JPH0530936U - Keyboard controller - Google Patents

Abstract

(57) [Abstract] [Purpose] To obtain a keyboard control device excellent in operation functionality such that the keyboard unit is always initialized each time the power of the CU unit is turned on / off repeatedly. [Structure] A current of a transistor 204 which operates according to an output logic level of a multivibrator 201 that oscillates with a power supply Vss as a trigger by a reset signal output by connecting a keyboard unit 1 and this CU unit 2 to a cable and turning on the power supply of the CU unit 2. A power supply control circuit that supplies Vss to the keyboard unit 1 side by controlling ON / OFF of the relay 205 driven by the CU unit 2 side is provided.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a keyboard control device, and more particularly to a keyboard control device for a keyboard unit provided on the control unit side of a circuit of a power supply line of a signal line connecting a control unit with a cable.

[0002]

[Prior Art]

 FIG. 2 is a schematic block diagram showing a circuit configuration of a conventional keyboard control device. The figure shows the connection relationship between the keyboard unit and the control unit (hereinafter referred to as CU unit) that controls the keyboard unit. In the keyboard unit 1, the power supply voltage Vss is supplied from the CU unit 2 through the Vss and 0V lines of the signal line 3. It is designed to operate after receiving the signal.

Further, a master flip-flop 4 and a slave flip-flop 5 are provided in the CU unit 2 and the keyboard unit 1, respectively, and these are composed of a plurality of negating circuits by a data line of a signal line 3 and a clock line. It is connected via an element (inverter) 6 so that the keyboard unit 1 and the CU unit 2 can communicate with each other. In addition to the control of the keyboard unit 1 as described above, the CU section also serves as an interface between the keyboard unit 1 and a main unit (not shown) including, for example, a CPU, and the keyboard unit 1 (not shown). It has the function to transfer the manually input data from the main unit.

The keyboard unit 1 initializes its controller when the power supply voltage Vss supplied from the CU unit 2 rises. That is, when the power source (not shown) of the CU unit 2 is turned on, Vss rises, and this is also supplied to the keyboard unit 1 via the signal line Vss, 0V. Along with this, a keyboard reset signal is input to the controller of the keyboard unit 1 with a delay due to the time constant determined by the resistance R and the capacitor C of the initialization circuit 7 provided on the keyboard unit 1 side, which causes the controller to initialize. It has been adapted.

[0005]

[Problems to be solved by the device]

 In the conventional keyboard control device as described above, when the power supply to the CU unit is repeatedly turned on / off in a short time, if the capacitor C of the initialization circuit provided in the keyboard unit cannot be discharged in time, the power supply voltage Vss is reduced. Since the reset signal is not generated despite the change of rising and falling, the keyboard unit is not initialized, and in the worst case, the CU unit and the keyboard unit cannot be synchronized. As a result, there was a problem that communication between the two parties could not be performed and keyboard input could not be performed.

Then, in order to avoid the above-mentioned inconvenience, the operator is provided with an operational restriction such that the power on / off operation is performed at intervals of a certain time or more. The point was that it was necessary.

The present invention has been made to solve the above-mentioned problems, and the keyboard unit is always initialized each time the CU power is turned on and off repeatedly for a short time. The object is to provide a keyboard control device having excellent operation functionality, so to speak.

[0008]

[Means for Solving the Problems]

 A keyboard control device according to the present invention is a multivibrator which connects a keyboard unit and this control device with a cable and which oscillates with a power supply voltage Vss as a trigger by a reset signal output at the same time when the power of a CU unit is turned on. A power supply control circuit for supplying a power supply voltage Vss to the keyboard side is provided in a power supply line on the CU section side by on / off controlling a relay driven by the presence or absence of a current of a transistor which operates according to a logic level output by .

