JPH0355885A - Light emitting and receiving module - Google Patents

Abstract

PURPOSE:To simplify the structure of an element which makes an integrated element to carry the function of a channel selector so as to simplify the manufacturing process of the title module by using a light emitting element array having self scanning function as a plurality of light emitting elements. CONSTITUTION:A P-type semiconductor layer 23, an N-type semiconductor layer 22, and a P-type semiconductor layer 21 are formed on a grounded N-type GaAs substrate 1. A light emitting element array 101 on which the layers 23, 22, and 21 are separated into single light emitting elements (T-2)-(T+1) and which has self-scanning function is used and an arbitrary one is used as a light receiving element 102. A negative resistance element composed of a laminated body of compound semiconductors such as GaAs, AlGaAs, etc., can be used as the light emitting element to be used for the array 101. Therefore, even a light emitting or receiving module which requires numerous photocouplers such as channel selectors, can be formed as an integrated element, because no additional complicated scanning circuit is required. Moreover, since no complicated wiring is used, manufacturing process can be simplified and manufacturing yield can be improved.

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to a light-emitting/light-receiving module using a photocoupler that uses a light-emitting element and a light-receiving element to convert an electrical signal into an optical signal and then transmitting the signal, and in particular uses a light-emitting element array having a self-scanning function as the light-emitting element. , a light-emitting/light-receiving module that can be integrated and used as a channel selector.

[Conventional technology]

Conventionally, photocouplers that combine a light emitting element and a light receiving element are well known. FIG. 12 shows an example of the configuration of a conventional photocoupler. In a photocoupler, a light emitting diode (101) and a light receiving element (here, a phototransistor) (102) are spatially separated and packaged. Light emitting diode (lOf
) The light emitting diode (101) emits light due to the current applied between the terminals (+) and (2), and this light enters the phototransistor (102). And phototransistor (1
Current can flow between terminals (3) and (4) of 02), and the switch is turned on. As a result, terminal (1),
(2) and the electrical signal between terminals (3) and (3). (4) It is possible to communicate between The feature of this photocoupler is that human power and output are completely electrically separated, so it works to prevent the transmission of power and external noise, and is used for system isolation.

[Question H that the invention attempts to solve]

The above-mentioned photocoupler is placed in the middle of the signal transmission path and is used to separate noise, but its functionality does not exceed this. Therefore, it was impossible to provide various functions to the photocoupler itself, and the processing had to be done externally. Also, it is possible to use multiple photocouplers as described above and use them as channel selectors, but if multiple photocouplers like the one above are lined up, it would take up a considerable amount of space and would require wiring for each one. Ta. It is also conceivable to arrange light emitting elements and light receiving elements in an array and make them function, but in order to make the light emitting element array function, a scanning circuit for the light emitting elements is required, and wiring of the scanning circuit etc. is required. There was a need.

[Means to solve the problem]

In order to solve the above conventional problems, the present invention provides a light emitting/light receiving module that uses a plurality of light emitting elements and a plurality of light receiving elements to convert an electrical signal into a light signal and then transmit the light signal. A light emitting element array having a self-scanning function is used as the light emitting element. The light-emitting element array having the self-scanning function includes: (a) a large number of light-emitting elements whose threshold voltages or threshold currents can be externally controlled are arranged one-dimensionally, two-dimensionally, or three-dimensionally; At least two light emitting elements located close to each other are connected by optical means, or control electrodes for controlling the threshold voltage or threshold current of at least two light emitting elements located close to each other are connected to each other by electrical means. (b) A power supply line is connected to each light emitting element using electrical means, and a clock line for applying a clock pulse and the electric signal is connected to the light emitting element array, and (b) a threshold voltage or threshold voltage. The control electrodes of each switch element of a switch element array, which has a large number of switch elements each having a control electrode whose threshold current can be controlled from the outside, are connected to each other by electrical means or optical means, and each switch element is connected to a power supply line. A self-scanning array is formed by connecting both using electrical means and a clock line, and a light-emitting element is an array of a large number of light-emitting elements each having a control electrode whose threshold voltage or current can be controlled from the outside. A light emitting element array in which an electrode for controlling each threshold voltage or threshold current of the array is connected to a control electrode of the switch element by electrical means, and a line for applying the electric signal to each light emitting element is provided. The present invention uses a light emitting element array having a self-scanning function as a plurality of light emitting elements, and any arbitrary thing can be used as a light receiving element. Any optical coupling method can be used, such as a method using a lens, a method using a shielding plate, a method using a fiber array, etc. Also, the number of light emitting elements and the number of light receiving elements is not limited to 1:1. , many to one by mechanical or optical means.
It does not matter if it has a one-to-many correspondence and/or a selection function. Examples of light emitting elements used in the light emitting element array having a self-scanning function include GaAs, AIG. An example is a negative resistance element made of layered compound semiconductors such as aAs. Further, a laser thyristor may be used as long as it has a light emitting function.

