JPS62205495A - Mode display circuit - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a mode display circuit.

[Summary of the invention]

This invention provides a tape recorder, etc., which has an operating mode changeover switch and an operating mode display LED when its operating mode is displayed, for example, by an LED.
By establishing a special connection relationship between the two, the number of external terminal pins of the IC to which the changeover switch and display LED are connected is reduced.

[Conventional technology]

For example, a tape recorder has operating modes such as play mode, record mode, fast forward mode, rewind mode, etc. If the system controller that controls these operating modes is converted to The changeover switch and the display element in the operating mode can be connected as shown in FIG. 8, for example.

That is, in the same figure, (ll indicates an IC for the system controller, and the external terminal pin Pi of this IC (ll)
For example, a playback switch Sp is connected to the external terminal bin P.
An LED (Dp) is connected to j.

Also, although not shown, other mode switches and LEDs
are also connected in the same way, as well as a plunger or the like for setting the tape recorder in a predetermined operating mode.

Then, an IC (system controller) (1) detects whether the playback switch Sp is on or off, and when the switch Sp is off, a mode other than the playback mode is set by the output of the IC (1), and the pin Pj is set to " H” level and the LED (Dp) is turned off. However, when the playback switch Sp is on, the playback mode is set by the output of the IC (11), and the pin Pj is set to “
The LED (Dp) is turned on at L'' level, thus indicating that the mode is playback mode.

However, such an Ic(11) and connection requires two pins Pi, Pj on the IC(11) for switches t, p and LED (Dp), two each for other operating modes as well. The external terminal pin is set to d. Therefore, in this case, the number of external terminal pins of the IC (11) increases, so (i) the external size of the IC (1) is increased.

(ii) The number of external terminal pins is reduced by keeping the external size of IC (1) small and giving up some functions.

(iii) I C (keeping the external size of 11 small,
Other functions are included, but the mode is not displayed using LEDs.

This would go against the basic and greatest features of ICs, which are small size, high performance, and multi-function.

Therefore, as shown in FIG. 9, a switch Sp is connected to pin Pi.
It is also conceivable to connect an LED (Dp).

That is, by doing this, when the regeneration switch Sp is off, the pin Pi is at the L'' level, and therefore, the output of the IC (υ) puts it into another operating mode, and t and ED' (Dp) are turned off. However, when the switch sp is on, the pin Pi goes to H'' level, so the output of IC (1) sets the playback mode, and the LED (Dp) lights up, indicating the playback mode. This will be displayed.

1 such IC (according to 11 and connections, 1
Only one external terminal pin is required for each set of mode switch and display LB[), and the number of external terminal pins can be avoided without reducing the number of external terminal pins. Therefore, without losing its features as an IC,
You can get many functions.

[The invention aims to solve the problem of MI R, f-3, but in response to switching of the mode switch, two LP,
If the mode is displayed by selectively lighting one or the other of D, the connection will be as shown in FIG. 1O.

In other words, the figure shows the case of a tape recorder that also has a reverse playback function, and the on/off of the direction switch Sd is (C
(1) and is detected by switch S (1) in playback mode.
When is off, the output of rc(11 sets E upward playback mode, pin Pj is set to "L" level, pin Pk is set to "■(" level), and ζLED(Df)
lights up, LED (Dr) disappears, and therefore L
ED (Df) indicates that the playback mode is in the forward direction.

Furthermore, when switch Sd is on in playback mode,
The reverse play mode is set by the output of lCf1), pin Pj is set to 'H' level, pin Pk is set to 'L' level, LED (Df) is turned off, LED (Dr) is illuminated, and therefore , LED (Dr) indicates that it is the reverse playback mode.

Therefore, in the case of this IC (1) and connection, one mode switch Sd, two ED(Dr, Df
) and three external terminal pins Pi” on the IC (11).
Pk is required, and the above-mentioned (i) to (iii)
) problem will arise.

This invention attempts to solve these problems.

[Failure to solve the problem]

Therefore, in this invention, the mode switch and the two
For example, the two display elements are connected as shown in FIG.

[Effect]

Only one of the display elements lights up according to whether the mode switch is turned on or off.

(Example) In FIG. 1, α [is a system control IC
This includes at least a system control circuit (11), which is an original circuit, and a constant current source (12). Also, for this ICQω,
Predetermined external terminal pins P1 to Pn are provided (only bins P1 to P3 are not shown), but bin P1 is a power supply bin, and bin P
2 is the grounding bin, and the bin P1 is connected from the power terminal T1? Ii
While the source pressure is supplied, the bin P2 is grounded.

