FR2542953A1 - Display device with television-type interlaced recurrent scanning, and digital oscilloscope comprising such a device - Google Patents

Abstract

Display device applicable to the visualising of a stored signal arising from sampling and restored by points or by interpolation vectors and comprising, in order to suppress the luminous pulsing effect of the interpolation segments P which represent the horizontal or mildly sloping portions of the luminous trace to be displayed, processing means associating with each interpolation segment P of specified energy, carried by one line of one of the frames, at least one and generally two other parallel so-called anti-flicker segments IA and IB with half the energy and carried by the other frame, by one or both lines of the other frame which flank the relevant line in the first frame. Application: digital oscilloscopes with television-type interlaced recurrent scanning.

Description

-1-

  RECURRENT INTERLACE TELEPHONE SCANNING DISPLAY

  VISION AND DIGITAL OSCILLOSCOPE INCLUDING SUCH A DEVICE

  The present invention relates to an interlaced recurrent scanning television type display device, as well as to a

  digital oscilloscope comprising such a device.

  French patent application N '80 00 718 filed by

  the company N V PHILIPS 'GLOEILAMPENFABRIEKEN describes an in-

  frame terpolator in which it is planned to avoid disturbing phenomena such as vertical flickering of the images on the display. One of the characteristics of a digital oscilloscope

  is that the real-time analog signal is first sampled

  read and then stored in digital memory before being restored At restitution, to avoid the operator unknowingly connecting two samples close on the screen but in reality not successive

  over time, an interpolation is planned between successive samples

  stops (for example in the form of additional samples) to resolve the uncertainties relating to the interpretation of the images displayed (see for example French patent application No 80 17 928, filed on August 12, 1980 in the name of the Company

  Tektronix) The simplest interpolation is li-

  which consists in constructing on the display screen a vector having its ends in coincidence with the representative points

  samples in memory.

  During the scanning of a television-type display device, the screen surface is scanned horizontally at

  regular speed line after line, which involves scanning

  vertical information The ends of the inter-

  polation are therefore generally located on different and non-contiguous scanning lines The principle of this interpolation

  clearly appears in Figure 1: the discrete nature of the reso-

  vertical lution requires the construction of said vector using -2-

  small horizontal segments S to S carried by the lines in-

  available intermediaries (corresponding to the arrows on the

  left side of the figure) and presenting between them a certain re-

  horizontal projection cover to ensure continuity

  apparent of the interpolation vector The number of these lines in-

  available intermediaries depends on the amplitude difference between two

  successive samples E (n) and E (n + 1).

  In case there is no scanning line available

  between two sample positions, the interpolating vector

  tion includes a single interpolation segment that lasts a

  full restitution period TR to ensure continuity of the

  trace (see such segments Su, SU + 1, etc. in Figure 2).

  To fully benefit from the contribution of the interpolation vector, it is necessary that the tracing of this vector has the best possible resolution; to do this, television type scanning

  is used in interlaced mode, but has the drawback of

  producing a flicker effect Indeed, when a part of the trace is horizontal or very slightly inclined, this part concerns only one scanning line and is therefore only carried out every two fields, even or odd: l energy of this

  horizontal part only appears for example every 40 milli-

  seconds at the frequency of 25 hertz (instead of every 20 mil-

  liseconds in non-interlaced scanning at 50 hertz), which is

  below the possibilities of integration of the eye

  light energy pulsating, flickering effect,

  is then felt by the observer.

  The object of the invention is therefore to propose a display device of interlaced recurring scanning type television in which is provided a processing circuit eliminating this flickering effect, but only when the light trace presents

  actually horizontal or slightly inclined parts.

  To this end, the invention relates to a display device

  interlaced recurring scan type television,

  nant, to suppress the effect of light pulsation of the segments of the light trace to be displayed, processing means associating with -3- segments of determined energy carried by a line of one of the frames of other parallel segments called antipapillotement, of twice the energy and each carried by one of the two lines of the other frame which surround the line considered in the first frame, characterized in that said processing means are only put into action '' after detection, using a so-called channel

  test, the existence of situations that correspond to the pre-

  sence of horizontal parts in one of the frames.

