JP2004222370A - Apparatus and method for automatically voltage regulating dc/dc converter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an automatic voltage regulator which can omit the labor hour of regulation, which can regulate a voltage with high accuracy, and which can reduce a cost. <P>SOLUTION: A series circuit of a resistor R1, a transistor Q and a resistor R2 is provided at the output side of a DC/DC converter 1, and an integrating circuit having a resistor R3 and a capacitor C is provided at the base of the transistor Q. The output voltage VDD of the DC/DC converter 1 read by using the inspecting unit 20 of a circuit substrate 10 is fed back to a microcomputer 2. A current flowing to the transistor Q is controlled by a PWM signal to be output from the microcomputer 2, and thereby the output voltage VDD is regulated to a suitable value by variably setting a reference voltage REF. A parameter 4 relating to the PWM signal at the time point of regulating the output voltage VDD to the suitable value is stored in a nonvolatile memory 3. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an apparatus and a method for automatically adjusting a voltage of a DC / DC converter built in a printer or the like.
[0002]
[Prior art]
2. Description of the Related Art A DC / DC converter is a device that converts an input constant DC voltage into a higher (or lower) DC voltage, and is widely used as a DC power supply in various electric devices. An application example of a DC / DC converter is described in, for example, Patent Document 1 below.
[0003]
FIG. 4 is a circuit diagram showing a conventional automatic voltage adjusting device built in a printer. In FIG. 4, reference numeral 50 denotes a circuit board incorporated in the printer, which includes a DC / DC converter 51 for supplying DC power to the printer, a microcomputer 52 for controlling the operation of the printer, and a memory for storing control data. 53 are provided. On the output side of the DC / DC converter 51, a diode D and a coil L are provided, and a resistor R1 and a semi-fixed resistor VR that constitute a voltage dividing circuit are provided. The microcomputer 52 outputs printer control signals for controlling the paper feeding operation, the carrier conveying operation, the printing operation, and the like of the printer, and the motor and the printing unit are driven based on these control signals. The memory 53 is composed of a nonvolatile memory such as an EEPROM.
[0004]
By the way, the DC / DC converter 51 is composed of an IC, but the output voltage VDD from the converter 51 varies about ± 5% due to the performance of the IC. Therefore, in order to obtain a power supply voltage of ± 2% or less, it is necessary to finely adjust the output voltage VDD. This fine adjustment is performed by operating the semi-fixed resistor VR. That is, the output voltage VDD of the DC / DC converter 51 is divided according to the voltage dividing ratio determined by the resistance values of the resistor R1 and the semi-fixed resistor VR, and the voltage at the point B is fed back as the reference voltage REF. Can be adjusted by adjusting the semi-fixed resistor VR to adjust the output voltage VDD.
[0005]
[Patent Document 1]
Japanese Patent Application Laid-Open No. 9-233881 [Patent Document 2]
JP-A-11-242502
[Problems to be solved by the invention]
However, in the above-described conventional apparatus, since the output voltage is adjusted by manually operating the semi-fixed resistor, there is a problem that the adjustment work is troublesome and the adjustment accuracy is poor. In order to solve this, there is a method in which the semi-fixed resistor is automatically operated by using a dedicated adjusting device to perform the adjustment, but this requires a large-scale adjusting device. Further, since the conventional device uses an expensive semi-fixed resistor, there is also a problem that the component cost increases.
[0007]
SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems, and an object of the present invention is to provide a DC / DC converter with automatic voltage adjustment that can reduce the time and effort for adjustment and can achieve high-accuracy adjustment and can reduce costs. An object of the present invention is to provide an apparatus and an adjustment method.
