Observation apparatus with illumination means

Abstract: The present invention is intended to enable the change of the operating mode of an observation apparatus of a video system between a fluorescent observation mode and an ordinary observation mode and to enable the observation apparatus to reproduce a clear image for observation. The observation apparatus in accordance with the present invention uses a principle that an image pickup system (11) provides three colour signals, namely, R-, G- and B-signals. The image pickup system of the observation apparatus is provided with an illuminating light selecting means (12) for selectively providing light in a specified wavelength region as illuminating light, and a colour signal selecting means (15) for selectively providing the colour signals. When the specified wavelength region is the visible region, at least the colour signals in a wavelength region including the specified wavelength region including the illuminating light are cut off. When the specified wavelength region is in an ultraviolet region, the colour signals in a wavelength region including the main wavelength region including fluorescent light emitted by excitation by the illuminating light in the ultraviolet region are provided selectively.

Description: The present invention relates to an observation apparatus of a video system and, more particularly, to an observation apparatus suitable for fluorescent observation. An observation apparatus of a video system reproduces the image of an object taken by an image pickup device on a reproducing monitor for observation. The image pickup device is provided with a small built-in video camera unit employing a solid state image pickup element, such as a CCD, and an illuminating system capable of illuminating the object with intense illuminating light. The observation apparatus enables the observation of a magnified image of the object illuminated with the illuminating light emitted by the illuminating system. Such a known observation apparatus is disclosed, for example, in Japanese Patent Publication JP-B-4020615 (1992). This known observation apparatus enables the observation of the object in various modes of observation by illuminating the object in various modes of illumination. A fluorescent observation mode is one of the various modes of observation. In a fluorescent observation mode, the object is illuminated with illuminating light selected among visible light in a specified wavelength region, such as a red light wavelength region, a green light wavelength region or a blue light wavelength region, and ultraviolet light, to relieve a fluorescent composite or a fluorescent structure that is excited specifically for luminescence by the illuminating light to emit fluorescent light for observation. Fig. 3 shows an example of a known observation apparatus that enables fluorescent observation. This known observation apparatus is provided with an image pickup device 1 having an illuminating system which transmits light emitted by an external illuminating lamp 2 through an optical fibre bundle 3. The light emitting ends of the optical fibres 3f of the optical fibre bundle 3 are arranged in a circular arrangement, and the illuminating light emitted through the illuminating ends is condensed in an observation field by a semispherical condensing light guide 4. The image pickup system of the observation apparatus comprises a camera unit 5 and an optical unit 6 for focusing the image of an object M on the image pickup device 5e of the camera unit 5. The illuminating system is provided with a first filter 7 for wavelength selection to pass light of a wavelength in a specified wavelength region, and the optical unit 6 is provided with a second filter 8 for region rejection to absorb the light passed through the first filter 7. The image taken by the image pickup device 1 is displayed on a monitor 9 for observation. In this observation apparatus, the second filter 8 absorbs the illuminating light reflected by the object M and passes only fluorescent light emitted by a fluorescent composite or a fluorescent structure in the object made luminous by excitation with the illuminating light so that only the fluorescent light falls on the image pickup system for luminescent observation. Accordingly, when using this known observation apparatus for fluorescent observation, the types of objects which can be observed are dependent on the combination of the first filter 7 and the second filter 8, and the filters 7 and 8 must be changed for other filters when observing another object or a fluorescent composite having another characteristic. Problems arise when changing the filters, particularly, the second filter. Since the second filter is disposed within the image pickup device having a small space available, it is difficult to design a mechanism for holding the second filter and it requires troublesome work to change the second filter for another filter. Furthermore, the second filter must be capable of being set for both ordinary observation and fluorescent observation. Fluorescent observation is particularly useful when used in combination with ordinary observation. To enable the observation apparatus both ordinary observation and fluorescent observation, the second filter needs to be removed from the image pickup device or moved away from the path of the image light for luminescent observation. Both removing the second filter from the image pickup device and moving the second filter away from the path of the image light need mechanisms which are difficult to design. When light in the ultraviolet region, i.e., ultraviolet radiation, is used as illuminating light for fluorescent observation, basically, the illuminating light reflected by the object need not be eliminated, and hence, there is no significant problem attributable to the second filter. However, if the illuminating light reflected by the object is not eliminated, the clearness of the fluorescent image is spoiled. As mentioned