Display System With Different Intensity Indication

Abstract

A display system for displaying place-indicating points darker than a decimal point to avoid misreading of the latter. Electrodes for place indication every three figures in indicator tubes are arranged to glow in a time-divisional manner with less duty cycle than an electrode for decimal point indication.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a display system according to which brightness of specified electrodes of a plurality of indicator tubes is made lower than that of the other electrodes so as to facilitate interpretation of a number being displayed.

2. Description of the Prior Art

With conventional tabletop calculators, a number containing a plurality of figures, for example, "1,234,567.89" is displayed in the form of "1234567.89" without indicating the place thereof, and accordingly this way of display does not allow easy interpretation of the number being displayed and is inconvenient in practical use. This defect can be overcome by lighting point electrodes every three figures to display the above number in the form of "1.234.567.87" but in the prior art indicator tubes the decimal point and the place-indicating points are not so distinguishable in brightness from one another. Of course, this problem can be readily settled by the provision of place-indicating-point electrodes of comma shape but this introduces complexity not only in the construction of the indicator tubes but also in a drive circuit therefor. Further, in gaseous glow indicator tubes their discharge conditions vary with individual indicator electrodes and tubes and it is regarded as difficult to change brightness of indication by altering a current or voltage applied thereto and, in addition, this is likely to introduce unstability in the display operation.

SUMMARY OF THE INVENTION

In accordance with this invention specific point-indicating electrodes are caused to glow with lower brightness than that of the decimal point to serve them as place-indicating points, thus eliminating the drawback encountered in the prior art.

Further, this system is applicable to the elimination of figures of less significance than a specific place and to the indication of unnecessary figures with less brightness than the other ones in the case of counting fractions of more than 0.5 inclusive as one and cutting away the rest.

The display device of this invention employs gaseous indicator tubes such, for example, as commercially known under the names of "Nixie Tube" (trademark) including an anode and a plurality of cathodes, "Pandecon" (trademark) adapted for indicating a plurality of figures in one envelope, the so-called "itron" (trademark) having contained in a vacuum envelope a cathode, a grid and a plurality of indicating anodes coated over their surfaces with a phosphor material, an electroluminescent display device and so on.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic circuit connection diagram showing one example of a display system of this invention; and

FIG. 2 is a series of waveforms, for explaining this invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

In FIG. 1 there is illustrated one example of this invention as being applied to an indicator device employing gaseous glow indicator tubes. For convenience of explanation and illustration, the following description will be made in connection with the indication of a number containing five figures.

Gaseous glow indicator tubes 1a, 1b, 1c, 1d and 1e each comprise one anode 2, cathode electrodes 3a to 3j for indicating, for example, numbers 0 to 9 and a point indicating cathode electrode 4. The corresponding cathode electrodes of the indicator tubes 1a to 1e are respectively connected to common lines 5a to 5j. Thus, the cathode electrode 3a of each tube is connected to the common line 5a, while each cathode electrode 3b is connected to the common line 5b, and so forth. The common lines 5a to 5j are grounded through switching means 7a to 7j respectively made up of transistors 6a to 6j. Further, it is preferred to supply the common lines 5a to 5j with a positive bias voltage +C through resistors 8a to 8j. This is to prevent discharge of other electrodes than those which are desired to glow and the bias voltage is preferred to be 50 to 60 volts. The anodes 2 of the indicator tubes 1a to 1e are respectively connected to a power source terminal +B of, for example, +150 volts through switching means 10a to 10e made up of transistors 9a to 9e.

Reference numeral 11 designates a counter circuit which converts pulses of a synchronizing clock pulse source 12 into signals of a predetermined long period. The output of the counter circuit 11 is supplied to a timing pulse generator 13 to derive at output lines 14a to 14e driving signals 15a to 15e such as shown in FIGS. 2A to 2E which are of the same duty cycle and are phased apart from one another. The resulting driving signals 15a to 15e are respectively applied to the base electrodes of the transistors 9a to 9e to supply a voltage to the anode of each indicator tube.

Reference numeral 16 indicates a computer register circuit and its binary signal output is applied to a matrix circuit 17 in synchronism with the output signals 15a to 15e of the timing pulse generator 13 to supply signals to lines 18a to 18j in accordance with the binary signal output. The lines 18a to 18j are respectively connected to the base electrodes of the transistors 6a to 6j to selectively ground the cathode electrodes according to the signals applied to these lines. Accordingly, when the indicator tube of a desired place supplied with the signal from the timing pulse generator 13 is supplied with the signals from the computer register circuit 16 in synchronism with the above signal, the cathodes of the indicator tube of the desired place only are caused to glow to provide a desired display. Since this system has been described in detail in the U.S. Pat. No. 3,414,764, issued to the same assignee as this invention on Dec. 3, 1968, no detailed description will be repeated for the sake of brevity.