[Effect]

The present invention uses a light emitting element array with a self-scanning function as a light source for a light emitting/light receiving module such as a photocoupler, which has been a problem in the past.
This is intended to promote integration. In the present invention, a self-scanning light emitting element array is used as the light emitting element as described above, which can have both the function of transferring light emitting points and the function of modulating the light emission intensity of the light emitting points. Even light-emitting/light-receiving modules that require a photocoupler can be formed as integrated elements because no complicated additional scanning circuit is required. Additionally, since no complicated wiring is required, the manufacturing process can be simplified and manufacturing yields can be improved.

【Example】

Example-1 A conceptual diagram of a first example of the present invention is shown in FIG. The light emitting/light receiving module of this example has a light emitting element (101
), an array of light-receiving sensors (102), and an imaging lens (l00) that optically makes a one-to-one correspondence between the light-emitting point of the light-emitting element (101) and the light-receiving point of the light-receiving sensor (102).
It consists of. First, the structure and manufacturing process of the array of light emitting elements (101) used in this example will be explained. As shown in Figures 2 and 3, the grounded N-type GaA
A P-type semiconductor layer (23), an N-type semiconductor layer (22), and a P-type semiconductor layer (2I) are formed on the s-substrate (1). Then, by photolithography and etching, each individual light emitting element T ( -2) to T (+1) (separation groove (50)). (Single light emitting element T (-2) to T
(+1) represents a part of these light emitting element arrays. ) 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) has an ohmic contact with the P-type semiconductor layer (21). It is desirable that the insulation Fl' (30), which serves as a protective film to prevent short-circuiting and at the same time prevent property deterioration, be made of a material through which light of the emission wavelength of the light-emitting thyristor can easily pass. N type Ga
The As substrate (1) serves as the cathode of this thyristor. For each single light emitting element, one of the transfer clock lines (φ, φ2, φ3) l: 7) connects φ1, φ2, φ3 II1'' in the horizontal direction. e
Connected repeatedly. A load resistor RL is also connected to the gate electrode. On the other hand, if optical coupling occurs between each element, the transfer operation of this embodiment may be affected. To prevent this, the part of the gate electrode is inserted into the separation groove between the light emitting elements, creating a structure that prevents optical coupling. To explain the operation of the above-mentioned light emitting element array, first, the transfer clock φ3 becomes high level, and the light emitting element T(0) becomes OFF.
Do N. At this time, the gate electrode Gθ of the light emitting element T(0) is pulled down to near zero volts due to the characteristics of the three-terminal thyristor. (In the case of a silicon thyristor, it is about 1 volt.) Furthermore, the light-emitting thyristor has a characteristic that its turn-on voltage decreases when it senses light. Since the light-emitting thyristor is configured so that its emitted light is emitted to neighboring elements, the turn-on voltage of elements that are close to the light-emitting element or elements that are placed so that they are well exposed to light will be reduced.
, When the power supply voltage is Vaκ, the gate voltage of the element closest to the light emitting element T (0) and receiving a large amount of incident light decreases the most, and thereafter the gate voltage increases as the distance from the light emitting element T (0) increases. I will do it. The next transfer clock pulse φ1 is the nearest light emitting element T(1
), T (-2), T (4), T (-5), etc., but among these, the element with the lowest ON voltage is the light emitting element T (!). The next lowest element is the light emitting element T (-2)
becomes. Therefore, the high level voltage of the transfer clock pulse φl is set to the gate voltage Gl of the light emitting element T (1) and the light emitting element T (-2
) and the gate voltage G"2, only the light emitting element T (1) can be turned on, and the high level voltages of the transfer clocks φ1, φ2, φ3 are alternately overlapped slightly with each other. If set as follows, transfer operation (three-phase drive self-scanning) can be performed. Next, the structure and manufacturing process of the array of light receiving sensors (102) will be explained. On an N-type silicon substrate doped with phosphorus etc. A thermal oxide film is formed on the surface of the thermal oxide film.
