JPH07282566A - Tape running amount counting device - Google Patents

Abstract

PURPOSE:To correctly measure a tape running amount with a simplified constitu tion by arranging a frequency divider and a computer and providing a mode discriminating means, an input port control means and a counting arithmetic means in the computer. CONSTITUTION:A tape running amount counting device is formed with a frequency divider 2 and a computer 5. Then, the frequency-divided pulse Sb of the frequency divider 2 is supplied to the interrupting input port P1 of the computer. The computer 5 sets the input port to a one-side edge interrupting port by the input port control means based on the discrimination result of the mode discriminating means at the time of a high speed running mode and sets the input port to a both edge interrupting mode at thc time of a normal running mode. Moreover, the counting arithmetic means of the computer measures the tape running amount with input port interrupting triggers by counting up by two counts at every one-side edge of the frequency-divided pulse at the time of the high speed running mode and by counting up by one count at every respective both edges of the frequency-divided pulse at the time of the normal running mode.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention counts up the software processing of a computer based on a control pulse for tracking control so that the tape can be fast-forwarded, rewound, or the like at a high speed, and reproduction, recording, or another normal tape can be run. The present invention relates to a tape running amount counter device for a video tape recorder which measures a tape running amount.

[0002]

2. Description of the Related Art Conventionally, a VHS type or β type video tape recorder (hereinafter referred to as VTR) is often equipped with a tape running amount counter device of FIG. 3 using a microcomputer.

The control pulse (hereinafter referred to as CTL pulse) Sa for the tracking control supplied to the pulse input terminal 1 is based on the tape loading of the full-loading method or the half-loading method. Is reproduced from the control track of the tape even when the tape is running at a high speed, and is formed by the output of an oscillator or the like during recording.

Further, the CTL pulse Sa is frequency-divided by the frequency divider 2 to form a frequency-divided pulse Sb, and both the pulses Sa and Sb are the normal traveling contact α of the changeover switch 3 for pulse selection and the high-speed traveling. It is supplied to the contact β.

This change-over switch 3 changes the binary level of the selection signal SW supplied from the output port Po of the control computer 4 having a microcomputer configuration to change the VTR.
It changes according to the operation mode of.

Then, in the operation mode of the tape normal running such as reproduction and recording, the changeover switch 3 operates the normal running contact α.
, And the CTL pulse Sa via this contact α is supplied to the interrupt input port Pi of the control computer 4.

In the operation mode of high speed tape running such as fast forward and rewind, the changeover switch 3 is switched to the high speed running contact β, and the divided pulse Sb via this contact β is input to the computer 4 as an interrupt. It is supplied to the port Pi.

The input port Pi is formed as a one-edge interrupt port in which an interrupt trigger is generated by one rising edge. For example, the computer 4 controls the entire VTR according to the main program (main routine processing).
When a pulse Sa or Sb is given during the execution of
The rising edge of its leading edge causes an interrupt trigger.

A so-called hardware interrupt is generated in the computer 4 by this trigger, the computer 4 shifts to the interrupt processing, and based on the determination result of the current operation mode,
The tape running amount is incremented by 1 or 2.

That is, in the tape normal running operation mode in which an interrupt trigger is generated by the CTL pulse Sa,
In the tape high-speed running operation mode in which the count value of the tape running amount is incremented by 1 at each rising edge of the CTL pulse Sa shown in FIG. 4A and an interrupt trigger input is generated by the frequency dividing pulse Sb, , The tape running amount is incremented by 2 for each rising edge of the divided pulse Sb shown in FIG.

In FIG. 4, ts indicates the timing to start counting the tape running amount based on the power-on of the VTR, the change of the operation mode, etc., +1 and +2 indicate the unit amount of counting up, ... Shows the amount of tape running from.

Then, the tape running amount is measured by counting up each rising edge of the pulses Sa and Sb, and the tape running amount of the measurement result is displayed on a display unit (not shown). When the interrupt process is completed, the computer 4 returns to the main routine process and restarts this process.

