Device for controlling the luminous intensity of superposed additional information in an optical viewing device

The invention relates to an optical viewing device with an information reflection, for example a stereo operating microscope.

Fading in by means of mirroring devices or the superimposition of information in the observation field of optical systems is being used more and more in many areas, since it leads to a considerable gain in information. In clinical applications, they give the surgeon the opportunity to record additional visual information without interrupting eye contact with the operating field. The surgeon can, for example, examine the site microscopically perceive the position and size of the target object, typically by superimposing the microscopic intermediate image with additional information - for example virtually real object contours - by means of a display, imaging optics and optical splitter.

In almost all applications, brightness, contrast and resolution of the overlaid image are important quality features for perfect functioning. For a good perception of the overlay, the reflected image signal must be significantly brighter than the optical image. However, it must also not be too bright so as not to disturb the view of the object through glare or overexposure.

In the single-mirror devices known today, the image of a corresponding monitor or LCD screen is imaged into the intermediate image of the microscope via a lens system and a divider prism or mirror and is superimposed on the image obtained by the main objective. The brightness and contrast of the reflected image are usually neither controlled nor regulated.

It has been recognized that these systems are disadvantageous in the following points:<ul id="ul0001" list-style="none"><li>i) A fixed brightness of the reflection can lead to overexposure or 'swallowing' of the object image.</li><li>ii) Manual brightness and contrast control can only be carried out over the entire image, but not over individual areas or pixels.</li><li>iii) With different image characteristics and brightness levels, manual brightness and contrast control leads to complex adjustments during viewing.</li></ul>

The invention is therefore based on the object of finding an improvement which avoids the stated disadvantages and enables an undisturbed, permanent view of the information reflected, regardless of the brightness or the contrast of the depicted object.

This object is achieved by the features specified in the characterizing part of patent claim 1. Advantageous developments of the invention are the subject of the dependent claims.

For the control process of the overlay, the basic brightness of the object image is determined by detecting the object, for example by means of a CCD or a video camera, and the spatial distribution of brightness and / or color. The basic brightness can then be set, for example in the case of an LCD or a monitor, by regulating the illuminating light source or, in the case of a monitor, the brightness of each overlay pixel on the basis of the object brightness and / or color determined at the pixel location x, y.

The following improvements can be achieved in the following steps:<ul id="ul0002" list-style="none"><li>a) The brightness of the entire information reflected can be adjusted to the brightness of the object.</li><li>b) The brightness of the information reflected can be adjusted pixel by pixel to the brightness of the individual areas of the object image (contrasts).</li><li>c) The overall brightness of the image is adjusted continuously and automatically.</li><li>d) The adjustment to the contrasts of the image is carried out automatically either zone by zone or pixel by pixel.</li><li>e) Overall, suppression of dark areas and glare in the object image are avoided without manual intervention.</li><li>f) The overall brightness and the overall contrast of the reflected image can, if required, also be controlled manually and / or, if appropriate, remotely by the respective viewer.</li></ul>

A special further development of the invention consists in that not only the brightness of the reflection is adapted to the respective object brightness, but also the color. For example, the contrast color of the color of the respective object image is selected for the reflection.

The text above refers to a surgeon and to a surgical microscope or to an operating field; however, the invention is not so limited. Rather, it can also be other optical devices with reflections, for example projections with additional information superimposed, video and photo cameras, monocular as well as other binocular applications.

The list of reference symbols and FIGS. 1, 2 and 3, together with the disclosure content of the claims, form an integral part of the disclosure of this application.

The invention will be explained in more detail below with the aid of the schematic figures:

FIG. 1 symbolically shows a main beam path 20, 22 of a viewing device for an object 8 running along an axis 10. A beam path 21 to an image recognition unit 1 is divided according to a main optic 7 on a beam splitter 5 and deflected along an axis 12. The beam path 23 of information reflected is faded in for the viewer 40 from the axis via a beam splitter 6 into the main beam path 20, 22. A display device is designed, for example, as a display 3.

FIG. 2 shows the brightness control of the fade-in device 3 according to the invention, which reflects the information, the control loop brightness and contrast measurement 53 of the object by means of, for example, a camera 1, the evaluation and control unit 30, 31 by means of, for example, a computer, and the input signal 54 to the fade-in device 3.

FIG. 3 symbolically shows an example of the effect of brightness control. The x, y pixels of an object image have a brightness according to curve 50. The brightness (intensity) for the fade-in according to curve 51 is regulated by a controller for clearly visible superimposition, so that there is an overall brightness according to curve 52. The contrast and / or the color is / are therefore sufficiently and automatically adjusted.

The device shown in the figures works as follows:

Part of the beam of rays 20 emanating from the object 8 to be viewed is deflected by means of a beam splitter 5 via optics 2 to a measuring device 1, for example a CCD or a video camera. The output signal 53 of this measuring device is forwarded to an evaluation unit 30 - for example a computer.

The overall brightness of the object image and the contrasts within the image are determined by zone or pixel by means of the evaluation unit (computer) (30). On the basis of this brightness, color and contrast determination, a fade-in device, for example a display 3 or a monitor, is activated, in which the overall brightness is determined on the basis of the object brightness and the pixel intensity on the basis of the contrasts within the object image.

This brightness and contrast-controlled information 23 is in turn reflected into the main beam path 22 via optics 4 and a beam splitter 6.

According to the invention, an overall image free of interference and radiation is thus generated.

In the context of the invention, either a self-illuminating or an externally illuminating insertion device 3 can be used. Fade-in device in the sense of the present invention is to be understood to mean all devices which bring optical information onto the retina of a user, for example also laser displays or the like.

Reference list

<dl id="dl0001" compact="compact"><dt>1</dt><dd>Image brightness and contrast measuring device (CCD) / image recognition unit / brightness detector</dd><dt>2</dt><dd>Optics for the measuring device</dd><dt>3</dt><dd>Fade-in device (display, monitor)</dd><dt>4</dt><dd>Fade-in device optics</dd><dt>5</dt><dd>Beam splitter output signal (CCD)</dd><dt>6</dt><dd>Beam splitter input signal (display, mirrored information)</dd><dt>7</dt><dd>Main optics</dd><dt>8</dt><dd>object</dd><dt>10</dt><dd>Axis of the main beam path</dd><dt>11</dt><dd>Axis of the input beam path (display)</dd><dt>12</dt><dd>Axis of the output beam path (CCD)</dd><dt>20</dt><dd>Object beam path / main beam path</dd><dt>21</dt><dd>Output beam path (CCD) / measuring beam path</dd><dt>22</dt><dd>Eyepiece beam path / observer beam path</dd><dt>23</dt><dd>Input beam path / brightness and contrast controlled information<img file="EP1220004A2_D0001.tif" /></dd></dl><dl id="dl0002" compact="compact"><dt>32</dt><dd>Manual input</dd><dt>40</dt><dd>Viewer</dd><dt>50</dt><dd>Brightness of object image / curve</dd><dt>51</dt><dd>Fade in / curve</dd><dt>52</dt><dd>Overall brightness / curve</dd><dt>53</dt><dd>Output signal (video) / control loop brightness and contrast measurement</dd><dt>54</dt><dd>Input signal (to the fade-in device)</dd></dl>