FR2713079A1 - Video-endoscope equipment for medical and industrial use - Google Patents

Abstract

The video-endoscope includes a light source (88) operating continuously and a sequential filtering device comprising a rotating disc carrying three filters (71-73) corresp. to the three primary colours of the spectrum. The filtered light is transmitted by a bundle of optical fibres (11) to the field of view. A monochrome CCD detector generates a signal representing the light reflected of a particular colour. Three images are built up in a memory representing the three colour components, and these are combined to form an RGB type colour television signal for display.

Description

BACKGROUND OF THE INVENTION
The present invention relates to a color videoendoscopy device and to a videoendoscope for implementing said device.

 The technical field of the invention is that of endoscopy devices.

 The term endoscopy generally refers to a visual examination carried out inside a cavity using an endoscope or a fibroscope.

The term endoscope designates a rigid probe which, introduced into a cavity, allows a user to observe the interior of said cavity. To do this, an endoscope integrates two devices: an optical device and a lighting device.

The optical device consists of a distal objective, an optical transport system for the image delivered by the distal objective, said transport system consisting of a series of achromatic lenses, and an eyepiece allowing the user to examine the observed area. The lighting device consists of a bundle of optical fibers, the distal end of which illuminates the area observed when its other end is connected to a light generator.

 The term “fibroscope” designates a flexible probe whose architecture is similar to that of an endoscope, except at the level of the optical transport system which, in the case of the fibroscope, consists of a flexible ordered bundle of optical fibers.

 The term videoendoscopy designates an examination making it possible to obtain on a television receiver the image of the interior of a cavity into which the distal end of a videoendoscope has been introduced.

 Among the known devices in videoendoscopy, two categories of videoendoscopes can be distinguished.

 The first category covers all the devices in which the image of the area observed inside a cavity is transmitted by optical means to a photosensitive sensor of the CCD sensor type located outside of said cavity .

 The second category covers all the devices in which the CCD sensor. is directly housed at the distal end of the videoendoscopic probe and is therefore introduced inside the cavity to be examined.

 Among the known devices falling into this second category, two subcategories of videoendoscopes can be distinguished.

 The first subcategory covers all the devices in which the distal CCD sensor is a "color" sensor which, associated with a lighting device delivering permanent and continuous white light, directly supplies a color video signal.

 The second sub-category covers all the devices in which the distal CCD sensor is a "monochrome" sensor naturally delivering a black and white video signal. In this case, obtaining a three-color video signal will require a generator delivering sequentially lightning corresponding to the three primary colors, a device for capturing primary video signals generated sequentially by the monochrome sensor during lightning, and a processor making it possible to store permanently the last three primary video frames and to reconstruct a color video frame from the three available primary frames.

 The present invention falls into this second subcategory.

 US Patent 4,074,306 (OLYMPUS JULY 76) describes a videoendoscope in which the analysis of the image of the observed area is carried out by a monochrome photosensitive sensor housed in the distal end of a videoendoscopic probe while the lighting of the observed area is provided by an optical fiber transmitting to the distal end of the videoendoscopic probe the light supplied by a generator of three-color flashes consisting of a lamp with permanent lighting in front of which rotates a rotary disc of sequential chromatic filtering equipped with three red / green / blue filters (or yellow cyan / magenta I). The acquisition of the three video frames generated by the photosensitive sensor during the occultation of the lamp by the three filters is carried out sequentially in synchronism with the rotation of the sequential chromatic filtering disc. These three frames are digitized and stored sequentially in three specific memories which can be read simultaneously. After reading and decoding the three frames are processed in an encoder delivering a composite video signal.

 US Patent 4,253,447 (WELCH ALLYN OCTOBER 78), US Patent 4,491,865 (WELCH ALLYN JANVIER 85) and FR Patent 2,438,999 (WELCH ALLYN AOUT 79) describe a videoendoscope operating on a similar principle but in which the three-color flash generator consists of three flash lamps respectively equipped with red / green / blue filters and transmitting their respective flashes to three separate lighting fibers having a common distal end.

The acquisition of the three video frames generated by the photosensitive sensor is then carried out in synchronism with the sequential lighting of the three lamps.

US Patent 4,532,918 (WELCH ALLYN AOUT 85), US Patent 4,535,758 (WELCH ALLYN AOUT 85) and Patent
US 4,546,379 (WELCH ALLYN OCT 85) describe a videoendoscope operating on a similar principle but in which the three-color flash generator consists of a single flash lamp in front of which rotates a rotary disc for sequential chromatic filtering. US Patent 4,523,224 (WELCH ALLYN JUNE 85) describes more precisely the device for controlling the rotation of the chromatic filtering disc.

In all cases, and whatever the architecture chosen for the tri-color flash generator, it proves difficult to obtain a color video image having chromatic characteristics exactly identical to those of the observed area. This problem of color balance results from the fact that the spectral characteristics (emission of the lamp, response of the video sensor, transmission of the lighting fiber) of the three components involved in the color balance have respectively different values in the three bands frequency specific to the three color filters. The purely electronic solution which would consist in adjusting the respective gains of the amplifiers assigned to the red / green / blue video components is therefore unsatisfactory. Such a solution would indeed lead to different noise levels, in particular at the level of digitization, in the three components of the video signal.