[0008]
[Means for Solving the Problems]
An automatic voltage regulator according to the present invention includes control means for controlling operation of an electric device, storage means for storing control data, and a DC / DC converter for supplying DC power to the electric device. In a voltage automatic adjustment device that divides an output voltage of a DC / DC converter, feeds back the reference voltage as a reference voltage, and adjusts the output voltage of the DC / DC converter by varying the reference voltage, the output voltage of the DC / DC converter is connected in series. A first resistor, a transistor connected in series with the first resistor, and a second resistor connected in series with the transistor. Then, the output voltage of the DC / DC converter is fed back to the control means, and the control means gives a predetermined control signal to the transistor based on the feedback, controls the current flowing through the transistor, and thereby varies the reference voltage to change the DC / DC voltage. Adjust the output voltage of the DC converter to an appropriate value. In addition, the parameter relating to the control signal when adjusted to the appropriate value is stored in the storage unit.
[0009]
Further, the automatic voltage adjustment method according to the present invention includes a control unit for controlling an operation of the electric device, a storage unit for storing control data, and a DC power supply for the electric device. A DC / DC converter for supplying the DC / DC converter, dividing the output voltage of the DC / DC converter, feeding back the divided voltage as a reference voltage, and adjusting the output voltage of the DC / DC converter by varying the reference voltage. In the above, when the operation is checked by setting the circuit board on the inspection device, the output voltage of the DC / DC converter is read, and the read output voltage is fed back to the control means via the inspection device. Then, a predetermined control signal is output from the control means based on the feedback, the control signal is supplied to the transistor, and the current flowing through the transistor is controlled to vary the reference voltage and to change the output voltage of the DC / DC converter. Adjust to an appropriate value. In addition, the parameter relating to the control signal when adjusted to the appropriate value is stored in the storage unit.
[0010]
As described above, the output voltage of the DC / DC converter is fed back to the control unit, and the reference voltage is varied by the control signal from the control unit to adjust the output voltage, thereby eliminating the need for manual adjustment work as in the related art. In addition, the trouble of adjustment can be omitted and the adjustment accuracy can be improved. In addition, since it is not necessary to use an expensive semi-fixed resistor and it can be realized using inexpensive circuit components such as a transistor and a resistor, the cost can be reduced.
[0011]
Furthermore, since the output voltage of the DC / DC converter is read out and fed back to the control means using the inspection device for checking the operation of the circuit board, a dedicated device for automatic adjustment is not required, and the output voltage is adjusted appropriately. Since the parameter of the control signal is stored in the storage unit when the value is adjusted, once the adjustment is made, the appropriate output voltage can always be obtained by reading the parameter from the storage unit thereafter.
[0012]
In an exemplary embodiment of the present invention, the DC / DC converter is provided on a circuit board built in the printer. The circuit board is also provided with a microcomputer as control means for controlling the operation of the printer and a non-volatile memory as storage means for storing control data. On the output side of the DC / DC converter, a first resistor, a transistor connected in series with the first resistor, a second resistor connected in series with the transistor, and an input connected to the transistor And an integrating circuit including a third resistor and a capacitor. The output voltage of the DC / DC converter read using the inspection device for the circuit board is fed back to the microcomputer, and a predetermined PWM signal is output from the microcomputer, and the PWM signal is supplied to the transistor via the integration circuit. Can be Then, by controlling the current flowing through the transistor with the PWM signal, the reference voltage changes and the output voltage is adjusted to an appropriate value, and the parameters related to the PWM signal at this time are stored in the nonvolatile memory.
[0013]
BEST MODE FOR CARRYING OUT THE INVENTION
FIG. 1 is a circuit diagram showing an automatic voltage regulator according to the present invention. Here, a case where the present invention is applied to a printer will be described. In FIG. 1, reference numeral 10 denotes a circuit board built in the printer, which includes a DC / DC converter 1 for supplying DC power to the printer, a microcomputer 2 for controlling the operation of the printer, and a memory for storing control data. 3 are provided. The microcomputer 2 constitutes control means in the present invention, and the memory 3 constitutes storage means in the present invention. On the output side of the DC / DC converter 1, a diode D and a coil L are provided, and a series circuit of a first resistor R1, a transistor Q, and a second resistor R2 forming a voltage dividing circuit is provided. ing. On the input side (base terminal) of the transistor Q, an integrating circuit including a third resistor R3 and a capacitor C is provided. The microcomputer 2 outputs printer control signals for controlling a paper feeding operation, a carrier conveying operation, a printing operation, and the like of the printer, and a motor and a printing unit are driven based on these control signals. The memory 3 is composed of a non-volatile memory such as an EEPROM, and the non-volatile memory 3 stores a parameter 4 of a PWM signal described later.
