KR102649792B1 - Hybrid LED Driver Circuit and LED Package Including the Same - Google Patents

Abstract

Disclosed is a hybrid LED driver circuit and an LED package including the same.
According to one aspect of this embodiment, in the driver circuit that controls the operation of the light source, the data signal is applied from the outside, and the data signal is analyzed to prevent the light source from operating, or the data signal is PAM (Pulse Amplitude Modulation) method, modulate the data signal by PWM (Pulse Width Modulation) method, or modulate the data signal by both PAM method and PWM method and apply it to the light source.

Description

Hybrid LED driver circuit and LED package including the same {Hybrid LED Driver Circuit and LED Package Including the Same}

The present invention relates to a hybrid driver circuit that controls the operation of a light source in a hybrid form of PWM and PAM and an LED package including the same.

The content described in this section simply provides background information for this embodiment and does not constitute prior art.

In controlling the operation of light sources such as display panels or LED packages, PM (Passive Matrix) driving has become the mainstream, but AM (Active Matrix) driving is necessary to reduce power consumption. Methods mainly used for AM driving include the PAM (Pulse Amplitude Modulation) method and the PWM (Pulse Width Modulation) method.

The conventional PAM driving circuit, which varies the amplitude of the driving current for each gray level to express gray levels, has the disadvantage that it is difficult to precisely control LED brightness due to current changes at low gray level. Additionally, the conventional PAM driving circuit has a color shift problem in which the color changes significantly for each gray level.

Meanwhile, the conventional PWM driving circuit, which varies the pulse width (or duty ratio) of the driving current depending on the gray level, generates flickering at low gray levels, and uses a high refresh rate to eliminate it. There is an inconvenience that requires a rate. Additionally, a conventional PWM driving circuit must secure a rapid rising time and falling time to generate a pulse with a narrow width. For this purpose, the conventional PWM driving circuit requires a large amount of current and has the problem of generating high power consumption.

Since the conventional methods for the driver circuit of the light source to control the light source in an active driving manner have fatal problems as described above, there is a demand for a new control method that solves the problems described above.

One embodiment of the present invention has the purpose of providing a hybrid driver circuit that operates to minimize problems of the conventional driving method and an LED package including the same.

According to one aspect of the present invention, in a driver circuit that controls the operation of a light source, a control signal for mode selection is received from the outside, and the control signal is analyzed and modulated using PAM (Pulse Amplitude Modulation) or PWM (PWM). Provides a driver circuit that selects whether to modulate using the Pulse Width Modulation (Pulse Width Modulation) method or both PAM and PWM methods, and applies a data signal to the light source according to the selected modulation method.

According to one aspect of the present invention, the driver circuit modulates the data signal into both the PAM method and the PWM method, dividing it into preset sizes and modulating each of them into one of the PAM method and the PWM method and the other. Do it as

According to one aspect of the present invention, the driver circuit is characterized in that the front end of the preset size of the data signal is modulated by one of the PAM method and the PWM method, and the remaining rear end of the data signal is modulated by the other one of the PAM method and the PWM method. Do it as

According to one aspect of the present invention, the data signal is characterized in that it is 16 bits.

According to one aspect of the present invention, the driver circuit modulates the first 8 bits of the data signal using the PAM method and the last 8 bits of the data signal using the PWM method.

According to one aspect of the present invention, an LED package is provided, comprising the driver circuit and a light source that operates by receiving a data signal modulated from the driver circuit.

According to one aspect of the present invention, a control signal for mode selection is received from the outside, the control signal is analyzed and modulated using PAM (Pulse Amplitude Modulation) method, PWM (Pulse Width Modulation) method, or PAM method. and PWM method are selected, a data signal is applied to the light source according to the selected modulation method, and for modulation using the PAM method, the number of bits of the applied data signal is included in the data signal value. It includes a plurality of first transistors that control the application of current according to the number of bits of the applied data signal, and a plurality of first transistors that control the flow of the output signal of the first transistor by adjusting the opening and closing of the circuit according to the data signal value. 1 switch and a second transistor that receives the output signal modulated by the PWM method and controls the application of current according to the output signal value, and receives the output signal modulated by the PWM method and opens and closes the circuit according to the output signal value. A second switch that controls the flow of the output signal of the second transistor by adjusting, a third transistor that receives the output signal of the first transistor or the second transistor, and the same size as the output signal applied to the third transistor. It provides a driver circuit comprising a fourth transistor that applies a current of to the light source.

