This application is based on and claims priority under 35 USC 119 from Japanese Patent Application No. 2022-052354 filed Mar. 28, 2022.
The present disclosure relates to a light emitting element, a light emitting element array, a light emitting component, an optical device, and an optical measurement apparatus.
JP2019-010749A discloses a laminate having an outermost layer/polyamide film/sealant layer structure, in which adhesive strength and pinhole generation during distribution/transportation are improved, and a method of producing the same.
Further, JP2000-294872A discloses an oxidized surface-emitting laser and a surface-emitting laser array, which have a simple fabrication process, are resistant to stress, and are highly reliable.
In the related art, a structure is known in which a plurality of semiconductor layers are laminated and a part of the post shape of a light emitting element configured like a post shape is connected to another semiconductor layer.
Here, in a case where the light emitting element is provided with a connection part with another semiconductor layer, oxygen is supplied not only to the center side of the semiconductor layer but also to the connection part side in a case where the semiconductor layer is oxidized. Thereby, there is a difference in the oxidized region between a part where the connection part is provided and a part where the connection part is not provided, and a shape of an unoxidized region of the semiconductor layer is distorted. Thus, there is room for improvement.
Aspects of non-limiting embodiments of the present disclosure relate to a light emitting element that is configured as follows. In a case where the light emitting element is provided with the connection part with another semiconductor layer, a ratio of a length in a direction along the connection part of the unoxidized region of the semiconductor layer to a length in a direction intersecting the direction along the connection part is made closer to 1:1.
Aspects of certain non-limiting embodiments of the present disclosure overcome the above disadvantages and/or other disadvantages not described above. However, aspects of the non-limiting embodiments are not required to overcome the disadvantages described above, and aspects of the non-limiting embodiments of the present disclosure may not overcome any of the disadvantages described above.
According to an aspect of the present disclosure, there is provided a light emitting element including: a light emitting unit that has a plurality of semiconductor layers laminated, the light emitting unit having a length from a center of the light emitting unit to an end portion in a first direction shorter than a length from the center to an end portion in a second direction intersecting the first direction, in plan view; and a connection part that extends from the light emitting unit in the first direction and connects the light emitting unit to another semiconductor layer.
Exemplary embodiment(s) of the present invention will be described in detail based on the following figures, wherein:
Hereinafter, referring to the accompanying drawings, the present exemplary embodiment will be described.
First, the first exemplary embodiment will be described.
The light emitting component 10 comprises a plurality of laser diodes LDs that emit laser light. The light emitting component 10 is configured as a self-scanning light emitting element array (SLED: Self-Scanning Light Emitting Device) to be described below. The laser diode LD is, for example, a vertical cavity surface emitting laser (VCSEL). Hereinafter, the light emitting element will be described as a laser diode LD. However, other light emitting devices such as a light emitting diode LED may be used.
The light emitting component 10 comprises a plurality of laser diode LD groups, each of which comprises a plurality of laser diodes LD. In
The light emitting component 10 comprises a setting thyristor S for each laser diode LD. The laser diode LD and a setting thyristor S are connected in series.
Here, laser diodes LD belonging to the laser diode LD group #1 are referred to as laser diodes LD11 to 14. Here, in a case where the laser diode LDij (j is an integer of 1 or more) is represented, “i” is the number of the laser diode LD group, and “j” is the number of the laser diode LD in the laser diode LD group. The same reference numerals are given to the setting thyristors S. That is, the setting thyristor S included in the laser diode LD11 is referred to as a setting thyristor S11. In the example shown in
In the present specification, the term “to” indicates a plurality of constituent elements, each of which is distinguished by a number, and means that the constituent elements described before and after “to” and the constituent elements having numbers therebetween are included. For example, the laser diodes LD11 to 14 include the laser diode LD11, the laser diode LD12, the laser diode LD13, and the laser diode LD14 in numerical order.
The light emitting component 10 further comprises a plurality of transfer thyristors T, a plurality of coupling diodes D, a plurality of power line resistors Rg, a start diode SD, and current-limiting resistors R1 and R2. Here, in a case of distinguishing a plurality of transfer thyristors T, the transfer thyristors T are numbered and distinguished, such as transfer thyristors T1, T2, T3, . . . . The same applies to the coupling diodes D and the power line resistors Rg. As will be described later, the transfer thyristor T1 is provided to correspond to the laser diode LD group #1. Therefore, in a case where the transfer thyristor T is represented as the transfer thyristor Ti, i corresponds to the same laser diode LD group. Accordingly, the transfer thyristor T may be referred to as a transfer thyristor T1. The same applies to the coupling diodes D and the power line resistors Rg. The transfer thyristor T is an example of the “setting unit”.