 In the case of videoendoscopes having a three-color flash generator equipped with a flashlight, the problem of the color balance can be solved by modulating the number of flashes generated during the blackout of the lamp by a filter according to the color of the filter concerned. This solution is described in US Patent 4,546,379 (WELCH ALLYN OCT 85).

 In the case of videoendoscopes having a three-color flash generator equipped with a lamp with permanent lighting, one solution consists in placing on the rotating disc a fourth filter which will be a neutral filter.

Such a device makes it possible to directly obtain the luminance component of the video signal during the occultation of the lamp by the neutral filter and this in addition to the red / green / blue components obtained during the occultation of the lamp by the three filters of corresponding colors. This solution, which of course leads to a marked increase in the number of electronic components used in the video signal processing processor, is described in the patent application.
FR 2 670 647 (FORT DEC 90).

 The present invention has set itself the first aim of naturally improving the quality of the color balance of a videoendoscope using a monochrome CCD sensor and a light generator equipped with a lamp with permanent lighting in front of which rotates a rotating disc. sequential color filtering equipped with three red / green / blue filters.

US Patent 4,532,918 (WELCH ALLYN AOUT 85) and US Patent 4,535,758 (WELCH ALLYN AOUT 85) describe two electronic devices for automatically regulating the level of the color video signal delivered by a videoendoscope according to the lighting conditions. of the observed area.

 The first of these devices is an automatic gain control (AGC) device allowing the gain of the video amplifier located at the input of the processor to be controlled as a function of the average level of the video signal delivered by the monochrome CCD sensor.

 The second of these devices makes it possible to control the frequency of the flashes generated by the flashlight (and therefore the average level of illumination of the area observed) as a function of the level of the control voltage of the AGC device mentioned above. .

 It is noted, on reading the patents cited above that these two devices are controlled by the AGC control voltage, that is to say by a voltage resulting from the difference existing between a first voltage corresponding to a set point and a second voltage resulting from the integration of several primary video signals generated sequentially by the monochrome CCD sensor.

 It is also noted that the implementation of such a principle of control of the level of the video signal generates fluctuations in the color balance. This defect arises from the fact that the control signal of such servo devices results from the integration of several successive sequences of red / green / blue video components, and not from the integration of several successive luminance components in accordance with the theory of video signal processing.

 A second object of the present invention is to present a device for regulating the level of the video signal as a function of the lighting conditions which does not modify the initial balance of the color balance of the color video signal delivered by a videoendoscope using a monochrome CCD sensor and a light generator equipped with a lamp with permanent lighting in front of which rotates a rotary disc of sequential chromatic filtering equipped with three red / green / blue filters.

 US Patent 4,539,586 (WELCH ALLYN SEPT 85) describes a device for connecting a videoendoscopic probe to a videoendoscopy processor.

This connection device makes it possible to simultaneously connect the connections relating to lighting, electronics and pneumatics.

 This patent represents a particular solution to a general problem of multiple connections, a problem dealt with in particular in patents US 4,261,345 (OLYMPUS 1979), US 4,402,313 (OLYMPUS 1979), US 4,494,823 (SUMITOMO 1982).

 The third object of the present invention is to present a multiple connection device having the first advantage of allowing the connection of a videoendoscopic probe to a videoendoscopy processor in which the lighting and video processing functions would be housed in two separate boxes, for the second advantage of eliminating any detrimental mechanical constraint at the level of the connections ensuring the continuity of the links concerning the electronics and the lighting, and for the third advantage of ensuring the interchangeability of the different probe models capable of being connected to the processor .

 The present invention finally gives itself for the fourth object to integrate into the videoendoscope a device making it possible to select an image portion of an area equal to a quarter of the total image analyzed by the photosensitive sensor and to multiply in real time by four the viewing area of the selected image portion.

SUMMARY DESCRIPTION OF THE INVENTION
The subject of the present invention is the production of a videoendoscope in accordance with the provisions described below.

I / A single source of white light with continuous lighting II / A mechanical diaphragm making it possible to measure the quantity of light transmitted to the bundle of lighting fibers, device consisting of a rotating metal disc comprising a circular slot of progressive width (or all similar device such as for example a rotary disc, preferably metallic, the area of which obscures the lamp consists of a ring comprising a network of circular orifices whose unit diameter varies gradually) more or less obscuring the beam of light delivered by the lighting source.

This disc is actuated by a DC motor, the direction of rotation of which is controlled by a servo device. The polarity of the control voltage of this control results from the difference between a first voltage corresponding to a set point manually adjustable by the user and a second voltage resulting from the integration of several successive components of the luminance signal extracted from the three video components
R / G / B of the endoscopic image produced by the electronic signal processing processor.