According to one aspect of the present invention, the data signal is applied to the gate terminal of each first transistor.

According to one aspect of the present invention, the first transistor is characterized in that a fixed voltage is applied to the drain terminal.

According to one aspect of the present invention, each first transistor forms channels having different widths.

According to one aspect of the present invention, an LED package is provided, comprising the driver circuit and a light source that operates by receiving a data signal modulated from the driver circuit.

According to one aspect of the present invention, a control signal for mode selection is received from the outside, the control signal is analyzed and modulated using PAM (Pulse Amplitude Modulation) method, PWM (Pulse Width Modulation) method, or PAM method. and PWM method, apply a data signal to the light source according to the selected modulation method, and increase the register and count value for storing the applied data signal by 1 for modulation in the PWM method. and a ring counter that compares whether the count value has the same value as the data signal stored in the register and generates an output corresponding to the count value.

According to one aspect of the present invention, the ring counter increases the size of a count value having the same number of bits as the data signal applied to the register by 1.

According to one aspect of the present invention, the ring counter is characterized in that it generates a pulse corresponding to the count value as an output.

According to one aspect of the present invention, the ring counter applies modulation to an output signal using the PAM method.

According to one aspect of the present invention, an LED package is provided, comprising the driver circuit and a light source that operates by receiving a data signal modulated from the driver circuit.

As described above, according to one aspect of the present invention, there is an advantage in that the light source can be driven to minimize the problems of the conventional driving method.

Figure 1 is a diagram showing the configuration of an LED package according to an embodiment of the present invention.
Figure 2 is a diagram showing the configuration of a driver circuit according to an embodiment of the present invention.
Figure 3 is a graph showing a data signal applied to a driver circuit according to an embodiment of the present invention.
Figure 4 is a diagram showing the configuration of a PWM control unit according to an embodiment of the present invention.
Figure 5 is a diagram showing the configuration of a PAM control unit according to an embodiment of the present invention.
Figure 6 is a diagram showing a PAM signal output from a driver circuit according to an embodiment of the present invention and a conventional driver circuit.
Figure 7 is a diagram showing a PWM signal output from a driver circuit according to an embodiment of the present invention and a conventional driver circuit.

Since the present invention can make various changes and have various embodiments, specific embodiments will be illustrated in the drawings and described in detail. However, this is not intended to limit the present invention to specific embodiments, and should be understood to include all changes, equivalents, and substitutes included in the spirit and technical scope of the present invention. While describing each drawing, similar reference numerals are used for similar components.

Terms such as first, second, A, and B may be used to describe various components, but the components should not be limited by the terms. The above terms are used only for the purpose of distinguishing one component from another. For example, a first component may be named a second component, and similarly, the second component may also be named a first component without departing from the scope of the present invention. The term and/or includes any of a plurality of related stated items or a combination of a plurality of related stated items.

When a component is said to be "connected" or "connected" to another component, it is understood that it may be directly connected to or connected to the other component, but that other components may exist in between. It should be. On the other hand, when it is mentioned that a component is “directly connected” or “directly connected” to another component, it should be understood that there are no other components in between.

The terms used in this application are only used to describe specific embodiments and are not intended to limit the invention. Singular expressions include plural expressions unless the context clearly dictates otherwise. In this application, terms such as "include" or "have" should be understood as not precluding the existence or addition possibility of features, numbers, steps, operations, components, parts, or combinations thereof described in the specification. .

Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as generally understood by a person of ordinary skill in the technical field to which the present invention pertains.

Terms defined in commonly used dictionaries should be interpreted as having a meaning consistent with the meaning in the context of the related technology, and unless explicitly defined in the present application, should not be interpreted in an ideal or excessively formal sense. No.

Additionally, each configuration, process, process, or method included in each embodiment of the present invention may be shared within the scope of not being technically contradictory to each other.

Figure 1 is a diagram showing the configuration of an LED package according to an embodiment of the present invention.

Referring to FIG. 1, an LED package 100 according to an embodiment of the present invention includes a driver circuit 110 and a light source 120.