  For cost considerations, we would be led, in.

  option, to use only one antipapillotement segment when the light trace is slightly ascending or descending In the case of a perfectly horizontal portion of trace, it is the

  complete solution selected: two antipapillote segments-

  are associated with the interpolation segment, and they correspond to them

  globally lays a packet of light energy having the same value as that of the interpolation segment (since these two segments have

  each half the energy) and the same center of gravity

  vity (since these two segments are identical and symmetrically placed

  only) - The luminous cadence is thus brought for example to 50hertz in the previously cited case of the interlaced scanning at 25 hertz, without the slight increase in trace width which occurs.

  produced at the place where this antipapillo treatment is carried out

  On the contrary, this treatment, visually pleasing since it transfers the pulsation of light energy to a double frequency, ensures the conservation of the center of gravity of the signal and therefore does not alter the precision of the measurement carried out by the eye in the examination of an oscillogram But above all, in accordance with the invention, the treatment is used only from place to place

  on the track, only for its horizontal or weak parts-

  inclined, which keeps the other parts of the track

  fineness and their maximum resolution.

  Other features and advantages of the invention ap-

  will now appear more precisely in the description which

  follows and in the accompanying drawings, given by way of non-limiting example

  mitative and in which: -4- Figures 1 and 2 highlight the principle

  already known interpolation between samples of a signal, res-

  pectively in the case where the interpolation vector comprises several horizontal segments and in the case where there is no scan line available between two samples and o the interpolation vector therefore comprises a single interpolation segment; Figure 3 is a block diagram of the anti-tilt processing circuit;

  Figure 4 shows for the current line "L" the different

  ferent situations in which it is useful to generate antipapillotement segments; Figure 5 shows the principle of construction of the suppression segments of the flicker phenomenon; FIG. 6 illustrates this same principle, on the one hand in the case where two segments are provided, and on the other hand in that

  o only one is planned, chosen according to the direction of inclination

origin of the light trace;

  Figure 7 is the decoding table of an ex-

  Delta pressure defined for research, in accordance with the invention

  tion, situations where antipapillotment treatment was born

cessaire;

  FIGS. 8 a to 8 g describe in detail a set of circles

  logic cooked which, from the possible values of the expression Delta, allows the delivery of a signal indicating the presence of said situations and intended to control the operation of the

  anti-tilt treatment device.

  We have seen above that the display device according to the invention is useful when, as a function of the local appearance of the quantity to be represented on the display screen, the trace, after all the interpolations, is formed in certain places long horizontal segments each belonging to only one frame It is in such cases that the energy linked to these parts of frame appears at a rate of 25 hertz and is painful for

the eye.

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  To detect such situations, the display device

  chage according to the invention comprises, in accordance with the functional diagram-

  nel of FIG. 3, a so-called test channel 10, placed in parallel on a video channel 20 for rendering the trace by interpolation, which connects a digital memory 30 and a display screen 40 The digital memory 30 contains, of course , the regular sequence of the digital values representing the respective amplitudes of the samples of the sampled signal presented to the oscilloscope (at the rate of an amplitude value per unit of time fixed by the sampling frequency), the content of this memory being renewable at the rate set by the not shown acquisition device of the oscilloscope (for example all the images, or at a slower rate) With this memory 30 is associated a memory reading device, coupled to the displacement of the spot the long

of a scan line.

  Test channel 10, which operates at the rate of res-

  sample titration, for example 5 megahertz, fixed by a

  sequencer 170, includes a detector 100 of the position of the exchangers

  tillons successively delivered by the memory 30 with respect to the current line identified by the reference "L" in FIG. 1 The detector 100 receives on the one hand the output of the memory 30, and on the other hand the end of a sequencer output connection (connection which conveys said information "L" of the line position number in the screen height), and presents three distinct outputs according to the result of the comparison between "L" and

  the position of the sample concerned E (n) This detector 100 comprises

  takes a first comparator which indicates if "L" is equal, greater

  or lower than the position of E (n), and a second comparator as-

  with an adder to compare L to E (n + 1) The detector 100 is followed by a delay circuit 110 which delays the position information obtained in the detector 100 relative to the sample E (n) of horizontal position N while again a position information is elaborated, this time concerning the following sample E (n + 1) of position N + 1 If "L" is therefore the order number giving the position of the line in during scanning in -6- screen height (this line being marked in Figure 4 by a 0, the two immediately upper and lower lines being marked respectively by + 1, + 2 and - 1, -2), six relative positions of the samples correspond, as shown in figure 4, to these situations where the antipapillotement treatment must be

  used in the display device.

