JPS6252388B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a tape position display device for a tape recorder or the like, and is particularly intended to display the absolute position of a tape with high precision.

Conventionally, various devices have been proposed for displaying tape position. As an example of such a device, a device is known in which a guide roller is rotated by a tape and a time is displayed according to the amount of tape movement. In this tape position display device, it is necessary to first reset the tape at a predetermined position, and it does not correspond to an absolute position.Furthermore, in a cassette tape recorder, etc., there is no space for using a roller, so it is difficult to realize in practice.

For this reason, some devices calculate the reel rotation speed and tape speed and display the tape position.
With this device, due to eccentricity of the tape reel, etc.
Since the positional accuracy is not perfect, there is a drawback that the time display varies even if the tape running is constant.

For this reason, it may be possible to remove the effect of eccentricity by detecting eccentricity every time the reel rotates, but in this case, it would be possible to detect the eccentricity every time the reel rotates. It becomes a display, which is different from the continuous display of nature.

SUMMARY OF THE INVENTION Accordingly, the main object of the present invention is to provide a tape position indicating device which eliminates the above-mentioned drawbacks.

Another object of the present invention is that by the rotation of the reel,
The absolute position of the tape can be displayed with high precision like a time display, and can be displayed continuously;
It is an object of the present invention to provide a tape position display device capable of displaying the beginning and end of a winding, for example, with changes every second.

In order to achieve the above object, the present invention counts signals from an oscillator, displays the count output continuously, and controls the base value with a signal obtained from a tape reel, etc., and displays it intermittently. Even if the data is large, it can be displayed continuously.

Hereinafter, one embodiment of the present invention will be described in detail with reference to FIGS. 1 to 4.

In FIG. 1, slit disks 1 and 1' are attached to the take-up reel and rewind reel shafts.
A pulse proportional to the rotational speed of the reel is applied to a counter circuit C, which is detected by detectors 3 and 3' such as light receiving elements arranged at the lower ends of the slits 2 and 2'.

The slit disks 1 and 1' are provided with two slits 2 and 2', respectively, at positions 180 degrees apart from the axis of rotation, as shown.

The pulses applied to the counter circuit C are then counted by using the oscillation signal of a reference oscillator (OSC), such as a crystal, applied thereto, and the output of the counter C is supplied to the latch circuits L1 and L2; There, they are latched alternately. This switching involves applying pulses from the detectors 3 and 3' to the flip-flop circuit FF1 and the gate circuits G1 and G2.
Therefore, to the latch terminals of latch circuits L1 and L2,
This is done by applying latch pulses T1 and T2, respectively.

The outputs of the latch circuits L1 and L2 are connected to the adder circuit S.
1 and its output is latched by latch circuit L3. As a result, the number of pulses corresponding to the time required for one rotation of the reel, ie, data corresponding to one rotation period, is output.

Although FIG. 1 only shows the circuit system for the detector 3, the same circuit system is also provided for the light receiving element of the slit disk 1', that is, the detector 3'. In this way, the rotation periods of both reels are added to the arithmetic circuit A1, and based on the output,
In the case of constant playback, the tape position, that is, the amount of tape corresponding to the playback time can be displayed on the display device 4 in time.

The calculation within the calculation circuit A1 can be determined by the following equation. That is, if the amount of tape to be wound is A, the total amount of tape is S, and the rotation periods of both reels are T1 and T2, then It can be expressed as Here, x is the area of the reel hub.

Note that the total tape amount S is a constant determined depending on the type of cassette, and takes a constant value for one type of cassette. Furthermore, since the tape winding amount A changes constantly over time during performance, the time T can be expressed as T=S/p·v (2). Here, p is the thickness of the tape, and v is the tape speed, both of which are constants.

If the above calculation is performed by the calculation circuit A1, the absolute position of the tape corresponding to the playback time can be determined.

Of course, if reversed, the number of hours remaining on the tape will be represented, and the results of these calculations will be displayed on the display device 4.

Here, since the data change corresponds to half a rotation of the reel, it does not behave like a time meter where the display increases by one second, for example. Further, since reel eccentricity is calculated for one rotation period, it does not cause an error, but if there is play or the like in the reel, an error occurs.
In such a state, data is displayed intermittently, making the display unnatural. Therefore, by using a circuit configuration as shown in FIG. 2, it is possible to improve the intermittent display.

In Figure 2, the output pulse of the oscillator OSC' is
The counting circuit C1 counts and the output is displayed on the display device 4'. The counter circuit C1 is an up/down counter circuit, and normally counts up. Then fast forward
The output of the arithmetic circuit A1 mentioned above is latched to the counter circuit C1 by the OR circuit OR output L of FF, rewind RWD, and stop STOP. That is,
In modes such as FF, RWD, and STOP, the output of the arithmetic circuit A1 is latched and displayed as is on the display device 4', and when the tape is placed in a normal constant running mode such as playback, it is output from the OR circuit OR. The output L disappears, and by the pulse of the oscillator OSC',
The counter circuit C1 operates, and for example, the display of the addition of one second of real time is also made continuous.
Here, when the tape is first set or the power is turned on, the tape is run for a certain period of time and the data obtained by calculating the running distance is latched into the counter circuit C1 as an initial (INITIAL) signal.