The LED package 100 is configured to receive power, clock signals, data signals, and scan signals and operate according to the data signals and scan signals. The LED package can be placed and used in any device that includes a light source that can control its operation, such as a display panel. The LED package 100 can control the operation of the light source by itself by including a driver circuit inside to control the operation of the light source.

The driver circuit 110 receives power, clock signals, data signals, and scan signals and controls the operation of the light source 120 according to the data signals and scan signals. The driver circuit 110 receives power and clock signals from the outside for operation of itself and the light source 120 connected to it. Additionally, the driver circuit 110 receives data signals and scan signals for controlling the operation of the light source 120 from the outside.

The light source 120 operates under the control of the driver circuit 110.

Figure 2 is a diagram showing the configuration of a driver circuit according to an embodiment of the present invention.

Referring to FIG. 2, the driver circuit 110 according to an embodiment of the present invention includes a power and data selection unit 210, a receiver 220, a clock signal generator 230, a timing control unit 240, and a first It includes a data separation unit 250, a second data separation unit 255, a PAM control unit 260, and a PWM control unit 265.

The power and data selection unit 210 receives power and scan signals from the outside. The power and data selection unit 210 receives power from the outside and supplies power to the remaining components in the driver circuit 110. In addition, the power and data selection unit 210 receives the scan signal and transmits it to the timing control unit 240, so that the timing control unit 240 can control the on/off of each light source 120. do. The power and data selection unit 210 includes a port 215 to receive each signal and receives each signal using the port 215.

The receiver 220 receives the clock signal and the data signal and transmits them to the clock signal generator 230 or the timing controller 240. The receiver 220 receives a clock signal from the outside and transmits it to the clock signal generator 230. Meanwhile, the receiver 220 receives the data signal and transmits it to the timing control unit 240. Likewise, the receiver 220 also includes ports 225a and 225b to receive each signal, and receives each signal using the port 225.

At this time, the data signal has the standards shown in FIG. 3.

Figure 3 is a graph showing a data signal applied to a driver circuit according to an embodiment of the present invention.

Referring to FIG. 3, the data signal includes mode information for operating the light source 120 at the front end 310. Mode information is divided into four types: the first mode is not operating (Off), the second mode is the light source operates in the PAM method (the data signal is modulated by the PAM method), and the light source operates in the PWM method (the data signal is modulated by the PWM method). It includes a third mode in which the light source operates in both the PAM method and the PWM method. For example, the first mode may be assigned 00, the second mode may be assigned 01, the third mode may be assigned 10, and the fourth mode may be assigned 11. In this way, the data signal includes mode information for operating the light source 120 at the front end 310.

The data signal includes synchronization information in the next stage 320 of the previous stage 310. Depending on the synchronization method, synchronization information may be '00011101' (in normal mode) or '11111111_11111111' (in deskew mode).

The data signal includes data to be transmitted to the next stage 330. Data signals may be transmitted as differential signals, and the signal level may swing within hundreds of mV.

The data signal includes a trailing sequence as the next step 340 of the data.

The data signal is transmitted and contains the above-described information.

Referring again to FIG. 2, the receiver 220 converts the received data signal into a digital signal of a preset size. For example, the receiver 220 may convert the received data signal into a 16-bit data signal.

The clock signal generator 230 receives a clock signal from the receiver 220 and allows the timing controller 240 to operate according to the clock signal.

The timing control unit 240 analyzes the received signal and separates the data signal into each data separation unit 250 and 255 or transfers it to one of them. The timing control unit 240 analyzes the data signal converted into a digital signal by the receiver 220. In particular, the timing control unit 240 analyzes the front-end mode information in the data signal and determines which data separation unit to transmit it to. The timing control unit 240 may transmit data to one or all data separators depending on the mode information, or may not transmit data to any data separator.

When transmitting data to each data separation unit 250 and 255, the timing control unit 240 divides the data and transmits it. For example, as described above, when a 16-bit digital signal is input to the timing control unit 240, the timing control unit 240 can divide the data into 8 bits and transmit the data to each data separation unit. Here, the timing control unit 240 can transmit the first 8 bits of the data signal to the first data separator 250 and the rear 8 bits of the data signal to the second data separator 250. However, this is only an example, and any method may be used as long as half of the input data signal can be transmitted to one data separator (separation into arbitrary sections, separation into odd/even numbers, etc.).

