KR20240059386A - Luminance measuring apparatus with automatic calibration function - Google Patents

Abstract

The present invention relates to a luminance measurement device with an automatic calibration function. A luminance measuring device according to the present invention includes an external enclosure; a camera for measuring luminance installed within the external enclosure; a calibration reference illuminant disposed on a front side of the luminance measurement camera; a light source drive supplying power to the calibration reference illuminant; It is characterized by comprising a control unit that controls the light source drive and processes automatic calibration related to luminance measurement by comparing shooting signals for each situation received from the luminance measurement camera.

Description

Luminance measurement device with automatic calibration function {LUMINANCE MEASURING APPARATUS WITH AUTOMATIC CALIBRATION FUNCTION}

The present invention relates to a luminance measurement device, and more specifically, to a luminance measurement device with an automatic calibration function.

Lighting for various purposes can be installed in the tunnel, and for that purpose, it can be divided into, for example, basic lighting, entrance lighting, and exit lighting.

'Basic lighting' is the basic lighting installed throughout the tunnel to provide the necessary brightness for drivers driving through the tunnel to check obstacles ahead.

'Entrance lighting' means that the eyes of drivers of cars that have been driving on the road outside the tunnel during the day approach the tunnel in a state adjusted to the outdoor brightness, so depending on the driver, the inside of the tunnel may appear completely black. To reduce this obstacle, the tunnel entrance is This is lighting that installs a higher level of lighting in the main part than the basic part and sequentially adapts to the speed of the vehicle (tunnel design speed) to reach the basic part.

'Exit lighting' is when the outdoor brightness near the exit is very high and the car in front blocks part of the opening, it becomes difficult to recognize vehicles or falling objects following it. To prevent this, it is necessary to brighten the tunnel exit area. It is a light that provides a similar level of brightness, although not the same as that of the entrance.

For reference, 'brightness' is distinct from 'illuminance'. While illuminance is the size of light that indicates the degree to which it illuminates, luminance is the size of light that indicates the degree of illumination. In other words, 'illuminance' refers to the degree of light brightness, the amount of light incident on the target surface, and its unit is lx or lux, while 'luminance' refers to the degree of glare, the amount of light reflected from the target surface. It represents the amount of light, and the unit is written as 'cd/m2'.

As mentioned above, when a driver enters a tunnel, the so-called 'black hole' phenomenon occurs in which the inside of the tunnel appears dark for a certain period of time due to the dark adaptation response of the eyes. To prevent this, lights of appropriate brightness are installed at the tunnel entrance. It is in operation.

As such, determining the brightness of the tunnel entrance lighting is essential to prevent the 'black hole' phenomenon, so a type of luminance measuring device is installed at the location before entering the tunnel to measure the luminance at the tunnel entrance to calculate the appropriate lighting brightness.

However, in the case of this conventional luminance measurement device, like other general measurement devices, errors related to luminance measurement occur over time, so periodic calibration is required.

Here, calibration means detecting measurement errors in the measuring device and correcting them.

However, in the past, the luminance measurement device was separated from the location where it was previously installed and calibration was performed at a specialized institution.

However, the luminance measurement device installed near the tunnel entrance is generally installed at a height of about 4-5 meters above the ground and is aligned to accurately measure luminance when first installed. As such, if it is desired to separate for luminance measurement, the height This is not easy, and furthermore, if a new device is installed after calibration, there is the inconvenience of having to perform alignment processing again.

Registered Patent No. 10-1416338

The present invention was devised to solve the above-described conventional problems, and its purpose is to provide a luminance measurement device that automatically corrects errors related to luminance measurement without the need for manual reinstallation by an operator.

In order to achieve the above object, a luminance measuring device according to the present invention includes an external enclosure; a camera for measuring luminance installed within the external enclosure; a calibration reference illuminant disposed on a front side of the luminance measurement camera; a light source drive supplying power to the calibration reference illuminant; It may be configured to include a control unit that controls the light source drive and processes automatic calibration related to luminance measurement by comparing shooting signals for each situation received from the luminance measurement camera.

Here, the control unit calculates the background luminance using a photographing signal received from the luminance measurement camera while controlling the light source drive so that the reference illuminant for calibration is turned off, and the light source so that the reference illuminant for calibration is turned on. With the drive controlled, the mixed luminance is calculated using the shooting signal received from the luminance measurement camera, the background luminance is subtracted from the mixed luminance to calculate the measurement standard luminance, and the calculated measurement standard luminance is After comparing with a preset initial reference luminance, automatic calibration can be performed considering the comparison result.

Here, the reference light emitter for calibration is composed of an LED (Liquid Emitting Diode), and the light source drive may be configured to supply a preset constant current to the reference light emitter for calibration.

