Fault-tolerant LED lighting device

Abstract

The present invention provides a fault-tolerant LED lighting device that maintains its lighting function, the LED lighting device including LED rows that are connected in series and in parallel and having a configuration characterized in that rows of small LEDs connected in series are connected in parallel to obtain small LED row groups which are further connected in series, the number of small LEDs in the rows of small LEDs being within a range such that, even if an LED of the LED lighting device fails, the failure cannot be perceived, thereby enabling the lighting function to be maintained when a single LED fails, and preventing LED rows other than that to which the failed LED belongs from being extinguished. The invention belongs to the field of LED lighting that uses a direct current or a pulsating current obtained by full-wave rectification of an alternating current to light the LEDs, and to implementation methods thereof and all lighting equipment using the same.

Description

Fault-tolerant LED Lighting Device

[0001] The present invention relates to a fault-tolerant LED lighting device that solves the drawbacks of conventional LED lighting control methods.

[0002] LED lighting control devices that increase the overall illuminance by further connecting in parallel LED lighting having a plurality of LED strings, and LED lighting equipment provided with the same are widely known (see, for example, Patent Document 1).

[0003] Japanese Patent Application Laid-Open No. 2020-061324

[0004] Usually, in LED lighting, it is often seen that the lighting function is lost due to a short circuit or an open-circuit fault in one of the LEDs in use. Specifically, in the case of an LED fault where the LED terminals are open, no current flows through the LED string and all the LEDs in the LED string are turned off. In the case of an LED fault where the LED terminals are short-circuited, as the forward voltage drop of the LED string decreases by one step, all the current that should originally flow through other LED strings also flows into this LED string, so all the other normal LED strings are turned off, or are in a state close to being turned off (hereinafter, this is referred to as being turned off). Accordingly, the lighting function cannot be maintained in any LED fault.

[0005] This problem will be described in more detail based on the drawings. Hereinafter, the case where an LED fault occurs in a conventional LED lighting device using a DC power supply will be described. For ease of viewing the drawings, etc., the number of LED stages is set to 10 in the description. FIG. 2 is a circuit diagram exemplarily showing the problems when an LED fault occurs in a conventional LED lighting device using DC. This LED lighting has LED strings connected in series connected in parallel, and the behavior during an LED fault will be analyzed below.

[0006] First, let's explain what happens when an LED malfunctions. In this explanation, we will refer to the number of LEDs in a row as m (where m is two or more). Let's consider the case where a short-circuit malfunction occurs in the LEDs in Figure 2, specifically in the LED element marked C on the right side of Figure 2 as an example. In the LED row where the short-circuit malfunction occurs, the forward voltage of the LEDs decreases by the amount of one malfunctioning LED, so most of the current that would normally flow to the other parallel LED rows flows into the malfunctioning LED row. This current is approximately m times the normal current, and even if the malfunctioning LED row can continue to operate with this current, almost no current will flow to the other LED rows, causing the LEDs to turn off and the lighting function to be lost. If the malfunctioning LED row cannot withstand the current and the other LEDs in the row experience an open-circuit malfunction, all the LEDs in that malfunctioning LED row will turn off, and the lighting function cannot be maintained.

[0007] Next, we will explain what happens when an open circuit failure occurs in an LED. Specifically, let's consider the case where an open circuit failure occurs in the LED element marked with an "x" on the left side of Figure 2 as an example. No current flows through the LED row with the open circuit failure, and that LED row turns off. The current that would have flowed through the faulty part is diverted to the other LED rows that are not faulty, and a current of m / (m-1) times the steady-state current flows through them. Here, m is the total number of parallel LED rows.

[0008] In this case, even if the aforementioned current flows through each LED row, if prior consideration is given to ensure that each LED row operates normally, the LED rows without faults will continue to light up, but the LED row with the open-circuit fault will all turn off. Since the turned-off LED row is visible and easily identifiable as a failure, it is clear that the lighting function cannot be maintained.

[0009] The object of the present invention is to provide a fault-tolerant LED lighting device that maintains lighting function even in the event of a single LED failure, prevents the LED row containing the faulty LED from going out, and maintains lighting function, in order to solve the problems revealed in the above-mentioned issues.