Next, the output data I of the arithmetic circuit A1 and the output data R of the counter circuit C1 are added to the subtraction circuit B, and the resulting difference signal data C is compared with the reference data d and e from the reference data sources R1 and R2. Comparisons are made in circuits F and G, and if data d is positive, that is, output data y of arithmetic circuit A1 is greater than output data d of counter circuit C1, and its value is greater than reference data d, comparator circuit F outputs. The output of the comparator circuit F and the output of the gate circuit G3 to which the counter circuit C1 receives, for example, a bit pulse number every second, are supplied to a monostable multivibrator M2 to drive it. The output of this monostable multivibrator M2 is passed through an exclusive circuit Ex to a counter circuit C1.
, increasing its count and increasing the pulses. Conversely, if the difference between the output data I of the arithmetic circuit A1 and the output data I of the counter circuit C1 is greater than or equal to the reference data e (predetermined value), the comparator circuit G
The output of this circuit operates a monostable multivibrator M1 through a gate circuit G4 to which a bit pulse number N is supplied. The output of this monostable multivibrator M1 is the counter circuit C
1 as a down clock, causing the counter circuit C1 to down count.

The operation of the circuit configuration according to the present invention described above is further explained as follows.
This will be described in detail with reference to FIGS. 3 and 4. As the tape recorder reproduces data, the output data from the arithmetic circuit A1 changes as the reel rotates, as shown by the solid line A in FIG. 3I, and the tape position and output data do not match. However, the output of the counter circuit C1 is continuous output data as indicated by the dotted line B in the figure. Here, if the output data C of the subtraction circuit B does not exceed the reference values (data) d and e, as shown by the solid line C in FIG. 3, the counter circuit C1 continues counting. If the deviation between the output data A and B becomes large and the output data H of the subtraction circuit B exceeds the reference value e, as shown in FIG. 4, for example, the monostable multivibrator M1 becomes Outputs a subtraction pulse as shown. Now, the frequency of the oscillator OSC' is 10Hz, and the minimum digit of the counter circuit C1 is 10Hz.
Assuming that the counter circuit C1 changes every second, the counter circuit C1 is a monostable multivibrator M
Since one pulse is decreased by one pulse, one second is displayed in 11 pulses, that is, 11 seconds.
As a result, the deviation in the display of the tape position, as shown by the solid line B in FIG. The data will start to settle down. At this time, the display device 4' is corrected with a deviation of 0.1 seconds each time.

Further, the difference between the value of the output data I of the arithmetic circuit A1 and the output data L of the counter circuit C1 is the reference value d.
If it becomes larger than this, the up pulse is increased by one pulse, and correction is performed. Incidentally, if the number of comparison circuits F and G is further increased and the deviation of the output data becomes large, the display changes more naturally if the number of correction pulses is increased.

FIG. 5 shows the main part of another embodiment of the present invention. In this example, the output of the subtraction circuit B is supplied to the digital-to-analog conversion circuit DA, thereby converting the output data I into an analog The analog output from this is supplied to a low-pass wave circuit consisting of a resistor R and a capacitor C, so that
The DC component is taken out and applied as a control voltage to the voltage controlled oscillator VCO, which replaces the oscillator OSC' in the example of FIG. The output of this voltage controlled oscillator VCO is added to the counter circuit C1, and the output of the voltage controlled oscillator VCO is added to the counter circuit C1.
If the frequency of the voltage controlled oscillator VCO is controlled so that the difference between the output data LO of the arithmetic circuit A1 and the output data I of the arithmetic circuit A1 is always minimized, the counter circuit C
The output data ``1'' can be made equal to the output data ``i'' of the arithmetic circuit A1.

In each of the embodiments described above, the tape position is detected using a slit disk, but it goes without saying that various methods can be considered, such as detecting the tape position from a tape speed signal and a reel rotational speed signal.

Since the present invention is configured and operates as described above, it is possible to display an absolute position that changes continuously at regular intervals.In particular, data obtained from conventional tape reel rotation speeds has many errors, and the tape It is not possible to display the absolute position smoothly, and the data changes suddenly due to play of the reel, etc. However, the present invention is very natural because it is controlled continuously and gradually. Further, since the detection data is always controlled to the average value, there is an effect that the absolute accuracy including the reproducibility of display data is improved.

[Brief explanation of the drawing]

FIG. 1 is a system diagram showing one embodiment of the detection section of the present invention, FIG. 2 is a digital system diagram of the present invention, and FIG.
4 and 4 are diagrams for explaining the present invention, and FIG. 5 is a system diagram showing main parts of another embodiment of the present invention. In the figure, 1 and 1' are slit disks, 2 and 2' are slits, 3 and 3' are detectors, OSC and OSC' are reference oscillators, VCO is a voltage controlled oscillator,
C and C1 are counter circuits, FF1 is a flip-flop circuit, L1, L2 and L3 are latch circuits,
S1 is an addition circuit, A1 is an arithmetic circuit, B is a subtraction circuit, G1, G2, G3 and G4 are gate circuits, M
1 and M2 are monostable multivibrators, and 4 and 4' are display devices.

Claims (1)

[Claims] 1. A rotation detecting means for detecting the rotation of the tape reel, an arithmetic circuit for calculating the tape position based on the rotation detection output from the rotation detecting means, a counter for counting a reference clock, and a counting output of the counter is supplied. a subtracter for subtracting the tape position calculation output from the arithmetic circuit and the counting output from the counter; and a subtractor output from the subtracter as a pair of reference data. and a comparator for comparison, and the count of the counter is controlled by the comparison output from the comparator so that the count output from the counter falls within the range of the pair of reference data. Features a tape position display device.