The number of transfer thyristors T in the light emitting component 10 may be a predetermined number. For example, the number may be 128, 512, or 1024.
The transfer thyristors T are arranged in the x direction in order of transfer thyristors T1, T2, T3, . . . . The coupling diodes D are arranged in the x direction in order of the coupling diodes D1, D2, D3, . . . . The coupling diode D1 is provided between the transfer thyristor T1 and the transfer thyristor T2. The same applies to the other coupling diodes D. Further, the power line resistors Rg are also arranged in the x direction in order of the power line resistors Rg1, Rg2, Rg3, . . . .
The laser diode LD and the coupling diode D are two-terminal elements each comprising an anode and a cathode. The setting thyristor S and the transfer thyristor T are three-terminal elements each comprising an anode, a cathode, and a gate. The gate of the transfer thyristor T is referred to as a gate Gt, and the gate of the setting thyristor S is referred to as a gate Gs. In addition, in a case of distinguishing each gate, i is added in the same manner as described above.
Here, a part composed of the laser diodes LD and the setting thyristors S is set as a light emitter 102, and a part composed of the transfer thyristors T, the coupling diodes D, the start diode SD, the power line resistors Rg, and the current-limiting resistors R1 and R2 is set as a transfer unit 101.
Next, the connection relationship of each element (laser diode LD, setting thyristor S, transfer thyristor T, and the like) will be described.
As described above, the laser diodes LDij and the setting thyristors Sij are connected in series. That is, in the laser diode LD, the anode is connected to a reference potential Vsub (ground potential (GND) or the like), and the cathode is connected to the anode of the setting thyristor Sij.
Here, in the light emitting component 10, the setting thyristors S are laminated on the laser diodes LD. Hereinafter, the semiconductor layer laminate of the laser diode LD and the setting thyristor S will be referred to as “LD/S”. Further, the laser diode LD, which belongs to each laser diode LD group, and the setting thyristor S, which is provided for each laser diode LD, are collectively referred to as an “LD/S group”. The LD/S is an example of the “light emitting element”, and the LD/S group is an example of the “light emitting element group”.
The cathode of the setting thyristor Sij is commonly connected to a lighting signal line 75 that supplies a lighting signal φI for controlling the laser diode LD such that the laser diode LD is in a light emitting or non-light emitting state.
As will be described later, the reference potential Vsub is supplied via an electrode (not shown) provided on a rear surface of a GaAs substrate 80 constituting the light emitting component 10.
In the transfer thyristor T, the anode thereof is connected to the reference potential Vsub. The cathodes of the odd-numbered transfer thyristors T1, T3, are connected to a transfer signal line 72. The transfer signal line 72 is connected to a φ1 terminal via the current-limiting resistor R1.
The cathodes of the even-numbered transfer thyristors T2, T4, . . . are connected to a transfer signal line 73. The transfer signal line 73 is connected to a φ2 terminal via the current-limiting resistor R2.
The coupling diodes D are connected with each other in series. That is, the cathode of one coupling diode D is connected to the anode of the coupling diode D which is adjacent in the x direction. In the start diode SD, the anode is connected to the transfer signal line 73, and the cathode is connected to the anode of the coupling diode D1.
Then, the cathode of the start diode SD and the anode of the coupling diode D1 are connected to a gate Gt1 of the transfer thyristor T1. The cathode of the coupling diode D1 and the anode of the coupling diode D2 are connected to a gate Gt2 of the transfer thyristor T2. The same applies to the other coupling diode D.
The gate Gt of the transfer thyristor T is connected to a power line 71 via the power line resistor Rg. The power line 71 is connected to a Vgk terminal.
A gate Gti of the transfer thyristor Ti is connected to a gate Gsi of the setting thyristor Sij.
A configuration of the control unit 20 will be described.