In the case of FIG. 3, in the operation mode of high-speed tape running in which the CTL pulse Sa is frequently generated, the dividing pulse Sb obtained by dividing the CTL pulse Sa by ½.
As a result, an interrupt trigger is generated, the tape running amount is measured while suppressing an increase in the occurrence frequency of interrupts of the computer 4, and delay of other processing of the computer 4 due to interrupts is prevented.

On the other hand, the computer 4 constantly monitors the automatic or manual change of the operation mode, and controls the level of the selection signal SW of the output port Po and changes the memory of the operation mode every time the operation mode is changed. .

[0015]

In the case of the conventional tape running amount counter device shown in FIG. 3, the changeover switch 3 provided outside the computer 4 is switched to change the pulse of the input port Pi to the CTL pulse Sa depending on the operation mode. Alternatively, since it is configured to switch to the divided pulse Sb, the mechanical (physical) operation of the changeover switch 3 is performed immediately after the operation mode is changed and after the computer 4 outputs the selection signal SW until the pulse of the input port Pi is changed. If a CTL pulse Sa or a frequency-divided pulse Sb is given to the input terminal 1 during this time delay and an interrupt trigger occurs, it is determined whether the changeover switch 3 is actually changed over. Four
Therefore, there is a problem in that the rising edge of the CTL pulse Sa is erroneously counted and the tape running amount cannot be accurately measured even though the operation mode is changed to the tape high speed running mode.

When the operation mode changes, paying attention to the fact that the operation mode is always switched through the tape stop state even if it is instantaneous, the state where the tape is completely stopped is confirmed, and the CTL pulse Sa is generated. It is conceivable that the changeover switch 3 is changed at an impossible timing to solve the above-mentioned problem, but in reality, it is difficult to confirm the complete stop of the tape, and the changeover cannot be performed at such a timing. .

Further, in the case of the conventional device of FIG. 3, the frequency divider 2,
In addition to the control computer 4, the changeover switch 3 is required, and there is a problem that the number of parts is increased. An object of the present invention is to accurately measure the tape running amount without miscounting immediately after changing the operation mode with a simple configuration having a small number of parts.

[0018]

In order to achieve the above object, in the tape running amount counter device of the present invention,
A frequency divider for dividing the CTL pulse for tracking control into two and a computer for supplying the divided pulse of the frequency divider to an input port for interruption are provided.

The computer is provided with a mode discriminating means for discriminating the operation mode of the VTR, and based on the discrimination result of the discriminating means, the input port is triggered by one edge of the divided pulse in the operation mode of the tape high speed running. Is set to a one-edge interrupt port that generates an interrupt, and the input port is set to a two-edge interrupt port where an interrupt trigger is generated by both edges of the divided pulse when in the tape normal running operation mode such as playback and recording. Input port control means,

Due to the occurrence of the interrupt trigger of the input port, the tape running amount is measured by incrementing by 2 in the tape high-speed running operation mode, and is incremented by 1 in the tape normal running operation mode. And a counting calculation means for measuring the tape running amount.

[0021]

In the tape running amount counter device of the present invention constructed as described above, the changeover switch and the like which are formed by the frequency divider and the computer and correspond to the conventional pulse selection changeover switch are omitted.

Then, the frequency-divided pulse of the frequency divider is supplied to the input port for interruption of the computer, and when the computer is in the tape high-speed running operation mode by the input port control means, based on the result of the operation mode determination means. Sets the input port to the one-edge interrupt port, and sets the input port to the both-edge interrupt port in the normal tape running mode.

Further, by the input port interrupt trigger,
The counting operation means of the computer counts the tape running amount by counting up by 2 for each edge of the divided pulse in the tape high-speed running operation mode, and measures both the divided pulses in the tape normal running operation mode. 1 for each edge
Count up one by one and measure the tape running amount.

At this time, the frequency-divided pulse in the tape high-speed running operation mode has a frequency N times that of the normal tape running operation mode, so that the interrupt trigger generation intervals in both operation modes are the same.

