KR100259975B1 - Remote controller - Google Patents

Abstract

The remote control disclosed herein includes an infrared diode; A key matrix having a plurality of keys for generating a code signal corresponding to the selected key; And a microprocessor unit having a first terminal to which the key matrix is connected and a second terminal to which the infrared diode is connected, and directly driving the infrared diode in response to the code signal to generate an infrared signal.

Description

REMOTE CONTROLLER

The present invention relates to a remote controller, and more particularly, to a microprocessor unit or a microcomputer in which a driving circuit for driving an infrared ray light-emitting diode (LED) is integrated therein. It relates to a remote controller having a.

Remote controllers generally have many keys that provide dozens of functions, whereby they can select those functions at a remote location from the equipment to be controlled. TV, videocassette recorder, disk player, air conditioner that can be controlled by a remote user in various modes via a remote controller that generates infrared ray signals ), And other kinds of things.

1 is a block diagram of a remote controller according to the prior art. The conventional remote controller 1 has a key matrix 10, a microprocessor unit 20 (or microcomputer), and one LED connected as shown in FIG. (32), an NPN transistor (34), and an infrared ray outputting section (30) consisting of one resistor (36).

The remote controller 1 of FIG. 1 used for the above-mentioned electronic device generates a command signal coded in a specific format corresponding to an operation designated by a user, and in response to the command signal, the infrared output unit. NPN transistor 34 of 30 is activated. As a result, the code command signal is converted into an infrared ray signal (IRS) by the LED 34 to be delivered as an output to an electronic device (not shown). The electronic device has an infrared receiving unit and a demodulating unit, although not shown in the figure, the former detects the output infrared signal and the latter converts the signal into an electrical command signal. Demodulate The electric command signal is input to a system control unit (not shown) which performs a control operation by initializing the command signal.

According to the remote controller according to the prior art described above, when the infrared signal IRS is generated from the LED 32, the current consumed by it is approximately 500 mA. As such a large current switching element, as shown in Fig. 1, a bipolar transistor 36 is used. One method that many manufacturers are attempting to reduce production costs is to place components (eg, microprocessor units and bipolar transistors) of the device (e.g., the remote controller described above) on as one chip as possible. To accumulate.

It is apparent to those skilled in the art that when the bipolar transistor 34 is turned on and an infrared signal IRS is generated from the LED 32, a power supply transient, that is, an overshoot, occurs. In addition, as described above, since the amount of current sufficient for the infrared signal IRS to be output as an effective signal from the LED 32 is approximately 500 mA, such power supply transient may occur more severely.

If the bipolar transistor 34 used as a switching device for high current on one chip is integrated inside the microprocessor unit 20, which occurs when an infrared signal IRS is generated from the LED 32, Power overshoot, which acts as the main cause of noise, is generated inside the microprocessor unit 20 so that the noise margin in the microprocessor unit 20 is reduced. As a result of this, a malfunction of the microprocessor unit 20 may be caused.

Therefore, it is very difficult to integrate a large current switching element therein because of the above-mentioned problem in the case of integrating a large current switching element such as the bipolar transistor 34 inside the microprocessor unit 20.

It is therefore an object of the present invention to provide a remote controller having a microprocessor unit in which an LED drive circuit for outputting infrared signals is integrated on a single integrated circuit.

1 is a block diagram of a remote controller according to the prior art;

2 is a block diagram of a remote controller according to the present invention; And

3 is a detailed circuit diagram of the LED driving circuit according to a preferred embodiment of the present invention.

* Explanation of symbols on the main parts of the drawings

1: remote controller 10, 100: key matrix

20, 120: microprocessor unit 30: infrared output circuit

32: LED 140: key detection circuit

160: ROM unit 180: CPU

200: RAM unit 220: pulse code generation unit

240: LED drive circuit 242: switch circuit

244: switch driving circuit 246-248: driving circuit

(Configuration)

According to an aspect of the present invention for achieving the above object, an infrared diode; A key matrix having a plurality of keys for generating a code signal corresponding to the selected key; And a microprocessor unit having a first terminal to which the key matrix is connected and a second terminal to which the infrared diode is connected, and directly driving the infrared diode in response to the code signal to generate an infrared signal.

In this embodiment, the microprocessor unit comprises: detecting means connected to the first terminal and detecting a code signal corresponding to the key so selected; A ROM unit for storing a remote controller control program; A pulse code generation unit for generating a pulse code signal corresponding to the code signal in accordance with the remote controller control program stored in the ROM unit; A plurality of switches, each of which is connected in parallel to the second terminal and electrically connects the second terminal and a reference voltage in response to corresponding drive signals; And a switch driving circuit which in turn generates the drive signals for respectively driving corresponding switches in response to the pulse code signal.