above, the image pickup device 1 of the observation apparatus of a video system can be held by hand and can be brought into contact with or near the object for observation. Although such a method of observation has a great advantage that the degree of freedom of observation is very large as compared with that of the conventional microscope employing a stationary stand for supporting the object, it is difficult to provide the image pickup device with a screening means for effectively screening the object from external light when ultraviolet radiation is used for fluorescent observation; consequently, the contrast of the image is reduced by undesired external light, i.e., disturbing light, to spoil the clearness of the fluorescent image. US-A-4742388 describes a colour video endoscope system with electronic colour filtering. Switching circuitry is provided to transfer data from an A/D convertor to a respective DRAM. A first aspect of the present invention provides an observation apparatus comprising: an illuminating system for illuminating an object with illuminating light and provided with an illuminating light selecting means for selecting illuminating light in a specified wavelength region for illuminating the object; an image pickup system which provides a plurality of colour signals on a respective plurality of colour output lines, each colour signal representing colour in a respective specified wavelength region; and a reproducing system for reproducing the image of the object taken by the image pickup system; characterised in that switching means is provided on each output line for selectively transferring the colour signals to the reproducing system, and in that each switching means is operable independently of the other switching means. A second aspect of the present invention provides a method of observing an object with an observation apparatus comprising an image pickup system which provides a plurality of colour signals each on a respective output line each representing colour in a respective wavelength region; a reproducing system for reproducing the image of an object taken by the image pickup system; and independently operable switching means provided on each output line for selectively transferring the colour signals to the reproducing system; the method comprising illuminating the object with light in a specified wavelength region; and operating the switching means such that the colour signal representing colour in the specified wavelength region is not transferred to the reproducing system when the object is being illuminated with light in the specified wavelength region. The present invention provides an observation apparatus of a video system capable of easily achieving the fluorescent observation of different kinds of objects, of easily changing the observation mode between a fluorescent observation mode and an ordinary observation mode by simple operations and of forming a clear image for observation when ultraviolet radiation is used for illumination. The present invention uses the principle in which the image pickup system composes a colour image from image signals by filtering. Since a colour image pickup system, in general, represents the image of an object by R-, G- and B-signals respectively representing the images of three primary colours, i. e., R, G and B (Red, Green and Blue), of the image, one of the R-, G- and B-signals is provided or eliminated selectively to provide a filtering effect and to eliminate disturbing light. More concretely, when the specified wavelength region is the visible region, the image pickup system functions in the following manner. If light in a region including B-light is selected as illuminating light, the image pickup system provides signals representing R-light and G-light and eliminates a signal representing B-light. Such a function of the image pickup system is equivalent to the function of a B-light absorbing filter. If light in a region including G-light is selected as illuminating light, the image pickup system provides signals representing R-light and B-light and eliminates a signal representing G-light. Such a function of the image pickup system is equivalent to the function of a G-light absorbing filter. When the specified wavelength region is an ultraviolet region, the image pickup system provides a colour signal representing a colour in a wavelength region corresponding to the main wavelength region of fluorescent light emitted by the object excited by the illuminating light in the specified wavelength region. In this case, the principle on which the image pickup system composes a colour image by image signals is used for eliminating disturbing light that reduces the clearness of the fluorescent image. More concretely, when the main wavelength region of the fluorescent light emitted by the fluorescent composite or the fluorescent structure of the object is included in the wavelength region of G-light, the image pickup system eliminates colour signals representing R-light and B-light and provides only a colour signal representing G-light. When the main wavelength region of the same fluorescent light is included in the wavelength region of B-light, the image pickup system eliminates colour signals representing R-light and G-light and provides only a colour signal representing B-light. The selection of a colour signal representing R-light, G-light or B light for filtering effect can be achieved electronically. Accordingly, the operating mode of the image pickup system can be very readily and quickly changed between fluorescent observation modes for observing different fluorescent objects and between an ordinary observation mode and a fluorescent observation mode by a simple mechanism. Furthermore, the possibility of changing the observation mode of the image pickup device without vibrating the image pickup device is particularly advantageous to an observation method that does not use any stand. It is preferable for the simple, quick change of the operating mode