The control unit 20 generates a signal such as a lighting signal φI and supplies the signal to the light emitting component 10. The light emitting component 10 operates in response to the supplied signal. The control unit 20 is composed of an electronic circuit. For example, the control unit 20 may be an integrated circuit (IC) configured to drive the light emitting component 10.
The control unit 20 comprises a transfer signal generation unit 21, a lighting signal generation unit 22, a power source potential generation unit 23, and a reference potential generation unit 24.
The transfer signal generation unit 21 generates transfer signals φ1 and φ2 so as to supply the transfer signal φ1 to the φ1 terminal of the light emitting component 10 and supply the transfer signal φ2 to the φ2 terminal of the light emitting component 10. The transfer signals φ1 and φ2 are signals which are “H (0 V)” or “L (−3.3 V)”. 0 V is a potential for turning off the transfer thyristor T, and −3.3 V is a potential for turning the transfer thyristor T from an OFF state to an ON state.
The lighting signal generation unit 22 generates the lighting signal φI and supplies the signal to a φ1 terminal of the light emitting component 10 via a current-limiting resistor RI. The lighting signal φI is a signal which is “H (0 V)” or “L (−3.3 V)”. 0 V is a potential for turning off the laser diode LD, and −3.3 V is a potential for turning the laser diode LD from the OFF state to the ON state. The current-limiting resistor RI may be provided in the light emitting component 10. Further, in a case where the current-limiting resistor RI is not necessary for an operation of the light emitting component 10, the current-limiting resistor RI does not have to be provided.
The power source potential generation unit 23 generates a power source potential Vgk to supply the potential to the Vgk terminal of the light emitting component 10. The reference potential generation unit 24 generates a reference potential Vsub to supply the potential to the Vsub terminal of the light emitting component 10. The power source potential Vgk is, for example, −3.3 V. As described above, the reference potential Vsub is a ground potential (GND) as an example.
In the light emitting component 10 shown in
The transfer thyristor Ti sets each LD/S group of the plurality of LD/S groups such that a lighting state or a non-lighting state propagates in sequence. Specifically, in a case where the transfer thyristor Ti is turned on, the setting thyristor Sij connected to the transfer thyristor Ti is set so as to be able to shift to the ON state. The transfer thyristor Ti is driven such that the ON state propagates. Therefore, the transfer thyristor Ti is referred to as a transfer thyristor T. In addition, in a case where the setting thyristor Sij is turned on, the laser diode LDij emits light. Therefore, since the laser diode LD is set to be capable of emitting light, a thyristor for the setting is referred to as a setting thyristor S.
Here, the plurality of LD/S groups are configured, the LD/S group is connected to each transfer thyristor T, and the laser diode LD belonging to the LD/S group emits light in parallel.
The laser diode LD may oscillate in, for example, a low-order single transverse mode (single mode). In the single mode, an intensity profile of the light (emitted light) emitted from a light emission point of the laser diode LD (light emission opening 47 in
The smaller the area of the light emission point, the easier it is for the laser diode LD to oscillate in the single transverse mode (single mode). Therefore, the single mode laser diode LD has a small light output. In a case where the area of the light emission point is increased in an attempt to increase the light output, the mode shifts to the multi mode as described above. Therefore, in the first exemplary embodiment, the plurality of laser diodes LD are designated as the laser diode LD group, and the plurality of laser diodes LD included in the laser diode LD group are made to emit light in parallel to increase the light output.
The light emitting component 10 is composed of a semiconductor material capable of emitting laser light. For example, the light emitting component 10 is composed of a GaAs-based compound semiconductor. Then, as shown in a cross-sectional view (refer to
The island 301A-i is provided with the laser diode LDij and the setting thyristor Sij, and the island 301B-i is provided with the transfer thyristor Ti and the coupling diode Di (in this example, j=1 to 4). Then, in the islands 301A-i, posts 311, each of which is configured in an elliptical cylinder shape in accordance with an outer shape of the laser diode LD, are arranged. The post 311 is a part of the LD/S from which laser light is emitted. The post 311 is an example of a “light emitting unit”.
A part of each post 311 belonging to each LD/S group is continuous in the y direction at the facing part. Hereinafter, a part in which a part of each post 311 is continuous in the y direction is referred to as a “connection part 60”. That is, in each LD/S group, the plurality of LD/Ss are connected to each other by the connection part 60. In
Further, the islands 301A-i are provided to be parallel to each other in the x direction. Here, the LD/S groups are one-dimensionally arranged in the x direction.