In this embodiment, the reference voltage is a ground voltage.

In this embodiment, each switch includes an NMOS transistor having a current path formed between the second terminal and a ground voltage, and a gate controlled by a corresponding drive signal.

In this embodiment, the switch driving circuit includes a plurality of driving circuits respectively corresponding to the switches.

In this embodiment, each of the driving circuits comprises: an input terminal for receiving an input signal; A first output terminal for outputting a corresponding drive signal; A second output terminal for outputting a complementary signal of the corresponding drive signal; A first PMOS transistor having a source connected to a power supply terminal receiving a power supply voltage, a gate connected to the input terminal, and a drain; A first NMOS transistor having a source connected to a ground terminal for receiving a ground voltage, a gate connected to the input terminal, and a drain connected to the first output terminal; An active load connected between the drain of the first PMOS transistor and the first output terminal and having a resistance according to the input signal; A second PMOS transistor having a gate controlled by a potential of a first connection point between the active load and the drain of the first PMOS transistor, and a current path formed between the power supply terminal and the second output terminal; A second NMOS transistor having a gate controlled by a potential of a second connection point between the active load and a drain of the first NMOS transistor, and a current path formed between the ground terminal and the second output terminal; The driving circuit corresponding to the first driving signal generated among the driving circuits receives the pulse code signal as the input signal, and the remaining driving circuits receive the corresponding complementary signal output from the previous stage.

In this embodiment, the outputs of each of the driving circuits are delayed based on the corresponding input signal by the time constant of the gate parasitic capacitance of the switch corresponding to the active load of each of the driving circuits when the state of the corresponding input signal is changed. do.

In this embodiment, the active load includes a plurality of NMOS transistors and PMOS transistors.

According to another feature of the invention, the infrared diode; A key matrix having a plurality of keys and generating a code signal corresponding to the selected key; Detection means coupled to the key matrix for detecting the code signal; A ROM unit for storing a remote controller control program; A pulse code generation unit for generating a pulse code signal corresponding to the selected key according to the remote controller control program stored in the ROM unit; A plurality of switches connected in parallel to the infrared diode; And a switch driving circuit which sequentially generates a plurality of driving signals for respectively driving the switches in response to the pulse code signal, wherein the detection means, the ROM unit, the pulse code generation unit, the switches, and the Both switch drive circuits are formed on a single integrated circuit to function as a microprocessor.

With such a device, instead of a separate bipolar transistor, the LED driving circuit is implemented so that the amount of change in the turn-on current with respect to time is distributed, that is, the overshoot which is the main cause of the noise when the infrared signal is generated is reduced. The LED driving circuit can be integrated in the microprocessor unit.

(Example)

The operation of the present invention will now be described in detail with reference to the drawings. In Figures 2 and 3, the same reference numerals refer to those having the same function as the components of FIG.

2 and 3, the novel remote controller 1 of the present invention includes a key matrix 100 having a plurality of keys and an infrared LED 32 which generates an infrared signal when one of the keys is selected; There is provided a microprocessor unit 120, to which LEDs are connected, respectively, through corresponding terminals Tl and T2, respectively. The microprocessor unit 120 directly drives the LED 32 in response to a code signal corresponding to the selected key when at least one of the keys is selected to generate an infrared signal.

Referring again to FIG. 3, there is shown a block diagram of a remote controller 1 according to the present invention. The remote controller 1 has a microprocessor unit 120 having a key matrix 100, a first terminal T1 to which the key matrix 100 is connected, and a second terminal T2 to which the LED 32 is connected. It includes. Although not shown in the figure, the key matrix 100 has a plurality of keys and generates a code signal corresponding to the selected key. The microprocessor unit 120 includes a key detecting circuit 140 connected to the first terminal T1, a well-known central processing unit 160, and a ROM unit in which a remote controller control program is stored. 160), a random access memory unit 200 which is a temporary data storage area, and a pulse code generation including an oscillator, a frequency division device and / or the like, although not shown in the drawing; Unit 220 (pulse code generating unit).

The pulse code generation unit 220 according to the remote controller control program stored in the ROM unit 160 when at least one of the keys of the key matrix 100 is selected to detect a code signal corresponding to the selected key. Generate a pulse code signal corresponding to the code signal. The microprocessor unit 120 also includes an LED driving circuit 240 for driving the infrared signal from the LED 32 to generate it. The LED drive circuit 240 is formed as a monolithic integrated circuit in the microprocessor unit 120, as shown in FIG.

It is not possible to integrate the bipolar transistor 34 into the microprocessor unit 20 as a switching element due to the large current (e.g. 500 mA) consumed when the infrared signal IRS is generated from the LED 32. Described in the background. However, as shown in FIG. 2, the remote controller 1 according to the present invention can recognize that the LED driving circuit 240 is implemented in the microprocessor unit 120. How a bipolar transistor used as a switching element can be integrated in the microprocessor unit 120 is described with reference to FIG. 3.

