JP4575730B2 - LED lighting device - Google Patents

Description

  The present invention relates to an LED lighting apparatus for a stage / studio using a light emitting diode (LED).

  Generally, halogen light bulbs and discharge lamps are used as light sources for spotlights used for lighting in the stage and television studios. This is because the light-emitting portion of the light source is sufficiently small with respect to the lens, and the lens can sufficiently capture the light from the light source and can irradiate efficiently. In a spotlight using a halogen bulb or a discharge lamp, the filament is heated as high as possible to generate light, so that not only visible light but also a lot of heat rays are emitted. Therefore, iron or light metal plates that can withstand heat are used for the housing that houses the light source, and heat-resistant glass is also used for the lens, making the spotlight heavier and requiring effort to move the spotlight. Yes.

Therefore, a large number of LEDs are arranged as light sources, and the irradiation beam of each LED is condensed at one point to constitute a virtual single point light source unit. An LED lighting device has been developed that changes illuminance and illuminance distribution (see, for example, Patent Document 1).
Japanese Patent Laid-Open No. 2001-307502 (FIGS. 2 and 3)

  However, when the LED, which is the light source of the LED lighting device, is turned on by PWM control and the irradiation surface (subject) of the LED is photographed by a television camera or the like, the image of the television camera flickers (flicker) depending on the PWM control frequency band. ) May occur.

  This is because the LED lighting control by PWM control repeatedly turns the LED on and off at a predetermined frequency, and controls the brightness of the irradiated surface by controlling the LED lighting time by the pulse width. This is because the timing of shooting with a television camera may not match the timing of turning on and off the LED.

  In general, a TV camera captures and captures the same video in odd and even fields. For example, the LED is lit when capturing an odd field image, and the LED is off when capturing an even field image. In this case, the odd field video is bright and the even field video is dark, and the same video flickers.

  An object of the present invention is to provide an LED lighting device that prevents flickering in an image captured by a television camera.

An LED illumination device according to a first aspect of the present invention includes an LED fixture that has a plurality of LEDs and is used for illumination of an object, and is controlled by PWM to turn on the LED; an image of the object imaged by a television camera An LED lighting device that turns on the LED by PWM control at a frequency of 4.5 KHz or more, in which a difference in lighting time of the LED by the PWM control between the odd field and the even field is not affected by the flicker of the image. It is characterized by that.

  In the present invention and the following inventions, definitions and technical meanings of terms are as follows unless otherwise specified. An LED illumination device is an illumination device that is used as a spotlight used for illumination in a stage or a television studio. A plurality of LEDs (light emitting diodes) are used as a light source and are collected by a condenser lens on a subject. Irradiate light. The LED includes both a so-called power type LED and a bullet type LED. When only the power type LED is arranged, when only the bullet type LED is arranged, both the power type LED and the bullet type LED are arranged. Including both cases. The light emission output of the LED is controlled by PWM (pulse width) control of the lighting power supplied to the LED by the LED lighting device at a predetermined frequency.

The LED lighting device performs PWM control of the lighting power supplied to the LED at a predetermined frequency, and lights the LED. That is, the control unit performs PWM control of the switch element at a predetermined frequency, controls the lighting power source supplied to the LED, adjusts the lighting time of the LED, and controls the light emission output of the LED. Predetermined frequency at that time shall be the odd and even fields and 4.5kHz or more frequencies difference LED lighting time does not affect the flicker of the image due to the PWM control of the image of the subject taken by the television camera.

  As a result, the difference between the odd field and the even field in the video photographed by the television camera by the PWM control is a maximum of one pulse, so even if the difference of one pulse occurs, the flicker of the video of the television camera is not affected. .

  According to the present invention, since the PWM control frequency is increased, even if a difference in brightness (1 pulse) occurs between the odd field and the even field of the TV camera image, the flicker of the TV camera image is affected. Get smaller. Therefore, the video shot with the television camera will not flicker.

  According to the first aspect of the present invention, since the frequency of PWM control is increased, even if a difference in brightness (1 pulse) occurs between the odd field and the even field of the TV camera image, flickering of the TV camera image occurs. The effect of. Therefore, the video shot with the television camera will not flicker.