of the image pickup system that the illuminating light selecting means and the colour signal selecting means of the observation apparatus are interlocked so that the colour signal selecting means operates according to the light selecting operation of the illuminating light selecting means. As is apparent from the foregoing description, the term "specified wavelength region" means a wavelength region having a fixed range overlapping the wavelength region including the wavelength of a colour signal provided by the image pickup system. Accordingly, the present invention does not intend to designate light of a fixed wavelength by the term "light in a specified wavelength region," but intends to designate light in a wavelength region having the centre wavelength corresponding to a specified wavelength by "light in a specified wavelength region." An example of the present invention will now be described in conjunction with the accompanying drawings, in which:- Fig. 1 is a block diagram of an observation apparatus in a preferred embodiment according to the present invention; Fig. 2 is a view of a filter unit; and Fig. 3 is a block diagram of a conventional observation apparatus. A preferred embodiment of the present invention will be described hereinafter, in which parts like or corresponding to those of the foregoing conventional observation apparatus are denoted by the same reference characters and the description thereof will be properly omitted. An observation apparatus in this embodiment, similarly to the foregoing conventional observation apparatus, employs an external luminous source. As shown in Fig. 1, an illuminating lamp 2 and an image pickup system 11 are disposed separately. Illuminating light emitted by the lamp 2 is transmitted through an optical fibre bundle 3 and a light guide 4 to illuminate an object M. A filter unit 12 is interposed between the illuminating lamp 2 and the entrance end 3a of the optical fibre bundle 3. As shown in Fig. 2, a filter unit 12 has four filters, namely, a white filter Fw, a blue filter Fb, a green filter Fg and an ultraviolet filter Fv, in a lateral arrangement. The filter unit 12 is moved laterally to use the filters selectively. The illuminating lamp 2 is a lamp capable of emitting light in the ultraviolet region as well as light in the visible region, such as a metal halide lamp. An optical unit 6 focuses an image of the object M onto an image pickup device 13e of a camera unit 13. An external signal processing unit 14 processes the output signals of the camera unit 13 built in the image pickup system 11 to give an R-Y signal and a B-Y signal to a colour signal selecting unit 15. The colour signal selecting unit 15 comprises a decoder 16 which converts the R-Y and B-Y signals into R-, G- and B-signals, and an encoder 17 for converting the output signals of the decoder 16 into signals conforming to the system of the reproducing monitor 9. The R-, G- and B-signals provided by the decoder 16 are transferred selectively to the encoder 17 through switches 18r, 18g and 18b interposed between the decoder 16 and the encoder 17. The switches 18r, 18g and 18b are operated in connection with the operation of the filter unit 15; that is, the switches 18r and 18g for the R and G-signals are closed and the switch 18b for the B-signal is opened when the blue filter Fb is set at the working position, the switch 18r for the R-signal is closed and the switches 18g and 18b for the G- and B-signals are opened when the green filter Fg is set at the working position, and all the switches 18r, 18g and 18b for the R-, G- and B-signals are closed when the white filter Fw is set at the working position for ordinary observation. When the ultraviolet filter Fv is used, for example, for observing an object that emits fluorescent light in a wavelength region included in a wavelength region in which light represented by the G-signal is included, the switch 18g for the G-signal is closed and the switches 18r and 18b for the R- and B-signals are opened. When the ultraviolet filter Fv is used for observing an object that emits fluorescent light in a wavelength region included in a wavelength region in which light represented by the B-signal is included, the switch 18b for the B-signal is closed and the switches 18r and 18g for the R- and G-signals are opened. Although the control of the condition of the switches 18r, 18g and 18b in connection with the operation of the filter unit 15 is preferable in respect of facility in operating the switches, if necessary, the switches 18r, 18g and 18b may be operated manually or by other suitable switch operating mechanism. When the reproducing monitor 9 is capable of receiving the R-, G- and B-signals, the encoder 17 is not necessarily needed. If the encoder 17 is omitted, the switches 18r, 18g and 18b are connected directly to the reproducing monitor 9. Although the image pickup device 11 in this embodiment receives the illuminating light from the external illuminating light source, the present invention may employ an image pickup device provided with an internal illuminating light source, such as the image pickup device disclosed in Japanese Patent Laid-open No. JP-A- 4 107 410 (1992) or Japanese Patent Application No. JP-A- 3 059 676 (1991). The advantageous effect of the present invention on the simplification of the mechanism of an observation apparatus will be particularly effective on an image pickup device provided subject to spatial restrictions. As is apparent from the foregoing description, according to the present invention, the colour separating function of a colour image pickup system is used for the filtering function of an absorption filter for fluorescent observation and hence the filtering function can be changed electronically. Accordingly, the operating mode can be easily changed between fluorescent observation modes for observing different fluorescent objects and between an ordinary observation mode and a fluorescent observation mode by a simple mechanism.