The island 302-i is provided with a power line resistor Rgi. The islands 302-i are provided so as to be parallel to each other in the x direction.
The island 303 is provided with the start diode SD. The island 304 is provided with the current-limiting resistor R1, and the island 305 is provided with the current-limiting resistor R2.
First, the island 301A-1, which is provided with the LD/S11, will be described.
The LD/S11 is configured as a surface-emitting semiconductor layer laminate using a distributed Bragg reflector (DBR) waveguide. Then, as shown in
In the laser diode LD, an n-type nDBR layer 41, a resonator 42, and a p-type pDBR layer 43 are laminated on a GaAs substrate 80.
Next, in the LD/S11, the tunnel cementing layer 45 is laminated on the pDBR layer 43. The tunnel cementing layer 45 is configured by cementing an n++ layer in which n-type impurities are added at a high concentration and a p++ layer in which p-type impurities are added at a high concentration. The n++ layer and the p++ layer each have a high impurity concentration of, for example, 1×1020/cm3.
In the LD/S11, the setting thyristor S is laminated on the tunnel cementing layer 45. The setting thyristor S is laminated in order of a cathode layer 51, a p-type A-gate layer 52, a n-type n-gate layer 53, and an anode layer 54. An electrode 55 is provided on the anode layer 54 of the setting thyristor S. The electrode 55 is provided in an elliptical shape to surround the light emission opening 47.
In the laser diode LD, laser light is generated through resonance of light having a specific wavelength between the upper pDBR layer 43 and the lower nDBR layer 41. Then, the laser light generated in the laser diode LD is emitted in the vertical direction from the light emission opening 47.
A part of the pDBR layer 43 is formed with a current constriction layer 43A generated by oxidation. The current constriction layer 43A is formed such that current flowing through the LD/S11 passes through the central part by constricting a current path of the current flowing through the LD/S11. Specifically, the central part of the current constriction layer 43A is formed as a current pass region K in which current easily flows, and a peripheral portion thereof is formed as a current block region in which current does not easily flow.
By providing such a current constriction layer 43A, power consumed for non-luminescence recombination is suppressed, and power consumption is reduced and a light emission efficiency is increased.
Here, the current constriction layer 43A is formed by oxidizing a part of the pDBR layer 43 as described above. It should be noted that oxidizing a part of the pDBR layer 43 to form the current constriction layer 43A may be referred to as oxidization constriction.
In the right end portion of the island 301A-1 in
Although not shown in
Next, the island 301B-1, which is provided with the transfer thyristor T1 and the coupling diode D1, will be described.
At the left end portion of the island 301B-1, an electrode 57 is provided on the anode layer 54. The electrode 57 is connected to the wiring line 78 (refer to
In a similar manner to LD/S11, in the transfer thyristor T1 and the coupling diode D1, the nDBR layer 41, the resonator 42, the pDBR layer 43, the tunnel cementing layer 45, the cathode layer 51, the p-gate layer 52, the n-gate layer 53, and the anode layer 54 are laminated on the GaAs substrate 80.
The transfer thyristor T1 is provided with the electrode 58 on the anode layer 54 and functions as a gate for controlling the operation of the transfer thyristor T1. The electrode 58 is connected to the transfer signal line 72 (refer to
The coupling diode D1 is provided with the electrode 59 on the anode layer 54. The electrode 59 is connected to the wiring line 77 (refer to
The right end portion of the island 301B-1 exposes the pDBR layer 43. The exposed pDBR layer 43 and the GaAs substrate 80 are connected through a wiring line 79. In addition, in the part in which the transfer thyristor T1 and the coupling diode D1 are provided on the semiconductor layers (nDBR layer 41, resonator 42, and pDBR layer 43) constituting the laser diode LD, the nDBR layer 41, the resonator 42, and the pDBR layer 43 are short-circuited by the wiring line 79 such that the laser diode LD does not operate.
As described above, the light emitting component 10 uses the plurality of laser diodes LD as the laser diode LD group, and causes the plurality of laser diodes LD included in the laser diode LD group to emit light in parallel. In such a case, in a case where a wiring line for supplying a signal for controlling light emission or non-light emission of the laser diode LD is provided from the transfer unit 101 for each laser diode LD included in the laser diode LD group, a distance between the laser diodes LD has to be increased. Thus, an area of the light emitting component 10 increases.