  A comparison and decision circuit 120 generates a particular indicator signal (called AP) if the existence of one of these relative positions is noted, and this indicator signal then controls the putting into operation of a generator 130 of antipapillotement processing. , which controlled at the same rate of restitution of the samples as previously (5 megahertz in the previous example) to ensure subsequent synchronization with the video signal of the interpolated trace, consists of a bistable rocker converting the indicator signal into a horizontal segment of duration equal to that which separates two successive samples to appear on only one or, as the case may be,

  on the two number lines (L-1) and (L + 1) of the other frame.

  When the comparison and decision circuit 120 observes during the scanning of the current line "L" of a frame the existence of one of the six relative positions of samples specified in FIG. 4, that is to say the graphic existence of a horizontal or slightly inclined signal part located on one or the other of the two adjacent graphic lines belonging to the second frame, the generator 130 controls the construction, on said current line of the first frame , of a segment among one or two segments of suppression of the phenomenon of flickering, parallel, of the same length and of energy here half as weak as that of the segment of graphic interpolation located

  on said second frame; the second segment of antipapil-

  lot will then be built during the scanning of the pro-

  string current line of the same first frame The main-

  cipe of this construction is shown in FIG. 5, -7- o, in a very enlarged view, is represented on a line, line 328 of the even frame for example, such a horizontal segment P of the light trace reconstructed by interpolation, carrying a Wp energy; lines 15 and 16 of the odd frame, framing line 328, then carry two segments IA and IB which frame segment P and each carry an energy WI =

  Wp / 2, with a length equal to that of the interpolation segments

  lation and an amplitude two times lower than these.

  In the case where the segment marked by the flicker phenomenon is not horizontal but slightly inclined, it is possible (see Figure 6) to do the construction, on

  the second frame, that of only one of the two parallel segments of an-

  flickering framing the initial segment: the one that is,

  with respect to said initial segment Pn, on the side towards which

  performs the inclined progression of the trace, i.e. the segment In located on the side where the next initial segment Pn + 1 is located

  also marked by the phenomenon of flicker.

  One of the possible embodiments of circuit 120

  of comparison and decision present in channel 10 is the following

  vant If the line number 'L "can vary from O to 511 (we limit ourselves to 512 useful lines) and also the value" E "defining

  the position of the samples, "L" and 'E "are defined by names-

  9-bit binary bres from which we can define the expression

  sion Delta = D = E L with 9 bits plus 1 possible carry bit, i.e. ten bits B O to B 8 plus the carry bit C Examination of the

  Figure 4 has shown that anti-tilting treatment is useful

  sand in six determined situations of sample E (n + 1)

  with respect to sample E (n) The indicator signal AP of com-

  generator 130 therefore only appears in these six situations

  according to the following logical equation AP = A Pl + AP with AP = ID (n) = + 1 I 1 (D (n + 1) = 0) + (D (n + 1) = + 1) + (D (n + 1) = + 2) j AP 2 = ID (n) = -11 1 (D (n + 1) = 0) + (D (n + 1) = -1) + (D (n + 1) = -2 ) j

  the operators being of course in these expressions of the opera-

  logic sensors (the AP signal must be used globally for -8-

  strictly horizontal traces, otherwise the antipapil energy

  resulting lot could not keep the same center of gra-

  that the energy corresponding to the exact trace of the signal, and the

  anti-tilting treatment would then generate an apparent vibration.

  vertical rent of this restored trace).