[0009]

[Action]

 In the present invention, the power supply control circuit including the multivibrator and the relay driven by the current of the transistor operating at this output logic level is provided on the CU section side so that the power supply to the keyboard unit is controlled by the CU section. When the output pulse of the multivibrator that oscillates with the reset signal at power-on is cut off and the control signal becomes logic level 1, the transistor turns on and the contact of the relay closes. As a result, power is supplied to the keyboard unit, the initialization circuit of the keyboard unit operates normally, and the reset signal is input to the keyboard controller. Therefore, the keyboard unit is always initialized when the power is turned on.

[0010]

【Example】

 FIG. 1 is a schematic block diagram showing a circuit configuration of a keyboard controller according to an embodiment of the present invention. In FIG. 1, the same reference numerals as those shown in the conventional example of FIG. 2 are the same components, and therefore the description thereof will be omitted.

First, when the power is turned on, a power supply unit (not shown) of the CU unit 2 outputs a reset signal indicated by RESET-N until the power supply voltage Vss becomes a normal value. This reset signal is input to the element that should not malfunction while Vss is indeterminate so that it does not operate.

When a reset signal is input to the multivibrator 201, a pulse is output with a time constant determined by the capacitor 202 and the resistor 203. The pulse width to be output is obtained by multiplying the coefficient x the capacitance of the capacitor x the resistance value, and it is in the range of several µS to several seconds. This can be set arbitrarily by changing the capacitance and resistance value of the capacitor. Here, the values of the capacitor C and the resistor R are selected so that the capacitor C of the initialization circuit 7 of the keyboard unit 1 can be sufficiently discharged.

On the other hand, the pulse output from the multivibrator 201 becomes a power supply control signal for the keyboard unit 1. That is, while the pulse is being output, the control signal becomes the logic level 0, the transistor 204 controlling the relay 205 is turned off, and the contact of the relay 205 is opened. During this time, the power supply voltage Vss is not supplied to the keyboard unit 1 and the capacitor C of the initialization circuit 7 of the keyboard unit 1 is discharged.

Next, when the pulse is cut off and the control signal becomes the logic level 1, the transistor 204 is turned on and the contact of the relay 205 is closed. As a result, the power supply voltage Vss is supplied to the keyboard unit 1, the initialization circuit 7 of the keyboard unit 1 operates normally, and the reset signal is input to the keyboard controller, that is, the slave flip-flop 5.

In this way, when the power is turned on / off repeatedly, the reset signal is always output when the power is turned on, so that the initialization circuit 7 operates and the keyboard unit 1 is always reset.

The same effect can be obtained by using a transistor or an FET instead of the relay 205. Also, instead of the multivibrator 201, a computer that controls the CU unit 2 may measure a required time and a control signal may be controlled by a command of a computer.

[0017]

[Effect of the device]

 As described above, according to the present invention, since the power supply control circuit is provided in the power supply signal line on the CU side so that the keyboard unit is always initialized when the power supply of the CU part is turned on, there is no restriction on powering on. It is possible to provide a keyboard control device that does not hinder operability.

[Brief description of drawings]

FIG. 1 is a schematic block diagram showing an embodiment of a keyboard control device according to the present invention.

FIG. 2 is a schematic block diagram showing a configuration of a conventional keyboard control device.

[Explanation of symbols]

 1 Keyboard Unit 2 CU Section 3 Signal Line 4 Master Flip-Flop 5 Slave Flip-Flop 6 Negative Circuit Element 7 Initialization Circuit 201 Multivibrator 202 Capacitor 203 Resistor 204 Transistor 205 Relay

Claims (1)

[Scope of utility model registration request] 1. A keyboard control device in which a keyboard unit and a control unit for controlling the keyboard unit are connected by a cable, and a multivibrator which oscillates at a power supply voltage Vss by a reset signal output at the same time when the power supply of the control unit is turned on. A power supply circuit for supplying the above-mentioned power supply voltage Vss to the keyboard side and a power supply circuit for supplying the above-mentioned power supply voltage Vss to the keyboard side are connected to the power supply line of the above-mentioned control section by controlling ON / OFF of a relay driven by the presence or absence of an operating current of a transistor which operates according to the logic level output by the multivibrator A keyboard control device characterized by being provided.