[0010] To solve the above-mentioned problems, the fault-tolerant LED lighting device according to claim 1 of the present invention is an LED lighting device in which LED rows are connected in series and parallel, wherein the constituent unit is a small LED row in which LEDs are connected in series such that even if a fault occurs in the series-connected LED row of the LED lighting device, the number of LEDs is within a range in which the fault cannot be recognized even if a fault occurs, the LED lighting device is composed of a group of small LED rows connected in parallel, or a group of small LED rows in which small LED rows with different numbers of stages are connected in parallel, each with a number of LEDs within a range in which the number of LEDs is within a range in which the fault cannot be recognized, the LED lighting device is composed of an LED row group obtained by connecting these in series, parallel, and series-parallel, the first important constituent unit being a small LED row in which LEDs are connected in series such that even if a fault occurs, the number of LEDs is within a range in which the fault cannot be recognized, and the second important constituent unit being a group of small LED rows in which the small LED rows are connected in parallel, series-parallel, and parallel. In other words, the number of LED stages in each small LED array constituting each small LED array is the same within the same small LED array constituting a different small LED array constituting a different small LED array constituting the same number of LED stages as the small LED array constituting the aforementioned small LED array constituting the same number of LED stages, and this is naturally included within the scope of the present invention.

[0011] Furthermore, the fault-tolerant LED lighting device according to claim 2 of the present invention is characterized in that, in the fault-tolerant LED lighting device according to claim 1, a fault-tolerant element is installed in each of the small LED rows of the LED lighting device, which has the function of allowing the current that flows during normal operation to pass through as is, but opening the terminals when a current exceeding normal operation flows, such as in the case of a short-circuit fault, so that even if a short-circuit fault occurs in the LED, a current exceeding normal operation flows through the fault-tolerant element and opens the terminals, thereby cutting off the current only to the small LED row where the short-circuit fault occurred, and allowing the other parallel-connected LED rows to continue to light up.

[0012] More specifically, the fault-tolerant LED lighting device according to the present invention first sets a fault tolerance range so that even if a fault occurs in an LED, the fault remains within a range that allows the lighting function to be maintained. Then, as a means to keep the LED fault within the predetermined range, the LED lighting is configured using a group of LEDs obtained by connecting multiple small LED rows in parallel, each of which is formed by connecting several such small LED rows in series. As mentioned above, the number of LED stages within each small LED row group may differ for each small LED row group. In this LED lighting device, even if a circuit breaker fault occurs in an LED, the faulted area remains within the fault tolerance range, making it possible to avoid the loss of lighting function.

[0013] Furthermore, in addition to the above measures, by adding a fault-tolerant element to each small LED row that falls within the fault tolerance range, which allows the current flowing through the LED element to pass through during normal operation but opens the terminals when a current exceeding normal operation flows during a short-circuit fault, even if a short-circuit fault occurs in an LED, the fault-tolerant element will open the terminals when a current exceeding normal operation flows, thereby cutting off the current only to the small LED row where the short-circuit fault occurred, and allowing the other small LED rows to continue lighting. Thus, even if a fault of either open circuit or short circuit occurs in one LED while the LED lighting is operating in the LED lighting device, the fault will remain within the tolerance range, maintaining the lighting function and preventing loss of lighting function, thereby ensuring the maintenance of the lighting function of the LED lighting.

[0014] Furthermore, the fault-tolerant LED lighting device according to claim 3 of the present invention is characterized in that, in the fault-tolerant LED lighting device according to claim 2, an element that opens both ends in the event of an overcurrent, such as a fuse resistor, is used as the fault-tolerant element.

[0015] Furthermore, the fault-tolerant LED lighting device according to claim 4 of the present invention is characterized in that, in the fault-tolerant LED lighting device according to any one of claims 1 to 3, the number of LED stages in the small LED rows constituting each small LED row group is within a range in which faults in the LED lighting device cannot be recognized, and the number of LED stages in the small LED rows constituting each small LED row group is the same within each small LED row group, but the number of LED stages in the small LED rows constituting each small LED row group can be individually defined.

[0016] Furthermore, the fault-tolerant LED lighting device according to claim 5 or claim 6 of the present invention is characterized in that, in the fault-tolerant LED lighting device described in claim 1 or claim 2, direct current is used for lighting the LEDs of the fault-tolerant LED lighting device.