  We chose, in the example described here, to express Delta

  in binary code complement to two, which gives for this express-

  the decoding table of figure 7, with the abscissa

  bit numbers and line numbers on the ordinate are

  tate on this table that we can define the logical functions

  xiliaries, using two AND gates (see Figures 8a and 8b respectively): FA 1 B 2 x B 3 x B 4 x B 5 x B 6 x B 7 x B 8 x C FA 2 B 2 x B 3 x B x B x B x BB 7 x B x C 2 2 3 '4 5 6 x B 7 x B From the expression of these two functions, we deduce the logical expressions of D (n + 1) = + 1 and D (n + 1) = -1, also using a single AND gate in each case (see Figures 8 c and 8 d respectively): ID (n + 1) = + 11 = (FA 1 x Bo x B 1) n + ID (n + 1) = -1 | = (FA 2 x Bo x B 1) n + We can then define the auxiliary logic functions FA and FA 4 intended to express A Pl and AP 2 (see Figures 8 e and 8 f respectively): F = FA 1 (n + 1 ) x (BO + B 1) (n + 1) x (D (n) = + 1) -3 1 (n + l) X (nl X FA 4 = IF Ain + x B x Bl x (D (n) = -1) I 4 1 (n + l) O (n + l) 1 (n + l) + IFA 2 x B x (D (n) = -1) I (n + 1) 1 (n + i) - 9- Finally, the AP indicator signal appears if at least one of the FA 3 or FA 4 functions is present on the inputs of a door

  OR, represented in FIG. 8 g and at the outlet of which is pre-

  sent AP, anti-treatment generator control signal 130

  flicker, which also receives from a circuit 150 of synchro-

  nisation connected to the sequencer 170 the rate of restitution of the samples. The antipapillotement signal, composed as we have seen of two segments carried by a frame surrounding the initial segment

  of interpolation carried by the other frame, is then delivered at the exit

  tie of the test and processing channel 10, for composition in an analog adder 140 with the video signal of the interpolated trace coming from the circuit 160 of reconstruction of the signal by the interpolation vectors and with the synchronization signal of the receiver and the electronic reticle signal both from

  of a sequencer 170, then is sent to the display screen 40.

  It will be noted here that the video channel 20 for rendering the trace by

  interpolation comprises a delay circuit, not shown, providing

  both the signals passing through it a delay multiple of the period

  of return TR and intended to allow at the level of the addition-

  neur 140 synchronization with the output signals of channel 10. The new light trace obtained, a little wider but not doubled, is now free of any flickering.

  further, as the sum of the energy of the two antipapil segments-

  added lot is equal to the energy of the interpolation segment

  initial, the center of gravity of this new energy is identical

  that of the energy of this initial segment, and there is no

  no generation of error on the position of the light trace,

  no offset from the center of it relative to the other parts

  parts of the trace which have not undergone the antipapillo- treatment

  which preserves the accuracy of the measurements.

  Of course, the present invention is not limited to the embodiments described above and shown, from which variants can be proposed without this - departing from the scope of the invention In particular, it is possible, in this which relates to FIGS. 8 a to 8 g, to use a different set of logic circuits if one wishes to take account of the partial results coming from the interpolation channel 20 Furthermore, it is possible, although this solution is currently more expensive, to provide a frame memory storing the result of the operations made on

the previous frame.

Claims (4)

  1 Interlaced recurring scanning display device of television type, comprising, to suppress the effect of light pulsation of the segments of the light trace to be displayed, processing means associating with determined energy segments carried by a line of 1 '' one of the frames of other parallel segments, said to be of antipapillotement, of lower energy,   one of the two lines of the other frame which surround the line   flabbergasted in the first frame, characterized in that said mo-   processing yen are only put into action after detection, using a so-called test channel, of the existence of situations which correspond to the presence of horizontal parts in one of the frames. 2 Device according to claim 1, characterized in that this test channel comprises a logic circuit comparing the   positions of successive samples of the light trace relative to   port to the current line of the scan and delivering an indi-   cator of control of the means of treatment if the existence of one   from these situations is deduced from the result of said comparison.   3 Device according to one of claims 1 and 2, charac-   terized in that the energy of the antipapillotement segment (s)   is twice as weak as that of the interpolation segment gra-   phique. 4 Interlaced recurrent scanning television type digital oscilloscope, characterized in that it includes a device   display according to one of claims 1 and 2.