A hole is made and a P-type impurity such as boron is doped into this part. After this surface is oxidized again, a hole is made in the oxide film on the P-type impurity and a metal film is deposited on the entire substrate. ● This metal film formed by the method is buttered by photolithography and etching to produce an upper electrode, and a PN junction is formed. A silicon light-receiving sensor array is fabricated. The array of light-emitting elements and the array of light-receiving sensors are formed to have the same number of elements, and face each other through an imaging lens (+00), so that the light-emitting points of the light-emitting elements (101) and the array of light-receiving sensors (IQ2) The light receiving points are fixed and modularized in an optical 1:1 correspondence. Next, the operation of the light emitting/light receiving module will be described. A start pulse φS is applied to the light emitting element section to start the transfer of light emission, and the light emission is carried by transfer clocks φ1, φ2, and φ3. An example of the driving pulse situation at this time is shown in FIG. The transfer clock 7 φ1 is at a high level at the same timing as φS, and at this time, the light emitting element T(1) is in the ON state (light emitting state). Then, at the next φ2, the light emitting element T(
2). They move one after another in this order, but...
In this figure, the transfer temporarily stops at the location of the light emitting element T(4).At this time, when the signal φ to be transmitted is added to the transfer clock φ1, the output L of the light emitting element T(5) becomes as shown in FIG. Change. At this time, the light incident on the light-emitting element T(5) & the light-receiving element at the optically corresponding position also changes, and the signal φ1 is taken out as an output from the terminals A2-K2 of the light-receiving element. By changing C4, the transmitted bit can be selected using C4, and it can function as a channel selector. At this time, the function of the photocoupler is not impaired at all, and high functionality of the photocoupler can be achieved. As described above, according to the light emitting/light receiving module of this embodiment, signals that could not be transmitted without using multiple photocouplers can be transmitted through the three transfer clock lines (φ1, φ2, . . .
φ3) and the modulated power supply voltage V6K. The light-emitting/light-receiving module of this embodiment is more integrated than a transmission device using multiple photocouplers, and has a scanning
It is a highly reliable transmission device with simplified wiring for positioning and scanning. In the above example,
An imaging lens is used for optical coupling between the light emitting element array and the light receiving sensor array, but the coupling is not limited to coupling using the imaging lens, but also coupling using a fiber array, spacer with a shielding plate, etc. Any combination method such as combination may be used. In particular, in order to prevent noise and the like and to achieve compactness, it is preferable to combine using a thin plate-shaped shielding plate that blocks the influence of light from adjacent elements. In addition, in the above embodiment, the number of light emitting elements and the number of light receiving sensors are the same and the whole is fixed and modularized, but the structure is not limited to the above. For example, the number of light receiving sensors is a multiple of the number of light emitting elements. However, it may be possible to switch using mechanical means. Further, in the above embodiment, three phases of φ, φ2, and φ3 are assumed as the transfer clock pulse, but if a more stable transfer operation is desired, this may be increased to four phases or more. Further, in this embodiment, the structure of the light emitting thyristor is shown in the simplest case, but in order to increase the light emitting efficiency, a more complicated structure or configuration, such as a double heterostructure, may be introduced. In addition, although the PNPN thyristor configuration has been explained here as an example, the configuration in which this potential is detected, the threshold voltage decreases, and this is used to perform the transfer operation is not limited to the PNPN configuration; There is no particular limitation as long as the element can achieve this. For example, instead of the PNPN four-layer structure, the same effect can be expected with a structure of six or more layers, and it is possible to achieve exactly the same self-scanning function. Furthermore, electrostatic induction (Sl)
The same is true when using a thyristor called a thyristor or a field controlled thyristor (FCT). Furthermore, in the above embodiment, light is used as a means for lowering the gate voltage of the light emitting element in the transfer direction, but
This can also be carried out by electrically connecting the electrodes that control the threshold voltage or threshold current of each light emitting element. The electrical connection means may be a resistive element, a diode, a transistor, or other unidirectional element. In particular, if a unidirectional element such as a diode is used, two-phase transfer clock pulses may be used. This is preferable because it can be used for self-scanning. Examples of structures of light emitting element arrays using diodes as the electrical connection means are shown in FIGS. 5, 6, 7, and 8.
