GB1601763A - Level indicating device - Google Patents
Level indicating device Download PDFInfo
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- GB1601763A GB1601763A GB1071378A GB1071378A GB1601763A GB 1601763 A GB1601763 A GB 1601763A GB 1071378 A GB1071378 A GB 1071378A GB 1071378 A GB1071378 A GB 1071378A GB 1601763 A GB1601763 A GB 1601763A
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- level
- voltage
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- input signal
- indicating device
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R13/00—Arrangements for displaying electric variables or waveforms
- G01R13/40—Arrangements for displaying electric variables or waveforms using modulation of a light beam otherwise than by mechanical displacement, e.g. by Kerr effect
- G01R13/404—Arrangements for displaying electric variables or waveforms using modulation of a light beam otherwise than by mechanical displacement, e.g. by Kerr effect for discontinuous display, i.e. display of discrete values
- G01R13/405—Arrangements for displaying electric variables or waveforms using modulation of a light beam otherwise than by mechanical displacement, e.g. by Kerr effect for discontinuous display, i.e. display of discrete values using a plurality of active, i.e. light emitting, e.g. electro-luminescent elements, i.e. bar graphs
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- General Physics & Mathematics (AREA)
- Control Of Indicators Other Than Cathode Ray Tubes (AREA)
- Measurement Of Current Or Voltage (AREA)
Description
(54) LEVEL INDICATING DEVICE
(71) We, MATSUSHITA ELECTRIC
INDUSTRIAL CO. LTD., a Japanese
Body Corporate, of 1006, Oaza Kadoma,
Kadoma-shi, Osaka-fu, Japan, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed to be particularly described in and by the following statement:
The present invention relates to an indicating arrangement and more particularly, to a level indicating device which does not employ a mechanical indicating meter for use in electrical and electronic equipment.
for example. acoustic equipment such as magnetic recording and reproducing apparatuses, stereophonic reproducing apparatuses. radio receiving apparatuses, etc.
Conventionally. most level indicating devices employ indicators or meters which function mechanically for indicating levels by the deflection of the pointer needles of these meters.
The known level indicating devices with the pointer needle meters as described above have serious disadvantages in that there is a delay of approximately several hundred m sec. in rise time before the pointer needle of the meter starts deflecting when a signal of which the level is to be indicated is supplied to the indicating device. and that the pointer needle tends to overshoot or undesirably deflect beyond the position corresponding to the level of this signal. Thus it is difficult to correctly indicate the level of a particular signal. The disadvantages as described above are inherent in the known indicating meters of the needle pointer type and are difficult to eliminate perfectly however accurately these meters are produced. Production of very high precision meters of this type not only results in an extreme increase in cost, but these meters are of delicate construction and tend to be comparatively easily broken even by slight external vibrations or shocks, thus not being suitable for actual use.
Furthermore. in the conventional level indicating devices of the pointer needle type as described above, since it is quite impossi ble, owing to their construction, to alter the configuration at the indicating portion thereof, for example, to form this indicating portion into wave-like or corrugated configuration, the design of acoustic appliances and the like is largely restricted by employment of meters of the above described type.
Thus it is very difficult to adopt a fundamentally unique design which may not be found elsewhere.
Additionally, level indication by pointer needle deflection is effective as an indicating means only when a user follows the tip of the pointer needle with his eyes and it is rather difficult to read off accurate measured values from moment to moment. In particular, it has been almost impossible to grasp variations of levels in numerical values, for example, in dB, etc.
In conventional level indicating devices of the kind, for example, used in magnetic tape recording and reproducing apparatuses, it has generally been arranged so that the average level of the signal is indicated by a
VU meter, while the peak level of this signal is shown by the lighting, for example, of light emitting diodes or the like. In other words, the variation of the average level of the signal is represented by the deflection of the pointer needle of the VU meter and any signals which cannot be fully followed by the
VU meter are indicated by lighting the light emitting diodes. In the known indicating devices of the above described type, however, it is extremely difficult to simultaneously read both these levels due to the different indicating methods. and furthermore, since the peak level is indicated by the lighting of light emitting diodes only when the level exceeds a predetermined value, the relation between the average level and peak level is difficult to grasp unless the value at which the light emitting diode is lit is memorized in advance. For simultaneous indication of the average level and peak level, there has conventionally been proposed an arrangement which employs two pointer needles for indicating the average level by the deflection of one pointer needle and the peak level by the deflection of the other pointer needle.