 III / A device for sequential chromatic filtering of the light transmitted by the diaphragm, a device made up of a rotating disc equipped with three red / green / blue filters corresponding to the three primary colors of the light spectrum. Each color filter is associated with a neutral attenuating filter chosen in such a way that the electrical signals generated by the distal CCD sensor have an identical amplitude for each of the three primary colors when the probe is introduced into a cavity containing a white target located in the field of observation. This arrangement makes it possible to correct the disparities existing between the specific frequency bands of the three color filters both at the level of the emission spectrum of the lighting lamp and at the level of the spectral response curve of the photosensitive sensor, and that 'at the level of the spectral transmission curve of the lighting fiber.

IV / A bundle of lighting optical fibers intended to transmit the light delivered by the sequential chromatic filtering device towards the field of observation.

 V / A monochrome CCD sensor intended to capture the image of an object located in the field of observation and lit by the bundle of optical fibers, and to deliver a specific electrical signal of said object.

VI / A distal observation head intended to be introduced into the cavity to be explored, this head containing the CCD sensor, the optical objective associated with said sensor as well as the end of the bundle of lighting optical fibers.

VII / A box secured to the videoendoscopic probe and making it possible to connect said probe to the light source and to the video signal processing processor using two separate connection cables.

This box also contains electronic devices allowing perfect interchangeability of the different models of videoendoscopic probes capable of being connected to the videoendoscope processor.

VIII / An electronic video signal processing processor receiving the electrical signals delivered by the CCD sensor and generating a composite color video signal as output. This processor includes in particular the provisions described below
VIII A / A general synchronization device making it possible in particular to synchronize the acquisition of the electrical signals delivered by the CCD sensor and the sequential filtering of light carried out by the rotary disc equipped with three filters. This synchronization device also generates the clock signals necessary for the correct functioning of the sensor
CCD.

VIII B / An electronic amplifier receiving the electrical signals generated by the CCD sensor. This amplifier has a gain variation control device. The control voltage applied to this device results from the difference between a first preset preset voltage and a second voltage resulting from the integration of a limited number of successive components of the luminance signal extracted from the three R / V / video components. B of the endoscopic image produced by the electronic signal processing processor
VIII C / An analog / digital converter which digitizes the electrical signal delivered by the amplifier.

VIII D / Three memories intended for the sequential storage of the digitized video frames delivered by the analogical digital converter. The general synchronization device assigns each video frame corresponding to a primary color to the specific memory of said color.

VIII E / An additional logical device makes it possible to process only a volume of digital information corresponding to an image fragment equal to a quarter of the total image analyzed by the photosensitive sensor.

The processing consists in reading twice each piece of information contained in a line of the image fragment and then in successively reading said line twice, which amounts to multiplying by four the display area of said fragment.

VIII F / Three digital / analog converters allow digital information stored in the three memories to be read simultaneously and simultaneously converted to analog.

VIII G / The three analog components delivered by the three digital / analog converters are processed by a matrixing device which delivers the luminance component which will be used to control the positioning of the diaphragm of the lighting lamp as well as the gain of the amplifier processor input video.

VIII H / The three analog components delivered by the three digital / analog converters are also processed by three amplifiers whose respective gain controls, offset on the front face of the processor box, allow the user to modify the initial setting of the color balance of the videoendoscope.

VIII I / An encoder, PAL or NTSC according to the processor standard, receives the three analog components generated by the three amplifiers with adjustable gain and delivers a composite color video signal. The analog components belonging to the even frames are offset with respect to those belonging to the odd frames, this in order to allow the processor to deliver a video image composed of two interlaced frames.

 In addition to the preceding arrangements, the invention also comprises other arrangements which will emerge from the descriptions which follow and which refer to the appended drawings.

SUMMARY PRESENTATION OF THE FIGURES ILLUSTRATING
THE INVENTION
Figure I concerns the general architecture of the videoendoscope.

 Figure II concerns the functional organization of the videoendoscope.

Figure IIIA concerns the calculation methods. transmission coefficients of the neutral attenuating filters associated with the color filters. The figure
IIIB concerns the architecture of the sequential chromatic filtering disc.

 FIG. IV relates to the description of the electronic circuits making it possible to control the level of the video signal to the lighting conditions.

 Figure VA concerns the mechanical architecture of the probe connection box. Figure VB concerns the description of the electronic circuits allowing interchangeability of the probes.

 FIG. VI relates to the description of the electronic circuits making it possible to magnify a previously selected fragment of the videoendoscopic image.

DETAILED DESCRIPTION OF THE INVENTION
FIGURE I
Figure I schematically illustrates the general organization of the videoendoscope which is the subject of the present invention. The videoendoscope comprises a videoendoscopic probe 10 and a processor 90 grouping the lighting and video signal processing devices.

 The videoendoscopic probe 10 is associated with a box 20. This box contains the electronic devices which ensure the interchangeability of the probes. I1 also makes it possible to ensure the mechanical fixing of the probe on the processor without causing detrimental mechanical stresses on the connectors ensuring the continuity of the electronic and lighting links.

This arrangement also has the advantage of allowing the connection of a probe to a processor in which the lighting and video processing functions are housed in two separate boxes.

 To this end, this box 20 is introduced into the receptacle 93 formed in the front panel of the processor 90.

