JPH05189892A - Power supply circuit for motor drive - Google Patents

Abstract

PURPOSE:To realize constant speed control and to suppress noise or vibration by feedforward controlling a rotational speed difference due to difference of DC power supply voltage of driving power supply circuit. CONSTITUTION:Power supply voltage is continuously sensed by means of comparators 6a-6e or the like and when the power supply voltage is high, OFF interval is set longer than ON interval by means of switching circuits 7a-7e to drive a motor otherwise DC driving takes place at full duty.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power supply circuit for driving a feed motor for a sled of a CD player or the like, and more particularly to a power supply circuit for driving a motor having a relatively wide range of use of a motor drive voltage.

[0002]

2. Description of the Related Art Conventionally, various feeding mechanisms for a sled electric motor (hereinafter referred to as a motor) for feeding an optical pickup from an inner peripheral position to an outer peripheral position of an optical disk in a portable CD player or the like have been proposed. .. Usually, a direct current motor, a stepping motor, a linear motor or the like is used as a drive source.

FIG. 5 is a schematic plan view of a sled servo mechanism using the most common rack and pinion mechanism.

In FIG. 5, reference numeral 11 denotes an optical disk, and a chucking fitted to a spindle 12 of a spindle motor 14 is fitted into a center hole 13 of the optical disk 11 to rotate the optical disk 11 in a clockwise direction, for example.

Reference numeral 15 is an optical pickup. A lens actuator 16 and the like are arranged on the optical pickup 15, and a laser beam from a laser source is focused on a pit provided on the optical disk 11 to reproduce a signal. ..

The optical pickup 15 is mounted on a movable table 23 which is integrated with a rack 18, and the movable table 23 is slidably fitted on a guide shaft 17. The rack 18 is meshed with a pinion 19, the pinion 19 is meshed with a gear 22 fitted on a motor shaft 21 of the sled motor 9, and the movable base 23 is moved along the guide shaft 17 in accordance with the rotation of the sled motor 9 along an arrow A. A rough seek is performed in which the optical pickup 15 is moved in the −A direction to seek in the radial direction of the optical disc 11.

Generally, a seek servo is composed of a coarse seek and a fine seek (tracking servo) operation, but the coarse seek is generally performed by a power source voltage of the sled motor 9 in order to reduce power consumption without servoing in a portable CD player or the like. Often driven directly.

[0008]

When the sled motor 9 and the spindle motor 14 are directly driven by the DC power source as described above, the moving table 23 of the optical pickup 15 is rough seeking (to the target track position) due to the difference in the power source voltage. seek)
When moving along the guide shaft 17, if the DC power supply voltage is high, it moves at high speed, and if the DC power supply voltage is low, it moves at low speed.

When such a moving speed is high, there is a problem that gear noise generated between the pinion 19 and the rack 18 becomes large and a large vibration is generated.

In order to eliminate such an adverse effect, it is conceivable to perform the speed control servo even during the rough seek, but not only the power consumption increases, but also a complicated seek servo IC or the like is required, which leads to an increase in cost. There was a problem.

The present invention solves the above-mentioned problems, and the object of the present invention is to solve the problem that the power supply voltage is different.
(EN) Provided is a power supply circuit for driving an electric motor capable of controlling a moving speed of an optical pickup when seeking and a speed of a spindle motor when kicking.

[0012]

As shown in FIG. 1, an example of the present invention is a power supply circuit for driving a motor, which can be driven by a voltage of a DC power supply 1, 2, 3 within a predetermined range. Based on the comparison outputs of the comparison means 6a to 6e for comparing the DC power supply voltage within the predetermined range and the plurality of reference voltages,
Switching means 7a to 7e whose duty ratio changes
And the electric motor 9 driven based on the outputs of the switching means 7a to 7e. In the range where the voltage of the DC power supplies 1, 2 and 3 is high, the DC power supply 1 is not driven by the DC voltage. The electric motor 9 is driven by a voltage whose duty ratio changes in accordance with a few voltages.

[0013]

According to the motor driving power supply circuit of the present invention, when the DC power supply voltage is the minimum voltage, the DC drive is performed at full duty, and the ON time is shortened and the OFF time is lengthened as the voltage increases. Since the sled motor 9 and the like are driven after switching, it is possible to obtain the one in which the speed at the time of coarse seek of the movable table can be kept constant regardless of the level of the DC voltage.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A motor drive circuit of the present invention will be described below as a portable CD
The case of driving the sled motor of the player will be described.

