JP3266300B2 - Opaque card lighting system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lighting device for a television opaque, and more particularly to a lighting device for illuminating an opaque card picked up by an image pickup device.

[0002]

2. Description of the Related Art An opaque card illuminating device uses an opaque card provided with characters to be superimposed on a television screen by CC.
It is used to illuminate the opaque card surface when the image is transmitted by a D camera or the like. In such a lighting device, a fluorescent lamp is used as a television opaque card illumination light source, and the fluorescent lamp is lit with a normal commercial power supply to illuminate the opaque card. (V cycle),
Extreme flicker may occur. In order to avoid this flicker, DC lighting of the fluorescent lamp is performed, or the power supply frequency of the fluorescent lamp is changed to the V cycle (frequency 60
Frequency (for example, 20 Hz).
KHz) is used.

[0003] The latter method is, for example, 20KH
In the case of a high-frequency power source of z, the fluorescent lamp repeats light and dark more than 600 times during the 1 V cycle of the television. However, the image pickup device of the television camera uses an integration method (which accumulates signal charges corresponding to incident light and takes out a scanning output. Therefore, on the light-receiving surface, repetition of light and dark more than 600 times is averaged, flicker does not occur, and even with the AC lighting of the fluorescent lamp, this high frequency lighting is sufficient for illumination of the TV opaque card. Can be used.

[0004]

However, in the case of TV opaque lighting, there is a need to reduce the size of the equipment in order to ensure uniform illumination without shading as much as possible and to secure the required illuminance. And a plurality of light sources. Therefore, even in the case of the above-described high frequency lighting, a plurality of fluorescent lamps (for example, four fluorescent lamps arranged in the vicinity of four sides of the card) are used. In this case, the shading is corrected by adjusting the primary side voltage of each of the plurality of fluorescent lamps. However, this shading correction is also significant. Because the size of the fluorescent lamp differs between the left and right, independent fluorescent lamp power supplies are used for each fluorescent lamp.In this way, multiple fluorescent lamps are used, and the high-frequency power supply is independent for each fluorescent lamp. However, there is a disadvantage that the beat of the fluorescent lamp illumination light (see FIG. 3) occurs due to a slight difference in the high frequency between the independent power sources. When such a beaty illumination is used for imaging an opaque card, flicker is likely to occur due to slight non-linearity of the image sensor (FIG. 3). It becomes a problem.

SUMMARY OF THE INVENTION It is an object of the present invention to eliminate the above-mentioned drawbacks, to prevent the occurrence of beats caused by a plurality of high frequency lighting fluorescent lamps, and to eliminate flicker caused by this, and to implement the invention simply and inexpensively. It is an object of the present invention to provide an opaque card lighting device that can perform the following.

[0006]

SUMMARY OF THE INVENTION The present invention provides a plurality of fluorescent lamps arranged so as to uniformly illuminate an opaque card imaged by an opaque card imaging device, and a plurality of fluorescent lamps provided corresponding to these fluorescent lamps. A high frequency oscillator and a plurality of power supply units for high frequency lighting of a corresponding fluorescent lamp by high frequency power obtained from a secondary winding of the high frequency oscillator. In the lighting device, means for interconnecting the transformers of the power supply units using a link coil is provided, and the high frequency generated by the power supply units is locked to one frequency by loose electromagnetic coupling by the link coil. It is characterized by the following.

[0007]

In the opaque card illuminating device according to the present invention, transformers having a resonance coil of a high-frequency oscillator as a primary winding in each power supply unit for illuminating each fluorescent lamp at a high frequency are mutually coupled using a link coil. When loose electromagnetic coupling by the link coil is performed, the oscillation conditions are mutually affected through this link coil, the oscillation frequencies are automatically balanced and settle down to a certain frequency, and the frequency generated by each power supply unit is reduced to one frequency. Locked to. Therefore, it is possible to prevent occurrence of a beat due to a plurality of high-frequency lighting fluorescent lamps, and as a result, it is possible to eliminate flicker caused by the beat.

[0008]

FIG. 1 shows an embodiment of an opaque card illuminating device according to the present invention, which shows a basic configuration in the case of using four fluorescent lamps. FIG. FIG. The opaque card 1 is set at a predetermined position of a device by a mechanism (not shown), and the opaque card is imaged by the television camera 2. The upper and lower fluorescent lamps 3a and 3b having a longer tube length and the left and right fluorescent lamps 3c and 3d having a shorter tube length are provided in accordance with the opaque image size so that illumination light can be given from all sides to the set opaque card surface.
Are arranged around to constitute a light source unit of the lighting device. As a fluorescent lamp to be used, for example, a cold cathode fluorescent lamp can be used.