The known arrangement as described above, however, has a disadvantage in that since the two pointer needles are deflected while intersecting each other in a complicated manner, it is difficult to distinguish clearly the deflection of the two pointer needles for a correct reading, while the problems related to the delay due to the rise time and "over-shooting" of the pointer needles and arising from the mechanical structure of the meter are further complicated. Thus the indication by such an indicating device is rather inaccurate.
According to the present invention there is provided a level indicating device for indicating simultaneously an average value and the peak value of an electrical input signal applied, in use, thereto, the device comprising a first circuit to which the input signal, in use. is applied, and for producing a first output signal proportional to the average value of the input signal,
a second circuit to which the input signal, in use, is applied, and for producing a second output signal proportional to the peak value of the input signal.
first and second voltage comparing units connected respectively to the first and second circuits, each unit comprising a plurality of voltage comparators having, re- spective stepwise threshold values, for generating indicating signals indicative of the level of the respective output signal applied, in use, thereto,
a luminescent indicator having a plurality of luminescent elements disposed in a row, each of the elements corresponding to a respective one of a plurality of input signal level ranges and arranged in the row in consecutive level range order, and
a third circuit connected to the first and second voltage comparing units and the luminescent indicator for illuminating at a first brightness the element or elements corresponding to the input signal level range or ranges up to and including the level of the first output signal, and for illuminating at a second brightness at least the element corresponding to the input signal level range including the level of the second output signal.
Two embodiments of the invention will now be described, by way of example, with reference to the accompanying drawings, in which
Figure 1 is a block diagram of a first embodiment of the invention;
Figure 2 is a schematic front view of the indicating surface of the fluorescent indicator tube employed in the embodiment of
Figure 1;
Figure 3 is an electrical circuit diagram showing the structure of a rectifier smoothing circuit employed in the embodiment of
Figure 1;
Figure 4 is a graph comparing the waveforms of the input and output signals in the rectifier smoothing circuit of Figure 3;
Figure 5 is an electrical circuit diagram showing the connections between the voltage comparators and the fluorescent indicator tube employed in the arrangement of
Figure 1;
Figure 6 is a block diagram, similar to
Figure 1 of a second embodiment of the invention;
Figure 7 is a front view of the indicating portion of the fluorescent indicator tube employed in the embodiment of Figure 6;
Figure 8 is an electrical circuit diagram of a rectifier smoothing circuit employed in the arrangement of Figure 6;
Figure 9 is a graph comparing the waveforms of the input and output signals in the rectifier smoothing circuit of Figure 8; and
Figure 10 is an electrical circuit diagram showing the connections of the voltage comparators, the OR circuits and the fluorescent indicator tube in the arrangement of Figure 6.
Before the description of the present invention proceeds, it is to be noted that like parts are designated by like reference numerals and symbols throughout the several views of the accompanying drawings.
Figures 1 to 5 show a level indicating device embodying the present invention, being intended for use. for example, as a level indicator in a magnetic tape recording and reproducing apparatus and is arranged to make it possible to read clearly the average level and the peak level of the signal to be indicated.
In the level indicating device according to the first embodiment of the present invention, the disadvantages and problems inherent in the conventional arrangement as described above are eliminated in a manner such that, without employing any meter for indicating levels by the movements of pointer needles, the average level and peak level of the signal are indicated at one place for simultaneous reading, with the two readings clearly distinguishable.
Figure 1 shows the fundamental circuit construction of the level indicating evice, the signal for the level indication being applied through an input terminal 101 to a buffer amplifier 102 for proper signal amplification and impedance conversion. The output from the buffer amplifier 102 is applied to the input terminals of two rectifier and smoothing circuits 103a and 103b.