This housing 20 is mechanically fixed using a screw 21 actuated by the thumb wheel 25. The light connection of the probe is made by the cable 31 which ends in a ferrule 33 which is plugged into the base 91 of the light generator integrated in the processor. The electrical connections are made by the cable 30 which ends in a socket 34 which is plugged into the base 92 of the processor. The processor 90 is equipped with a protective cover inside which the control keyboard 63 is integrated. The front panel of the processor 90 comprises a certain number of operating commands including in particular three rotary buttons 94, 95 and 96, allowing the user to adjust the respective levels of the red, green and blue video components, and therefore to modify the initial adjustment of the color balance of the videoendoscope.

FIGURE II
Figure II schematically illustrates the functional organization of the videoendoscope which is the subject of the present invention.

 The reference 88 represents an arc lamp supplied by a switching power supply 87. With this lamp are associated, in a manner known per se, an ignition device (not shown), a radiator (not shown), a cooling fan ( not shown), a heat filter (not shown) and possibly (for lamps emitting light in parallel rays) an optical condenser (also not shown).

 A disc 80, provided with a diaphragm 81 constituted by a crown comprising a network of circular orifices whose unit diameter varies gradually (or any similar device such as for example a circular slot of progressive width), is used to adjust the 'light intensity. This disc 80 is driven by a DC gear motor 83. This motor 83 is powered by a power amplifier 84, a position sensor 82 secured to the axis of the motor ensuring the stopping of the motor at the start and at the end of the diaphragm stroke. The input signal of the power amplifier 84, the polarity of which determines the direction of rotation of the motor, is produced by the card 86. The polarity of this control signal results from the difference existing between a corresponding first voltage 85 at a set point set by the user and a second voltage resulting from integration over approximately 200 ms. of several successive components of the luminance signal 54 suitably extracted from the three video components 97/98/99 of the endoscopic image produced by the processor. The electronic circuits making it possible to arrive at such a result are detailed below in the text relating to FIG. IV.

 Between the diaphragm 80 and the end 33 of the bundle 31 of optical fibers for lighting is arranged the device for sequential chromatic filtering of the light emitted by the lamp 88. This filtering device consists of a rotating disc 70 comprising three zones 71/72/73 filters intended to periodically illuminate the three basic colors red / green / blue at the end 33 of the bundle of optical fibers, and therefore the interior of the cavity to be examined.

Each filtering zone results from the association by bonding of a color filter and a neutral attenuating filter according to the methods described in the text relating to FIG. IIIB. The characteristics of the three attenuating filters are calculated such that the average amplitude of the video signal measured at the level of the link 35 is identical for each of the three primary colors when the videoendoscopic probe is introduced into a white cavity.

The method for calculating the attenuation coefficients of these three filters is detailed below in the text relating to FIG. IIIA, and this for a videoendoscope equipped with an OSRAM HTI 250 / W 32 lighting lamp, of a TEXAS TC 210 CCD sensor and a six meter long bundle of HOYA LB66 lighting fibers.

The rotary disc 70 is driven by a motor 78 integral with the axis of the disc. The motor 78 is a stepping motor, the pitch of which is equal to 3.60. The disc 70 has a screen-printed reference 74 which moves in the field of an optocoupler 75.

The information delivered by the optocoupler 75 during the passage of the reference 74 is formatted by the electronic device 76 before being transmitted to the device 40 for general synchronization of the videoendoscope. This information will be used in particular to switch the three memories 43/44/45 in which will be sequentially stored the video frames generated by the CCD sensor 14 at the time of the passage of each filter in front of the lighting lamp.

This information will also be used to control the device 77 intended to control the rotation speed of the motor 78. The nominal rotation speed of the disc 70 is fixed as a function of the video standard chosen, ie 1,200 rpm for the NTSC standard, and 1,000 rpm / minute for the PAL standard.

The dimensioning of the filters obviously corresponds to a passage time in front of the lamp 88 of sufficient duration to allow the CCD sensor 14 to acquire a video frame.

Between two successive filters there is an opaque zone.

It is during the passage time of this opaque zone in front of the lamp 88 that the video frames generated by the CCD sensor 14 are processed.

The lighting delivered during the successive passages of the filtering zones 71/72/73 in front of the lamp 88 is transmitted by a continuous bundle of optical fibers taking the path identified by the references 33/31/11 and this up to the distal end. of said bundle of fibers. The image of the area to be observed is analyzed by the CCD sensor 14 using an optical objective 15.

The video signal delivered by the distal CCD sensor 14 is shaped by the head circuit 13, transmitted by the cable 12 included in the probe 10, reshaped by the circuit 23 integrated in the housing 20, then transmitted by the connector 34, the connection base 92 and the link 35 to the video amplifier 41 entering the processor. In parallel, the device 40 for general synchronization of the processor generates the clock signals necessary for the operation of the CCD sensor 14. These signals are transmitted by the link 36, the connection base 92, the connector 34 and the cable 30. The characteristic parameters (amplitude, offset level) of these clock signals are then preset according to the length of the videoendoscopic probe by the circuit 22 integrated in the housing 20, then transmitted to the CCD sensor 14 via the connection cable 12 included in probe 10.