An example is given below based on the figure. As shown in Figures 6 and 7, the grounded N-type GaA
N-type GaAs layer (24b) and N-type AI on the s-substrate (1)
GaAs layer (2 4 b), P-type GaAs layer (23)
, N-type GaAs layer (22), P-type AIGaAs layer (2l
b) Sequentially forming each layer of the P-type GaAs layer (21a). Then, a separation groove (50) is formed by photolithography etc. and etching, and each individual light emitting thyristor T (11) to
Separate into T (+1). (Single light emitting element T (-1
) to T (+1) represent a portion of these light emitting element arrays. ) Next, P type G a A s N (21a)
, a part of the P-type AIGa As N (2 lb) is removed to form a portion M l (51) to provide separation between the light emitting thyristor and the coupling diode. The entire surface is covered with an insulating film (30), a contact hole C1 is provided on the electrode, and an electrode connection (40) and a transfer clock line φ1 are made using metal thin film wiring.
Connect φ2. Here, the transfer clock lines φ1 and φ2 are connected to every other element. Figure 8 shows an equivalent circuit diagram of the above light emitting element array. The light-emitting thyristors T (-2) to T (+2) are arranged in a line. Each of the light-emitting thyristors T (-2) to T (+2) has a gate electrode G-2 to G-2. G and 2 are provided, and adjacent gate electrodes are electrically connected to each other by diodes D-2 to D2. The diodes D-2 and D2 are light emitting thyristors T (-
2) to T (+2) are arranged so that a current flows in one direction. To explain the operation of the above light emitting element array, first, the transfer clock φ2 becomes high level, and the light emitting thyristor T(0)
Suppose that is ON. At this time, due to the characteristics of a three-terminal thyristor, the gate electrode GI1 of the light emitting thyristor T(0) is pulled down to nearly zero volts (in the case of a silicon thyristor, it is approximately 1 volt). When electric voltage VGK is 5V, load resistance RL. The gate voltage of each light emitting thyristor is determined from the network of diodes D-2 to D2. The gate voltage of the element closest to the light emitting thyristor T (0) decreases the most, and thereafter the gate voltage increases as the element moves away from the light emitting thyristor T (0). However, due to the unidirectionality and asymmetric nature of the diode characteristics, the effect of lowering the voltage only works on one side (the right half in FIG. 8) of the light emitting thyristor T (0). That is, the light emitting thyristor T(1
) gate electrode GI of the light emitting thyristor T(0) has a forward rising voltage V of the diode with respect to the gate electrode G8 of the light emitting thyristor T(0).
The light emitting thyristor T(2) is set to a higher voltage by d'.
The gate electrode G2 is set to a voltage higher than the gate electrode GI by the forward rising voltage Vdr of the diode. On the other hand, no current flows through the gate electrode G-+ of the light-emitting thyristor T (-1) corresponding to the opposite side (the left half in FIG. 8) because the diode D-+ is reverse biased, so that the power supply voltage VGK They have the same potential. The next transfer clock valve φ1 is the nearest light emitting thyristor T(1),
Among them, the element with the lowest ON voltage is the light emitting thyristor T(1), which is approximately 2Vd+. The next lowest element is the light emitting thyristor T (3), which is about 4V
It becomes ar. Light emitting thyristor T (-1), T (-3
) is approximately VoK+Vdr. From the above, the high level voltage of the transfer clock pulse should be changed from 2Va+ to 4Vd.
If set between +, only the light-emitting thyristor T(1)
N, and transfer operations can be performed. In the above example, the N-type GaAs layer (22) of the light emitting element is used as the load resistor (63) R L, but another layer may be used. For example, a p-layer (23) may be used.
Alternatively, another resistance region may be provided and used. Further, the self-scanning light emitting element array used in the present invention is not limited to the above example, but may have an improved structure in which blocks as shown below are formed. A third structural example will be explained below using FIGS. 9 and 10. FIG. 9 shows a plan view of the light emitting element array of this example, and FIG. 10 shows an equivalent circuit diagram. First, n-type GaA
On the s substrate (1), an n-type GaAs layer (24b), n
type AIGaAs layer (24a), p-type GaAs layer (23
a), n-type GaAs layer (22a), p-type AIGaAs
layer (2 l b), and p-type GaA sN (2
1a) are sequentially stacked. The stacked semiconductor layers are separated into each light emitting element T by a separation groove (50). In addition, each light emitting element TOp type GaA
S layer (21a) and p-type AIGaAs layer (2lb)