[0014]
Reference numeral 20 denotes a circuit board operation inspection device (hereinafter simply referred to as an inspection device) for checking the operation of the circuit board 10. The inspection apparatus 20 is an inspection jig that is installed on an inspection line in a factory and checks whether the circuit board 10 built in the printer operates normally. FIG. 2 shows an external view of the inspection device 20. 11 is a box-shaped main body, 12 is a plurality of contact pins provided so as to protrude above the main body 11, 13 is a display unit for displaying inspection results and the like, and 14 is an LCD provided on the display unit 13. (Liquid crystal display). Reference numeral 10 denotes a circuit board shown in FIG. 1. The circuit board 10 is set on an upper portion of a main body 11, and a wiring section of the circuit board 10 and the contact pins 12 are electrically connected to each other. , A predetermined operation check on the circuit board 10 is performed.
[0015]
FIG. 3 shows a block diagram of the inspection device 20. 12 is the above-mentioned contact pin, 14 is the above-mentioned display unit, 16 is an interface for connecting the circuit board 10 and a circuit inside the inspection device via the contact pin 12, 21 is a CPU for controlling the entire inspection device, and 22 is a CPU. A ROM 23 for storing an inspection program and the like is a RAM for temporarily storing data. Reference numeral 24 denotes a pseudo carrier, which is a circuit for electrically checking a signal applied to an ink cartridge mounted on an ink carrier of an ink jet printer, and is not an actual ink carrier. Reference numeral 25 denotes a feed motor for feeding the paper of the printer, and reference numeral 26 denotes a carrier motor for conveying the ink carrier of the printer. These are actual motors. Reference numeral 27 denotes a power supply for supplying a drive voltage to each unit, and reference numeral 28 denotes a power outlet.
[0016]
Next, a procedure for automatically adjusting the output voltage VDD of the DC / DC converter 1 of the circuit board 10 using the above-described inspection apparatus 20 will be described. First, the circuit board 10 is set on the inspection device 20, and the circuit board 10 and the inspection device 20 are electrically connected by the contact pins 12. Thereafter, the inspection device 20 is operated, various commands for testing are sent from the CPU 21 to the microcomputer 2 of the circuit board 10 via the interface 16, and a printer control signal output from the microcomputer 2 is transmitted via the interface 16 to the inspection device. The CPU 21 checks whether the pseudo carrier 24, the feed motor 25, the carrier motor 26 and the like operate normally. The check result is displayed on the display unit 14. The above procedure is conventionally performed.
[0017]
In the present invention, when checking the circuit board 10 as described above, the output voltage VDD of the DC / DC converter 1 is read using the inspection device 20. That is, one of the contact pins 12 of the inspection device 20 constitutes the probe 5 shown in FIG. 1 and is originally provided in the inspection device 20 as a probe for measuring the output voltage. The inspection device 20 captures the output voltage VDD read by the probe 7 and outputs a feedback signal FB (FIG. 1) corresponding to the value of the captured output voltage VDD. This feedback signal FB is provided to the microcomputer 2 of the circuit board 10.
