltage or threshold current of each light-emitting element are mutually connected. A contact image sensor, which is a self-scanning light emitting element array in which each light emitting element is connected to a clock line for externally applying a voltage or current to the light emitting element. 3. An optical printer for irradiating light on a photosensitive drum from a light emitting element array through a rod lens array, wherein the light emitting element array has a large number of light emitting elements whose threshold voltage or threshold current can be controlled by light from the outside. The light emitting elements are arranged one-dimensionally so that at least a part of light emitted from each light emitting element is incident on another light emitting element in the vicinity of each light emitting element. An optical printer, which is a self-scanning light emitting element array connected with a clock line for applying a voltage. 4. An optical printer for irradiating a photosensitive drum with light from a light emitting element array through a rod lens array, wherein the light emitting element array has a threshold voltage or threshold current electrically controllable from the outside. A clock for arranging a large number of elements in a one-dimensional manner, connecting electrodes for controlling the threshold voltage or threshold current of each light emitting element to each other by electrical means, and applying a voltage or current from the outside to each light emitting element An optical printer comprising a line-connected self-scanning light emitting element array. 5. A plurality of light emitting elements whose threshold voltage or threshold current can be controlled by light from the outside are arranged one-dimensionally, and at least a part of the light generated from each light emitting element is in the vicinity of each light emitting element. A display in which a plurality of self-scanning light emitting element arrays are arranged in a plane and are configured to be incident on other light emitting elements, and each light emitting element is connected to a clock line for applying voltage or current from the outside. 6. A multiplicity of light-emitting elements whose threshold voltage or threshold current can be electrically controlled from the outside are arranged one-dimensionally, and electrodes for controlling the threshold voltage or threshold current of each light-emitting element are provided. A display in which a plurality of self-scanning light emitting element arrays, which are electrically connected to each other and each of which is connected to a clock line for externally applying a voltage or a current, are arranged in a plane.