are partially removed so as to remain on the n-type GaAs layer (22a) in the form of six islands in order to fabricate a gate electrode and a unidirectional coupling element. The five islands are two small islands and three relatively large islands that are continuous, and the three relatively large islands are arranged in a line in the longitudinal direction of the light emitting element array. Two small islands are located in the longitudinal direction of the light emitting element array.
They are arranged in a repeating manner: island, island, valley, island, island, valley, island, island, valley. Here, one relatively large island corresponds to one light emitting element, the island, island, valley corresponds to one scanning circuit element coupled to three light emitting elements, and the valley is an exposed n-type G
The gate electrode portion of the aAS layer (22a) is shown. Next, an insulating film (30) is coated over the entire substrate. Then, the deleted n of the insulating coating (30) is
type GaAs layer (22a) and five p-type GaAs layers
A contact hole C1 for connection is opened at a position on the layer (21a). Next, on the insulating film (30), the n-type GaAs layer (22a) of each scanning circuit element and the p-type GaAs layer (22a) of the adjacent scanning circuit element are coated.
The aAs layer (21a) is connected to the T-shaped metal thin film wiring (45) for connecting the power supply electrode and the gate electrode using the contact hole CI, and the three thick island-shaped p-type GaAs layers of the light emitting element are connected to the aAs layer (21a) using the contact hole CI. (21a) a metal thin film wiring (44) that transmits a clock pulse through the contact hole C1;
A metal thin film wiring (42) for supplying a driving voltage to the remaining island-shaped p-type GaAs layer (21a) of the light emitting element via the cositact hole C1 is provided. Next, a resistance R between the gate electrode and the power supply electrode is placed on a part of the metal thin film wiring (45).
Non-quality silicon doped with phosphorus (1
63) to a thickness of approximately 1 μm. The non-quality silicon (163) is separated, one for each light emitting device. Next, cover the entire board with an insulating film (3L). Then, a connection contact hole C2 is formed in the insulating film (31) at a position above the non-quality silicon (+63), the metal thin film wiring 02), and the metal thin film wiring (44).
between. Next, a contact hole C2 is formed on the insulating film (3l).
A write line (S
in++ S inz. S in3), metal thin film wiring (43) (gate electrode of scanning circuit element) via contact hole C2 (amorphous silicon (163))
A power supply line (4l) for transmitting a power supply voltage to the contact hole C2, and clock lines φ1 and φ2 for transmitting clock pulses to the metal thin film wiring (40) (anode electrode of the scanning circuit element) through the contact hole C2 were provided. Here, metal thin film wiring for clock line coupling (40b)
The position of the contact hole C2 on one side provided above is such that the anode electrode of each scanning circuit element is connected to the clock lines Sin+, S
It is adjusted to repeat in the order of Sinn, Sin2, and Sins in the length direction on either one of in2 and Sin3. FIG. 10 is an equivalent circuit diagram of the above light emitting element array.
The above circuit differs from the above embodiment in that the light emitting element is used as a scanning circuit, a light emitting element having the same structure as the scanning circuit is provided separately from the scanning circuit, and three new light emitting elements are provided. The light emitting elements in one block are controlled by one scanning circuit element, and the light emitting elements in one block are connected to separate clock lines to control the light emission of the light emitting elements. In the figure, light emitting elements Ll(-1), L2(-1),
L3(-1), light emitting element Ll(0), L2(of, L
3(, light emitting element + (- 1). L2 (-
1), L3(-1), etc. indicate blocked light emitting elements. Transfer of light emission is performed block by block by the scanning circuit element, and the light emission of each light emitting element is controlled by each clock line. Example-2 A second example of the present invention is shown in FIG. This figure is the first
The configuration is almost the same as in the figure, but the difference is that the light emitting element (10
1) There are three arrays instead of one. Since each light emitting element array (+1), (12), and (13) functions as described in the first embodiment, a multi-input, multi-channel selector is possible in the example shown in FIG. 11. In the above embodiment as well, the light emitting element (101) and the light receiving sensor (+02) do not necessarily need to be coupled through a lens, and a physical light shielding wall may be provided. Also, a multi-channel selector may have more channels than just the three channels mentioned above. Further, the light receiving element is not limited to the phototransistor described in the conventional example, but may be any other type including a photodiode.