The four fluorescent lamps 3a to 3d are connected to a power supply unit 4 for illumination.
Each high frequency power supply for high frequency lighting is provided according to 3b, 3c, 3d. In each of the power supply systems, the light output of the fluorescent lamp is individually adjusted to perform shading correction.

In FIG. 2 showing a high-frequency power supply, high-frequency power supplies 11, 12, 13, and 14 are provided for each fluorescent lamp, and high-frequency oscillators 21, 22, 23, and 24 for generating high-frequency voltages are provided, for example. Operate by supplying 24 VDC. Each high-frequency oscillator 2
1, 22, 23, 24 LC resonant circuit coils 31, 32, 33, 34
Is wound as the primary side winding of each transformer 41, 42, 43, 44, the high frequency oscillation output of each oscillator is boosted and taken out from the secondary side windings 36, 37, 38, 39, and each fluorescent lamp 3a, 3b, 3c,
It is configured to be applied to 3d. The oscillation frequency of each oscillator is determined by an LC resonance circuit, and its circuit constant is selected so as to have a frequency of, for example, 20 KHz. In this example, the as shown in the figure, the variable resistor VR ₁ to VR ₄ provided in each power supply system, it is assumed subjecting them to use the shading correction.

In this embodiment, as shown in the figure, a link coil 50 is further provided over all of the oscillation transformers 41 to 44 in which a resonance coil of a high-frequency oscillator is wound. Is configured to be performed. As described above, when the oscillation transformers of the power supplies 11 to 14 provided with the respective oscillators are coupled in a chain by the coupling link coil 50 of about one turn, any of the oscillators does not draw in any of the oscillators, and the balance is automatically adjusted. As a result, the frequencies of the four high-frequency oscillators 21 to 24 as a whole settle down to a certain frequency, so that the high-frequency lighting frequencies of the fluorescent lamps 3a, 3b, 3c, 3d do not differ from each other.

That is, when a resonance circuit of another oscillator is coupled to an oscillator, the oscillation condition is affected by the coupled resonance circuit. In the above description, the oscillation condition interacts through the link coil 50, and as a result, loose electromagnetic coupling occurs. This causes the frequency to calm down and balance to one frequency. Therefore, the high frequency generated by each fluorescent lamp power supply can be locked to one frequency even if the oscillation frequencies of the respective oscillators are different from each other. Beats can be removed. Further, since no beat is generated as described above, it is possible to eliminate the following flicker that degrades the image quality, regardless of the linearity of the characteristics of the image sensor of the television camera 2 to be used.

Now, using a plurality of high-frequency lighting fluorescent lamps,
In addition, the power of the fluorescent lamp is independent for each fluorescent lamp, and considering the light output, first, the brightness of one fluorescent lamp is:

L _i = A _i (M + sin 2ωt) --- 1 where A _i , M: constant (M ≧ 1) ω: can be represented by the angular frequency of a high-frequency power supply (for example, 20 KHz). Therefore, in the case of illumination by two fluorescent lamps,
It can be written as: That is,

[Number 2] _{L = L 1 + L 2 =} A 1 [M + sin2ωt] + A ₂ [M + sin {(2ω + Δω ) t} ] = A [M + 2sin {(2ω + Δω / 2) t} · cos ｛(Δω / 2) t｝] --- 2 to produce a so-called beat. Δω in the above equation is
Since there is an angular frequency difference between the two power supplies and the power supplies are independent of each other, if there is a slight difference Δω between the generated high frequencies in this way, the optical output will eventually become a solid line in FIG. ), The DC component (broken level in the figure)
The sum of the sin 2ωt components modulated with cos {(Δω / 2) t} is the sum of the components, and illumination is performed when the opaque card is imaged. Also, in this case, each power supply is basically designed so that the generated high frequency is the same frequency, and all the power supplies are made to be substantially the same. (Frequency error)
If the value is extremely low compared to the high frequency, cos {(Δω / 2) t} in the above equation becomes close to the V cycle of the television.

The phenomenon of such beats having slightly different high-frequency frequencies is not limited to beats caused by fluorescent lamp illumination using two independent power supplies, but can be generally applied to a case where a plurality of fluorescent lamps are used. In the case of a fluorescent lamp, light waveforms as shown in FIG. 3 are further superimposed, and various beats are generated, although the complexity is further increased.

On the other hand, if the sensitivity of the image pickup device of a television camera is linear in an integrating system, the flicker should not normally occur in the captured opaque card image even if such a beat is present. If there is non-linearity in photoelectric conversion such as integral charge / discharge characteristics in the afterimage characteristic region of the used image sensor, this beat is detected, and in the case of beat (a) due to illumination of two fluorescent lamps in FIG. As indicated by the one-dot chain line (b), flicker due to the beat occurs. The flicker of the image signal caused by such non-linearity of the image sensor is smaller than the case of the fluorescent lamp illumination with the commercial power supply described above, but the image quality when the opaque card image is inserted is deteriorated, and actually, An image of an illuminated opaque card was taken using a CCD camera and illuminated by illuminating four cold cathode fluorescent lamps with high frequency using four conventional independent power supplies, and it was found that flicker of several percent occurred. Was.

