JP3736810B2 - Tape counter - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to a tape counter suitable for use in, for example, an audio cassette deck.
[0002]
[Prior art]
For example, in an audio cassette deck, a tape counter is configured by detecting the rotation of a reel base. In other words, the display value of the tape counter is changed, for example, by one count for the count value of the tape counter for two revolutions of the reel base. Whether to increase or decrease the count value is determined according to the mode of the cassette deck. This count value is displayed on a liquid crystal display or the like.
[0003]
The rotation of the reel base is generally detected by optical rotation detection means such as a photo interrupt. From this rotation detection means, a fixed number of rotation detection clocks are generated per one rotation of the reel base. Conventionally, the rotation detection clock is input to the I / O port of the microcomputer, and the microcomputer detects an edge of the rotation detection clock or a change in level between high level and low level, and outputs the detected output. The number of rotations of the reel base is detected and the display value of the tape counter is determined.
[0004]
[Problems to be solved by the invention]
By the way, when using a rotation detection means that generates, for example, 8 clocks per rotation of the cassette deck reel base, a normal speed tape top (the reel tape winding radius is the largest) is used. The period of the rotation detection clock is, for example, about 800 msec, and the period of the rotation detection clock at the fast forward / rewind tape end is 7 msec.
[0005]
For this reason, it is necessary to monitor the rotation of the reel base at any time with a time accuracy of 7 msec or less in terms of software in the microcomputer. Therefore, when trying to perform high-speed control of the operation of the tape counter and other operations of the cassette deck with one microcomputer, an expensive very high-speed microcomputer is required. Therefore, conventionally, two microcomputers have been used.
[0006]
An object of this invention is to provide the tape counter which can eliminate the above fault.
[0007]
[Means for Solving the Problems]
In order to solve the above problems, a tape counter according to the present invention is
Rotation detection means for generating a fixed number of clocks per rotation of the reel base;
A microcomputer that receives a clock from the rotation detection means and generates a display value of the tape counter;
Display means for displaying a display value of the tape counter from the microcomputer ;
Consists of
The microcomputer is
A plurality of types of tasks are sequentially performed one task at each first fixed time, and are repeatedly performed at a second fixed time that is a length of the task times the first fixed time. And a tape counter display task for generating a display value of the tape counter and outputting it to the display means as one of the plurality of tasks.
As a software function of the microcomputer,
A counter means for counting a clock from said rotation detecting means,
Detecting means for detecting the number of clocks within the first predetermined time from the count value of the counter means at every first fixed time for executing each of the tasks and cumulatively adding the detected number of clocks ; ,
When the tape counter display task is executed, the number of clocks within the second predetermined time is detected from the number of clocks cumulatively added by the detection means, and the tape is calculated from the detected number of clocks within the second fixed time. Display value determining means for determining the display value of the counter;
It is characterized by providing.
[0008]
[Action]
In the above configuration, the rotation detecting hands stage so generates a clock of a predetermined number per rotation of the reel base, it is possible to detect the reel stand rotation speed from the count value of the clock.
[0009]
That is, in the counter hand stage, counts the clock of the rotation detecting hand stage or al. The detection means detects the number of clocks within the first fixed time from the count value of the counter means at each first fixed time for executing each of the tasks performed by the microcomputer, and the detected clock number. Cumulative addition.
The display value determining means detects the number of clocks within a second fixed time from the number of clocks cumulatively added by the detecting means during execution of the tape counter display task, and the detected number of clocks within the second fixed time. The display value of the tape counter is determined from the above.
[0010]
The number of clocks within the second fixed time is proportional to the number of rotations of the reel base . Therefore, in the display value determining means, the tape counter display value is calculated from the number of clocks in the second predetermined time.
[0011]
The tape counter display value is supplied to the determined hand-stage or we display hand stage is displayed as a count value of the tape counter.
[0012]
【Example】
FIG. 1 shows an embodiment of a tape counter according to the present invention. This example is an input for a function (FRC function; free running counter function) that can always count a clock input to a predetermined input port. This is an example when the present invention is applied to a cassette deck having a port and a microcomputer with a built-in counter function.
[0013]
A microcomputer having an FRC function is called an FRC capture unit, and can constantly count a clock input from an input port even while the microcomputer is performing other tasks. The interval time can also be measured simultaneously.