Claims: An observation apparatus comprising: an illuminating system (2,3) for illuminating an object with illuminating light and provided with an illuminating light selecting means (12) for selecting illuminating light in a specified wavelength region for illuminating the object; an image pickup system (11) which provides a plurality of colour signals on a respective plurality of colour output lines, each colour signal representing colour in a respective specified wavelength region; and a reproducing system (9) for reproducing the image of the object taken by the image pickup system; characterised in that switching means (18r,18g,18b) is provided on each output line for selectively transferring the colour signals to the reproducing system, and in that each switching means is operable independently of the other switching means. Apparatus according to claim 1 wherein the apparatus has a mode of observation in which the object is illuminated with light in a specified wavelength region, and in which the switching means can be independently operated such that the colour signal representing colour in the specified wavelength region is not transferred to the reproducing system. Apparatus according to claim 1 or 2 wherein the apparatus has a mode of observation in which the object is illuminated with light in an ultraviolet region, and in which the switching means can be independently operated such that the colour signal representing colour in a main wavelength region in which fluorescent light is emitted by the object is transferred to the reproducing system. Apparatus according to any of the preceding claims further comprising means for operating the light selecting means (12) in cooperation with the switching means (18r,18g,18b). A method of observing an object with an observation apparatus comprising an image pickup system (11) which provides a plurality of colour signals each on a respective output line each representing colour in a respective wavelength region; a reproducing system (9) for reproducing the image of an object taken by the image pickup system; and independently operable switching means (18r,18g,18b) provided on each output line for selectively transferring the colour signals to the reproducing system; the method comprising illuminating the object with light in a specified wavelength region; and operating the switching means such that the colour signal representing colour in the specified wavelength region is not transferred to the reproducing system when the object is being illuminated with light in the specified wavelength region. A method according to claim 5 wherein the specified wavelength region is an ultraviolet region and the switching means is operated such that a colour signal representing colour in a main wavelength region in which fluorescent light is emitted by the object is transferred to the reproducing system when the object is being illuminated with light in the ultraviolet wavelength region.

Inventors: HIRAI MASANORI, ISHIKAWA SEIJI, MURAKAMI HAJIME, YAMAMOTO MASAO, HIRAI, MASANORI, ISHIKAWA, SEIJI, MURAKAMI, HAJIME, YAMAMOTO, MASAO, HIRAI, MASANORI C/O MITSUBISHI KASEI CO.,, ISHIKAWA, SEIJI C/O MITSUBISHI KASEI CO.,, MURAKAMI, HAJIME C/O MITSUBISHI KASEI CO.,, YAMAMOTO, MASAO C/O SCALAR CO.,
Applicants: MITSUBISHI CHEM CORP, SCALAR CORP, MITSUBISHI CHEMICAL CORPORATION, SCALAR CORPORATION
Application year: 1993
Main classification: H04N5
IPC codes: H04N9, H04N5