 The circuits 22 and 23 integrated in the housing 20 allow the interchangeability of the different models of video probes capable of being connected to the processor 90: these circuits will be the subject of a detailed description in the text accompanying FIG. VB. The video signal coming from the CCD sensor 14 is finally transmitted by the link 35 to the input amplifier 41 of the processor.

Amplifier 41 is a variable gain amplifier. The gain control signal is produced by the card 56. This control signal results from the difference between a first voltage 55 corresponding to a preset setpoint and a second voltage resulting from the integration during approximately 20 ms of several successive components of the luminance signal 54 suitably extracted from the three video components 97/98/99 of the endoscopic image produced by the processor. The electronic circuits making it possible to arrive at such a result are detailed below in the text relating to FIG. IV. The electrical signal delivered by the amplifier 41 is digitized by the analog / digital conversion device 42. Each digitized video frame delivered by the device 42 is routed to one of the three memories 43, 44 or 45 according to the color of the filter which was in use during the generation of the analog video frame which gave rise to said frame. digitized.

This switching function is provided by the device 40 for general synchronization of the processor. The contents of the three memories 43/44/45 are read simultaneously according to a periodicity depending on the video standard used, ie 1 / 50s in PAL and 1 / 60s in NTSC. The three digital information read simultaneously from the three memories are then simultaneously decoded by three digital / analog conversion devices 47/48/49. The three analog frames resulting from these simultaneous decodings correspond to the three red / green / blue frames of a video encoder 57 of PAL or NTSC type according to the standard of the videoendoscope.

 The video signals belonging to the even frames are shifted with respect to those belonging to the odd frames in order to allow the processor to deliver a video image composed of two interlaced frames.

The encoder 57 delivers a signal 58 which is a composite color video signal. The signal 58 then arrives at the first input of a multiplexer 59, the second input of which is connected to another video signal produced by a chain successively comprising a keyboard 63, a character generator 62 and a video keyer 61. The signal 60 delivered by the multiplexer 59 is displayed by the video monitor associated with the videoendoscope. The device 46 is a logic control card for the three memories 43/44 / 45. This device 46 which makes it possible to obtain an image magnification, commonly called "zoom" will be described in the text associated with FIG. VI.

FIGURES IIIA and IIIB
Figure IIIB schematically recalls the general organization of the sequential filtering disc of the light emitted by the lighting lamp. The explanations given below specify the methods for calculating the transmission coefficients of the neutral attenuating filters associated with the color filters in order to naturally balance the color balance of the video image delivered by the videoendoscope.

 The main sources of chromatic distortion are located in the circuit consisting of the following elements: lighting lamp / color filters / lighting fibers / CCD sensor.

Each of the elements of this circuit having specific spectral characteristics.

The graph in FIG. IIIA brings together the spectral transmission curves relating to the following elements (L) Emission spectrum of the lighting lamp (OSRAM
HTI 250 / W 32) (R) Transmission spectrum of the red filter (Filter 712
low pass - cut-off wavelength = 575 nm) (V) Transmission spectrum of the green filter (filter 722
bandpass between the wavelengths 575 nm and
500 nm) (B) Transmission spectrum of the blue filter (filter 732
high pass - cut-off wavelength = 500 nm) (F) Transmission spectrum of the lighting optical fiber (HOYA LB 66 in 6 meters in length) (S) Response spectrum of the monochrome CCD sensor (TEXAS
TC 210)
These six curves allow the relative values of the TR / TV / TB transmission coefficients specific to the spectral bands of the three color filters to be calculated using the following formulas
Red component
Green component
Blue component

 The differences between the values of the three parameters actually characterize the imbalance in the color balance of the videoendoscope.

The present invention notably consists in associating with each color filter a specific attenuating filter whose KTR / KTV / KTB transmission coefficients will be calculated so as to make identical the transmission coefficients specific to the spectral bands of the three color filters, and therefore to rebalance of course the color balance of the videoendoscope. The values of the transmission coefficients of the three attenuating filters result from the following calculation
Red component: KTR = TB / TR = 30/100 = 30% (Filter 713)
Green component: KTV = TB / TV = 30/75 = 40% (Filter 723)
Blue component: KTB = TB / TB = 30/30 = 100% (Filter 733)
The disc, preferably metallic, 70 comprises three identical windows 711, 721, and 731, the dimensions of which correspond to a time of passage in front of the lighting lamp of a duration at least equal to the time of acquisition by the CCD sensor d 'a video frame. Each color filter is bonded to its specific attenuating filter, the assembly being bonded to the disc, preferably metallic, and covering the window which has been assigned to it. It will be noted that the blue filter is associated with a transparent filter having a transmission coefficient of 100%, in order to preserve the dynamic balancing of the disc 70.

 It was specified above that the transmission coefficients of the attenuating filters were calculated so as to balance the color balance of a videoendoscope equipped with a probe whose lighting is provided by a bundle of lighting fibers of six meters in length. The color balance will therefore be unbalanced when a probe requiring a bundle of lighting fibers with a length different from six meters is connected to the processor. It is to overcome this drawback that the three amplifiers assigned to the red / green / blue components of the video signal delivered by the processor are equipped with gain control buttons allowing the user to modify the respective levels of the three chromatic components and therefore to modify the initial setting of the color balance of the videoendoscope.