The circuit (11) is supplied with the power supply voltage of the terminal T1 through the bins Pl and P2.

Furthermore, the bin P3 is a mode bin, which is connected to the mode input of the control circuit (11) and is connected to the constant current 1jJi? The output end of (12) is connected.

In addition, a constant current source (12) is connected to the control circuit (11).
A control signal rc of the output current Io is supplied to the output current Io.

In this case, the signal 1c turns off the current 1o when the potential of the bin P3 is at the "L" level, and turns on when the potential at the bin P3 is at the ')]' level.

Further, a mode switch S1 is connected between the bin P3 and the ground, and an LED is connected between the terminal T1 and the ground.
(Dl, D2) are connected in series, and the midpoint of the connection is connected to bin P3 through resistor R1.

Note that other mode switches, loads, etc. are connected to the remaining bins P4 to Pn of TC(1ω, although not shown).

According to such a configuration, when the switch S1 is turned on, the bin P3 becomes the 9 level, which is detected by the control circuit (11), and the control circuit (11) switches to the first mode. be done.

Also, since the switch S1 is on, the terminals 'r, -LF,
A current flows through the line D (OL) -> resistor R1 -> switch S1 - ground, and the LED (Dl) lights up. Furthermore, by selecting the resistor R1 and the current flowing through it, the voltage across the terminals of the resistor R1 will be LE
The lighting voltage of D (D2) (generally 1.2 V −1,
4V), and therefore, in summer, ED (
D2) goes out.

Furthermore, since the bin P3 is at the "L" level, the voltage 1o is turned off by the signal 1c, thereby saving power.

In this way, when the switch S1 is on, the control [r'1vIr (11) is controlled to the first mode, the LEI) (Dl) is lit, and the LED (D2) is turned off to switch to the first mode. It is shown that

On the other hand, when switch S1 is turned off, terminal 'l''
+ = LF, D (Dt) → Resistor R1 → Control circuit (11) - Current flows through the ground line, and the pin P
The potential of No. 3 is momentarily raised to the "I" level side. Then, this is detected by the control circuit (11), and the No. 21 control circuit (11) is set to the second mode.

Then, when the potential of the bin P3 becomes "H" level, the signal 1c causes ? ! Since the voltage 1o is turned on and flows into the control circuit (11), the potential of the bin P3 becomes even higher and is completely held at the "I(" level).

Also, at this time, when the bin P3 reaches the II'' level, the L
The voltage between the terminals of ED (DL) becomes lower than the lighting voltage, the LED (Dl) turns off, and the LED (Dl) turns off.
Since the voltage between the terminals of D2) is higher than that of the lighting type JE, the LED (D2) lights up.

In this way, when the switch S1 is off, the control circuit (11) is controlled to the second mode, and the L
F and D (Dl) are turned off, and the LED (D2) is turned on to indicate the second mode.

As described above, according to the present invention, the system control circuit (11) is switched to the first or second mode by turning on/off the switch S1, and the corresponding LED (D+) or LED (D2) lights up. However, in this case, especially according to the present invention, the output of the switch S3 can be taken in by the minimum one external terminal pin P3, and at the same time, the output of the two LEDs (D+
, Dz) can be controlled. Therefore, all of the problems (i) to (iii) mentioned above can be solved.

In the example shown in FIG. 2, the constant current source (12) always outputs a current to. And between the terminal T1 and ground, there is an LED (DI) and a resistor Rz.

R2, LF, and D (Dz) are connected in series, and the resistor Rr
, R2 are connected to bin P3.

Therefore, in this example, L, F, D (D+
.

Since the current flowing through the terminal Dz) is limited by the resistors Rt and R2 separately, the power supply voltage Vcc of the terminal TL
But, Vcc≧2Vp +I (RL +R2)Vp ;L
Stipple voltage 1 of ED (Dt, Dz): LED (
Dt , Dz ) and ζ also
(Dz, Dz) are never lit at the same time.

Further, in this example, the current I of the constant current dot (12).

Therefore, there is no need to change ζ1 and the system control I/roll circuit (12) from the conventional one, which is simple.

In the example shown in FIG. 3, the constant current source (12) is composed of complementary transistors Ql and Q2 and a resistor R3. Therefore, when the switch S1 is on, the pin P3 becomes "L" level, the control circuit (11) becomes in the first mode, the transistor Q2 is turned off, and the transistor Q1 is also turned off. Current ro is turned off. Also, at this time, the LED (
D+) is lit, and LED (Dz) is off.