One circuit 103a has its charge and discharge time constants set to correspond to the average value of the input signal, while the other circuit 103b has its time constants set to correspond to the peak value. The outputs of the two rectifier circuits 103a and 103b are respectively connected to the input terminals of a pair of voltage comparator units 104a and 104b each constituted by a plurality of voltage comparators. The above voltage comparator unit 104a is arranged to have all of its output voltages higher than the output voltages of the voltage comparator unit 104b. A plurality of output terminals C1, C1 ... C(n-1) and Cn for the voltage comparator unit 104a and D1, D2 D(n- 1) and Dn for the voltage comparator unit 104b are connected for mixing to OR circuits 105" 1052 ... 1()5(n-1) and 105n at each corresponding terminal, for example, in such a manner that C1 and D1 are connected to OR circuit 105,. C2 and D2 are connected to OR circuit 1()5, and Cn and Dn are connected to OR circuit 105n.
The output terminals of the plurality of OR circuits 1()5,, 1052... 105(n-1) and 105n are connected to respective anode electrodes
Al, A2 ... A(n-l) and An of the fluorescent indicator tube 106.
By the above arrangement, when a voice signal having a waveform containing a pulse component X as shown in Figure 1 is applied to the input terminal 101, this voice signal is applied to the rectifier and smoothing circuits 103a and 103b through the buffer amplifier 102. Thus a voltage corresponding to the average level m of the above signal is produced by the circuit 103a, while a voltage corresponding to the peak level p of the above signal is developed by the other circuit 103b. On the assumption that high potential outputs are obtained, for example, at the terminals C1 to C6 of the voltage comparator unit 104a from the output of the rectifier and smoothing circuit 103a, and low potential outputs are obtained, for examples at the terminals D7 to D10 of the voltage comparator unit 104b from the output of the rectifier circuit 103b, these outputs are subsequently applied to the plurality of OR circuits for being mixed. Thus the OR circuits 1051 to 1056 develop outputs of high potential, while the OR circuits 1057 to 105iso produce outputs of low potential.
These outputs are applied to the anode electrodes Alto A10 of the indicator tube 106 to illuminate the latter, in which case, the intensity of illumination of the anode electrodes Alto A6 is higher than that of the anode-electrode A7 to A10. If the anode electrodes Al, A2 ... A(n-l) and An are each formed into a rectangular shape and are laterally arranged in one row as shown in Figure 2, the electrodes Al to A6 on the left hand side are illuminated comparatively brightly, while the electrodes A7 to A10 on the right hand side are lit to be somewhat dimmer. The length of the former electrodes Alto A6 thus illuminated indicates the average level m (-5 dB in Figure 2), and the length of the latter electro'des A7 to A10 represents the peak level P (5 dB in Figure 2), thus indicating both of the levels simultaneously and distinctively. Since the number of the electrodes illuminated is varied according to any changes in the level of the input signal, the user has an impression that the length of a line is varied when reading the indications and can grasp the transition of levels in a very natural manner.
Based on the foregoing description of the general construction an operation of the first embodiment of the present invention, detailed structure of each part of the level indicating device of the invention will be described here-in-below.
Referring particularly to Figures 3 and 4, further construction of the rectifier and smoothing circuits 103a and 103b and determination of the time constant thereof will be explained. In Figure 3, the rectifier and smoothing circuit 103a includes a resistor
Rcl coupled to the output of the buffer amplifier 102 and also connected in series with a rectifier diode Dcl which is further coupled to a parallel-connection of a smoothing capacitor Cv and a resistor Rv, The other rectifier and smoothing circuit 103b includes a rectifier diode Dc2 also coupled to the output of the buffer amplifier 102 and in turn, connected to a parallel-connection of a smoothing capacitor Cp and a resistor
Rp as shown. Accordingly, the rise time of the circuit 103a is mainly determined by the time constant Ret and Cv, and the fall time is determined by the time constant Cv and
Rv. The rise time of the circuit 103b is determined by the time constant of the output impedance Z (which is ordinarily a very small value) of the buffer amplifier 102, the resistance component of the diode Dc2 in the forward direction and the capacitor
Cp, and the fall time is determined by the time constant Cp and Rp. In the above arrangement, if the rise time of the rectifier and smoothing circuit 103b is selected to be sufficiently short or fast as compared with the rise time of the rectifier and smoothing circuit 103a and the fall time of the rectifier and smoothing cicuit 103b is selected to be sufficiently long br slow as compared with the fall time of the circuit 103 a, even when a signal having a waveform as shown by a line 107 of Figure 4 is applied to the terminal 101, the voltage developed at the output terminal 109 of the circuit 103b is as shown by line 109a in Figure 4, while the voltage appearing at the output terminal 108 of the circit 103a has a waveform as shown by line 108a in Figure 4. In other words, the output from the circuit 103a represents the average level of the input signal, while output from the circuit 103b indicates the peak level of input signal.