The timing control unit 240 transmits the data signal to each data separation unit 250 and 255 according to the scan signal and the clock signal.

Each data separation unit 250, 255 is disposed in the middle of the timing control unit 240 and the PAM/PWM control unit 260, 265 (on the path through which the signal is transmitted), and transmits the received signal to each PAM/PWM control unit 260, 265).

Each PAM/PWM control unit 260, 265 performs PAM and PWM on the received data signal. Each PAM/PWM control unit 260 and 265 has the structure shown in FIGS. 4 and 5 and modulates the received data signal into a pulse signal.

Figure 4 is a diagram showing the configuration of a PWM control unit according to an embodiment of the present invention.

Referring to FIG. 4, the PWM control unit 265 according to an embodiment of the present invention includes a register 410 and a ring counter 420.

The register 410 receives the data signal received from the PWM control unit 265 and stores it. The data signal divided by the timing control unit 240 and transmitted through the data separation unit 250 is received and stored.

When a clock signal is applied, the ring counter 420 increases the count value from 0 to 1 and compares it to see if it has the same value as the data signal applied to the register 410. The ring counter 420 increases the size of the count value having the same number of bits as the data signal applied to the resistor 410 by 1 and compares it with the data signal. For example, as described above, when the data signal received by the PWM control unit 265 is an 8-bit signal, the ring counter 420 increases the count value by 1 from 0 to 255 (8 bits), and combines the count value and the data signal Compare. The ring counter 420 goes through the above-described comparison process and generates an output corresponding to the same count value as the data signal applied to the register 410. The ring counter 420 generates as output a pulse corresponding to a count value having the same number of bits as the data signal. More specifically, the ring counter 420 can generate a pulse with a magnitude of '1' for bits with a value of '1', and a pulse with a magnitude of '0' for bits with a value of '0'. For example, if the count value and the data signal have the value 3 (00000011), as shown in FIG. 4, the ring counter 420 generates a pulse 430 with 1 only in the last bit and the previous bit. You can.

Meanwhile, as will be described later, the ring counter 420 applies the generated pulse value to the PAM control unit 260.

Figure 5 is a diagram showing the configuration of a PAM control unit according to an embodiment of the present invention.

Referring to FIG. 5, the PAM control unit 260 according to an embodiment of the present invention includes first transistors 510a to 510h, second transistors 510i, first switches 520a to 520h, and second switches 520i. ), a bias current source 530, a third transistor 540a, and a fourth transistor 540b.

The first transistors 510a to 510h include the number of bits of the data signal applied to the PAM control unit and control the application of current according to the data signal value. A fixed voltage (VCC1) is applied to the drain terminal of each first transistor, and a data signal is applied to the gate terminal. The data signal has a certain number of bits, and the first transistor 510 also includes the same number of bits as the data signal. The value of each bit in the data signal is applied to the gate terminal of each first transistor. For example, when the value of a specific bit of the data signal is '1', a gate voltage (higher than the threshold voltage) according to the data signal is applied. Accordingly, when the value of a specific bit of the data signal exists, a channel through which current can flow is formed by each voltage applied to the gate terminal and the drain terminal.

At this time, channels having different widths are formed for each first transistor 510. That is, because each first transistor 510 forms a channel with a different width, currents of different sizes flow through each first transistor 510. For example, the width of the channel gradually formed from the first transistor 510a to the first transistor 510h may increase. Accordingly, just as the size of the applied data signal changes, it may change to correspond to the size of the current data signal that ultimately flows through the first transistor 510.

The second transistor 510i receives the output signal from the PWM control unit 265 and controls the application of current according to the output signal value. Like the first transistors 510a to 510h, the second transistor 510i also has a fixed voltage (VCC1) applied to its drain terminal, and the output signal of the PWM control unit 265 is applied to its gate terminal. However, the signal applied to the second transistor 510i is an output signal from the PWM control unit 265, and the pulse width is important, not the pulse size. Therefore, only one second transistor 510i is implemented, and a channel is formed only when the signal value applied to the gate terminal is 1, and a current of a certain size flows.

The first switches 520a to 520h and the second switches 520i are connected to the source terminals of the first transistors 510a to 510h and the second transistor 510i, respectively, and are turned on/off depending on the size of the applied signal. It is controlled.

