KR100976245B1 - Method and apparatu for sensor leveling, and automatic machine with the same - Google Patents

Abstract

The present invention relates to a sensor leveling method and apparatus, and an automated apparatus using the same. The present invention includes an infrared sensor 10 composed of a light emitting element 11 and a light receiving element 12. One of a plurality of resistors 16 having different levels is connected to the light emitting element 11. When the light emitting element 11 emits infrared rays, a main controller 24 is provided to control the leveling operation based on the light quantity value output from the light receiving element 12 that senses the emitted infrared rays. According to a control operation of the main controller 24, a selector 14 is provided to select and connect a resistor 16 having a predetermined value to the light emitting device 11 of the infrared sensor 10 that requires leveling. The selector 14 selects a sensor selector 14a for sequentially selecting the light emitting elements 11 to be leveled, and a resistor 16 having a predetermined value required for leveling for each of the selected light emitting elements 11. A resistance selector 14b is provided. In addition, the infrared sensor 10 is provided with a leveling control unit 20 for controlling a plurality of sensor groups to form a plurality of groups, and to perform the leveling operation for each sensor group at the same time. The leveling control unit 20 is controlled by the main control unit 24. Accordingly, the present invention has the advantage of shortening the leveling time, and prevents the failure and malfunction of the system due to data errors.

 Infrared sensor, leveling, light emitting element, MUX

Description

METHOD AND APPARATU FOR SENSOR LEVELING, AND AUTOMATIC MACHINE WITH THE SAME}

The present invention relates to a signal leveling method, and more particularly, to a sensor leveling method and apparatus for leveling signal strength by adjusting a reception sensitivity of an infrared sensor, and an automatic device using the same.

As used herein, the term "medium" refers to a bill, a check, a ticket, a certificate, or the like, and may be variously thinner than a width or a length.

The media teller machine is applied to financial teller machines such as banknote dispensers, vending machines, money exchangers, and media handlers such as certificate issuers and ticket vending machines to perform various functions such as storing, depositing, exchanging, and issuing media.

When describing using a banknote teller machine among the media cashier, the banknote teller machine is equipped with an infrared sensor for sensing the bill using infrared light. The infrared sensor is provided with a light emitting device that emits infrared light, and a light receiving device that detects the infrared light and outputs an output signal according to the detected amount. The light emitting element and the light receiving element serve to detect the current position of the bill to be transferred. The amount of light output from the infrared sensor when detecting the position of bills should be more than a predetermined reference value. The reference value is greater than or equal to the optimum value for detecting bills. The reference value may be applied differently according to the device specification.

However, the infrared sensor is contaminated by foreign matter such as dust or dust, or as the life of the product approaches, the light quantity value output from the light receiving element is gradually reduced. If the light quantity value is lower than the reference value, an error occurs in the sensor data of the paper money dispenser, which causes a malfunction of the paper money dispenser.

Therefore, the reception and reception of the infrared ray sensor, that is, the light quantity value, is connected to the banknote dispenser by selecting and connecting any one of resistors provided at different levels, for example, four levels according to a decrease in the light quantity value output from the light receiving element. A leveling circuit for leveling is provided. The term 'leveling' refers to a process of selecting and connecting a predetermined level of resistance to the infrared sensor so as to maintain a light amount value of the infrared sensor higher than a reference value. However, the leveling circuit should be provided for each of the infrared sensors. Thus, as the number of the infrared sensors is increased, the circuit configuration becomes more complicated and the number of devices used increases.

In order to solve this problem, the banknote dispenser uses a method in which a plurality of infrared sensors share one leveling circuit by using a leveling circuit having two analog multiplexers in the light receiving device. The leveling circuit sequentially selects each light receiving element one by one when performing the leveling of the infrared sensor, and selects and connects a resistor having a level corresponding thereto. In this case, since the time required for stabilizing the light receiving element and the resistance, the leveling circuit must wait for a predetermined delay time (delay time). The delay time includes a stabilization time necessary for changing the infrared sensor and operating the changed infrared sensor normally. Accordingly, the banknote dispenser using the conventional leveling circuit using a serial method of sequentially leveling the infrared sensor as described above has a problem that the leveling time is increased due to the delay time of the number of sensors.

In addition, the banknote dispenser using the conventional leveling circuit has a problem that the system is unstable due to the increase in the load that the control device must perform because the control device must control the entire leveling process of each infrared sensor.