In Figure 5, showing the circuit construction from the voltage comparator units 104a and 104b to the fluorescent indicator tube 106 more specifically, the positive input terminals of the plurality of voltage comparators 2001, 2002 ... 2()0(n- 1) and 200n constituting the voltage comparator unit 104a are all connected to the terminal 108 (Figure 3), while those of the plurality of voltage comparators 201,. 2012... 201(n-1) and 201n are all coupled to the terminal 109 (Figure 3). To arrange the threshold values of the above voltage comparators 2001 to 200n and 2011 in an order in terms of level, the negative input terminals of these voltage comparators are connected to respective potential points obtained by dividing the voltage of the DC power source E3 by the resistance R1 ... R(n+ 1) in such a manner that the voltages applied thereto are sequentially higher from the negative input terminals of the voltage comparator 2001 and 201, toward the negative input terminals of the voltage comparators 200n and 201n. In the above case, the voltage comparators 2001 and 201, are arranged to be actuated by the same threshold value to develop an output signal, while the power supply voltage for the voltage comparator unit 104a including the voltage comparator 200, is supplied by the DC voltage source E3, and the power supply voltage for the voltage comparator unit 104b including the voltage comparator 2011 is supplied by the DC voltage source
E2 having a voltage lower than the DC voltage source E3. Therefore. the output voltage E3 of the voltage comparator 2011 is higher than the output voltage E2 of the voltage comparator 2ole.
Accordingly, if the level of a signal applied to the input terminals of the voltage comparator units 104a and 104b from the terminals 108 and 109 exceeds the threshold value of one of the voltage comparators, i.e., the voltage across the resistor R1, for example, for the voltage comparator 2001 or 2011, the output voltage of this voltage comparator is equal to the level of the corresponding power supply voltage source
E3 or E2. However, if this input level falls below the threshold value, the output voltage becomes ground potential level.
A plurality of output terminals C1, C2 ...
C(n-l) and Cn for the voltage comparator unit 104a and D1, D2 ... D(n-l) and Dn for the voltage comparator unit 104b are commonly connected through diodes constituting OR circuits 1051, 1052 ... 105(n-1) and 105n respectively. and are further connected to the anode electrodes A1,A2 ... A(n-1) and An of the fluorescent indicator tube 106. The filament F of the fluorescent indicator tube 106 is heated by the DC power source El.
Accordingly, if the output voltages of the voltage comparators 2001 to 200i and the output voltage of the voltage comparators 2011 to 201j (where 1%iAn) are sequentially converted from the ground potential to the potentials of the power source voltages E3 and E2 respectively, the potential of the anode electrodes Al to Aj becomes sufficiently higher than the voltage El of the filament F of the indicator tube 106, and the electrons emitted from the filament F collide with the anode electrodes Al to Aj to excite and to illuminate the fluorescent substance applied to these electrodes. In the above case, since the potential E3 of the anode electrodes Al to Ai is higher than the potential E2 of the anode electrodes A(i+ 1) to Aj, the potential difference between the electrodes Al to Ai and filament F is larger than the potential difference between the electrodes A(itl) to Aj and the filament F.
Thus the electrodes Alto Ai are illuminated more brightly than the electrodes
A(i+1) to Aj due to the characteristics of the fluorescent indicator tube whose intensity of illumination is varied approximately in proportion to the magnitude of the potential difference. Therefore, the average level and peak level indications are effected as described with reference to Figure 2.