The point-indicating cathode electrodes 4a to 4e of the indicator tubes 1a to 1e are interconnected by a line 19 and are grounded through switching means 21 made up of a transistor 20. The line 19 is supplied with a positive bias voltage +C through a resistor 22 in the same manner as the other lines.

Reference character SW.sub.1 identifies a decimal point switch and SW.sub.2 a place indicating switch, which are designed to be ganged with each other. Fixed contacts 23a to 23e of the decimal point switch SW.sub.1 are respectively connected to the lines 14a to 14e and a movable contact 24 is connected to the base of the transistor 20 through an "or" circuit 25.

Fixed contacts 26a and 26b of the place indicating switch SW.sub.2 are respectively connected to the lines 14d and 14e and a movable contact 27 is connected to the base of the transistor 20 through a counter 28 and the "or" circuit 25.

When the indicator tube 1d is selected to indicate the decimal point as shown in the figure, the moving contact 24 is supplied with a signal 15d such as depicted in FIG. 2D and the movable contact 27 of the place indicating switch SW.sub.2 is supplied with a signal 15a such as shown in FIG. 2G. In the illustrated example the mechanical switches SW.sub.1 and SW.sub.2 are employed but may be substituted with electric circuits.

In the event that the counter 28 is a scale-of-three counter, the counter 28 derives at its output a signal 29 such as depicted in FIG. 2H and the base of the transistor 20 is supplied with a signal such as shown in FIG. 2I. Consequently, the point-indicating cathode electrode 4d of the indicator tube 1d is caused to glow in synchronism with the signal 15b and on the same duty cycle as the latter, thus providing a display of a usual decimal point. Since the point indicating cathode electrode 4a of the indicator tube 1a glows only when supplied with the signals 15a and 29 at the same time, the duty cycle of the glowing of the electrode 4a is 1/3of that of the signal 15a and the brightness of the electrode 4a is lower than that of the point-indicating cathode electrode 4d. Accordingly, in the case of indicating a number, for example, "1,234.5," the point indicating cathode electrode 4a for place indication of the third order glows dark to display the number in the form of "1.234.5," thus preventing misinterpretation of the number displayed.

FIG. 2J shows a signal which is applied to the base of the transistor 20 when the movable contact of the switch SW.sub.1 is held in contact with the fixed contact 23a. In this case, the point-indicating cathode electrode 4e of the indicator tube 1e glows bright to indicate the decimal point, while the point indicating cathode electrode 4b of the indicator tube 1b glows dark to indicate the third order.

In the case of further darkening the point indication, the duty cycle can be readily changed by the use of a scale-of-four or scale-of-five counter as the counter 28.

While the point indication is darkened by changing the duty cycle of the switching means connected to the cathode electrode in the foregoing example, the purpose can be attained by changing the duty cycle of the switching means connected to the anode.

In the event of employing indicator tubes such as "itron" (trademark), the relationship between the cathode and anode is reversed, of course.

The indication of the place, which has become unnecessary in the cases of emission of fractions and counting fractions over 1/2as one and disregarding the rest, can be rendered darker by actuating the switching means 7a to 7i with a circuit for changing their duty cycle as in the foregoing.

It will be apparent that many modifications and variations may be effected without departing from the scope of the novel concepts of this invention.

Claims

We claim as our invention

1. A display system comprising a plurality of electrically energized indicator devices, each having a first electrode and a plurality of electrodes to provide different indications according to a particular second terminal which becomes connected in a circuit with a first electrode, means for connecting each one of said second electrodes of said indicator devices, first drive means for actuating said first electrodes sequentially, second drive means for selectively actuating said connected electrodes in synchronism with said first drive means, and means for controlling indication of at least one of said connected second electrodes on less duty cycle than that of the other second electrodes.

2. A display system as claimed in claim 1 wherein said one of second electrodes is a point-indicating electrode.

3. A display system as claimed in claim 1 wherein said one of the second electrodes is a numeral-indicating electrode.

4. A display system as claimed in claim 1 wherein the indication control means includes a counter for lengthening the period of the signal.

5. A display system comprising a plurality of electrically energized indicator devices, each having a first electrode and a plurality of second electrodes to provide different indications according to a particular terminal which becomes connected in a circuit with the first electrode, a plurality of first switching means respectively connected to each of said first electrodes, means for connecting each one of said second electrodes of said indicator devices, second switching means connected to said connecting means, first drive means for applying signals to a plurality of said first switching means sequentially, second drive means for applying signals of the same duty cycle as said first drive means to said second switching means, and third drive means for applying signals of less duty cycle than that of said first drive means to said second switching means.

6. A display system as claimed in claim 5 wherein said one of the second electrodes connected together is a point indicating electrode.

7. A display system as claimed in claim 5 wherein said one of the second electrodes is a numeral-indicating electrode.

8. A display system as claimed in claim 5 wherein the third drive means includes a counter for lengthening the period of the signal.