Accordingly, an object of the present invention is to solve the above problems, and an object of the present invention is to provide a sensor leveling method and apparatus for leveling an infrared sensor to maintain a signal intensity output from an infrared sensor, that is, a light quantity value, by a predetermined reference or more, And to provide an automated device using the same.

Another object of the present invention is to shorten the leveling time of the infrared sensor.

According to a feature of the present invention for achieving the above object, the sensor leveling device according to the present invention comprises a plurality of light emitting elements; A plurality of leveling elements connected to the light emitting elements; A light receiving element corresponding to the light emitting element and outputting a light quantity value for the light emitting element; And a controller for controlling the leveling process by connecting the leveling device to the light emitting device requiring leveling based on the light quantity value of the light receiving device.

The plurality of leveling elements are resistors having different resistance levels.

According to another feature of the invention, the sensor leveling device according to the present invention comprises a plurality of sensor groups comprising a plurality of light emitting elements and light receiving elements; A first controller which performs a leveling process based on an output value of the light receiving element; And a second controller for controlling the leveling process of the light emitting device to be performed simultaneously with respect to the sensor group.

The present invention includes a first selection unit for selecting the light emitting element; And a second selector configured to select a resistance having a predetermined resistance level in the selected light emitting device.

The first control unit is composed of a programmable logic integrated circuit.

According to another feature of the invention, the automated device using the sensor leveling device according to the present invention includes a media taking-out module for taking in and out of the medium; And a sensor leveling device according to any one of claims 1 to 3, which performs leveling of a sensor provided in the media unloading module so as to sense the media transported during transport of the media.

According to another feature of the invention, the sense leveling method according to the present invention comprises the steps of sensing the light amount value of the light receiving element corresponding to the light emitting element; Determining whether leveling of the light emitting device is necessary based on the detection result; And when the leveling result is necessary, performing leveling on the light emitting device.

According to another feature of the invention, the sensor leveling method according to the present invention comprises the steps of simultaneously driving a plurality of sensor groups including two or more light emitting elements; Selecting sequentially from the first light emitting device for each sensor group simultaneously; Determining whether leveling is necessary for the light emitting device; And if leveling is necessary as a result of the determination, performing leveling on the corresponding light emitting device.

In the determining step, the detected light quantity value is compared with a predetermined reference value, and if the light quantity value is less than or equal to the reference value, it is determined that leveling of the light emitting device is necessary.

In the performing of the leveling step, the light quantity value is equal to or greater than the reference value by sequentially connecting a resistance having a different level from the resistor currently connected to the light emitting device.

As described above, the present invention simultaneously performs leveling on a plurality of sensor groups having a predetermined number of infrared sensors. Accordingly, the present invention has the following effects.

First, since the present invention performs leveling by selecting and connecting a light emitting element and a resistor of the infrared sensor, it is possible to prevent malfunction and failure due to the infrared sensor data error.

In addition, the present invention can shorten the entire leveling time since the maximum time required for the infrared sensor leveling is only required as the leveling time of the number of infrared sensors designated as one sensor group even if the number of infrared sensors is increased.

In addition, since the present invention performs the infrared sensor leveling using the leveling control unit, it is possible to reduce the load of the central control unit that previously controlled each infrared sensor leveling.

In addition, the present invention can reduce the number of circuit elements configured in the leveling circuit, thereby reducing the manufacturing cost.

Hereinafter, a sensor leveling method and apparatus according to a preferred embodiment of the present invention, and an automated device using the same will be described in detail with reference to the accompanying drawings.

Although the present embodiment has been described using a banknote dispenser, it should be noted that the present invention can be applied to a media handling apparatus that handles various types of media such as checks, gift certificates, and tickets.

1 is a block diagram of a banknote dispenser including a sensor leveling device according to a preferred embodiment of the present invention, Figure 2 is a detailed configuration diagram of the infrared sensor and the selection unit shown in Figure 1, FIG. 3A and 3B illustrate a sensor level data table and a sensor data table for each sensor group stored in the storage shown in FIG. 1, respectively.