It should be noted here that in the foregoing first embodiment of the present invention, although description is mainly given with reference to the case wherein the average level and peak level of one particular signal are to be indicated, a number of circuits as shown in Figure 1 may be prepared corresponding to the number of signals if two or more signals are to be dealt with and that the fluorescent indicator tube 106 described as employed in the foregoing embodiment may be readily replaced, for example, by light emitting diodes formed by incorporating a plurality of luminescent chips in a casing.
As is clear from the foregoing description, in the first embodiment of the invention, the following effects can be obtained:
(i) Since an illuminating indicating member having a plurality of luminescent elements is employed as the level indicator, the manufacture of the indicating device is appreciably facilitated as compared with the conventional arrangements using the VU meters or the like, and the design of the indicating member can be altered comparatively freely. Furthermore, the arrangement of the invention is quite free from problems related to poor following characteristics of the pointer needle to the signal owing to the mechanical construction thereof such as delay in rising or "over-shoot" of the pointer needle, thus making possible a level indication which correctly follows the signal.
(ii) Another advantage is that the average level and peak level of the signal are simultaneously indicated in the same indicating place, with the levels being clearly distinguished from each other by the difference in illuminating intensity. By this feature of the level indicating device, the problem in the conventional arrangements that the peak indicator employed therein only serves for watching the average level, with the occurrence of distortion and the like in the peak level being undesirably overlooked due to the indicating method for the peak level being different from that for the average level is substantially eliminated.
Referring to Figures 6 to 10, there is shown a second level indicating device embodying the present invention which is an improvement of the arrangement of the first embodiment. The indicating device of the second embodiment has for its object to facilitate further the distinction between the average level and the peak level.
In Figure 6 showing a fundamental circuit construction of the second level indicating device, the signal for the level indication is applied, through the input terminal 301, to a buffer amplifier 302 for proper signal amplification and impedance conversion. The output from the buffer amplifier 302 is applied to the input terminals of two rectifier and smoothing circuits 303a and 303b.
One circuit 303a of the above described two circuits 303a and 303b has its charge and discharge time constants set to correspond to the average value of the input signal, while the other circuit 303b has its time constants set to correspond to the peak value. The outputs of the above two rectifier circuits 303a and 303b are respectively connected to the input terminals of a pair of voltage comparator units 304 and 305 each constituted by a plurality of voltage comparators. It is to be noted that the above voltage comparator unit 305 is constructed to develop an output voltage from the voltage comparator having a threshold value which is the closest to the output of the rectifier circuit 303b only. Meanwhile, -a plurality of outputs C1, C2 ... C(n-l) and
Cn, D1-B1,D2-B2 to D(n-l).B(n-l) and Dn-Bn for each of these voltage comparator units 304 and 305 are applied for mixing to
OR circuits 306l, 3062... 306(n-1) and 306n at respective corresponding terminals, for example, in such a manner as C1 and Dl, B1, C2 and D2, and Cn and Dn outputs of the plurality of OR circuits 306l, 3062 ...
306(n-1) and 306n are connected to respective anode electrodes Al, A2 ... A(n-l) and An of the fluorescent indicator tube 307.
By the above arrangement, when a voice signal having a waveform containing a pulse component X as shown in Figure 6 is applied to the input terminal 301, this voice signal is applied to the rectifier and smoothing circuits 303a and 303b through the buffer amplifier 302. Thus a voltage corresponding to the average level m of the above signal is produced by the circuit 303a, while a voltage corresponding to the peak level P of the above signal is developed by the other circuit 303b. On the assumption that output signals are obtained, for example, at the terminals C1 to C6 of the voltage comparator unit 303a by the output of the rectifier and smoothing circuit 303a, and also output signals are obtained, for example, at the terminals Dl0 and B10 of the voltage comparator unit 305 by the output of the rectifier and smoothing circuit 303b, these outputs are subsequently applied to the plurality of OR circuits for being mixed.
Thus the OR circuits 306 to 3066 and the
OR circuit 3061() develop outputs. These outputs are applied to the anode electrodes
Alto A6 and A10 of the indicator tube 307 to illuminate the latter. If the anode electrodes Al, A2 ... A(n-l) and An are each formed into a rectangular shape and are laterally arranged in one row as shown in
Figure 7, the electrodes Al to A6 on the left hand side and the electrode A10 are illuminated, and the length of the former electrodes Alto A6 thus illuminated indicates the average level m (-5 dB in Figure 7).