Data signals to the PAM control unit are applied to the first switches 520a to 520h, respectively. Like the first transistors 510a to 510h, the first switches 520a to 520h are included in the same number as the number of bits of the data signal, and the value of each bit in the data signal is applied to the first switches 520a to 520h. do. The first transistors 510a to 510h and the first switches 520a to 520h operate according to the data signal applied to the PAM control unit to allow the output signal to flow.

Meanwhile, the output signal of the PWM control unit 265 is applied to the second switch 520i, and is turned on/off in the same way as the second transistor 510i, allowing the output signal to flow.

The bias current source 530 applies bias current to each transistor.

Each transistor (510a to 510i) and each switch (520a to 520i) operates and the flowing output signal (current) is applied to the third transistor (540a). The third transistor 540a and fourth transistor 540b are arranged in the form of a current mirror. When current is applied to the third transistor 540a, a channel is formed in the fourth transistor 540b and a current of the same magnitude flows therethrough. The current flowing through the fourth transistor 540b is applied to the light source 120.

The PAM control unit 260 has the above-described structure and performs PAM modulation on the applied data signal. In addition, the PAM control unit 260 receives the output signal of the PWM control unit 265, and regardless of the presence or absence of a data signal (transmitted from the first data separator) applied to the PAM control unit 260, the PAM control unit 260 receives the output signal of the PWM control unit 265. A current (pulse) having a constant size and a variable width according to can be applied to the light source 120.

Referring again to FIG. 2, the PAW controller 260 outputs an output signal (current) of a size corresponding to the applied data signal and the output signal of the PWM controller 265, as described above. Accordingly, the PAW control unit 260 can operate like a current source that outputs a variable current.

The PWM control unit 265 generates pulses through the above-described operations. An output signal is generated whose pulse width is variable rather than the size (or amplitude) of the generated pulse. Accordingly, the PWM control unit 265 can operate like a switch. If no output signal is generated, the corresponding switch is opened, and only the output value from the PAM control unit 260 is applied to the light source 120. When an output signal is generated, the corresponding switch is short-circuited, and an output signal (from the PAM control unit 260) reflecting its output signal is generated.

As the PAW control unit 260 and the PWM control unit 265 have the above-described structure, the effects shown in Figures 6 and 7 can be obtained.

Figure 6 is a diagram showing a PAM signal output from a driver circuit according to an embodiment of the present invention and a conventional driver circuit.

Figure 6(a) shows a PAM signal output from a conventional driver circuit, and Figure 6(b) shows an output signal output from the PAM control unit 260. It can be seen that the size (Apmlitude) output from the PAM control unit 260 has become relatively small. This has the following effects:

A data signal with a relatively small bit size compared to the prior art is applied to the PAM control unit 260. This can have the effect of reducing grayscale and relatively reduce sensitivity when performing PAM control. Accordingly, the color shift phenomenon due to changes in current size can be significantly reduced.

Figure 7 is a diagram showing a PWM signal output from a driver circuit according to an embodiment of the present invention and a conventional driver circuit.

Figure 7(a) shows a PWM signal output from a conventional driver circuit, and Figure 7(b) shows an output signal output from the PWM control unit 265. It can be seen that the width of the pulse output from the PWM control unit 265 is relatively increased. This has the following effects:

Likewise, a data signal with a relatively small bit size compared to the prior art is applied to the PWM control unit 265. Accordingly, the PWM control unit 265 or the PAM control unit 260 to which the corresponding output signal is applied can perform PWM modulation with a relatively small number of switching operations. Additionally, the width of the output signal becomes relatively wider, making it easier to secure rise and fall times. As in the past, when the width of the output signal is narrow and it is difficult to secure the rise time and fall time, the peak value of the output signal pulse may be generated and the light source may cause a flickering phenomenon. However, since the PWM control unit 265 is relatively easy to secure the rise time and fall time, it is possible to prevent the flickering phenomenon from occurring.

The above description is merely an illustrative explanation of the technical idea of the present embodiment, and those skilled in the art will be able to make various modifications and variations without departing from the essential characteristics of the present embodiment. Accordingly, the present embodiments are not intended to limit the technical idea of the present embodiment, but rather to explain it, and the scope of the technical idea of the present embodiment is not limited by these examples. The scope of protection of this embodiment should be interpreted in accordance with the claims below, and all technical ideas within the equivalent scope should be interpreted as being included in the scope of rights of this embodiment.