As shown in these figures, the banknote dispenser of the present invention is provided with an infrared sensor 10 for detecting the bill using infrared light. The infrared sensor 10 serves to detect the current position of the bill to be transferred. The infrared sensor 10 includes a light emitting element 11 for emitting infrared rays and a light receiving element 12 for detecting the infrared rays. The light emitting element 11 is provided with an infrared light emitting diode (Infrared Light Emitting Diode), and emits infrared rays when the transfer of the bill is started. The light receiving element 12 detects infrared rays reflected by a prism (not shown) or the banknote among the emitted infrared rays and outputs an output signal according to the detected amount. That is, when the conveyed banknote arrives at the position where the infrared sensor 10 is installed, the infrared ray is absorbed or scattered in the banknote, so that the light quantity value of the infrared rays reflected from the banknote becomes significantly smaller. Accordingly, the paper money dispenser recognizes the point where the light quantity value of the infrared sensor 10 changes to a value smaller than a predetermined level as the current position where the paper money is transferred.

The light emitting element 11 and the light receiving element 12 are provided with the same predetermined number to form one sensor group. For example, eight of the light emitting elements 11 are set to the first sensor group G1. Similarly, eight of the light receiving elements 12 (T0 to T7) are set to the first sensor group G1. Although not shown, a second sensor group G2 and a third sensor group G3 are provided. In addition, a resistor RT having a value calculated in advance according to the distance from the light emitting element 11 is connected to the light receiving element 12 in series.

In order to perform the leveling of the infrared sensor 10, a resistor unit 16 including a plurality of resistors having different levels is provided. The resistor unit 16 includes eight resistors R0 to R7 for each sensor group G1, G2, and G3, and a total of 24 resistors are provided. The resistors are provided in order from the first resistor R0 having the lowest level of '0' to the eighth resistor R7 having the highest level of '7'. Accordingly, when the first resistor R0 having the smallest resistance value is connected to the light emitting device 11, the voltage applied to the light receiving device 12 increases according to the principle of the voltage divider. The light quantity value output from (12) becomes the largest. On the other hand, when the eighth resistor R7 of the '7' level having the highest resistance value is connected to the light emitting element 11, the light quantity value output from the light receiving element 12 is minimized. However, you can also do the opposite. That is, the first resistor R0 may be provided at the highest resistance level (seventh level), and the eighth resistor R7 may be provided at the lowest resistance level (zeroth level).

The selection unit 14 selects one of the light emitting elements 11 and selects and connects one of the resistors R0 to R7 of the resistor unit 16 to the selected light emitting element 11. The selection unit 14 is provided one by one for each sensor group (G1, G2, G3). For example, the selector 14 provided to be connected to the first sensor group G1 may include a sensor selector 14a for selecting any one of the light emitting elements D0 to D7 of the first sensor group G1. And a resistor selector 14b for selecting any one of the resistors R0 to R7. The sensor selector 14a and the resistor selector 14b use an analog multiplexer (MUX) operated to select one channel among a plurality of input signals. In particular, the sensor selector 14a sequentially selects the light emitting elements D0 to D7 according to the clock signal edge state of the main controller 24 to be described below.

A leveling control unit 20 is provided to control the selection unit 14 according to the control of the main control unit 24 to be described below. The leveling controller 20 selects the light emitting elements D0 to D7 according to the edge state of the clock signal, and selects the light emitting elements D0 to D7 according to the light quantity value output from the light receiving elements T0 to T7. Performs leveling. In addition, the leveling control unit 20 may control the first to third leveling modules 22a, 22b, and 22c provided in correspondence with the sensor groups G1, G2, and G3. Is used. Of course, the leveling controller 22 may include a programmable read only memory, a programmable logic array, a programmable array logic, a simple programmable logic device, and a field programmable gate array. It can be changed to various types of programmable logic integrated circuits.

When the edge state of the clock signal output from the main control unit 24 is a falling edge state, the leveling control unit 20 sequentially levels each infrared sensor 10 at the same time for each sensor group (G1, G2, G3). The order of the infrared sensor 10 is counted. Then, the selector 14 is controlled to select a sensor and a resistance to be leveled according to the counted order. When the clock signal is in the rising edge state, the leveling controller 20 outputs an amount of light output from the light receiving element 12 corresponding to the light emitting element 11 to each of the sensor groups G1, G2, and G3. It is stored in the storage unit 21 to be described below.