The position of the illuminated electrode A10 represents the peak level P (5 dB in
Figure 7), thus both of the levels being indicated simultaneously and distinctively.
Since the number of the electrodes illuminated varies according to any change in the level of the input signal, the user has an impression that the length of a line is varied when reading the indications to grasp the transition of levels in a very natural manner as in the first embodiment of the invention described earlier. Moreover, the electrode illuminated in the spot spaced from the indication of the average level enables the user readily to observe the transition of the peak level through movement of the illuminated spot. Additionally, if the output voltage of the voltage comparator unit 304 is arranged to be lower than the intensity of the voltage comparator unit 305 in the second embodiment, the intensity of illumination of the electrodes Al to A6 becomes lower than that of the electrode A10 indicating the peak level as shown in Figure 7 for a clearer distinction between the two levels.
Based on the foregoing description of the general construction and operation of the second embodiment according to the present invention, detailed structure of each part of the level indicating device of the invention will be described hereinbelow.
Referring particularly to Figures 8 and 9, further construction of the rectifier and smoothing circuits 303a and 303b and determination of their time constants will be explained. In Figure 8, the rectifier and smoothing circuit 303a includes a resistor
Rcl coupled to the output of the buffer amplifier 302 and also connected in series with a rectifier diode Dcl which is further coupled to a parallel-connection of a smoothing capacitor Cv and a resistor Rv. The other rectifier and smoothing circuit 303b includes a rectifier diode DC2 also coupled to the output of the buffer amplifier 302 and in turn, connected to a parallel-connection of a smoothing capacitor Cp and a resistor
Rp as shown. Accordingly. the rise time of the circuit 3()3a is mainly determined by the time constant Rcl and Cv, and the fall time is determined by the time constant Cv and
Rv. The rise time of the circuit 303b is determined by the time constant of the output impedance Z (which is ordinarily a very small value) of the buffer amplifier 302.
the resistance component of the diode Dc2 in the forward direction and the capacitor
Cp, and the fall time is determined by the time constant Cp and Rp. In the above arrangement, if the rise time of the rectifier and smoothing circuit 303b is selected to be sufficiently short or fast as compared with the rise time of the rectifier and smoothing circuit 303a and the falling time of the rectifier and smoothing circuit 303b is selected to be sufficiently long or slow as compared with that of the circuit 303a, when the signal having the waveform shown at line 308 in Figure 9 is applied to the terminal 301, the voltage developed at the output terminal 400 of the circuit 3()3b is as shown by a line 400a in Figure 9, while that appearing at the output terminal 309 of the circuit 303a takes the waveform shown by line 309a in Figure 9. In other words, the output from the circuit 303a represents the average level of the input signal, while the output from the circuit 303b indicates the peak level of the input signal.
In Figure 10, showing the circuit construction from the voltage comparator units 304 and 305 to the fluorescent indicator tube 307 more specifically, the positive input terminals of the plurality of voltage comparators 4ole, 4012 ... 401(n-1) and 401n constituting the voltage comparator unit 304 are all connected to the terminal 309 (Figure 8), while the positive input terminals of the plurality of voltage comparators 402i, 4022 ... 402(n-1) and 402n and the negative input terminals of the voltage comparators 403l, 4032 ... 403(n-1) and 403n are all coupled to the terminal 400. To arrange the threshold values of the above voltage comparators 401l to 401n and 4021 to 402n in an input level falls below the threshold value, the output signal becomes ground potential level. Simultaneously, for example, in the voltage comparator 4031, if the signal applied to terminal 400 exceeds the voltage across the resistance (R1+R2), the output voltage is reduced to ground potential level, and the output voltage becomes the level of the power source voltage E3 when the input signal is below the threshold voltage thereof. Accordingly, in the voltage comparator unit 304, a plurality of the voltage comparators up to the one having a threshold value closest to the input signal level simultaneously develop output signals equivalent to the voltage E2. In the voltage comparator unit 305, except for the voltage comparator 402n, the output of each pair of corresponding voltage comparators, for example, the voltage comparators 402 and 403, is passed through respective AND circuits 4041 to 404(n-1), and therefore, the output of the voltage E3 is developed only from the AND circuit at the output sides of two voltage comparators having threshold values closest to the input signal level.