Here, the control unit controls the light source drive to supply a constant current to the calibration reference light emitter so that the calibration reference light emitter lights up, and measures the voltage at both ends of the LED to determine if the measured voltage is within a preset range. , the automatic calibration can be performed.

Here, as a result of measuring the voltage at both ends of the LED, the control unit may correct the measurement reference luminance using the following equation if the measured voltage is outside a preset range.

L(VV _s ) = L _s + a ₀ + a ₁ * (VV _s ) + a ₂ * (VV _s ) ² + a ₃ * (VV _s ) ³

Here, L: corrected luminance value, Ls: standard luminance value, V: consumed voltage, Vs: reference consumed voltage, a _0, a1 _, a2 are constants preset for each LED.

Here, the control unit controls the light source drive to supply an alternating current based on a preset constant current value to the reference light emitter for calibration, then measures the voltage at both ends of the LED, and matches the measured voltage change with the alternating current. It is possible to determine whether an abnormality has occurred in the reference light emitter for calibration based on the difference between the corresponding preset voltage changes.

Here, it may further include an external illumination sensor, and the control unit may determine a time to set a correction value for the automatic calibration based on a signal received from the external illumination sensor.

As described above, according to the present invention, the luminance measurement device performs auto-calibration on its own, thereby maximizing convenience of management.

In other words, since there is no need to separate the luminance measurement device from the existing installation site as in the past, the problem of reinstallation can be solved, and calibration is performed using its own function, thereby enabling rapid error correction.

In particular, precise and accurate luminance measurement is possible by determining whether there is an abnormality in the reference light emitting element (LED) for calibration provided for auto-calibration and performing calibration by additionally considering the error.

1 is a schematic configuration diagram of the entire system including a luminance measurement device according to an embodiment of the present invention;
FIG. 2 is a schematic cross-sectional view of the luminance measuring device of FIG. 1.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

Each embodiment according to the present invention below is only an example to aid understanding of the present invention, and the present invention is not limited to these embodiments. In particular, the present invention may be comprised of a combination of at least one of the individual components, individual functions, or individual steps included in each embodiment.

The schematic configuration of the entire system including the luminance measurement device according to an embodiment of the present invention is as shown in FIG. 1.

In FIG. 1, the tunnel light 200 refers to a light installed in the tunnel as described above, and in particular, in this embodiment, includes a light installed at the tunnel entrance.

In the same drawing, the lighting control device 300 individually controls the amount of light installed in the tunnel, and in particular, controls the amount of light in the tunnel, especially the light installed at the tunnel entrance, based on information received from the luminance measuring device 100. Control.

Since the configuration and function of the lighting control device 300, which controls the amount of light as well as the lighting in the tunnel, corresponds to known technology, detailed descriptions will be omitted.

The luminance measuring device 100 is a device that is installed toward a specific location to measure luminance. In this embodiment, it is installed toward the tunnel entrance from the outside of the tunnel as an example.

An example of a specific configuration of the luminance measuring device 100 is shown in FIG. 2.

As shown in the figure, the luminance measurement device 100 includes an external enclosure 110, a camera 120 for luminance measurement, a reference illuminator 130 for calibration, a light source drive 140, and a control unit 150. It can be.

The external enclosure 110 protects the luminance measurement device 100, and performs the function of protecting the luminance measurement device 100 from weather influences such as snow or rain, and further protects the luminance measurement device 100 from other external light. It has a structure to prevent things from entering the luminance measurement device 100 and interfering with precise luminance measurement. Since the general configuration of the external enclosure 110 itself corresponds to known technology, a more detailed description will be omitted.

In particular, the external enclosure 110 may have a structure in which each component of the luminance measurement device 100 is seated.

As described above, the luminance measurement camera 120 may be installed within the outer enclosure 110 toward the tunnel entrance. In this case, the outer enclosure 110 has a transparent window for the luminance detection function of the luminance measurement camera 120. Can be installed.

The camera 120 for measuring luminance may be configured by combining a predetermined lens and a CCD (Charge Couple Device) module. Here, the CCD module corresponds to a type of optical sensor semiconductor that receives light and converts it into an electrical signal.

Since the configuration of the luminance measurement camera 120 itself corresponds to known technology, detailed description will be omitted.

However, the photographing signal detected by the luminance measurement camera 120 is transmitted to the control unit 150, which will be described later, to measure luminance and serve as basic data for other calibration processes.

The reference light emitter 130 for calibration turns on or off according to a current supplied from the outside, and in this embodiment, is placed on the front side of the luminance measurement camera 120 and is used for luminance calibration.