The leveling control unit 20 includes a storage unit 21 for storing sensor level data of the resistors R0 to R7 connected to the light emitting element 11 and sensor data of the light receiving element 12. An address is assigned to the storage 21, and the address informs that data for a sensor of a sensor group is stored. The sensor level data is a level value of the resistor 16 connected to the light emitting element 11. As illustrated in FIGS. 3A and 3B, the storage unit 21 is an area A for storing sensor level data for each sensor group (G1, G2, G3) input from the main controller 24, and the light receiving unit. A region B for storing the light quantity value output from the element 12, that is, sensor data for each sensor group (G1, G2, G3) is provided. Since the area A and the B store information of each sensor at each address allocated to the size of 1 bit, each sensor group is allocated to the size of 8 bits, that is, 1 byte.

The main controller 24 is configured to control the leveling controller 20 so that the light quantity value of the light receiving element 12 is equal to or greater than the reference value. The main controller 24 uses the sensor-specific address information of the storage unit 21 to sense sensor level data and sensor data of the infrared sensor 10, that is, a resistor 16 connected to the light emitting element 11. ) And the light quantity value output from the light receiving element 12. The main controller 24 compares the read light quantity value with the reference value. As a result of the comparison, when the light quantity value is less than or equal to the reference value, the main controller 124 controls to change the read sensor level data by one step until the light quantity value is output above the reference value. The main controller 24 applies the clock signal in the form of a pulse width modulation signal to the light emitting element 11 to drive the infrared sensor 10. In this embodiment, the clock signal has a duty of about 3% and a period of about 100 ms. The main controller 24 controls to perform the leveling operation of the infrared sensor 10 at the time of initial driving of the paper money dispenser and at the time of abnormality of the infrared sensor 10. The main control unit 24 is a central processing unit (Central Processing Unit) for controlling the entire banknote and withdrawal machine, as well as the leveling operation of the infrared sensor 10, as well as various processing processes such as transfer operation, loading operation, operation operation for deposit and withdrawal, etc. Control to perform.

Next, the sensor leveling method of the banknote dispenser according to a preferred embodiment of the present invention will be described in detail.

In this embodiment, the state of the infrared sensor is checked when the banknote dispenser is initially driven, and the leveling process of the infrared sensor according to the result and the leveling process of the infrared sensor which occurred abnormally during normal operation will be described.

First, the process of performing the leveling of the infrared sensor during the initial driving of the banknote machine.

4 is a flowchart illustrating a step-by-step sensor leveling method of a banknote dispenser according to a preferred embodiment of the present invention. 5 is an operation state diagram illustrating an operation method of the sensor leveling method illustrated in FIG. 4.

In the tenth step S10 of FIG. 4, when power is applied to the paper money dispenser and driven for the first time, power is also applied to the main controller 24, and the main controller 24 controls the paper money dispenser as a whole while outputting a predetermined clock signal. To start. The clock signal has a duty of about 3% and a period of about 100 ms. In operation 12, the main controller 24 reads the level value of the resistor currently connected to the light emitting device, that is, the sensor level data, and stores the sensor level data in the storage 21. The sensor level data may be a sensor level value of a resistor connected to the light emitting device when the banknote dispenser is driven, or a level value of a resistor connected when the banknote dispenser is booted during initial operation.

Once the sensor level data for the light emitting device is stored, the first to third leveling modules 22a, 22b, and 22c are driven by the control signal of the main controller 24 in the fourteenth step S14. The driving of the first to third leveling modules 22a, 22b, and 22c means that the first to third sensor groups G1, G2, and G3 corresponding thereto are driven. That is, the first to third sensor groups G1, G2, and G3 are driven at the same time.

The first to third sensor groups G1, G2 and G3 are also controlled by the control of the main controller. Therefore, the light emitting devices provided in the first to third sensor groups G1, G2, and G3 perform different operations according to the clock signal edge state of the main controller. This will be described in detail.

First, the case in which the clock signal is in the falling edge state in the sixteenth step S16 will be described. In this case, in the eighteenth step (S18), the sensor selection unit 14a is the first light emitting device provided in the first to third sensor groups G1, G2, and G3, that is, the first sensor block S1 of FIG. Allow sensor 0, sensor 8 and sensor 15 to be selected. In the twentieth step S20, the resistance selector 14b selects and connects a resistance having a level corresponding to the sensor level data stored in the twelfth step S12 to the sensor 0, the sensor 8, and the sensor 15. Subsequently, in step 22, the sensor 0, the sensor 8, and the sensor 15 and the resistance connected thereto are waited for a delay time required to stabilize.