[0017] Furthermore, the fault-tolerant LED lighting device according to claim 5 or claim 6 of the present invention is characterized in that, in the fault-tolerant LED lighting device described in claim 1 or claim 2, a pulsating current obtained by full-wave rectifying an AC current is used for lighting the LEDs of the fault-tolerant LED lighting device.

[0018] According to the present invention, it is possible to provide a fault-tolerant LED lighting device that maintains lighting function even in the event of a single LED failure, prevents the LED row containing the faulty LED from going out, and maintains lighting function.

[0019] More specifically, this device, i.e., the fault-tolerant LED lighting device according to the present invention, regardless of whether it is voltage-driven or current-driven, or DC-driven or AC (full-wave rectified pulsating current-driven), realizes a lighting device configuration obtained by connecting in series, or further connecting these in parallel, or in series-parallel, a group of small LED rows in which the fault prevention element of the present invention is installed in each LED row within a predetermined fault range, regardless of whether the LEDs are voltage-driven or current-driven, or DC-driven or AC (full-wave rectified pulsating current-driven) driven. In this configuration, even if a short-circuit or open-circuit failure occurs in the LEDs used, the area affected by the failure is kept within a predetermined range, maintaining the lighting function, avoiding the extinction of all LEDs or all LEDs in a row, and enabling the maintenance of lighting function even in the event of an LED failure.

[0020] This circuit diagram is illustrative to illustrate the effects of the present invention when an LED failure occurs in a fault-tolerant LED lighting device according to the present invention using a DC power supply. This circuit diagram is illustrative to facilitate understanding of the problems that occur when an LED failure occurs in a conventional LED lighting device using a DC power supply.

[0021] The embodiments of the present invention will be described below with reference to the drawings. This embodiment aims to solve the problems that have conventionally occurred when an LED failure occurred in a fault-tolerant LED lighting device according to the present invention that uses a DC power supply.

[0022] First, I will explain the general content that constitutes the essential part of the present invention. The fault-tolerant LED lighting device according to the present invention is an LED lighting device having multiple LED rows, wherein an acceptable fault range is set in advance for when an LED fault occurs in the LED lighting, and means are provided to keep the LED fault within the aforementioned range. A group of small LED rows are connected in parallel, and these groups are further connected in series to obtain a group of LED rows—however, the number of LED stages in series-connected in each small LED row group is the same, and different numbers of LED stages are allowed in other small LED row groups as long as they are within the acceptable range—and the necessary number of such groups are connected in series, or these are further connected in series, parallel, or series-parallel, thereby maintaining the lighting function and avoiding loss of function even when an open circuit fault occurs in an individual LED.

[0023] Furthermore, to ensure that the fault-tolerant LED lighting device can maintain lighting functionality even in the event of an LED short-circuit failure, each small LED row is further equipped with a fault-tolerant element that allows the current flowing through the LED element to pass through during normal operation, but opens the terminals when a current exceeding normal operation flows, such as during a short-circuit failure. The fault-tolerant element has the function of opening the terminals when the current exceeds that of normal operation. As a result, even if an open circuit or short-circuit failure occurs in one LED while the LED lighting is in operation in the fault-tolerant LED lighting device, the fault can be kept within an acceptable range, maintaining lighting functionality and avoiding loss of lighting function.

[0024] Furthermore, as a fault-tolerant element, it is preferable to use an element that opens its terminals in the event of an overcurrent, such as a fuse resistor, which acts as a fuse to interrupt the current without causing excessive heat generation or ignition when an overload is applied. In Figure 1, which will be described below, this fault-tolerant element is shown as an element marked with an "x" connected to the bottom of each row of small LEDs in each row of small LEDs connected in series.

[0025] Figure 1 is an illustrative circuit diagram showing the effects of the present invention when an LED failure occurs in a fault-tolerant LED lighting device according to the present invention using a DC power supply, and Figure 2 is an illustrative circuit diagram showing the case when an LED failure occurs in a similar location in conventional LED lighting. The "fault-tolerant elements," which are an important component of the present invention, are connected to the underside of the lowest LED in each small LED row in Figure 1, as indicated by the symbol F.