Therefore, in the light emitting component 10, the setting thyristor S for setting the laser diode LD to be capable of emitting light is provided for each laser diode LD, and the setting thyristor S and the laser diode LD are laminated. Thereby, an increase in area of the light emitting component 10 is suppressed. Further, for each LD/S group, it is not necessary to provide a wiring line for supplying a signal for controlling light emission or non-light emission of the laser diode LD from the transfer unit 101 by connecting the semiconductor layer constituting the setting thyristor S by the connection part 60.
As shown in
In the post 311 in plan view, a length α from the center, which is the intersection (origin) of the major axis and the minor axis of the ellipse, to the end portion in the y direction is shorter than a length β from the center to the end portion in the x direction which intersects the y direction. Here, the directions are orthogonal to each other. The y direction is an example of a “first direction”, and the x direction is an example of a “second direction”. Further, the x direction that intersects the y direction does not have to be orthogonal thereto, and may be tilted by several degrees from the vertical state.
Although not shown in
Here, in a case where the connection part 60 is provided in the LD/S, oxygen is supplied not only to the center side of the post 311 but also to the connection part 60 side in a case where the pDBR layer 43 (refer to
Therefore, in the first exemplary embodiment, as described above, the length α of the post 311 is made shorter than the length β in plan view. Thereby, in the first exemplary embodiment, the length of the post 311 in the x direction perpendicular to the connection part 60 increases. Therefore, even in a case where more regions than the part where the connection part 60 is provided are oxidized, the oxidized shape is not distorted. For example, in
Further, the post 311 shown in
Here, in
Next, a second exemplary embodiment will be described while omitting or simplifying an overlapping part with the other exemplary embodiments.
In the second exemplary embodiment, the plurality of LD/Ss constituting the light emitter 102 are arranged in an orthorhombic grid pattern. In this point of view, the second exemplary embodiment is different from the first exemplary embodiment in which the plurality of LD/S constituting the light emitter 102 are arranged in a square grid pattern. In such a case, in the second exemplary embodiment, the length from the center of one LD/S in one LD/S group of the plurality of LD/S groups to the center of the LD/S adjacent to the one LD/S is longer than the length from the center of one LD/S to the center of the LD/S adjacent to one LD/S in another LD/S group adjacent to one LD/S group. For example, in
With such a configuration, according to the second exemplary embodiment, the light emitter 102 as the light emitting element array can be miniaturized as compared with the case where the lengths between the centers of all the adjacent LD/S are equal.
Next, a third exemplary embodiment will be described while omitting or simplifying the overlapping part with the other exemplary embodiments.
A plan view shape of the post 311 in the third exemplary embodiment is not configured as an elliptical shape unlike plan view shapes of the post 311 in the other exemplary embodiments.
As shown in
As shown in
As described above, the configuration, in which the length from the center of the post 311 to the end portion in the y direction is shorter than the length from the center to the end portion in the x direction, is not limited to a configuration in which the plan view shape of the post 311 is made elliptical, but both end portions of each post 311 in the x direction may be extended in the x direction.
Next, a fourth exemplary embodiment will be described while omitting or simplifying the overlapping part with the other exemplary embodiments.
The optical device 30 in the fourth exemplary embodiment employs the light emitting component 10 described in the first to third exemplary embodiments.
The optical device 30 comprises a light emitting component 10 and an optical element (not shown). The light emitting component 10 comprises nine LD/S groups (LD/S groups #1 to #9) and a transfer unit 101 one-dimensionally arranged in the x direction on the light emitter 102. The detailed description of the transfer unit 101 will not be repeated. Then, the optical device 30 comprises an optical element that sets a direction or a spread angle of the light emitted from each LD/S group in the plurality of LD/S groups included in the light emitting component 10 to a predetermined direction or a predetermined spread angle. Hereinafter, for example, a description will be given in a case where the optical element is a convex lens (hereinafter referred to as a lens LZ) and the emission direction of light is deflected in the predetermined direction. For example, the LD/S group #1 is disposed with the center of the lens LZ shifted in the x direction with respect to the center of the light emission opening 47 (refer to
In a case where the lens LZ is a small lens such as a micro lens, the deflection angle may be small. In such a case, another lens may be provided on the front surface of the optical device 30 provided with the lens LZ so as to increase the deflection angle. Further, the lens LZ has been described as a convex lens but may be a concave lens or an aspherical lens.