Next, a case in which the clock signal is a rising edge in step 24 (S24) will be described. When the clock signal is in the rising edge state, the sensor 0, the sensor 8, and the sensor 15 emit infrared rays, and the infrared rays are transmitted to the first light receiving element corresponding to the first light emitting element in step 26. . The first light receiving element detects infrared rays emitted from the sensors 0, 8, and 15, and outputs a light quantity value according to the detected amount.

Then, in the 26th step S26, the first to third leveling modules 22a, 22b, and 22c receive the light quantity values of the first light receiving element and store them in the storage unit 21. Subsequently, in a 28 th step S28, the main controller compares the light quantity value of the first light receiving element with the reference value. As a result of the comparison, when it is determined that at least one light quantity value of the light quantity value of the first light receiving element of the first sensor group G1 is equal to or less than the reference value, in step 29 (S29), the main controller 24 is less than or equal to the reference value. The level value of the resistor connected to the determined light emitting device, that is, the sensor level data, is changed by one step. Then, the first leveling module 22a performs the leveling process for the corresponding light emitting device by repeating steps 20 through 28 (S28) using the changed sensor level data. At this time, the second and third leveling modules 22b and 22c do not immediately go to the second light emitting device even if the light quantity value of the first light receiving device of each sensor group G2 or G3 is greater than or equal to the reference value. Wait until the first light emitting device leveling process of the leveling module 22a is completed.

As a result of the comparison, when it is determined that all of the light quantity values of the first light receiving element are greater than or equal to the reference value and have a suitable light quantity value, the first to third leveling modules 22a, 22b, and 22c have the next second light emitting element, that is, A sensor count is set to select the sensor 1, the sensor 9, and the sensor 17 of the second sensor block S2 of FIG. In addition, by checking whether the infrared sensor to be leveled remains in the thirtieth step (S30), the main controller 24 repeats the sixteenth step (S16) to the thirtieth step (S30) according to the set sensor count, The light emitting device S2 to the eighth light emitting device S8 are repeatedly performed.

On the other hand, in this embodiment, the time for leveling one infrared sensor 10 is equal to the period of the clock signal, so a maximum of 100 ms is required. One sensor group leveling time in which eight infrared sensors 10 are configured in series takes about 800 ms. In addition, since each sensor group (G1, G2, G3) is configured in parallel to perform the leveling at the same time, because the leveling of the entire infrared sensor 10 is about 800 kHz, it is finished within a maximum of about 1 kHz. As a result, as shown in FIG. 5, in this embodiment, the infrared sensors 10 are connected in series by eight, and are configured in parallel with three sensor groups G1, G2, and G3. Accordingly, the total infrared sensor leveling time is shortened to the leveling time of the number of infrared sensors included in one sensor group, for example, about 800 [mu] s, which is shorter than the sensor leveling time using a conventional serial method that increases with the number of sensors.

Next, the leveling process of the infrared sensor in which an abnormality occurs during the normal operation will be described.

In this embodiment, it will be described using the banknote deposit transaction of the banknote dispenser.

6 is a flowchart illustrating a step-by-step method of leveling an infrared sensor in which a banknote dispenser has an error according to a preferred embodiment of the present invention.

In step 40 of FIG. 6, each infrared sensor 10 sequentially detects bills sequentially transferred.

At this time, if the amount of light output from the at least one infrared sensor 10 in step 42 (S42) is less than the reference value or the amount of light is not output from the infrared sensor 10, in step 44 (S44) The main controller 24 displays a message indicating an abnormal occurrence of the infrared sensor 10 on the display unit (not shown).

Subsequently, in the 46th step S46, the main controller 24 changes the sensor level data of the infrared sensor, in which an abnormality occurs, by one step to perform leveling.

Forty-eighth (S46) to forty-eighth (S48) until the amount of light output from the light receiving element of the infrared sensor in step 48 is greater than or equal to the reference value and the infrared sensor 10 operates normally. Repeat.

Through the above process, the present invention performs a leveling process by simultaneously driving a plurality of sensor groups provided with a plurality of infrared sensors.

As described above, the present invention has been described with reference to the embodiments shown in the drawings, which are merely exemplary, and a person of ordinary skill in the art without departing from the spirit and scope of the present invention. It will be apparent that various modifications, changes, and equivalent other embodiments are possible. Therefore, the true technical protection scope of the present invention will be defined by the technical spirit of the appended claims.