[0014]
In FIG. 1 , reference numeral 11 denotes a reel base. For example, a light reflecting surface 12a and a non-reflecting surface 12b are alternately arranged on a rotation plane of the reel base 11 (for example, a surface opposite to the surface on which the reel is placed). Reflective paper 12 formed at equiangular intervals is affixed. In the case of this example, the reflecting paper 12 is divided into, for example, 16 in the circumferential direction, and the light reflecting surface 12a and the non-reflecting surface 12b are alternately formed.
[0015]
A photo interrupter including a light emitting diode 13 and a phototransistor 14 is provided at a position of the reel base 11 facing the reflective paper 12. Therefore, when the DC voltage + B is applied to the power supply terminal 15, the light from the light emitting diode 13 enters the reflecting paper 12 of the reel base 11, and when the incident position is the reflecting surface 12a, the reflected light enters the phototransistor 14. Incident light turns on the phototransistor 12. On the other hand, when the incident position of the light from the light emitting diode 13 is the non-reflecting surface 12b of the reflecting paper 12, since the light is not incident on the phototransistor 14, the phototransistor 14 is turned off.
[0016]
Therefore, a negative rotation detection pulse is obtained at a connection point between the phototransistor 14 and the resistor 16 at a cycle corresponding to the rotation speed of the reel base 11. Then, eight rotation detection pulses are generated per one rotation of the reel base 11. This pulse is supplied to the inverting transistor 17 and is taken out as a positive clock pulse SC to the collector of the transistor 17, and this clock SC is connected to the FRC of the microcomputer 20 having the FRC function via the waveform shaping amplifier 19. To the input port 20p.
[0017]
In the microcomputer 20, the input clock SC is always counted by the FRC function, and the software processing as shown in FIG. 2 is performed, and as described later, the count value of the clock SC is set every certain time, in this example, every 2 msec. Further, the display value of the tape counter is determined as one of a plurality of main tasks (work) in the main routine. Then, the tape counter display value obtained as a result is sent to the display drive circuit 21 every predetermined time. The display drive circuit 21 drives the liquid crystal display 22 to change the display value of the tape counter every 64 msec, for example.
[0018]
FIG. 2 is a flowchart of a main routine executed by the microcomputer 20. In this example, in this example, the 16 main tasks are sequentially performed one task at a time every 2 msec, and one main routine is completed in 32 msec.
[0019]
That is, first, in step 101, it is determined whether or not 2 msec has elapsed. When it is determined that 2 msec has elapsed, the process proceeds from step 101 to step 102. In step 102, the count value of the clock SC at that time is detected, and the number of clocks SC input to the input port 20a within a certain time, that is, 2 msec, is calculated from the difference between this count value and the count value of the clock SC 2 msec before. To detect. Then, the count value obtained by increasing the previous count value by the number of clocks is read into, for example, a FIFO memory.
[0020]
In this step 102, if there is a command for automatic cueing of a song (referred to as AMS (registered trademark)) by detecting a silent period, for example, processing is also performed.
[0021]
Next, the process proceeds from step 102 to step 103, and when there is an input of a command from the remote controller, processing according to the input is performed. Then, the process proceeds from step 103 to step 104.
[0022]
As described above, in the main routine, 16 types of main tasks are sequentially performed one task every 2 msec. Therefore, in step 104, the number of tasks to be performed this time is determined from the 16 types of main tasks. That is, the next task after the last task is determined. If it is determined that the task is the first task, the process proceeds from step 104 to step 105a. If it is determined that the second task is present, the process proceeds from step 104 to step 105b, and so on. If so, the process proceeds from step 104 to step 105p.
[0023]
Then, in one of the steps 105a to 105p of the 16 types of main tasks, for example, step 105f, the number of revolutions of the reel base 11 is detected from the count value of the clock SC read into the FIFO memory in step 102. The display value of the tape counter is determined from the operation mode of the motor drive system. Here, the timing for referring to the count value of the clock SC stored in the FIFO memory in step 105f is every 32 msec since step 105f is executed in 32 msec. In step 105f, the rotational speed of the reel base is detected from the count value of the clock SC of the FIFO memory 32 msec ago and the count value of the clock SC of the FIFO memory this time, and the display value of the tape counter is determined. In this case, the display value is determined so that the display value of the tape counter is changed by one count when the number of clocks SC that has changed during the previous 32 msec from the previous time is equal to two revolutions of the reel base 11.