FIGURE IV
Figure IV schematically illustrates the architecture of electronic circuits which allow to control on the one hand the positioning of the mechanical diaphragm associated with the processor lamp and on the other hand the gain level of the video amplifier processor input.

The three digital / analog converters 47/48/49 deliver three signals 97/98/99 corresponding to the three R / G / B components of the video signal corresponding to the endoscopic image. These three components are processed by the matrixing device 53 which generates a luminance signal in accordance with the following algorithm
SIGNAL 53 = Y = 0.59 R + 0.30 V + 0.11 B.

It will be noted that the R / G / B components processed by the matrixing device 53 are taken directly from the output of the converters 47/48/49, this in order to avoid polluting the control signal of the servo devices described above. afterwards by the chromatic corrections likely to be implemented further downstream in the video signal processing processor.

 The luminance signal 54 is processed by the device 56 responsible for amplifying and integrating said signal. The gain of this device is adjusted by the potentiometer 55 while the capacity 561 fixes the integration time at around 20 ms. The signal 541 resulting from this processing supplies the negative input of the input amplifier 41, amplifier whose second positive input receives the signal 35 which is the video signal coming from the distal CCD sensor of the videoendoscope. The device 41 therefore makes it possible to control the level of the video signal delivered by the distal CCD sensor as a function of the luminance of the color video endoscopic image. It is the signal 421 generated by the device 41 which will then be digitized. The luminance signal 54 is simultaneously processed by the device 86. The first stage of the device 86 makes it possible to amplify and integrate the luminance signal = the gain of this first stage is adjusted by the potentiometer 861 while the capacity 862 sets at approximately 200 ms integration time. The signal 542 delivered by the first stage of the device 86 is then processed by the second stage of the device 86. The second stage of the device 86 makes it possible to compare the signal 542 with a threshold adjustable by the user and to control the direction of rotation of the diaphragm motor depending on the polarity of the resulting signal. To this end, the remote potentiometer 85 on the front panel of the processor makes it possible to adjust the value of the comparison threshold. This device makes it possible to obtain at the output of the comparator 863 the signal 841 which will be transmitted to the device for supplying the DC motor controlling the rotation of the diaphragm.

Signal 841 provides the following operating mode
Signal 542 above the comparison threshold
diaphragm closure
Signal 542 below the comparison threshold
diaphragm opening
Signal 542 equal to the comparison threshold: stop of
diaphragm
The advantage of the present invention lies in particular in having chosen the luminance component extracted from the three R / G / B video components of the endoscopic image to control both the gain of the input amplifier of the processor and the positioning of the diaphragm associated with the lighting lamp. It is indeed well known by specialists in the field that the luminance component of a three-color video signal is the only parameter which can be used to simultaneously modify the amplitude of the red / green / blue components of said three-color video signal without modifying the color balance. of said signal.

FIGURES VA and VB
FIG. VA schematically illustrates the mechanical organization of the box integral with the videoendoscopic probe. FIG. VB illustrates the electronic organization of the devices integrated in this box and which make it possible to ensure the interchangeability of the different models of probes capable of being connected to the processor.

The mechanical structure of the housing 20 is constituted by the assembly of two cylindrical covers: the cover 202 which constitutes the rear part of said housing and the cover 201 which constitutes the front part thereof.

The present invention consists in particular in separating the mechanical structure of this box from the connectors responsible for ensuring the continuity of the electrical connections and of the light connection between the videoendoscopic probe and the processor. This arrangement makes it possible to avoid any mechanical constraint at the level of the connections and also makes it possible to connect the videoendoscopic probe without modifications to a processor in which the electronic and lighting functions would be housed in two separate boxes.

To this end, the front face of the cover 201 has been made integral with the cable 10 which constitutes the videoendoscopic probe proper, with the cable 31 equipped with a fiber end piece 33 intended to be connected in the base of the light generator, and with the cable 30 equipped with a multi-pin socket 34 intended to be connected to the connection base of the video signal processing processor.

The bundle of lighting optical fibers 11 integrated in the cable 10 passes through the cover 201 and is taken up without break in the cable 31. The electric cables ensuring the transport of the clock signals necessary for the operation of the CCD sensor and integrated in the cable 10 pass through the electronic device 22 mechanically secured to the cover 201 before being taken up by the cable 30. The electric cables ensuring the transport of the video signals generated by the CCD sensor and integrated in the cable 10 pass through the electronic device 23 mechanically integral with the cover 201 before being taken up by the cable 30. The cables carrying the supply voltages of the CCD sensor and integrated in the cable 10 pass through the electronic device 22 before being taken up in the cable 30. The front face of the cover 201 comprises a rotary knurled button which constitutes the end of an axially traversing metal rod The covers 201 and 202. The threaded end 21 of this metal rod crosses the rear face of the cover 202, thus making it possible to mechanically fix the entire housing inside a cylindrical receptacle provided for this purpose in the panel. on the front of the processor.