Although the above embodiments have been described using a banknote dispenser and a banknote deposit transaction thereof, the present invention provides not only banknotes but also financial automatic machines, vending machines, money exchangers, and various certificates and tickets. It can also be applied to the media publisher that handles it.

According to the present invention, the number of infrared sensors per sensor group and the number of sensor groups can be variously changed according to the number of infrared sensors, and the level of the resistance part can be changed in various steps according to the accuracy required in the media handling apparatus.

In the above embodiment, the selector is connected to the light emitting device, but the selector may be connected to the light receiving device. However, when the selector is connected to the light emitting device, the stabilization speed of the infrared sensor is improved as compared to the case where the selector is connected to the light receiving device. Therefore, it is preferable that the selection unit is connected to the light emitting element to shorten the overall leveling time.

In the above embodiment, the light receiving device is installed on the same side as the light emitting device so as to sense the reflected infrared light. However, when the transmission method is used, the light receiving device may be installed at symmetrical positions of the light emitting device.

In addition, in the above embodiment, it is described that the sensor group is driven at the same time so that the leveling is performed immediately so that the light quantity value of each sensor is equal to or greater than the reference value. However, in the present invention, after performing leveling using predetermined sensor level data with respect to the entire infrared sensor, the sensor level data may be changed to additionally perform leveling by changing the sensor level data only for an infrared sensor having a light quantity value less than or equal to a reference value. .

1 is a block diagram showing the configuration of a banknote teller machine according to a preferred embodiment of the present invention.

2 is a detailed configuration diagram of the infrared sensor and the selection unit shown in FIG.

3A is a sensor level data table for each sensor group stored in a storage shown in FIG. 1.

3B is a sensor data table for each sensor group stored in a storage unit shown in FIG. 1.

4 is a flowchart illustrating a sensor leveling method of a banknote dispenser according to a preferred embodiment of the present invention.

FIG. 5 is an operational state diagram illustrating a sensor leveling method shown in FIG. 4.

6 is a flowchart illustrating a sensor leveling method when an infrared sensor abnormality occurs in a banknote dispenser according to a preferred embodiment of the present invention.

`` Explanation of symbols for main parts of drawings ''

10 infrared sensor 11 light emitting element

12: light receiving element 14: selection unit

16: resistance unit 20: leveling control unit

21: storage unit 22: leveling module

24: main control unit

Claims (10)

A plurality of light emitting elements; A plurality of leveling elements connected to the light emitting elements; A light receiving element corresponding to the light emitting element and outputting a light quantity value for the light emitting element; And And a controller for controlling the leveling process by connecting the leveling device to a light emitting device requiring leveling based on the light quantity value of the light receiving device. The method of claim 1, wherein the plurality of leveling elements, Sensor leveling device, characterized in that each having a different resistance level. A plurality of sensor groups including a plurality of light emitting elements and light receiving elements; A first controller which performs a leveling process based on an output value of the light receiving element; And And a second controller for controlling the leveling process of the light emitting device to be performed simultaneously with respect to the sensor group. The method of claim 2 or 3, A first selector for selecting the light emitting element; And a second selector configured to select a resistance having a predetermined resistance level in the selected light emitting device. The method of claim 3, wherein the first control unit, Sensor leveling device, characterized by consisting of a programmable logic integrated circuit. A media taking-out module which takes in and receives a medium; Sensor leveling device comprising the sensor leveling device of claim 1 or 3 to perform the leveling of the sensor provided in the media unloading module to detect the transported medium during the transport of the medium. Automation equipment using. Detecting a light quantity value of a light receiving element corresponding to the light emitting element; Determining whether leveling of the light emitting device is necessary based on the detection result; And And performing leveling on the light emitting device if leveling is necessary as a result of the determination. Simultaneously driving a plurality of sensor groups including two or more light emitting devices; Selecting sequentially from the first light emitting device for each sensor group simultaneously; Determining whether leveling is necessary for the light emitting device; And And when the leveling result is necessary, performing leveling on the corresponding light emitting device. The method of claim 7 or 8, wherein the determining step, And comparing the sensed light quantity value with a predetermined reference value, and if the light quantity value is equal to or less than the reference value, determining that the leveling of the light emitting device is necessary. The method of claim 7 or 8, wherein the performing of the leveling step, And sequentially connecting a resistor having a different level to a resistor currently connected to the light emitting device so that the light quantity value is equal to or greater than the reference value.

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