  FIG. 1 is a configuration diagram of an LED lighting device according to an embodiment of the present invention, and FIG. 2 is a front view. The LED lighting device 11 includes an LED fixture 12 and an LED lighting device 13. The LED fixture 12 includes an LED array unit 15 in which a plurality of LEDs 14 are arranged, and a condensing lens 16 that collects the emitted light emitted from the plurality of LEDs 14 of the LED array unit 15 and irradiates the light to the outside. It is stored.

  The condensing lens 16 is disposed away from the LED array portion 15 and condenses the emitted light emitted from the plurality of LEDs 14 of the LED array portion 15 and is formed of a spherical lens or a flat lens. . FIG. 1 shows a case where one Fresnel lens is used.

  In addition, a moving mechanism 17 is provided that makes the distance between the condenser lens 16 and the LED array portion 15 relatively variable. The moving mechanism 17 includes a light source focus handle 17a and a lens focus handle 17b. By focusing with this moving mechanism 17, the irradiation area on the irradiated surface of the subject is continuously changed, and the light quantity is continuously changed. Further, a bander 18 is provided on the light collecting lens 16 side of the LED fixture, and the irradiation range of light from the LED fixture 12 is adjusted by adjusting the opening / closing angle of the bander 18.

  The LED lighting device 13 performs PWM control of the lighting power source supplied to the LED 14 by driving the switch element based on a command from the control unit 19 and dimming control of the LED based on the dimming signal. (Pulse width) The driver 20 is controlled. Thereby, the light output of the LED 14 is dimming controlled based on the dimming signal.

  FIG. 3 is a characteristic diagram showing an example of PWM control of the LED 14 by the LED lighting device 13. The LED lighting device 13 performs PWM control on the supply time of the lighting power supplied to the LED 14 based on the dimming signal. The frequency of the PWM control is a frequency that does not affect the flickering of the subject image taken by the television camera. The synchronization frequency of the television camera is 59.94 Hz, which is about 60 Hz. Therefore, the odd field in one frame of the video is about 16.7 ms, and the even field is also about 16.7 ms. During this 16.7 ms, even if a difference in brightness due to the difference of one pulse occurs between the odd field and the even field, the frequency is set such that the human eye does not feel the flicker of the image. For example, the PWM control frequency is set to 4.5 kHz or more.

  In this way, since the difference in the lighting time of the LED 14 by the PWM control between the odd field and the even field of the subject image captured by the TV camera is PWM controlled at a frequency that does not affect the flickering of the image, the LED 14 is turned on. Even the video shot in the camera will not flicker.

  FIG. 4 is a characteristic diagram showing another example of PWM control of the LED 14 by the LED lighting device 13. An example of FIG. 4 is that the frequency of PWM control in the LED lighting device 13 is an integral multiple of the synchronization frequency of the television camera that captures the image of the subject, and 5 times the synchronization frequency of the television camera, that is, 299.7 Hz or more. PWM control is performed at a frequency of By setting the PWM control frequency to an integral multiple of the synchronization frequency of the television camera, the number of pulses in the odd and even fields of the video captured by the television camera becomes the same. Therefore, the odd field and the even field have the same brightness.

  Note that even if the number of pulses in the odd field and even field of the video captured by the TV camera is the same, flickering is visually perceived by the human eye at frequencies below about 300 Hz. The frequency is 5 times the frequency (299.7 Hz) or more of the camera synchronization frequency (59.94 Hz). Thereby, the flicker at the time of image | photographing the irradiation surface of the to-be-photographed object by the LED fixture 12 with a television camera can be suppressed.

The block diagram of the LED lighting apparatus concerning embodiment of this invention. The front view of the LED lighting apparatus concerning embodiment of this invention. The characteristic view which shows an example of PWM control of LED by the LED lighting device in embodiment of this invention. The characteristic view which shows another example of the PWM control of LED by the LED lighting device in embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 ... LED lighting device, 12 ... LED fixture, 13 ... LED lighting device, 14 ... LED, 15 ... LED arrangement part, 16 ... Condensing lens, 17 ... Moving mechanism, 18 ... Banda, 19 ... Control part, 20 ... Driver

Claims (1)

An LED fixture that has a plurality of LEDs and is used for illumination of a subject and is PWM controlled to turn on the LEDs;
The difference between the odd-numbered field and even-numbered field in the video of the subject photographed by the TV camera is controlled by PWM at a frequency of 4.5 KHz or more so that the difference in the lighting time of the LED by the PWM control does not affect the flickering of the video. An LED lighting device;
An LED lighting device comprising:

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