In the case of luminance measurement through the luminance measurement camera 120, luminance measurement may be performed based on light coming within a range of 20 degrees from the lens center point of the luminance measurement camera 120. In order not to interfere with this general luminance measurement, correction is required. It is preferable that the reference light emitting body 130 is disposed at a position outside the corresponding 20 degree range.

That is, in FIG. 2, area A is an area within a 20-degree range, and area B is an area where the luminance measurement camera 120 can capture images, and the reference illuminator 130 for calibration is disposed in an area outside of area A among area B. desirable.

This calibration reference light emitter 130 may be made of, for example, a Liquid Emitting Diode (LED), and in particular, it may be made of a Chip On Board (COB) type LED.

COB-type LEDs have the advantage of being able to contain several times more light sources than standard LEDs occupy in the same area, resulting in significantly improved brightness per square inch.

In particular, COB LEDs can power multiple embedded diode chips using a single circuit with only two contacts, reducing the number of components per LED chip required for proper operation, and further eliminating the packaging of traditional LED chip structures. This has the advantage of reducing the heat generated from each LED chip.

A heat dissipation device such as a heat sink may be attached to the standard light emitter 130 for calibration in this embodiment, that is, an LED, which functions to minimize damage to the LED by quickly dissipating heat generated during operation of the LED to the outside. do.

In particular, the LED used in this embodiment is preferably driven with a rated current and illuminated for more than 500 hours to obtain mechanical and electrical stability.

The light source drive 140 performs the function of supplying power to the reference light emitter 130 for calibration. As described above, when the reference light emitter 130 for calibration is an LED, the light source drive 140 uses a preset constant current for calibration. It may be configured to supply to the reference light emitter 130.

Due to the nature of the LED, current control is desirable, and the light source drive 140 supplies a preset constant current in a safe range suitable for the LED, that is, a constant current to the LED.

For example, the light source drive 140 may be configured to supply a constant current equivalent to 50% of the allowable current of the LED to the LED.

Meanwhile, the control unit 150 controls the light source drive 140 and performs automatic calibration related to luminance measurement by comparing shooting signals for each situation received from the luminance measurement camera 120.

That is, the control unit 150 controls the light source drive 140 to control whether or not current is supplied to the reference light emitter 130 for calibration and the size and method of the supplied current. For example, the control unit 150 controls the light source drive 140. A constant current of a set size may be controlled to be supplied to the reference light emitter 130 for calibration, or in special cases, an alternating current of a specific pattern may be controlled to be supplied to the reference light emitter 130 for calibration.

In particular, the control unit 150 performs the so-called automatic calibration process as described above. Specifically, the control unit 150 controls the light source drive 140 so that the reference illuminator 130 for calibration is turned off, and the camera for luminance measurement ( The background luminance is calculated using the photographing signal received from 120, and the photographing signal received from the luminance measurement camera 120 is used while the light source drive 140 is controlled so that the reference illuminator 130 for calibration is turned on. After calculating the mixed luminance, calculate the measurement standard luminance by subtracting the previously calculated background luminance from this mixed luminance, compare the calculated measurement standard luminance with the preset initial reference luminance, and then consider the comparison result. This allows automatic calibration to be performed.

In other words, the photographing signal received from the luminance measurement camera 120 in a state in which the calibration reference illuminator 130 is turned off is due to the light coming from the tunnel entrance, so the luminance of the tunnel entrance (in this embodiment, referred to as 'background luminance') In contrast, when the reference illuminator 130 for calibration is turned on, the shooting signal received from the camera 120 for measuring luminance is the light coming from the tunnel entrance and the reference illuminator for calibration ( Since all the light from 130) is combined, the term 'mixed luminance' was used in this example for the luminance measured accordingly.

That is, the control unit 150 may refer to the luminance obtained by subtracting the background luminance from the mixed luminance as the pure luminance (referred to as 'measurement standard luminance' in this embodiment) by the calibration reference luminance 130, and at this time, the calibration reference luminance. The luminance of the light emitter 130 is measured in advance and compared to the stored 'initial reference luminance' to determine whether a difference occurs or how much the difference is, and accordingly to determine whether the luminance measurement is being performed properly. It is possible.

At this time, if it is determined that an error occurs in the luminance measurement by the luminance measurement camera 120, the control unit 150 performs an automatic calibration to correct the error.

For example, by setting a predetermined correction value and later routinely judging the background luminance, the correction value is reflected to determine the final luminance.

The premise of performing automatic calibration in this way is that the calibration reference illuminator 130 emits a stable and constant amount of light when turned on, and the calibration reference illuminator 130 itself also changes its characteristics somewhat over time. It can change.