In FIG. 1, in a small portable CD player or the like, a rechargeable secondary battery 1 such as a Ni-Ca battery or a Ni-Zn battery is used in addition to a primary battery 2 such as an alkaline or manganese battery. It is also possible to use a DC power source or the like which is converted from the commercial AC power source 3 into a predetermined DC voltage by using the AC adapter 4.

The voltage of the above-mentioned primary battery is 1.5 V and is usually 2
In this case, the sled motor 9 can be driven up to a rated battery voltage of about 3V to 2V. Also, commercial AC power supply 3
In the secondary battery 1 or the like to be charged and used from the battery charger 31 from, for example, a Ni-Zn battery or the like, 3.5V to 2.6V.
Used at a voltage of the order. Further, there are various direct current voltages converted into direct current by the AC adapter.

Now, if the primary battery 2 having a 3V rating is used and the secondary battery 1 is replaced with a Ni-Zn battery, a rated voltage of 3.5V is supplied. Therefore, when the movable contact piece a of the power source changeover switch 5 is switched from the fixed contact c to the fixed contact b side, the voltage supplied to the sled motor 9 through the fixed contact b and the movable contact piece a of the switch 8 is 1.5V. As the height rises, the thread motor 9 rotates at a high speed, and the optical pickup 15 mounted on the movable table 23 described in FIG. 5 seeks at a high speed.

Therefore, in this embodiment, the DC voltage within these predetermined ranges is applied to the plurality of comparators 6a, 6b, 6c, 6
d, 6e ... One of the input terminals is supplied to the other input terminals of the comparators 6a, 6b, 6c, 6d, 6e ... And predetermined reference voltages V ₀ , V ₁ , V ₂ , V ₃ , V ₃ . ₄
Are supplied via input terminals T ₁ , T ₂ , T ₃ , T ₄ , T ₅ .

The reference voltages V _{1 to} V ₄ are DC voltage sources 1,
A variable voltage range of 2 or 3 or, for example, an appropriate voltage obtained by dividing the maximum voltage to the minimum voltage (3.5 V to 2.6 V) of one DC voltage source 1 by a predetermined voltage is selected, and finally the sled motor 9 is selected. A voltage is selected such that the rotation of the sled motor 9 is always constant according to the DC voltage supplied to the.

Comparators 6a, 6b, 6c, 6d, 6
e comparison signal 6a₁, 6b₁, 6c ₁, 6d₁, 6e₁
Are switching circuits 7a, 7b, 7c, 7 of the next stage, respectively.
d, 7e.

Such comparison signals 6a ₁ , 6b ₁ , 6
Switching circuit 7 based on c ₁ , 6d ₁ , 6e ₁
a, 7b, 7c, 7d, and 7e output switching signals having different on-time and off-time determined according to each of these switching circuits.

The reference voltage is V ₀ <V ₁ <V ₂ <V ₃ <V ₄
If so, the switching circuit 7a has, for example, an ON period of 10
Outputs DC 7a ₁ with mm / s and off period 0 (Fig. 2A).
reference). Further, in the switching circuit 7b, the ON period is 10
The pulse output signal 7b ₁ having a longer ON period of mm / s and an OFF period of 1 mm / s than that of the OFF period is output (see FIG. 2B). Hereinafter, similarly, switching circuits 7c, 7d, 7e
.., the on period is 10 mm / s, and the off period is
The pulse output signal 7c ₁ , whose off period is longer than the sequential on period of 2 mm / s, 3 mm / s, 4 mm / s ...
7d ₁ and 7e ₁ are output.

Switching circuits 7a, 7b, 7c, 7
DC 7a ₁ and pulse output signal 7b from d, 7e ...
₁ , 7d ₁ , 7e _1, ... Are smoothing circuits R ₀ C ₀ , R
A DC voltage corresponding to the duty of the switching circuit is supplied to the sled motor 9 from the fixed contact c → the movable contact a of the switch 8 via ₁ C ₀ , R ₂ C ₀ , R ₃ C ₀ , and R ₄ C ₀ , If the DC voltage of the DC voltage sources 1 to 3 is high, a low DC voltage is generated and supplied to the sled motor 9, and if it is the lowest voltage, the sled motor 9 is regarded as full-duty DC.
Will drive.

