JPH05236790A - Spindle motor driver ic - Google Patents

Abstract

PURPOSE:To realize accurate switching between start and reverse start by judging the rotational state of motor by means of a signal based on the counter- electromotive force. CONSTITUTION:Output from a starting pattern generating circuit is fed to a phase exciting pulse generating circuit in order to drive a transistor thus rotating a three-phase motor. A rotation detecting circuit then makes decisions whether the motor is rotating and whether the motor is rotating normally or not and produces a start/reverse start switching signal. A constant charging circuit 29 performs charging operation depending on a Low or High output from a comparator selecting circuit (CS). A peak value is held in a peak value hold circuit 30 and then subjected to subtraction through a subtraction circuit 31 and the subtraction result is compared with a voltage reference 33 through a comparator (CP) 32. Consequently, the duty of the output from the CS can be detected. Since the duty is about 50% when a motor 22 is rotating normally, the voltage reference 33 is set such that the CP 32 is inverted. Switching is then made between start and reverse start depending on the output level from the CP 32.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sensorless spindle motor driver IC.

[0002]

2. Description of the Related Art In a conventional sensorless spindle motor driver IC, a counter electromotive voltage is used to generate a drive pulse to rotate a motor. However, since the counter electromotive voltage does not appear unless it rotates, a start pulse is required at the start.

In the conventional sensorless spindle motor driver IC, it is difficult to judge whether the motor is rotating or not because the generation of the start pulse and the change from the start to the back electromotive are performed externally or internally. I was switching from startup to back-up.

[0004]

However, with this conventional spindle motor driver IC, the system design becomes complicated when it is controlled externally, and there is a possibility that it will fail at the start of rotation even if it is performed internally. There was a drawback.

In view of the above-mentioned drawbacks, a technical object of the present invention is to provide a spindle motor driver IC for accurately detecting the presence / absence of motor rotation and abnormal rotation.

[0006]

According to the present invention, in a spindle motor driver IC that uses a back electromotive force for switching the excitation phase of a motor, a judgment based on the signal based on the back electromotive voltage is made. A spindle motor driver IC characterized by having means is obtained.

Further, according to the present invention, in the spindle motor driver IC, the judging means detects the duty of the signal based on the back electromotive force and starts / starts the motor based on the output level of the duty. A spindle motor driver IC characterized by making a back electromotive determination can be obtained.

That is, the spindle motor driver IC of the present invention has a function of determining the presence or absence of rotation and abnormal rotation based on the signal obtained by the back electromotive force.

[0009]

Embodiments of the present invention will now be described with reference to the drawings.

FIG. 1 is a circuit diagram of an embodiment of the present invention.
FIG. 3 is a timing chart of the internal operation. FIG. 4 is a rotation detection circuit diagram constituting FIG. FIG. 2 is a function table of internal operation.

First, the motor driving operation at the time of starting will be described.

The signal output from the start-up pattern generation circuit 3 is input to the phase excitation pulse generation circuit 5 to drive the output transistors Q _{1 to} Q ₆ , (13 to 18), and the three-phase motor 22
Turning the.

In the excitation sequence I in which Q ₅ (13) and Q ₄ (16) are turned on, the comparator O in which both the high side transistor and the low side transistor are turned off
(8) is selected by the comparator selection circuit 2. In the excitation sequence II, the comparator 1 (7) is selected. This is to detect the back electromotive force generated by the rotation of the motor 22.

The correct back electromotive force cannot be detected by the comparator in which the high side or low side transistor is turned on. If the output of the comparator selection circuit 2 rotates normally, the output waveform 26 of the comparator selection circuit (see FIG. 3)
become.

Next, the rotation detection circuit 1 will be described with reference to FIG. The rotation detection circuit 1 determines the presence / absence of rotation and abnormal rotation, and outputs a start-back electromotive switching signal. The constant current charging circuit 29 outputs the output waveform 26 of the comparator selection circuit.
A charging waveform A27 for charging when low and a charging waveform B28 for charging when high are created. Each peak value is held by the peak value hold circuit 30, and the subtraction circuit 31 subtracts it. The comparator 32 compares it with the reference voltage 33.

As a result, the duty of the output waveform 26 of the comparator selection circuit can be detected. If the motor 22 rotates normally, the duty becomes about 50%. Therefore, when the duty becomes about 50%, the reference voltage 33 is set so that the comparator 32 is inverted. The back electromotive force is determined based on the output level of the comparator 32.

[0017]

As described above, the present invention has the function of determining the presence or absence of rotation and the abnormal rotation based on the signal obtained by the back electromotive force, so that the start back electromotive switching can be accurately performed. Have.

[Brief description of drawings]

FIG. 1 is a circuit diagram of an embodiment of the present invention.

FIG. 2 is a function table of internal operation.

FIG. 3 is a timing chart of internal operation.

FIG. 4 is a rotation detection circuit diagram forming FIG.

[Explanation of symbols]

 1 rotation detection circuit 2 comparator selection circuit 3 startup pattern generation circuit 4 startup circuit ← → back electromotive detection circuit switching circuit 5 phase excitation pulse generation circuit 6 comparator 2 7 comparator 1 8 comparator 0 9 L2 10 L0 11 L1 12 rotation speed setting signal 13 Q5 14 Q6 15 Q3 16 Q4 17 Q1 18 Q2 19 Motor current detection circuit 20 Operational amplifier 21 Rotation speed control circuit 22 Three-phase motor 23 Comparator 0 output waveform 24 Comparator 1 output waveform 25 Comparator 2 output waveform 26 Comparator selection circuit output waveform 27 Charging Waveform A 28 Charging Waveform B 29 Constant Current Charging Circuit 30 Peak Value Hold Circuit 31 Subtraction Circuit 32 Comparator 3 33 Reference Voltage

Claims (2)

[Claims] 1. A spindle motor driver IC using a back electromotive voltage for switching an excitation phase of a motor, comprising a determination means for determining a rotation state of the motor based on a signal based on the back electromotive voltage. Driver IC. 2. The spindle motor driver IC according to claim 1, wherein the determination means detects the duty of the signal based on the counter electromotive voltage, and starts / reverses the motor based on the output level of the duty. A spindle motor driver IC characterized by making the following determination.