Therefore, the control unit 150 can perform automatic calibration by also considering the error of the reference light emitter 130 for calibration. Specifically, the control unit 150 controls the light source drive 140 to apply a constant current to the reference light emitter 130 for calibration. When the reference light emitter 130 for calibration is controlled to turn on, the voltage at both ends of the LED is measured to determine whether the measured voltage is within a preset range, and automatic calibration can be performed according to that judgment.

For example, when the light source drive 140 supplies a constant current to the calibration reference light emitter 130 and controls the calibration reference light emitter 130 to turn on, the control unit 150 measures the voltage at both ends of the LED. If the voltage is within a preset range, automatic calibration is performed. Otherwise, it is determined to be an error situation and notified to the manager, etc., or automatic calibration can be performed by additionally reflecting the error.

For example, as a result of measuring the voltage at both ends of the LED, the control unit 150 may correct the measurement standard luminance using the following equation if the measured voltage is outside a preset range.

L(VV _s ) = L _s + a ₀ + a ₁ * (VV _s ) + a ₂ * (VV _s ) ² + a ₃ * (VV _s ) ³

here,

L: corrected luminance value, Ls: standard luminance value, V: consumed voltage, Vs: reference consumed voltage, and a _0, a1 _, a2 are constants preset for each LED.

In this way, it is important to determine whether the reference light emitter 130 for calibration is operating normally, and for this purpose, the control unit 150 can determine this by periodically supplying alternating current.

For example, the control unit 150 controls the light source drive 140 to supply an alternating current based on a preset constant current value to the reference light emitter 130 for calibration, then measures the voltage at both ends of the LED, and measures the measured voltage. Based on the difference between the change and the preset voltage change corresponding to the alternating current, it can be determined whether an abnormality has occurred in the reference light emitter 130 for calibration.

For example, the control unit 150 causes the light source drive 140 to supply a sine wave alternating current that moves up and down based on a preset constant current to the reference light emitter 130 for calibration once a day, and at this time, the LED (i.e., calibration The change in voltage across both ends of the reference light emitter 130 is measured, and if the measured change pattern of the voltage across both ends of the LED is different from the preset voltage change pattern for the corresponding sine wave alternating current, an abnormality occurs in the reference light emitter 130 for calibration. It can be judged that it was done.

An example of this is shown in Figure 3(a).

The drawing shows an example in which a sine wave alternating current moving up and down by 20% based on a preset constant current (i.e., a current corresponding to 50% of the allowable LED current) is supplied to the reference light emitter 130 for calibration.

As another example, in order to minimize damage to the LED, the control unit 150 may supply a lower alternating current to the LED based on a preset constant current normally supplied to the LED and then go through the above-described decision process.

Most preferably, the control unit 150 supplies an alternating current of up to 10% or more to the LED based on a preset constant current (i.e., a current corresponding to 50% of the allowable current of the LED) normally supplied to the LED, and then A judgment can be made.

For example, the control unit 150 sets the temporary reference value to a current that is 10% lower than the preset constant current normally supplied to the LED (i.e., a current corresponding to 50% of the LED allowable current). After supplying the LED with a sine wave alternating current (i.e. a sine wave alternating current that moves between 20% and 60% of the allowable current of the LED) whose peak value rises and falls up to 20% of the current corresponding to 40%, the above-mentioned You may go through a judgment process. In this case, it is possible to easily determine whether there is an abnormality in the LED by collecting the LED's response (voltage) pattern due to a certain increase or decrease in current while minimizing damage to the LED.

An example of this is shown in Figure 3(b).

In this way, when a sine wave-based current having a peak value higher than a preset constant current is allowed to flow through the reference light emitter 130 for calibration, it is possible to know more quickly and in advance whether there is an abnormality in the reference light emitter 130 for calibration.

In the above-described embodiment, a sine wave is used as an example of an alternating current signal, but the control unit 150 determines whether the reference light emitter 130 for calibration is abnormal by applying a PWM (Pulse Width Modulation) signal and detecting the corresponding voltage change pattern. You can also judge.

In this case, too, the PWM signal is varied (i.e., the pulse width is varied) and the resulting change pattern of the voltage across the calibration reference light emitter 130 is compared with a preset change pattern to determine whether the calibration reference light emitter 130 is abnormal. You can judge.

In other words, the determination of whether there is an abnormality may not be accurate using only the terminal voltage of the reference light emitter for calibration, that is, LED 130, measured in a specific constant current state. In this way, currents of various sizes/types are applied and the corresponding voltage pattern is created. When detected, it is possible to more accurately determine whether the LED 130 is abnormal.