Bouncing that occurs when an infrared signal (IRS) is generated from the LED 32, i.e., a rise in the level of the ground voltage, is well known to those skilled in the art. Is generated instantaneously when switching on / off a switching element (see FIG. 1). The concept of the present invention is such that instantaneous bounces occur over several intervals. Therefore, even if bounce occurs when the infrared signal IRS is generated, the internal noise margin of the microprocessor unit 120 is not affected by such reduced bounce. A detailed circuit diagram of the LED driving circuit 240 to which the concept of the present invention is applied is shown in FIG. 3.

In FIG. 3, the LED drive circuit 240 is connected to the pulse code signal PCS provided from the switch circuit 242 connected to the LED 32 via the second terminal T2 and the system bus of FIG. 2. In response to driving signals DRV1, DRV2,..., For driving the switch circuit 242. , A switch driving circuit 244 generating (DRVn), where n is an integer.

The switch circuit 242 of the preferred embodiment of the present invention according to the concept described above includes a plurality of NMOS transistors SW1, SW2,. , (SWn). The NMOS transistors SW1, SW2,... , Drains of SWn are commonly connected to the LED 32 via the terminal T2, and their sources are grounded. And the transistors SW1, SW2,... , Gates of (SWn) correspond to corresponding driving signals DRV1, DRV2,... And (DRVn) respectively. In Fig. 3, for convenience of illustration, the drive circuits 246, 267,... Constituting the switch drive circuit 244. Only a detailed circuit diagram of the driving circuit 246 for generating the first driving signal DRV1 of 248 is shown, but the remaining driving circuits also have the same circuit configuration. The driving circuits 246, 247,... , 248, only the driving circuit 246 accepts the pulse code signal PCS as an input signal and the remaining driving circuits are input signals of the previous stage output signals (i.e., the driving signal output from the preceding driving circuit). Complementary signal) (NDRV1), (NDRV2),... Note that it accepts (NDRV _n-1 ).

The driving circuit 246 for generating the first driving signal DRV1 includes two PMOS transistors MP1 and MP5, two NMOS transistors MN1 and MN7, and an active load. 245. The PMOS transistor MP1 and the NMOS transistor MN1, the PMOS transistor MP5 and the NMOS transistor MN7 each function as an inverter. The active load 245 is connected between the drains of the PMOS and NMOS transistors MP1 and MN1, that is, the connection points N1 and N2, which serve as inverters, as shown in FIG. It consists of three connected PMOS transistors MP2-MP4 and five NMOS transistors MN2-MN6.

The operation of the drive circuit 246 is described below. When at least one of the keys of the key matrix 100 of FIG. 2 is selected, the key detection circuit 140, the ROM unit 160, the CPU 180, the RAM unit 200, and the pulse code generation unit 220 are selected. Is generated a pulse code signal (PCS) corresponding to the selected key. The drive circuit 246 generates a corresponding drive signal DRV1 in response to the pulse code signal PCS transitioning from the high level to the low level.

This will be described in more detail as follows. Connection points N1 and N2 are both kept low when the pulse code signal PCS is at high level, and when the pulse code signal PCS is at low level, the connection points N1 and N2 is kept at a high level.

When the pulse code signal PCS transitions from a high level to a low level, the PMOS transistors MP2-MP4 of the active load 245 are turned on by the pulse code signal PCS and it NMOS transistors MN2-MN4 and MN6 of are turned off. Then, both the connection points N1 and N2 go from a low level to a high level. At this time, the connection points N1 and N2 are not set to the same potential at the same time. This is because parasitical capacitance seen from the gates of the turn-on resistance and the connection point N2 of the transistors constituting the active load 245 and the corresponding NMOS transistor SW1 of the switch circuit 242. The voltage on connection point N2 is changed based on the RC time constant of C1), whereas the voltage on connection point N1 is only at the turn-on resistance of the PMOS transistor MP1 without a delay time corresponding to such RC time constant. Is changed by That is, since the voltage on the connection point N2 does not change instantaneously according to the RC time constant but is dispersed and changed for a predetermined time (RC time constant), the PMOS and NMOS transistors MP1 during signal transition according to the characteristics of the CMOS inverter. ) And (MN2) can be prevented overshoot that occurs when turned on at the same time.

When the pulse code signal PCS, which is an input signal of the driving circuit 246, transitions from low level to high level, that is, the NMOS transistor SW1 of the switch circuit 242 corresponding to the driving circuit 246 is turned on. When turned off, the operation of the drive circuit 246 is the same as described above. It is different from the former that the NMOS transistors MN2-MN6 of the active load 245 are turned on, and the PMOS transistors MP2-MP4 are turned off.