A plurality of output terminals C1, C2 ...
C(n-l) and Cn. Dl.Bl to D(n-l)'B(n-l) and Dn for the voltage comparator units 304 and 305 are commonly connected through diodes constituting OR circuits 306,. 3062...
306(n-1) and 306n respectively. The OR circuits 306 is 306n are connected to the anode electrodes Al, A2 ... A(n-l) An of the fluorescent indicator tube 307, the fila
ment F of which is heated by the DC power source El.
Accordingly, if the outputs of the voltage comparators 401, to 401i from the lower order and those of the voltage comparators 402 to 402j (where 1Aisjsn) from the
lower order are sequentially converted from the ground potential to the potentials of the power source voltages E3 and E2 respec timely a voltage E3 is produced only by the
AND circuit 404j, since in the above case,
the outputs from the voltage comparators 4031 to 4()3(j-i) are of ground potential and
only the output of the voltage comparator
403j equals the voltage E3. Therefore, the
potential of the anode electrodes Al to Ai
and Aj becomes sufficiently higher than the
voltage El of the filament F of the indicator
tube 307, and the electrons emitted from the
filament F collide with the anode electrodes
Alto Ai and Aj to excite and to illuminate
the fluorescent substance applied to these
electrodes. In the above case, since the
potential E2 of the anode electrodes Alto
Ai is lower than the potential E3 of the
anode electrode Aj, the potential difference
between the electrodes Al to Ai and fila
ment F becomes smaller than the potential
difference between the electrode Aj and the
filament F. The electrodes Al to Ai are illuminated somewhat dimmer than the electrode Aj due to the characteristic of the fluorescent indicator tube whose intensity of illumination varies approximately in proportion to the magnitude of the potential difference. Thus the average level and the peak level indications are effected as described with reference to Figure 7.
It should also be noted here that in the foregoing second embodiment of the present invention, although the description is mainly given with reference to the case in which the average level and the peak level of one particular signal are indicated, a number of circuits as shown in Figure 6 may be prepared corresponding to the number of signals if two or more signals are to be dealt with, and that the fluorescent indicator tube 307 described as employed in the foregoing embodiment may be readily replaced, for example, by light emitting diodes formed by incorporating a plurality of luminescent chips in a casing.
As is clear from the foregoing description, according to the level indicating device of the second embodiment of the invention, not only are effects similar to those in the first embodiment obtained, but the average level is more clearly distinguished owing to the spot indication of the peak level,
Although the present invention has been fully described by way of example with reference to the attached drawings, it is to be noted that various changes and modifications are apparent to those skilled in the art.
Therefore, unless these changes and modifications depart from the scope of the present invention as defined in the appended claims, they should be construed as included therein.
WHAT WE CLAIM IS:
1. A level indicating device for indicating simultaneously an average value and the peak value of an electrical input signal applied, in use, thereto, the device -comprising
a first circuit to which the input signal, in use, is applied, and for producing a first output signal proportional to the average value of the input signal,
a second circuit to which the input signal, in use, is applied, and for producing a second output signal proportional to the peak value of the input signal,
first and second voltage comparing units connected respectively to the first and second circuits, each unit comprising a plurality of voltage comparators having respective stepwise threshold values, for generating indicating signals indicative of the level of the respective output signal