In particular, for more accurate judgment, the voltage pattern across both ends of the LED 130 is measured while sequentially supplying current based on a sine wave followed by a PWM signal, and then compared with a preset pattern to determine whether the LED 130 is abnormal. .

Meanwhile, the luminance measuring device 100 may further include an external illuminance sensor 160.

The external illumination sensor 160 measures the amount of light received from the outside and generates a corresponding output signal, and in this embodiment, it can be used as data to distinguish between night and day, for example.

That is, the control unit 150 may determine the time to set the correction value for automatic calibration based on the signal received from the external illuminance sensor 160.

For example, the control unit 150 performs a process for automatic calibration processing, that is, calibration, when the amount of external light decreases below a preset level (for example, in the middle of the night) based on a signal received from the external illuminance sensor 160. A process of turning on the reference light emitter 130, determining the mixed luminance, and determining a correction value based on the difference from the background luminance is performed.

This is because, for example, compared to the day, external interference light is minimized at night, and the lighting at the tunnel entrance also emits at the lowest illuminance, making it the most optimal condition for performing the calibration process.

In this embodiment, the external illuminance sensor 160 is configured separately as an example, but the control unit 150 makes a decision (e.g., You can also distinguish between night and day.

Meanwhile, of course, the process of performing each of the above-described embodiments can be performed by a program or application stored in a predetermined recording medium (eg, computer-readable). Here, the recording medium includes all electronic recording media such as RAM (Random Access Memory), magnetic recording media such as hard disks, and optical recording media such as CD (Compact Disk).

At this time, the program stored in the recording medium can be executed on hardware such as a computer or smartphone to perform each of the above-described embodiments. In particular, at least one of the functions of the control unit according to the present invention described above may be implemented by such a program or application.

In addition, the present invention is not limited to the specific embodiments described above, but can be implemented with various changes and modifications without departing from the gist of the present invention. It will be apparent that such changes and modifications are included in the present invention if they fall within the scope of the appended claims.

100: Luminance measurement device 200: Tunnel lighting
300: Lighting control device 110: External enclosure
120: Camera for luminance measurement 130: Reference illuminant for calibration
140: light source drive 150: control unit
160: External light sensor

Claims (7)

an external enclosure;
a camera for measuring luminance installed within the external enclosure;
a calibration reference illuminant disposed on a front side of the luminance measurement camera;
a light source drive that supplies power to the calibration reference light emitter;
A luminance measurement device comprising a control unit that controls the light source drive and processes automatic calibration related to luminance measurement by comparing shooting signals for each situation received from the luminance measurement camera. According to paragraph 1,
The control unit calculates the background luminance using a photographing signal received from the luminance measurement camera while controlling the light source drive so that the reference illuminant for calibration turns off, and operates the light source drive so that the reference illuminator for calibration turns on. In a controlled state, the mixed luminance is calculated using the shooting signal received from the luminance measurement camera, the background luminance is subtracted from the mixed luminance to calculate the measurement standard luminance, and the calculated measurement standard luminance is used. A luminance measuring device characterized in that it compares the luminance with a set initial reference luminance and then performs automatic calibration by considering the comparison result. According to paragraph 2,
The reference luminous body for calibration consists of an LED (Liquid Emitting Diode),
The light source drive is configured to supply a preset constant current to the reference light emitter for calibration. According to paragraph 3,
The control unit measures the voltage at both ends of the LED when the light source drive supplies a constant current to the calibration reference light emitter to light the calibration reference light emitter, and when the measured voltage is within a preset range, the control unit measures the voltage at both ends of the LED. A luminance measurement device characterized in that it performs automatic calibration. According to clause 4,
The control unit measures the voltage at both ends of the LED, and when the measured voltage is outside a preset range, the control unit corrects the measurement standard luminance using the following equation.
L(VV _s ) = L _s + a ₀ + a ₁ * (VV _s ) + a ₂ * (VV _s ) ² + a ₃ * (VV _s ) ³

here,
L: Corrected luminance value,
Ls: standard luminance value,
V: voltage consumed,
Vs: Standard voltage consumption
a _0, a1 _, a2 are constants preset for each LED
According to paragraph 1,
The control unit controls the light source drive to supply an alternating current based on a preset constant current value to the calibration reference light emitter, then measures the voltage at both ends of the LED, and responds to the measured voltage change and the alternating current. A luminance measuring device characterized in that it determines whether an abnormality has occurred in the reference light emitter for calibration based on the difference between preset voltage changes. According to paragraph 1,
Further comprising an external illuminance sensor,
The control unit determines a time to set a correction value for the automatic calibration based on a signal received from the external illuminance sensor.