The electrical connections 361, 362, 363 and 364 coming from the cable 30 and from the connection base 34 transport the clock signals generated by the processor (serial clock, parallel clock, anti-glare clock commonly called "anti blooming") and the supply voltage of the CCD sensor. All these signals are processed by the electronic device 22 which is mechanically secured to the cover 201. The three clocks are processed by circuits each comprising an amplifier 368, an adjustment potentiometer 369 making it possible to adjust the gain of said amplifier and an adjustment potentiometer 367 for adjusting the continuous component (offset level) of said clock. The electrical signals produced by the device 22 are then transmitted to the CCD sensor by the electrical connections 121, 122., 123 and 124 integrated in the cable 10. The electrical connection 120 coming from the CCD sensor via the cable 10 carries the video signals generated by the sensor
CCD. This signal is processed by the electronic device 23 which is mechanically secured to the cover 201. This device comprises a lowpass filter intended to eliminate the clock residues present in the video signal and an amplifier 358 provided with an adjustment potentiometer 359 allowing 'adjust the gain of said amplifier. The electrical signal produced by the device 23 is then transmitted to the processor by the link 35 integrated in the cable 30 and leading to the connector 34. The adjustment potentiometers provided on the devices 22 and 23 make it possible to ensure the electrical interchangeability of the various models. videoendoscopic probes of different lengths that can be connected to the processor.

FIGURE VI
FIG. VI schematically illustrates the electronic organization of the control device, which associated with the three memories of the processor, makes it possible to obtain a magnification, commonly called "zoom effect", of a previously selected part of the image delivered by the processor. .

 The three red / green / blue frames making it possible to generate a color video-composite signal are permanently available in digital form in the three memories 43, 44 and 45 assigned to said frames.

Obviously, it suffices to interrupt memory writing to prohibit the refreshing of said frames and obtain an image freeze. It is also relatively easy to use traditional computer means to carry out the delayed magnification of a video image whose chromatic components have been previously memorized.

The advantage of the present invention lies in particular in the fact that the electronic devices used make it possible to carry out a magnification of image of ratio two in real time and this throughout the duration of an endoscopic observation process. The TEXAS TC-210 distal CCD sensor used in the videoendoscope makes it possible to obtain a square video image made up of 165 lines each comprising 192 three-color pixels. The devices 460 and 461 make it possible to generate a window corresponding to a quarter of the endoscopic image, or 82 lines of 96 pixels. This movable window, the contours of which appear highlighted on the endoscopic image, allows the user to select the portion of image he wishes to magnify. The upper left corner of the window is the window reference point. This reference point must have a number of pixels between 0 and 96 for horizontal coordinate, and a number of lines between 0 and 82 for vertical coordinate.

The positioning of this reference point is obtained by actuating the horizontal movement control keys 601 and the vertical movement control keys 602. By pressing the keys 601, the number of offset pixels characterizing the difference existing between the reference point and the left side of the endoscopic image is obtained at the output of the counter 603. This information as well as the information delivered by the counter 605 which determines the right end of the window 96 pixels further to the right are transmitted to the device 607.

Pressing the keys 602 makes it possible to obtain at the output of the counter 604 the number of offset lines characterizing the difference existing between the reference point and the upper side of the endoscopic image.

This information as well as the information delivered by the counter 606 which determines the lower end of the window 82 lines below are transmitted to the device 607.

The device 607 suitably synchronized by the general synchronization device 40 delivers a pulse for each pixel of the video frame of the endoscopic image located on one of the four sides of the window.

These pulses are simultaneously transmitted to the reference inputs of the digital / analog converters 47, 48 and 49 which process the video information stored in the memories 43, 44 and 45 in parallel. These pulses force the output of these converters to a maximum level which allows you to view the pixels corresponding to the window with maximum brightness. The devices 460 and 462 make it possible to manage the information stored in the memories 43, 44 and 45 so as to process four times each pixel of the endoscopic image located inside the window previously selected, process consisting in fact of reading two times the address of each pixel located in the window, and to increment the line counter only once every two lines inside said window.

To this end, the information delivered by the counters 603 and 604 and characterizing the address of the window reference point are transmitted to the addressing logic device 622. The line clock delivered by the general synchronization device 40 is also transmitted to the device 622 through the divider by two 624. From this information and from the various service signals transmitted by the general synchronization device 40 the logic device 622 address calculates the addresses characterizing the start of each line of the image entered in the window. Each address thus produced is loaded into the address counter 623 of the memory at the start of the corresponding line of the image written in the window.

The pixel clock delivered by the general synchronization device 40 is also transmitted to the device 623 through the divider by two 621. The content of the counter 623 is thus incremented at a frequency equal to half the frequency of the pixel clock . The rate of reading of the memories 43, 44 and 45 also remaining unchanged, it can be seen that the address counter 623 makes it possible to address the same pixel twice in a row and the same line twice, for all of the image registered in the window previously selected.

The device described above makes it possible to multiply by four the display area of a square fragment of image previously selected and having an area equal to a quarter of the square image analyzed by the CCD sensor. It goes without saying that any device extrapolated from the device described above and making it possible, for example, to multiply by nine (or by sixteen, etc.) a square image fragment with an area equal to the ninth (or to the sixteenth ... ) of the square image analyzed by the CCD sensor would only constitute a variant of the present invention.