100: LED package
110: driver circuit
120: light source
210: Power and data selection unit
215, 225: Port
220: receiver
230: clock signal generator
240: Timing control unit
250, 255: data separation unit
260: PAM control unit
265: PWM control unit
410: Ring counter
420: register
510, 540: transistor
520: switch
530: bias current source

Claims (16)

In the driver circuit that controls the operation of the light source,
A control signal for mode selection is received from the outside, and the control signal is analyzed to determine whether to modulate it using the PAM (Pulse Amplitude Modulation) method, the PWM (Pulse Width Modulation) method, or both the PAM method and the PWM method. Select and apply the data signal to the light source according to the selected modulation method,
A driver circuit characterized in that when modulating the data signal by both the PAM method and the PWM method, it is separated into preset sizes and modulated into one of the PAM method and the PWM method and the other. delete According to paragraph 1,
The driver circuit is,
A driver circuit characterized in that the front end of the preset size of the data signal is modulated by one of the PAM method and the PWM method, and the remaining rear end of the data signal is modulated by the other one of the PAM method and the PWM method. According to paragraph 3,
The data signal is,
Driver circuit characterized in that it is 16 bit. According to paragraph 4,
The driver circuit is,
A driver circuit characterized in that the front 8 bits of the data signal are modulated by the PAM method, and the rear 8 bits of the data signal are modulated by the PWM method. The driver circuit of any one of claims 1 and 3 to 5; and
A light source that operates by receiving a data signal modulated from the driver circuit.
An LED package comprising: In the driver circuit that controls the operation of the light source,
A control signal for mode selection is received from the outside, and the control signal is analyzed to determine whether to modulate it using the PAM (Pulse Amplitude Modulation) method, the PWM (Pulse Width Modulation) method, or both the PAM method and the PWM method. Select and apply a data signal to the light source according to the selected modulation method,
For modulation using the PAM method,
a plurality of first transistors that are included in the number of bits of the applied data signal and control the application of current according to the data signal value;
a plurality of first switches including the number of bits of the applied data signal and controlling the flow of the output signal of the first transistor by adjusting the opening and closing of the circuit according to the data signal value;
a second transistor that receives the PWM modulated output signal and controls the application of current according to the output signal value;
a second switch that receives the PWM modulated output signal and controls the flow of the output signal of the second transistor by adjusting opening and closing of the circuit according to the output signal value;
a third transistor that receives the output signal of the first transistor or the second transistor; and
A driver circuit comprising a fourth transistor that applies a current of the same magnitude as the output signal applied to the third transistor to the light source. In clause 7,
The data signal is,
A driver circuit characterized in that the applied signal is applied to the gate terminal of each first transistor. According to clause 8,
The first transistor is,
A driver circuit characterized in that a fixed voltage is applied to the drain stage. In clause 7,
Each first transistor is:
A driver circuit characterized by forming channels having widths of different sizes. The driver circuit of any one of claims 7 to 10; and
A light source that operates by receiving a data signal modulated from the driver circuit.
An LED package comprising: In the driver circuit that controls the operation of the light source,
A control signal for mode selection is received from the outside, and the control signal is analyzed to determine whether to modulate it using the PAM (Pulse Amplitude Modulation) method, the PWM (Pulse Width Modulation) method, or both the PAM method and the PWM method. Select and apply a data signal to the light source according to the selected modulation method,
For modulation in the PWM method,
a register that stores the applied data signal; and
A ring counter that increases the count value by 1, compares whether the count value has the same value as the data signal stored in the register, and generates an output corresponding to the count value.
A driver circuit comprising: According to clause 12,
The ring counter is,
A driver circuit characterized in that the size of the count value having the same number of bits as the data signal applied to the register is increased by 1. According to clause 12,
The ring counter is,
A driver circuit characterized in that it generates a pulse corresponding to the count value as an output. According to clause 12,
The ring counter is,
A driver circuit characterized in that it is applied when modulating an output signal using the PAM method. The driver circuit of any one of claims 12 to 15; and
A light source that operates by receiving a data signal modulated from the driver circuit.
An LED package comprising:

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