When a plurality of fluorescent lamps are used as described above, flickering may occur even if high-frequency lighting is performed. In this embodiment, the frequencies of the four power supplies 11 to 14 are locked and four fluorescent lamps are used. The individual lighting of the fluorescent lamps 3a to 3d can be performed in the same manner as the high-frequency lighting by a single fluorescent lamp, so that the above-described flicker can be completely removed while performing shading correction satisfactorily. Also, as shown in FIG. 1, the fluorescent lamps 3a, 3b having different sizes vertically and horizontally.
Even when the opaque card 1 is illuminated using the opaque card 3 and 3d, since the power supply is separate, the shading correction can be finely performed, so that it is suitable for such a case. Furthermore, if the method of providing an oscillator of a reference frequency separately to lock the frequency of each power supply and injecting its output to the power supply, a separate reference oscillator besides the power supplies 11 to 14 is required. However, even if an oscillator is not separately provided, each oscillation transformer 41 is simply used.
Since the components .about.44 need only be connected by a link coil 50 of about one turn, the configuration is simple and inexpensive.

Although the frequency of each power supply may be different even if the frequency is locked, the frequency is completely locked even if the phase is different. For example,

L = A ₀ ｛M + sin (2ωt + α)｝ + B ₀ ｛M + sin (2ωt + β)｝ + C ₀ ｛M + sin (2ωt + γ)｝ + D ₀ ｛M + sin (2ωt + δ)｝ = P ｛M + sin (2ωt + ξ)｝, and there is no problem since it is considered to be the same as high-frequency lighting with a single fluorescent lamp.

The present invention is not limited to the above-described embodiment, but can be variously modified and modified. For example, the number of fluorescent lamps is not limited to two or four, but is applicable when a plurality of fluorescent lamps are used. Further, the V cycle of the imaging cycle can be similarly implemented even when the cycle is not a cycle of a frequency of 60 Hz.

[0019]

According to the opaque card lighting device of the present invention, transformers having a resonance coil of a high frequency oscillator of each power supply unit as a primary winding are mutually coupled by a link coil, and each power supply unit is generated by loose electromagnetic coupling. Since the high frequency is locked to one frequency, even if there is a slight frequency difference in the generated high frequency, no beat is generated by the illumination of each fluorescent lamp, and as a result, the linearity of the image sensor used for imaging is affected. Regardless, flicker caused by the beat can be eliminated. On the other hand, since a plurality of fluorescent lamps are provided and a plurality of power supplies are provided in accordance with the corresponding fluorescent lamps, shading correction can be performed easily and finely, and this does not impair the function described above. Shading correction can be performed, and both can be achieved. Further, since the link coil is used, it is not necessary to separately provide an oscillator having a reference frequency for locking the frequency of the power supply, so that the operation can be performed simply and inexpensively.

[Brief description of the drawings]

FIG. 1 is a diagram showing an overall basic configuration of an embodiment of an opaque card lighting device according to the present invention.

FIG. 2 is a circuit diagram showing a detailed configuration of an example of a high-frequency lighting power supply portion of the power supply device.

FIG. 3 is a diagram for explaining generation of a beat by illumination of two fluorescent lamps by two independent high-frequency power sources and generation of flicker caused by the beat;

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Opaque card 2 TV camera 3a, 3b, 3c, 3d Fluorescent lamp 4 Illumination power supply 11-14 High frequency power supply 21-24 High frequency oscillator 31-34 Resonant coil (primary winding) 36-39 Secondary winding 41- 44 Transformer 50 link coil VR _{1 to} VR ₄ Variable resistor

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-64-60067 (JP, A) JP-A-2-284395 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H04N 5/222 H05B 41/24 H05B 41/392

Claims (1)

(57) [Claims] 1. A plurality of fluorescent lamps arranged so as to uniformly illuminate an opaque card imaged by an opaque card image pickup device, and a high-frequency oscillator and a high-frequency oscillator provided respectively corresponding to these fluorescent lamps And a plurality of power supply sections for illuminating a corresponding fluorescent lamp at high frequency with high frequency power obtained from the secondary winding of the transformer. Opaque card lighting characterized by comprising means for mutually coupling transformers of each unit by using a link coil, and locking the high frequency generated by each of the power supply units to one frequency by loose electromagnetic coupling by the link coil. apparatus.