According to the LED driving circuit 240 having the above-described configuration, instead of one bipolar transistor, a plurality of NMOS transistors SW1, SW2,... , SWn are implemented, and each of the transistors SW1, SW2,... , The switch driving circuit 244 for driving (SWn) also includes a plurality of driving circuits 246, 247,. , (248). And each of the driving circuits 246, 247,... , 248 generates a corresponding drive signal DRVn in response to the complementary signal NDRV _{n-1 of} the drive signal outputted therefrom. In this case, each of the driving signals DRVn corresponds to the RC time constant due to the parasitic capacitance seen from the gate of the NMOS transistor of the active switch 245 in the respective driving circuits and the corresponding switch circuit 242. They are activated sequentially (in turn) at timed intervals. Therefore, the overshoot that occurs when the infrared signal IRS is generated from the LED 32 is reduced, so that even if the overshoot occurs, it can be reduced to a level such that it does not affect the noise margin in the microprocessor unit 120. have. As a result, the LED drive circuit 240 can be integrated on the microprocessor unit 120 and on a single integrated circuit.

As described above, the overshoot dispersion scheme can be used to prevent overshoot that occurs when an infrared signal corresponding to the selected key is generated when a key of the key matrix is selected. As a result, in the microprocessor unit, an LED driving circuit using an NMOS transistor instead of a bipolar transistor can be integrated so as to directly drive the LED to generate an infrared signal.

Claims (9)

An infrared diode; A key matrix having a plurality of keys for generating a code signal corresponding to the selected key; A remote controller having a first terminal to which the key matrix is connected and a second terminal to which the infrared diode is connected, and a microprocessor unit for directly driving the infrared diode in response to the code signal to generate an infrared signal . The method of claim 1, The microprocessor unit, Detection means connected to said first terminal and detecting a code signal corresponding to said selected key; A ROM unit for storing a remote controller control program; A pulse code generation unit for generating a pulse code signal corresponding to the code signal in accordance with the remote controller control program stored in the ROM unit when the code signal is detected; A plurality of switches, each of which is connected in parallel to the second terminal and electrically connects the second terminal and a reference voltage in response to corresponding drive signals; And a switch driving circuit which in turn generates the drive signals for respectively driving corresponding switches in response to the pulse code signal. The method of claim 2, And the reference voltage is a ground voltage. The method of claim 2 wherein: Wherein each switch comprises an NMOS transistor having a current path formed between the second terminal and a ground voltage and a gate controlled by a corresponding drive signal. The method of claim 4, wherein And the switch driving circuit includes a plurality of driving circuits respectively corresponding to the switches. The method of claim 5, Each of the driving circuits, An input terminal for receiving an input signal; A first output terminal for outputting a corresponding drive signal; A second output terminal for outputting a complementary signal of the corresponding drive signal; A first PMOS transistor having a source connected to a power supply terminal receiving a power supply voltage, a gate connected to the input terminal, and a drain; A first NMOS transistor having a source connected to a ground terminal for receiving a ground voltage, a gate connected to the input terminal, and a drain connected to the first output terminal; An active load connected between the drain of the first PMOS transistor and the first output terminal and having a resistance according to the input signal; A second PMOS transistor having a gate controlled by a potential of a first connection point between the active load and the drain of the first PMOS transistor, and a current path formed between the power supply terminal and the second output terminal; A second NMOS transistor having a gate controlled by a potential of a second connection point between the active load and the drain of the first NMOS transistor, and a current path formed between the ground terminal and the second output terminal, A driving circuit corresponding to a driving signal generated first of the driving circuits receives the pulse code signal as the input signal, and the remaining driving circuits receive a corresponding complementary signal output from a previous stage. The method of claim 6, Outputs of each of the driving circuits are delayed based on the corresponding input signal by a time constant of the parasitic capacitance seen from the gate of the transistor corresponding to the active load of each of the driving circuits when the state of the corresponding input signal changes. The method of claim 6, The active load includes a plurality of NMOS transistors and PMOS transistors. An infrared diode; A key matrix having a plurality of keys and generating a code signal corresponding to the selected key; Detection means coupled to the key matrix for detecting the code signal; A ROM unit for storing a remote controller control program; A pulse code generation unit for generating a pulse code signal corresponding to the selected key according to the remote controller control program stored in the ROM unit; A plurality of switches connected in parallel to the infrared diode; And A switch driving circuit for sequentially generating a plurality of driving signals for respectively driving the switches in response to the pulse code signal, The detecting means, the ROM unit, the pulse code generating unit, the switches, and the switch driving circuit are all formed on a single integrated circuit and function as a microprocessor.