applied, in use, thereto,
a luminescent indicator having a plurality
of luminescent elements disposed in a row,
each of the elements corresponding to a
**WARNING** end of DESC field may overlap start of CLMS **.
Claims (8)
1. A level indicating device for indicating simultaneously an average value and the peak value of an electrical input signal applied, in use, thereto, the device -comprising
a first circuit to which the input signal, in use, is applied, and for producing a first output signal proportional to the average value of the input signal,
a second circuit to which the input signal, in use, is applied, and for producing a second output signal proportional to the peak value of the input signal,
first and second voltage comparing units connected respectively to the first and second circuits, each unit comprising a plurality of voltage comparators having respective stepwise threshold values, for generating indicating signals indicative of the level of the respective output signal
applied, in use, thereto,
a luminescent indicator having a plurality
of luminescent elements disposed in a row,
each of the elements corresponding to a
respective one of a plurality of input signal level ranges and arranged in the row in consecutive level range order, and
a third circuit connected to the first and second voltage comparing units and the luminescent indicator for illuminating at a first brightness the element or elements corresponding to the input signal level range or ranges up to and including the level of the first output signal, and for illuminating at a second brightness at least the element corresponding to the input signal level range including the level of the second output signal.
2. A level indicating device as claimed in Claim l wherein each of the elements corresponding to the level ranges from the range next above that including the level of the first output signal up to the range including the level of the second output signal are illuminated at the second brightness.
3. A level indicating device as claimed in either Claim 1 or Claim 2 wherein the second brightness is lower than the first brightness.
4. A level indicating device as claimed in Claim 1 wherein only the element corresponding to the input signal level range including the level of the second output signal is illuminated. in use. at the second brightness.
5. A level indicating device as claimed in Claim 4 wherein the second voltage comparing unit comprises a second plurality of voltage comparators corresponding to its first-mentioned plurality of voltage comparators, but having reverse stepwise threshold values, the first and second plurality of voltage comparators cooperating to illuminate, in use. the said only element at the second brightness.
6. A level indicating device as claimed in either Claim 4 or Claim 5 wherein the second brightness is greater than the first brightness.
7. A level indicating device substantially as hereinbefore described with reference to and as shown in Figures 1 to 5 or Figures 6 to 10 of the accompanying drawings.
8. 8. A level indicating device as claimed in Claim 7, in combination with acoustic equipment to which a multiple channel input is applied, said level indicating device being adapted to provide a visual indication of the signal level of each channel of said input.
Applications Claiming Priority (11)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP3092577A JPS53116136A (en) | 1977-03-18 | 1977-03-18 | Level display device |
| JP3423377U JPS53129374U (en) | 1977-03-18 | 1977-03-18 | |
| JP3423577U JPS53129376U (en) | 1977-03-18 | 1977-03-18 | |
| JP3092777A JPS5853431B2 (en) | 1977-03-18 | 1977-03-18 | level display device |
| JP3423477U JPS5738575Y2 (en) | 1977-03-18 | 1977-03-18 | |
| JP3423777U JPS53129377U (en) | 1977-03-18 | 1977-03-18 | |
| JP3092877A JPS599099B2 (en) | 1977-03-18 | 1977-03-18 | level display device |
| JP3423677U JPS53129344U (en) | 1977-03-18 | 1977-03-18 | |
| JP3671577U JPS53132375U (en) | 1977-03-25 | 1977-03-25 | |
| JP3726077A JPS53122400A (en) | 1977-03-31 | 1977-03-31 | Audio unit |
| JP3726277A JPS53122464A (en) | 1977-03-31 | 1977-03-31 | Level display device |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| GB1601763A true GB1601763A (en) | 1981-11-04 |
Family
ID=27581933
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB1071378A Expired GB1601763A (en) | 1977-03-18 | 1978-03-17 | Level indicating device |
Country Status (3)
| Country | Link |
|---|---|
| DE (1) | DE2811661A1 (en) |
| DK (1) | DK122978A (en) |
| GB (1) | GB1601763A (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS58190767A (en) * | 1982-04-20 | 1983-11-07 | Regie Natl Usines Renault | Display for speedmeter of automobile |
-
1978
- 1978-03-17 DE DE19782811661 patent/DE2811661A1/en not_active Withdrawn
- 1978-03-17 DK DK122978A patent/DK122978A/en not_active IP Right Cessation
- 1978-03-17 GB GB1071378A patent/GB1601763A/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| DK122978A (en) | 1978-09-19 |
| DE2811661A1 (en) | 1978-09-21 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PS | Patent sealed | ||
| PCNP | Patent ceased through non-payment of renewal fee |
Effective date: 19930317 |