[0018]
When receiving the feedback signal FB, the microcomputer 2 generates a PWM (Pulse Width Modulation) signal having a duty ratio according to the feedback signal FB, and outputs this as a control signal. Since the PWM control is known as described in Patent Document 2, for example, a detailed description is omitted. The PWM signal output from the microcomputer 2 is a pulse output, and is applied to an integrating circuit including a resistor R3 and a capacitor C. The voltage integrated by the integrating circuit is input to the transistor Q. As a result, the transistor Q is turned on, and the potential at the voltage dividing point A determined by the current flowing through the transistor Q is fed back to the DC / DC converter 1 as the reference voltage REF. The DC / DC converter 1 generates and outputs an output voltage VDD corresponding to the reference voltage REF. Here, since the output of the integration circuit changes according to the output (duty ratio) of the PWM signal and the current flowing through the transistor Q changes according to the output of the integration circuit, the reference voltage REF can be varied by the PWM output. it can. That is, the microcomputer 2 can adjust the output voltage VDD of the DC / DC converter 1.
[0019]
When the output voltage VDD is adjusted to an appropriate value, the microcomputer 2 stores the parameter 4 (such as the duty ratio) of the PWM signal at that time in the nonvolatile memory 3. When the power is turned on thereafter, the microcomputer 2 reads the parameter 4 from the non-volatile memory 3, sets the output of the PWM signal based on the value of the parameter 4, and controls the transistor Q, so that the potential at the point A is set. That is, the reference voltage REF always has a constant value. As a result, the output voltage VDD output from the DC / DC converter 1 always has an appropriate value.
[0020]
As described above, in the above-described embodiment, the output voltage VDD of the DC / DC converter 1 is fed back to the microcomputer 2, and the reference voltage REF is varied by the PWM signal from the microcomputer 2 to adjust the output voltage VDD. Therefore, it is not necessary to manually adjust the semi-fixed resistor as in the related art, so that it is not necessary to perform the adjustment, and the adjustment accuracy is improved. In addition, since it is not necessary to use an expensive semi-fixed resistor and it can be realized using inexpensive circuit components such as a transistor and a resistor, the cost can be reduced. Since the microcomputer 2 and the non-volatile memory 3 originally used for controlling the printer are used, it is not necessary to add a new circuit component for generating the PWM signal and storing the parameter 4.
[0021]
In addition, since the output voltage of the DC / DC converter 1 is read using the inspection device 20 for checking the operation of the circuit board 10 and fed back to the microcomputer 2, there is no need for a dedicated device for automatic adjustment. Can be used as it is. Further, the parameter 4 of the PWM signal is stored in the non-volatile memory 3 when the output voltage VDD is adjusted to an appropriate value. Therefore, once the adjustment is performed, the parameter 4 is read out from the non-volatile memory 3 thereafter. This is unnecessary, and an appropriate output voltage VDD can always be obtained.
[0022]
In the above-described embodiment, an example has been described in which the microcomputer 2 is used as the control means and the current of the transistor Q is controlled using the PWM signal as the control signal. However, a circuit that outputs an analog signal is used as the control means. Alternatively, the current of the transistor Q may be controlled using the analog signal as a control signal.
[0023]
Further, in the above embodiment, an example in which the present invention is applied to a printer has been described. However, the present invention can be applied to various electric devices other than the printer.
[0024]
【The invention's effect】
As described above, according to the present invention, manual voltage adjustment work is not required, so that adjustment work can be omitted and adjustment accuracy can be improved. In addition, since it is not necessary to use an expensive semi-fixed resistor and it can be realized using inexpensive circuit components such as a transistor and a resistor, the cost can be reduced.
[0025]
In addition, using an existing inspection device eliminates the need for a dedicated device for automatic adjustment, and saves the parameters of the control signal when the output voltage is adjusted to an appropriate value. An appropriate output voltage can always be obtained.
[Brief description of the drawings]
FIG. 1 is a circuit diagram showing an automatic voltage regulator according to the present invention.
FIG. 2 is an external view of the inspection device.
FIG. 3 is a block diagram of an inspection device.
FIG. 4 is a circuit diagram showing a conventional automatic voltage regulator.