[0024]
When the main task process of one step selected from the 16 types of main tasks is completed, the process proceeds to step 106 from that step. In step 106, main processing of the motor drive system is performed. Next, the process proceeds from step 106 to step 107. In step 107, the main processing in the tuner attached to the cassette deck of this example, for example, processing such as channel selection is performed.
[0025]
Following this step 107, the routine proceeds to step 108 where the main processing of the attached CD player is performed. After step 108, the process returns to step 101, and after 2 msec, step 102 and subsequent steps are repeated. In this way, the 16 main tasks are sequentially executed every 2 msec.
[0026]
In this way, the main routine operates with 32 msec that completes execution of the 16 types of main tasks as one cycle. Then, in one of the 16 types of main tasks, processing for transferring the display value data of the tape counter determined in step 105f to the display drive circuit 21 is performed.
[0027]
For example, the display drive circuit 21 changes the display value every 64 msec in the minimum time. When the display value change timing is not reached, the display value change value is held, and when the change timing comes, the actual display value is rewritten and changed.
[0028]
In the above example, the FRC capture unit has a function capable of simultaneously measuring and recording the time interval of the input clock SC as described above. Therefore, by using this function, the remaining tape amount can be judged and displayed from the information on the tape hub diameter and the tape thickness. This is because the period of the rotation detection clock SC of the reel base 11 corresponds to the rotational angular speed of the reel base. When the tape speed is constant as in the normal running mode, the rotational angular speed of the reel base 11 is This is because it corresponds to the tape winding radius of the reel.
[0029]
In the above example, the tape counter is realized by detecting the number of rotations of one of the supply side reel stand and the take-up side reel stand. By detecting the rotation speed, a so-called linear tape counter can be measured.
[0030]
Moreover, although the Example described above is an example at the time of using the microcomputer which has a FRC function, even if it is a microcomputer which does not have this FRC function, a counter is connected via an I / O port, A similar effect can be obtained by supplying the clock SC to the counter and reading the count value of the counter every 2 msec.
[0031]
【The invention's effect】
As described above, according to the present invention, the clock is not directly detected by the microcomputer, but the clock is counted by the counter, and the count value is read at regular intervals. The computer can perform other controls such as the operation of the tape counter and the motor drive system. In particular, when a microcomputer having an FRC function is used, the effect of the present invention is remarkable.
[0032]
In the present invention, the tape counter display task is performed every second constant time. The count value of the counter means for counting the clock from the rotation detecting means is taken every first constant time, and the taken count is taken. From the value, the number of clocks within the first fixed time is detected, and the detected number of clocks is cumulatively added.
[0033]
Therefore, the count value of the counter means within the second constant time is a count value that is cumulatively added every first constant time, and the count value of the counter means is captured only at the timing of every second constant time. The effect that the accuracy is improved as compared with the case of detecting the count value within the second fixed time can be expected.
[Brief description of the drawings]
FIG. 1 is a block diagram of an embodiment of the present invention.
FIG. 2 is a flowchart for explaining the operation of the main part of one embodiment of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1,11 Reel stand 2 Rotation detection means 3 Counter means 6 Clock number detection means within fixed time 7 Tape counter display value determination means 8 Display means 13 Light emitting diode 14 Phototransistor 20 Microcomputer 22 Liquid crystal display

Claims (2)

Rotation detection means for generating a fixed number of clocks per rotation of the reel base;
A microcomputer that receives a clock from the rotation detection means and generates a display value of the tape counter;
Display means for displaying a display value of the tape counter from the microcomputer ;
Consists of
The microcomputer is
A plurality of types of tasks are sequentially performed one task at each first fixed time, and are repeatedly performed at a second fixed time that is a length of the task times the first fixed time. And a tape counter display task for generating a display value of the tape counter and outputting it to the display means as one of the plurality of tasks.
As a software function of the microcomputer,
A counter means for counting a clock from said rotation detecting means,
Detecting means for detecting the number of clocks within the first predetermined time from the count value of the counter means at every first fixed time for executing each of the tasks and cumulatively adding the detected number of clocks ; ,
When the tape counter display task is executed, the number of clocks within the second predetermined time is detected from the number of clocks cumulatively added by the detection means, and the tape is calculated from the detected number of clocks within the second fixed time. Display value determining means for determining the display value of the counter;
A tape counter comprising: The microcomputer has a function of always counting a clock input to a predetermined input port, and the clock from the rotation detection means is input to the microcomputer through the predetermined input port.
The tape counter according to claim 1 .

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