[0026] In the case of an LED failure in an example of a fault-tolerant LED lighting device using a DC power supply, this embodiment pre-sets an acceptable failure range for LED failures and provides means to keep the failure within that range. This ensures that even in the event of an open circuit or short circuit, only the affected LED row will be turned off while the other LEDs remain lit, thus maintaining the lighting function.

[0027] The combinations of LEDs connected in series in Figure 1 and the LEDs exemplified by the *R and *L marks fall within the aforementioned acceptable fault range, and their details are explained below.

[0028] (1) When a short-circuit fault occurs in an LED specifically identified with an *R mark Let's consider what happens when a short-circuit fault occurs in the LED element marked with an *R shown on the right side of Figures 1 and 2. In the LED row where the short-circuit fault occurs, the forward voltage of the LED decreases by the amount of one faulty LED, so the current that would normally flow to the other LED rows also flows into the short-circuit faulty LED row.

[0029] *Under normal circumstances, the current flowing through the element marked with R lights up the *R LED element and then flows sequentially to the next LED. However, in the event of a short circuit, the forward voltage drop of the LED decreases by the amount of the faulty LED, so almost all of the current that was flowing through the other parallel LED rows flows into the faulty LED row. As a result, approximately m times the normal current (where m is the number of parallel LED rows) flows through the LED row to which the *R LED belongs. In the case of the conventional technology shown in Figure 2, as long as the LED can continue to flow m times the current, the LED row to which the faulty LED belongs will continue to light up, and all other LED rows to which no current flows will turn off. If an LED in the LED row to which the faulty LED belongs becomes unable to continue operating and is released, the LED row to which the faulty LED belongs will turn off and the other LED rows will start lighting up again. In either case, some LED rows will turn off, so the lighting function cannot be maintained. However, in the present invention, if an excessive current flows through the LED row to which the faulty LED in Figure 1 belongs, the fault prevention element opens up, and only the portion of the LED row to which the faulty LED belongs turns off, while the other LED rows continue to operate. Therefore, the area that goes out is limited to the portion of the LED row that caused the short-circuit fault, and the other LED rows continue to light up, maintaining the lighting function.

[0030] (2) When an open circuit failure occurs in an LED specifically identified by the *L mark Let's consider the case where an open circuit failure occurs in the LED element marked with the *L mark shown on the left side in both Figure 1 and Figure 2. No current flows through the LED row where the open circuit failure occurs, and that LED row turns off. However, the current that would have flowed through the faulty part is diverted to the other parallel-connected LED rows that are not faulty, and if the number of parallel LED rows is m, then a current of m / (m-1) times the steady-state current flows. By taking into consideration in advance that each LED row will operate normally even if the above current flows through each LED row, the other LED rows will continue to operate without problems. In Figure 1 using the present invention, the LED row to which the open circuit failure LED marked with the *L belongs turns off, but all other LED rows continue to light up. In Figure 1 according to the present invention, the LED row to which the faulty LED belongs turns off, but all remaining LED rows light up, the failure is limited to a part, and the lighting function is maintained. In Figure 2 of the conventional technology, all LED rows to which the open circuit failure LED belongs turn off. Although other rows of LEDs light up, the lighting function cannot be maintained because the off state of one row of LEDs is detected.

[0031] Furthermore, regarding the method for realizing the fault-tolerant LED lighting described above, the method for providing fault tolerance is the same whether it is driven by alternating current (AC) or direct current (DC). Therefore, it goes without saying that this method can also be used to address LED failures in AC-driven fault-tolerant LED lighting devices that use pulsating current obtained by full-wave rectification of AC.

[0032] To further explain this, the AC-driven fault-tolerant LED lighting to which the present invention is applied, like the fault-tolerant LED lighting device using a DC power supply described in the previous section, first sets an acceptable fault range in the event of an LED failure. The method for keeping the failure within the aforementioned range and the behavior when any of the LEDs fail are the same as in the fault-tolerant LED lighting device using a DC power supply described above, in the case of a short circuit in the LED marked *R and an open circuit in the LED marked *L. Therefore, even in the case of AC drive, the lighting function is maintained by keeping the failure within the acceptable fault range of the LEDs that fail, while the other LEDs continue to light up.