[Explanation of symbols]
Reference Signs List 1 DC / DC converter 2 Microcomputer 3 Non-volatile memory 4 Parameter 10 Circuit board 20 Inspection device Q Transistor R1, R2, R3 Resistance C Capacitor REF Reference voltage FB Feedback signal VDD Output voltage

Claims (4)

A microcomputer for controlling the operation of the printer, a nonvolatile memory for storing control data, and a DC / DC converter for supplying DC power to the printer are provided on a circuit board built in the printer. In a voltage automatic adjusting device that divides an output voltage of a converter, feeds back the reference voltage as a reference voltage, and adjusts the output voltage of the DC / DC converter by varying the reference voltage.
A first resistor connected to the output side of the DC / DC converter, a transistor connected in series with the first resistor, a second resistor connected in series with the transistor, and an input side of the transistor An integration circuit comprising a third resistor and a capacitor connected to
The output voltage of the DC / DC converter read using the circuit board inspection device is fed back to the microcomputer,
The microcomputer outputs a predetermined PWM signal based on the feedback, applies the PWM signal to the transistor via the integration circuit, and controls a current flowing through the transistor to change a reference voltage and to control a DC voltage. An automatic voltage adjustment device for a DC / DC converter, wherein an output voltage of a DC / DC converter is adjusted to an appropriate value, and a parameter relating to a PWM signal when the output voltage is adjusted to the appropriate value is stored in the nonvolatile memory. Control means for controlling the operation of the electric equipment, storage means for storing control data, and a DC / DC converter for supplying DC power to the electric equipment are provided, and the output voltage of the DC / DC converter is divided. In a voltage automatic adjustment device that adjusts the output voltage of a DC / DC converter by feeding back as a reference voltage and varying the reference voltage,
A first resistor connected in series to the output side of the DC / DC converter, a transistor connected in series with the first resistor, and a second resistor connected in series with the transistor;
Feeding back the output voltage of the DC / DC converter to the control means;
The control means applies a predetermined control signal to the transistor based on the feedback, controls a current flowing through the transistor, varies a reference voltage, and adjusts an output voltage of the DC / DC converter to an appropriate value. An automatic voltage adjustment device for a DC / DC converter, wherein a parameter relating to a control signal when adjusted to the appropriate value is stored in the storage unit. A microcomputer for controlling the operation of the printer, a nonvolatile memory for storing control data, and a DC / DC converter for supplying DC power to the printer are provided on a circuit board built in the printer. In a voltage automatic adjustment method in which an output voltage of a converter is divided and fed back as a reference voltage, and the output voltage of the DC / DC converter is adjusted by varying the reference voltage,
When setting the circuit board in an inspection device and performing an operation check, the output voltage of the DC / DC converter is read, and the read output voltage is fed back to a microcomputer via the inspection device. A predetermined PWM signal is output from the computer, the PWM signal is applied to a transistor via an integration circuit, and a current flowing through the transistor is controlled to vary a reference voltage so that an output voltage of the DC / DC converter becomes an appropriate value. A method for automatically adjusting the voltage of a DC / DC converter, comprising adjusting the parameters related to the PWM signal and adjusting the parameters to the appropriate value in the nonvolatile memory. A circuit board built in the electric device is provided with control means for controlling the operation of the electric device, storage means for storing control data, and a DC / DC converter for supplying DC power to the electric device. In a voltage automatic adjustment method of dividing an output voltage of a DC / DC converter and feeding back the divided reference voltage as a reference voltage, and varying the reference voltage, the output voltage of the DC / DC converter is adjusted.
When the circuit board is set in an inspection device to perform an operation check, the output voltage of the DC / DC converter is read, and the read output voltage is fed back to control means via the inspection device, and the control is performed based on the feedback. Means for outputting a predetermined control signal, applying the control signal to the transistor, and controlling the current flowing through the transistor to vary the reference voltage to adjust the output voltage of the DC / DC converter to an appropriate value; A method for automatically adjusting a voltage of a DC / DC converter, wherein a parameter relating to a control signal when adjusted to a value is stored in the storage means.

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