From this, the tape running amount is measured under the same conditions as the conventional device, and the tape running amount is measured.

Further, the judgment of the operation mode and the setting of the interrupt trigger of the input port are both performed by the software processing of the computer, and there is no mechanical time delay as in the conventional device, and the operation mode can be changed. Since it is possible to determine by the computer whether or not the setting change of the input port interrupt trigger has been completed, an erroneous count is not generated immediately after the operation mode is changed, and the tape running amount is accurately measured.

[0027]

EXAMPLE One example will be described with reference to FIGS. In FIG. 1, the same reference numerals as those in FIG. 3 indicate the same parts, and the difference from the conventional device of FIG. 3 is that the changeover switch 3 of the same figure is omitted and the frequency dividing pulse Sb of the frequency divider 2 is used instead of the computer 4. The point is that a control computer 5 having a microcomputer configuration is supplied to the interrupt input port P _I.

The input port P _I is selectively switched between the rising edge and the rising and falling edges by the software port control.

Further, the computer 5 has a function of executing a VTR control main program, a mode discrimination program, a port control program and a tape running amount calculation interrupt processing program.

The mode discriminating program is incorporated in, for example, a part of the main program and is executed in the course of the main routine processing. By this execution, the mode discriminating means for discriminating the operation mode of the VTR is formed. This discriminating means is the VTR. Always monitor for automatic or manual changes in the operating mode of.

When the operation mode is changed, the port control program is executed to form the input port control means, and the control means determines the high speed running of the tape such as fast forward and rewind according to the determination result of the mode determining means. In the operation mode, the input port P _I is set to the one-edge interrupt port in which the interrupt trigger is generated by the one edge of the rising edge of the divided pulse Sb, and is input in the operation mode of the tape normal running such as reproduction and recording. The port P _I is set as a double-edge interrupt port in which an interrupt trigger is generated by both the rising and falling edges of the divided pulse Sb.

Further, each time an interrupt trigger of the input port P _I is generated, a hardware interrupt is generated in the computer 5, the interrupt processing program is executed to form a counting operation means, and this means is the input port P _I. 2 in the normal tape running mode due to the occurrence of the interrupt trigger of FIG.
As shown in (a), the tape running amount of the software is incremented by 1 at each rising and falling edge of the divided pulse Sb to measure the tape running amount, and the tape runs at high speed. In the operation mode, the tape counter is incremented by 2 at each rising edge of the divided pulse Sb to measure the tape running amount, as shown in FIG.

In FIG. 2, Ts indicates the timing at which measurement of the tape running amount is started by turning on the power of the VTR, changing the operation mode, etc., +1 and +2 indicate the count-up amount of the tape counter, ... Indicates the count value of the tape counter.

Therefore, the interrupt trigger of the input port P _I in both operation modes is generated under the condition of almost the same time interval as that of the conventional apparatus of FIG. 3, and the occurrence frequency of the interrupt trigger in the operation mode of high speed tape running. The increase is prevented as in the conventional device.

Furthermore, the count-up condition of the tape counter for each interrupt trigger of the input port P _I becomes the same as the count-up condition of the tape running amount of the conventional device, and the tape running similar to that of the conventional device is obtained by the count value of the tape counter. The quantity is measured.

The change of the interrupt trigger condition of the input port P _{I according} to the change of the operation mode is performed by the software processing of the computer 5 without a mechanical time delay element like the changeover of the changeover switch 3 of FIG. Since the setting of the interrupt trigger of the input port P _I is changed to be performed quickly, an erroneous interrupt trigger rarely occurs between the change of the operation mode and the completion of the change of the interrupt trigger condition.

In addition, the determination of the operation mode, the measurement of the tape running amount based on the interrupt trigger, and the port control of the input port P _I are all performed by the software processing of the computer 5, so that the operation trigger is changed from the change of the operation mode. Even if a pulse edge of the divided pulse Sb occurs until the change of the input pulse Pb is completed, at this time, the computer 5 causes the input port P _I
It is possible to discriminate whether or not the setting change of the interrupt trigger is completed, and it is possible to discriminate whether the interrupt trigger is valid or invalid based on the result of the discrimination and prevent the generation of an erroneous interrupt trigger.