【Effect of the invention】

As described above, in the present invention, by using a light emitting element array with a self-scanning function as a light emitting element, the channel selector function of selecting a sensor to send a signal and transmitting information is integrated. It can be supported on the device. In addition, the element has a simple structure and does not have a complicated scanning element, so it is highly reliable and the manufacturing process can be simplified.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the first embodiment of the present invention, FIGS. 2 and 3 are sectional views and plan views schematically showing the self-scanning light emitting element array used in the first embodiment, Figure 4 is the first
6, 6, 7, and 8 are plan views, cross-sectional views, and cross-sectional views in different directions showing different configurations of the self-scanning light emitting element array. , and equivalent circuit diagrams, FIGS. 9 and 10, which do not show the configuration of yet another self-scanning light emitting element array.
FIG. 1 is a block diagram showing a second embodiment, and FIG. 12 is a conceptual diagram showing a conventional photocoupler. In the figure, 101 self-scanning light emitting element array + 02 light receiving element array 100 imaging lens. Figure 1 Figure 61 Light barrier Figure 4 Figure Y Figure 5 Figure 9 Figure 10

Claims (2)

[Claims] (1) In a light-emitting/light-receiving module that uses a plurality of light-emitting elements and a plurality of light-receiving elements to convert an electrical signal into a light signal and transmit it, a light-emitting element array has a self-scanning function as the plurality of light-emitting elements. A light emitting/light receiving module characterized by using. (2) The light emitting element array having the self-scanning function is (a
) A large number of light emitting elements whose threshold voltages or threshold currents can be controlled externally are arranged one-dimensionally, two-dimensionally, or three-dimensionally, and at least two light-emitting elements located near each other are connected by optical means. Alternatively, control electrodes for controlling the threshold voltage or threshold current of at least two light emitting elements located near each other may be connected to each other by electrical means, and a power supply line may be connected to each light emitting element using electrical means. or (b) a large number of switch elements each having a control electrode whose threshold voltage or threshold current can be controlled from the outside. It is formed by connecting the control electrodes of each switch element of the arranged switch element array to each other by electrical means or optical means, and by connecting a power line to each switch element using electric means and also connecting a clock line. The switch element controls each threshold voltage or threshold current of a light emitting element array in which a large number of light emitting elements are arranged, each having a self-scanning array and a control electrode whose threshold voltage or threshold current can be controlled from the outside. 2. The light emitting/light receiving module according to claim 1, wherein the light emitting element array is connected to a control electrode of the light emitting element by electrical means and is provided with a line for applying the electric signal to each light emitting element.