Illumination – Photographic lighting – Including specific light modifier
Patent
1993-10-14
1997-04-01
Lazarus, Ira S.
Illumination
Photographic lighting
Including specific light modifier
362 17, 362 32, 362272, 362277, 362285, 362293, 348370, G03B 1502
Patent
active
056159382
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The invention relates to a device for illuminating objects in particular those to be recorded with a video camera, the device having at least one lamp, the light of which projects via a condenser system onto an optical system which directs the light at the object or objects to be illuminated as well as having a control means for regulating the intensity of the light with which the object is to be illuminated.
There are numerous cases in which devices of this type are needed. Typical applications are in medical or technical video endoscopy or image processing, in particular, of technical scenes.
STATE OF THE ART
In the state of the art generic devices lamps, in particular, halogen lamps or arc lamps (Xenon, HMI, etc.), are employed. To control, respectively regulate, illumination brightness, a voltage regulation means is frequently utilized with halogen lamps, whereas in the case of arc lamps a mechanical motor shutter regulation means is usually employed.
Brightness control by means of lamp voltage, respectively the power of the lamp, has the disadvantage that the color temperature changes dependent on the voltage, respectively, the power. This is undesirable in both video endoscopy and image processing, because as a result there is a color shift in the picture. In particular, this type of control cannot be applied with arc lamps.
The use of a shutter, as by way of illustration, an iris stop, has the disadvantage that the shutter warms up too much. This warming up is not only unpleasant, but can also lead to distortion of the lamina. Furthermore, shading effects may occur.
DESCRIPTION OF THE INVENTION
The object of the present invention is to improve a device for illuminating objects, in particular, those to be recorded with by a video camera, the device having at least one lamp, the light of which projects via a condenser system onto an optical system, which directs the light at the object or objects to be illuminated and having a control means for regulating the intensity of the light with which the object is to be illuminated, in such a manner that illumination brightness can be quickly and reliably adjusted without using, in particular, mechanical shutters and without regulating the power of the lamp, i.e. in particular, without color shifting.
An element of the present invention is that the control means moves the lamp, the condenser system and/or the optical system in the direction of the optical axis of the condenser system, respectively of the optical system or in perpendicular direction thereto, respectively pivots one of the aforementioned elements.
In other words, an element of the present invention is that the position of the focus of the condenser system in relation to the optical system arranged thereafter is regulated while constant voltage, respectively constant power, is advantageously, but not necessarily applied to the lamp.
As it is not necessary to control and respectively regulate, lamp brightness, any lamps, by way of illustration the halogen lamps, but also arc lamps or other and, in particular, cost-favorable types of lamps, can be used in an invented device. In any event, the color temperature of the lamp does not change, because the point of operation of the lamp is not moved.
Furthermore, brightness control, respectively regulation, can occur utilizing little power, because the invented brightness control by shifting the focus position requires only small distances.
According to another embodiment, a control unit activates the control means. A manually entered or program-control-entered positioning signal, but also a control signal of a light measurement device, may be transmitted to the control unit. It is especially advantageous if the control signal is derived from a video signal from a video camera. Another embodiment sets forth that the control signal is derived from the output signal of the image recorder prior to signal processing by the camera electronics. This improvement has the advantage that the video camera amplification control means and the
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Cariaso Alan B.
Lazarus Ira S.
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