Further, in the above description, the emission direction of light is deflected, but the spread angle may be changed. For example, the convex lens may be employed to focus the light on the irradiated surface, or the light may be spread so as to be irradiated in a predetermined range on the irradiated surface.
The light receiving unit 11 is a device that receives the light reflected by the measurement target object 13. The light receiving unit 11 may be a photodiode. The photodiode is, for example, a single photon avalanche diode (SPAD) that can accurately measure the light receiving time.
The processing unit 12 is configured as a computer including an input output unit for inputting and outputting data. Then, the processing unit 12 processes the information about the light so as to calculate the distance to the measurement target object 13 and the two-dimensional or three-dimensional shape of the measurement target object 13.
The processing unit 12 of the optical measurement apparatus 1 controls the light emitting component 10 of the optical device 30 so as to emit the light from the light emitting component 10. That is, the light emitting component 10 of the optical device 30 emits the light in a pulse shape. Then, the processing unit 12 calculates an optical path length until light is emitted from the optical device 30, then reflected by the measurement target object 13, and reaches the light receiving unit 11, on the basis of the time difference between the time at which the light emitting component 10 emits light and the time at which the light receiving unit 11 receives the reflected light from the measurement target object 13. Therefore, the processing unit 12 measures a distance from the optical device 30 and the light receiving unit 11 or a distance from a point serving as a reference (hereinafter referred to as the reference point) to the measurement target object 13. In addition, the reference point is a point provided at a predetermined position from the optical device 30 and the light receiving unit 11.
For example, light from the LD/S group #1 of the light emitting component 10 in the optical device 30 travels toward a region @1 of the irradiated surface 15 virtually set. Further, the light from the LD/S group #2 travels toward a region @2. In such a manner, light is emitted from the LD/S groups #1 to #9 toward different regions @1 to @9. Then, the light receiving unit 11 receives the reflected light. Then, the processing unit 12 measures the time that elapses until the light is emitted and then the light receiving unit 11 receives the reflected light. Then, it is possible to detect which direction the measurement target object 13 is located in. That is, the optical measurement apparatus 1 is a proximity sensor. Further, the two-dimensional or three-dimensional shape of the measurement target object 13 is measured from the distance to the measurement target object 13.
The method is a surveying method based on a light arrival time, and is called a time-of-flight (TOF) method. In the method, for example, light having a shape of a plurality of pulses is emitted in order to improve a measurement accuracy. Further, the number of pulses may be increased to improve the measurement accuracy, in a specific direction, for example, in
The optical device 30 sequentially emits light in the predetermined direction. Therefore, the optical device 30 has a resolution lower than that in a case where light is emitted simultaneously in multiple directions, but consumes less power. Further, in a case where light is emitted simultaneously in multiple directions, it is necessary to identify the direction in which the reflected light comes by using the light receiving elements in which the light receiving elements are arranged two-dimensionally. In contrast, in the optical measurement apparatus 1 that emits light by sequentially changing the direction, it is not necessary to use a light receiving element in which light receiving elements are arranged in two dimensions, and it suffice to use a light receiving element capable of measuring a change in the intensity of the received light at high speed. Therefore, the configuration of the optical measurement apparatus 1 is simplified.
The light emitting component 10 in the optical device 30 shown in
As described above, the optical device 30 in the fourth exemplary embodiment sequentially drives the LD/S groups in the light emitting component 10 along the arrangement so as to irradiate the light in a planar manner. That is, light is emitted into a two-dimensional space through a one-dimensional operation.
The foregoing description of the exemplary embodiments of the present invention has been provided for the purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise forms disclosed. Obviously, many modifications and variations will be apparent to practitioners skilled in the art. The embodiments were chosen and described in order to best explain the principles of the invention and its practical applications, thereby enabling others skilled in the art to understand the invention for various embodiments and with the various modifications as are suited to the particular use contemplated. It is intended that the scope of the invention be defined by the following claims and their equivalents.
Number | Date | Country | Kind |
---|---|---|---|
2022-052354 | Mar 2022 | JP | national |