SCOPE OF THE INVENTION
It goes without saying that the applications of the videoendoscope according to the present invention can be both medical and industrial.

 It also goes without saying, as is apparent from the above, that the present invention is in no way limited to the embodiments, embodiments or applications which have just been described explicitly. The present invention on the contrary embraces all the variants which can come to the mind of the technician in the matter without thereby departing from the scope of the present invention.

Claims (5)

 - An electronic processor making it possible to process the electrical signals (35) supplied by the CCD sensor (14) in order to obtain the electrical signals (58) making it possible to generate a normalized color video image made up of two interlaced frames.  - A monochrome CCD sensor (14) generating the electrical signals (35) specific to the image of a target located in the field of observation;  - A bundle (11) of optical fibers transmitting to the field of observation the light filtered sequentially;  - A device ensuring the sequential filtering of the light emitted by the lighting source (88), this device consisting of a rotating disc (70) equipped with three filters (71), (72) and (73) corresponding to the three primary colors red / green / blue of the light spectrum;  - A light source (88) with continuous operation;  CLAIMS 1 / Videoendoscope delivering a color composite video signal compatible with standard format television apparatus in which each image is composed of two interlaced frames, said videoendoscope comprising  Said videoendoscope being characterized in that said device ensuring the sequential filtering of the light emitted by the light source (88) is arranged to simultaneously balance the color balance of the videoendoscope, the filters (71), (72 ) and (73) equipping said rotary disc (70) being composite filters comprising a first composite filter (71) resulting from the association by bonding of a red filter (712) and a neutral filter (713) having a KTR transmission coefficient, a second composite filter (72) resulting from the association by bonding of a green filter (722) and a neutral filter (723) having a KTV transmission coefficient and a third composite filter (73) resulting from the association by bonding of a blue filter (732) and a neutral filter (733) having a transmission coefficient KTB; the transmission coefficients KTR, KTV and KTB of the three neutral filters (713), (723) and (733) being calculated in such a way that the electrical signal (35) generated by the sensor. Distal CCD (14) has an identical amplitude for each of the three primary colors when the probe is introduced into a cavity containing a white target located in the field of observation. 2 / Videoendoscope according to claim 1 comprising a device for regulating the quantity of light transmitted to the bundle of lighting fibers, said device consisting of a rotating disc (80) whose area which obscures the lamp consists of a ring (81) comprising a network of orifices, the unitary section of which varies gradually, this rotary disc (80) being driven by a DC motor (83). Said device being characterized in that the direction of rotation of the motor (83) is controlled by the polarity of a control voltage, the sign of which results from the difference existing between a first voltage (85) corresponding to an adjustable set point by the user and a second voltage resulting from the integration during approximately 200 milliseconds of the luminance component (54) extracted from the three R / G / B video components (97) (98) and (99) directly produced by digital conversion / analog information stored in memories (43), (44) and (45). Said device having the advantage of ensuring, without modifying the balance of the color balance of the videoendoscope, the regulation of the lighting level, and consequently the regulation of the level of the electrical signals (35) delivered by the sensor CCD (14) as a function of slow variations in the level of the luminance component of the video signal generated by the videoendoscope. 3 / Videoendoscope according to claim 1 comprising a device (41) for amplifying the electrical signal (35) generated by the CCD sensor (14). Said device consisting of an amplifier, the gain of which is controlled by a control signal. Said device being characterized in that the control voltage of the gain of the amplifier (41) results from the difference existing between a first voltage (55) preset preset and a second voltage resulting from the integration during approximately 20 milliseconds of the luminance component (54) extracted from the three R / G / B video components (97), (98) and (99) directly produced by digital / analog conversion of the information stored in the memories (43), (44) and (45 ). Said device having the advantage of ensuring, without modifying the balance of the color balance of the videoendoscope, the gain control of the amplifier receiving the electrical signals (35) delivered by the CCD sensor (14) as a function of the rapid variations in the level of the luminance component of the video signal generated by the videoendoscope. 4 / Videoendoscope according to claim 1 characterized in that it comprises an image magnification device in real time. The devices (460) and (461) initially making it possible to view and move the outline of a square window on the screen of the videoendoscope video monitor, the surface of which corresponds to a quarter of the square image analyzed by the CCD sensor. The devices (460) and (462) making it possible to successively read twice any information stored in the memories (43), (44) and (45) and characterizing a color pixel belonging to a line fragment located inside the window, then successively read said line fragment twice. 5 / Videoendoscope according to claim 1 characterized in that it comprises a housing (20) integral with the videoendoscopic probe (10) and intended to be mechanically fixed in a receptacle (93) formed on the front face of the box (90). Two cables (31) and (30) distinct and integral with the box (20) make it possible to connect said box to the processor and to the light source without risk of damaging mechanical stresses at the light (91) and electronic connection bases ( 92) located on the front face of the box (90). The housing (20) being further provided with two electronic devices (22) and (23) making it possible to ensure the electrical interchangeability of the various models of videoendoscopic probes capable of being thus connected.