On the other hand, when switch S1 is off, terminal TI-=L
E D (Dt) -Resistance'aRL-Peer P3-
JIL anti-t4 R3→A current flows in the line of the base of transistor Q2, turning on transistor Q2, which turns on transistor QL, and pin P3 becomes "
It becomes H” level.

Furthermore, since the bin P3 is at the "H" level, the LED (Dl) disappears and the LED (Dz) lights up.

In the example shown in FIG. 4, the switch S1 is of the transfer type. Therefore, in the state shown in the figure, the bin P3 is at the ``L'' level, the control circuit (11) is in the first mode, and the
ED (DL) is the month of birth, and LED (Dz) goes out.

Furthermore, when the switch S+ is in the opposite state as shown in the figure, the bin P3 becomes "H" level, and the control circuit (11)
becomes the second mode, and the LED (Dl) turns off and the LED (LEI) (Dz) turns on.

In the example shown in FIG. 5, two bins P3°R4 are used. That is, when the switch S1 is on, the control circuit (11) becomes the first mote because the bin P4 becomes "H level". Also, at this time, the transistor Q is connected through the switch SL and the resistor R3.
2 is forward biased and turned on, and transistor Ql is reverse biased and turned off. Therefore, Hif Pt HA” L 'L/</L/to?), L
ED (Dt) lights up, and LED (Dz) disappears.

Furthermore, when the switch S1 is off, the bin P4 is “L”.
” level side, and this causes the control circuit (11
) is set to the second mode, and the constant current circuit (12
) is turned on and current To is caused to flow, thereby turning on transistor Q1 and turning off transistor Q2.

Therefore, the bin P3 becomes "H" level, and the LED (
Dt) is turned off, and the LED (Dz) is turned on. Furthermore, the current Io flows, so that the bin P4 is held at the "L" level.

In the example shown in FIG. 6, when the switch S1 is on, the bin P3 becomes the 11 H1 level, and the control circuit (11) is placed in the first mode. Also, bottle P3
Since is at the "H" level, LP, 1) (Dl) is turned on, transistor Qs is turned on, transistor Q2 is turned off, and 2, F, I) (Dz) are turned off.

However, when switch S1 is off, bin P3 is “
11m level, and the control circuit (11) is at the second level.
mode. Further, since the pin P3 is at the "'L" level, the LED (DL) goes out, the transistor Q1 is turned off, and the transistor Q is turned on, so that the LED (D2) is turned on.

In the example shown in FIG. 7, when the switch S1 is in the state shown in the figure, the pin P4 is at the "H" level, so the control circuit (11) is in the first mode, the transistor Q1 is on, and the transistor Q2 is in the first mode. Therefore, L l', D (D*) are lit, and the LED
(D2) is turned off.

However, when the switch S1 is in the opposite state as shown in the figure, the pin P4 becomes "L level", so the control circuit (1
1) is set to the second mode, and the transistor Q
1 is off and transistor Q2 is turned on, so the LED (Dl) is turned off and the LED (D2) is turned on.

Note that in the above description, the constant current source (12) may be replaced by a resistor. In addition to the mode switching of forward playback/reverse playback of a tape recorder and its 7-key display, it is also capable of recording/playback, fast forwarding/rewinding, radio of a tape recorder with a radio/AM of a tape recorder, and radio.
/l”M, TV VI-[F/U HF etc.2
The present invention can be applied to any case where two modes are to be switched and the mode is to be displayed.

〔Effect of the invention〕

The number of external terminal pins to which the LED, which does not require a mode switch or a mode table, is connected can be reduced without reducing the number, and therefore, all of the problems in items (i) to (iii) can be solved.

[Brief explanation of drawings]

1 to 7 are connection diagrams of an example of the present invention, and FIGS. 8 to 10 are diagrams for explaining the same. αω is an IC, (11) is a system control circuit, (
12) is a constant current circuit, Sl is a mode switch, and Dx. D2 is an LED. All a circuit closed Diagram 1 All A water - Circuit diagram Diagram 2 Whole, body / 1 box ■ Customer record 3 Diagram I Tree #Ro 1 Each leap Diagram 4 All rice / 10 routes Fifth diagram #10 Fukiko Figure 8 + vce Figure 7 Zenbayashi circuit diagram Zenbayashi 1 road] Figure 8
Figure 9

Claims (1)

[Claims] A mode switch, a control circuit to which the output of the mode switch is supplied, a first display element connected to a first potential point, and a second display element connected to a second potential point. The control circuit is selectively switched between a first mode and a second mode by switching the mode switch, and the first display element and the second display element are selectively switched between the first mode and the second mode. A mode display circuit that displays the selected operating mode of the control circuit.