[0033] Therefore, since the explanation of AC-driven fault-tolerant LED lighting is equivalent to that of DC-driven fault-tolerant LED lighting and the gist of the present invention, the explanation of the method for realizing DC-driven fault-tolerant LED lighting described above will be used to replace the explanation of AC-driven fault-tolerant LED lighting.

[0034] It should be noted that the embodiments and circuit diagrams described above are merely examples of the present invention, and it goes without saying that the structure, materials, circuit configuration, etc., can be appropriately modified within the scope that allows the effects of the present invention to be realized.

[0035] Specifically, for example, the "fault-tolerant element" in the present invention was described in the above-described embodiment and in Figure 1 as being indicated by the symbol F below the lowest LED in each LED row. However, the arrangement of the "fault-tolerant element F" is not limited to this, and the effects of the present invention can be similarly achieved if it is provided in any arbitrary location in each LED row.

[0036] Furthermore, in this invention, the number of LEDs in each series-connected group of small LEDs is set to a number within which no fault can be recognized, and the number of LEDs in each small LED series constituting each small LED series is set to be the same within each small LED series. In addition, the number of LEDs in each series-connected small LED series constituting each small LED series can be individually defined.

[0037] For example, in Figure 1, which is illustrated to facilitate understanding of the present invention, the number of LEDs in each of the small LED arrays constituting the upper left and middle left rows, and the upper right and middle right rows, is 3, while the number of LEDs in each of the small LED arrays constituting the lower left and lower right rows, respectively, is 4.

[0038] However, the number of LEDs in each of the small LED arrays constituting each small LED array may be set to the same number of four. For example, in Figure 1, the number of LEDs in one or more of the small LED arrays constituting each small LED array may be set to two, while the number of LEDs in some of the remaining small LED arrays may be set to three, and the number of LEDs in the remaining small LED arrays may be set to four. Various combinations are possible within the scope of the present invention, provided that the number of LEDs is within a range where no malfunction can be detected. Industrial application fields

[0039] The industrial application field of this invention relates to LED lighting that uses pulsating current obtained by full-wave rectification of DC or AC to light an LED, as well as methods for realizing this, and all lighting equipment using the same.

Claims

1. An LED lighting device comprising LED rows connected in series and parallel, characterized in that a group of small LED rows, each consisting of a number of LEDs connected in series such that a failure in one of the LEDs of the LED lighting device cannot be detected, is further connected in parallel to form a single unit, and these small LED row groups are further connected in series and parallel.

2. The LED lighting device according to claim 1, characterized in that each of the small LED rows constituting each group of small LED rows of the LED lighting device is equipped with a fault-tolerant element that allows the current flowing through the LED element to pass through during normal operation, but opens the terminals when a current exceeding normal operation flows due to a short-circuit fault or the like, thereby interrupting the current only in the small LED row where the short-circuit fault occurred, and allowing the other parallel-connected LED rows to continue lighting.

3. The LED lighting device according to claim 2, characterized in that, as the fault tolerance element, an element that opens both ends in the event of an overcurrent, such as a fuse resistor, is used.

4. The LED lighting device according to any one of claims 1 to 3, characterized in that, in each of the small LED arrays in the small LED arrays of the small LED array configuration, the number of LEDs is within a range in which no fault can be recognized, and the number of LED stages in each small LED array constituting each small LED array is the same within the small LED array to which each belongs, and that the number of LEDs in each series-connected small LED array constituting each small LED array can be individually defined.

5. The fault-tolerant LED lighting device according to any one of claims 1 to 3, characterized in that DC is used for lighting the LEDs of the fault-tolerant LED lighting device.

6. The fault-tolerant LED lighting device according to claim 4, characterized in that DC is used for lighting the LEDs of the fault-tolerant LED lighting device.

7. The fault-tolerant LED lighting device according to any one of claims 1 to 3, characterized in that it uses a pulsating current obtained by full-wave rectifying an AC current for lighting the LEDs of the fault-tolerant LED lighting device.

8. The fault-tolerant LED lighting device according to claim 4, characterized in that it uses a pulsating current obtained by full-wave rectifying an AC current for lighting the LEDs of the fault-tolerant LED lighting device.

Images