Therefore, the rotation of the sled motor 9 is always constant, and the optical pickup 15 can always move on the guide shaft 17 at a constant speed.

Although FIG. 1 of the above-described embodiment shows this example as a functional block, the case of performing control by software will be described with reference to FIGS. 3 and 4.

In FIG. 3, in the sled motor 9, a tracking error signal or the like is obtained from a photodetector or the like and supplied to the input terminal T ₆ at the time of fine seek such as tracking servo, and the preamplifier 25 and the drive amplifier 27 for driving the sled motor 9 are supplied. Tracking servo is performed via the above, but in this example, consider a case where the optical pickup 15 is moved to the vicinity of a predetermined track position by rough seek.

The drive amplifier 27 is connected to the primary battery 2 and the secondary battery 1 via the power source changeover switch 5 as well as the AC adapter 4 by the AC adapter 4.
The DC converted voltage is supplied directly.

In this example, the preamplifier 25 and the drive amplifier 27
A switching transistor 26 and a capacitor C ₁ are interposed between the CPU and the switching transistor 26, and a switching control similar to that described with reference to FIG. 1 is performed by the CPU 28 via a digital-analog conversion circuit (DAC) 29 on the base of the switching transistor 26. A signal is supplied and the signal from the preamplifier 25 is shunted at a predetermined duty ratio.

The CPU 28 senses a DC voltage via an analog-digital conversion circuit (ADC) 30 in order to constantly detect the voltage at the movable contact point a of the switch 5.

The CPU 28, for example, according to the flow chart shown in FIG. 4, sets reference voltage values V ₀ , V set in a predetermined range.
₁ , V ₂ , V ₃ , V _4, ... Are compared with the sensed DC power supply voltage (see first step ST _{1 to} fifth step ST ₅ ).

Then, as shown in the sixth step ST _{6 to} the tenth step ST ₁₀ , the reference voltage is V ₀ <V ₁ <V ₂
If <V ₃ <V ₄ ..., full-duty direct current is output at the lowest reference voltage V _0. If the reference voltage is not higher, the OFF period of switching is lengthened and the ON period is shortened (in the embodiment, the ON period is shortened). Control).

Since the present invention is operated as described above, the power source circuit for driving the electric motor which causes the optical pickup to seek constantly even if there is a difference in the voltage of the DC power source and does not cause noise or vibration in the gears, etc. Is obtained.

Although the driving of the sled motor 9 has been described in the above embodiment, the kick voltage which is not influenced by the power supply voltage can be obtained by applying the present example to the driving of the spindle motor 12 at the time of kicking off.

[0034]

According to the power supply circuit for driving a motor of the present invention, the motor can be controlled at a constant speed even if the power supply voltage varies within a predetermined range, and when driven at a high voltage, the motor rotates at a high speed to cause gear noise. It is possible to obtain the one that does not generate vibration or the like.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an embodiment of a power supply circuit for driving an electric motor of the present invention.

FIG. 2 is a waveform diagram for explaining the operation of FIG.

FIG. 3 is a configuration diagram showing another example of the power supply circuit for driving the electric motor of the present invention.

FIG. 4 is a flow chart for explaining the operation of FIG.

FIG. 5 is a block diagram for explaining seeking of a conventional thread motor.

[Explanation of symbols]

 1 Secondary Battery 2 Primary Battery 4 AC Adapter 6a to 6e Comparator 7a to 7e Switching Circuit 9 Thread Motor 27 Drive Amplifier 28 CPU

Claims (1)

[Claims] 1. A power supply circuit for driving an electric motor, which can be driven by a voltage of a DC power supply within a predetermined range, and a comparing means for comparing the DC power supply voltage within the predetermined range with a plurality of reference voltages. The switching means has a duty ratio that changes based on the means comparison output, and an electric motor that is driven based on the output of the switching means. In the range where the voltage of the DC power supply is high, the electric motor is driven by the DC voltage. A power supply circuit for driving an electric motor, characterized in that the electric motor is driven by a voltage whose duty ratio changes according to the voltage of the DC power supply without performing the operation.