Therefore, it is possible to accurately measure the tape running amount without checking that the running of the tape is completely stopped and preventing an erroneous count immediately after changing the operation mode.

The operation mode of the high speed tape running and the operation mode of the normal tape running are not limited to the fast-forwarding, rewinding, reproducing and recording of the embodiment. When applied to a camera-integrated VTR, for example, the operation mode of the tape normal running may be only the recording mode.

[0040]

Since the present invention is configured as described above, it has the following effects. The divided pulse Sb of the frequency divider 2 obtained by dividing the control pulse Sa for tracking control by 1/2 is supplied to the interrupt input port P _I of the computer 5, and the computer 5 determines the operating mode discriminating means based on the discrimination result. The input port control means sets the input port P _I to the one-edge interrupt port in the operation mode of the tape high-speed running, and sets the input port P _I to the both-edge interrupt port in the operation mode of the tape normal running. To do.

Further, by the trigger of the interrupt of the input port P _I , the counting operation means of the computer 5 counts up by 2 for each edge of the divided pulse Sb in the operation mode of the tape high-speed running to increase the tape running amount. In the normal tape running mode, the tape running amount is measured by incrementing by 1 for each edge of the divided pulse Sb.

At this time, the frequency-divided pulse Sb in the tape high-speed running operation mode has a frequency N times that of the tape normal running mode, so that the interrupt trigger generation intervals in both operation modes are the same, and the tape high-speed operation is performed. If the count is incremented by 2 for each trigger in the running operation mode and incremented by 1 for each trigger in the tape normal running operation mode, the tape running amount is counted under the same conditions as in the conventional device. Is performed and the tape running amount is measured.

Further, the judgment of the operation mode and the setting of the interrupt trigger of the input port are both performed by the software processing of the computer 5, and there is no mechanical time delay as in the conventional apparatus, and the change of the operation mode is made. Since the computer 5 judges whether or not the setting change of the interrupt trigger of the input port P _I based on the above is completed, an erroneous count is not generated immediately after the change of the operation mode, and the tape running amount can be accurately measured. Done.

Therefore, with a simple structure in which the number of parts formed by the frequency divider 2 and the computer 5 is small, the tape running amount can be accurately measured without erroneous counting immediately after changing the operation mode.

[Brief description of drawings]

FIG. 1 is a block diagram of an embodiment of a tape running amount counter device of the present invention.

2A and 2B are waveform diagrams of divided pulses for explaining the operation of FIG. 1, respectively.

FIG. 3 is a block diagram of a conventional device.

4A and 4B are waveform diagrams of a control pulse and a divided pulse for explaining the operation of FIG.

[Explanation of symbols]

Input port Sa control pulse Sb division pulse 2 frequency divider 5 for controlling computer P _I interrupt

Claims (1)

[Claims] 1. A video tape recorder for generating a control pulse for tracking control having a frequency N times as high as that of a normal tape running during reproduction, recording, etc. during fast tape running such as fast forward and rewind. In a tape running amount counter device for measuring a tape running amount by a counting operation based on the above, a computer in which a frequency divider for dividing the control pulse by 2 and a divided pulse of the frequency divider are supplied to an input port for interruption. And a mode discriminating means for discriminating an operation mode of the video tape recorder, and based on a discrimination result of the discriminating means, the input is made when the tape is in a high-speed operation mode such as fast forward or rewind. Set the port as a one-edge interrupt port where an interrupt trigger is generated by one edge of the divided pulse and Input port control means for setting the input port to both edge interrupt ports in which an interrupt trigger is generated by both edges of the divided pulse in an operation mode of tape normal running such as recording, When a tape trigger is generated, the tape running amount is measured by counting up by 2 in the tape high-speed running operation mode, and is incremented by 1 in the tape normal running mode by measuring the tape running amount. A tape running distance counter device, comprising: