JP2002027739A - Dc/dc converter and recoder using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a small-sized DC/DC converter having many outputs and a recorder using the converter. SOLUTION: An expensive main switching element having a large circuit area, a rectifier element and an inductance element for voltage conversion are used in common, and the output from the inductance element is outputted by using a switch which is subjected to time division control.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a DC / DC converter and a recording apparatus using the same.

[0002]

2. Description of the Related Art In recent years, portable electronic devices have been further reduced in size and weight, and power supply devices used in these devices have been required to be thinner and smaller.

On the other hand, as voltages used in these devices, +5 V, +3.3 V, etc. are used in logic circuits, and +12 V, etc., are used in driving systems such as motors. Crossing. A multi-output DC / DC converter that supplies each of these voltages includes, for example, a circuit called a forward DC / DC converter as disclosed in Japanese Patent Application Laid-Open No. 9-93914.

FIG. 5 is a circuit diagram of a forward DC / DC converter disclosed in the publication.

In FIG. 5, a DC input voltage terminal (Vi)
And a ground terminal (GND) as a DC power supply,
A secondary battery or a DC output from an AC adapter (not shown) is connected. As shown in FIG. 5, a primary winding P1 of a transformer T and a switching element Q1 are connected in series between both terminals Vi and GND of these DC input voltage sources. A diode D is connected to the secondary side of the transformer T.
0, secondary circuits SC1, SC2,..., SCn each including a choke coil LC and a capacitor C0.

[0006] A secondary circuit SC1, on the secondary side of the transformer T,
, SCn are provided with secondary windings S1, S2,..., Sn in accordance with the required number of outputs.
, N2n and output voltages V1, V2,..., Vn determined by the product of the ratio of each of the secondary windings N21, N22,.
Are obtained from the secondary circuits SC1, SC2,..., SCn.
Here, the relationship between the output voltage (Vn) of the secondary circuit and the DC input voltage (Vi) on the primary side is as follows.

Vn = Vi × β × N2n / N1, where β = Ton / (Ton + Toff).

[0008] As a multi-output DC / DC converter other than the forward type multi-output DC / DC converter described above,
Many circuit configurations have been proposed, including a flyback type, and each of the circuits uses a transformer.

In some multi-output DC / DC converters, a plurality of independent DC / DC converters having different output voltages are used in parallel on a common input voltage without using a transformer. It is formed in the upper part, it is put in one case, and if only the relation of input and output is seen, multi-output DC /
Although there is an example in which the configuration is a DC converter, it is larger than a multi-output DC / DC converter using a transformer.

[0010]

On the other hand, portable electronic devices are expected to be further miniaturized in the future together with the development of high-performance batteries. There is also a demand for further thinning and miniaturization of each component used therein. The DC / DC converter is one of the indispensable components for modern small-sized portable electronic devices, but is required to be thinner and smaller, like other components.

However, in a multi-output DC / DC converter using a transformer as in the above-described conventional example, the size of the transformer is the biggest obstacle to realizing a thinner and smaller device. That is, since the turns ratio between the primary side and the secondary side of the transformer directly determines the DC output voltage number and the DC output voltage value, the number of turns for reducing the thickness and size of the transformer is naturally reduced. There is a limit. If the number of windings is reduced beyond this limit, the required number of DC outputs and DC output voltage values cannot be obtained.

The present invention has been made in view of the above conventional example, and has as its object to provide a multi-output, small-sized DC / DC converter and a recording apparatus using the same.

[0013]

In order to achieve the above object, a DC / DC converter according to the present invention has the following configuration.

That is, an input terminal for inputting a DC voltage, a first output terminal for outputting a first DC voltage, and a second output terminal for outputting a second DC voltage different from the first DC voltage. A DC / DC converter comprising:
And a shared circuit including a switching element used for voltage conversion for obtaining a second DC voltage, a rectifier element, and an inductor element, and a first circuit connected between the inductor element and the first output terminal. , A second switch connected between the inductor element and the second output terminal, and a control circuit that controls opening and closing of the first and second switches in a time-division manner. DC /
It has a DC converter.

Here, the control circuit closes the first switch and outputs the first DC voltage from the first output terminal during a first time interval, and outputs the first DC voltage from the first output terminal during a second time interval. May be closed so that the second output terminal outputs a second DC voltage.

Further, it is preferable to provide first and second smoothing capacitors connected in parallel to the first and second output terminals, respectively.

The control circuit detects voltages output from the first and second output terminals and adjusts the switch timing of the switching element so that the first and second DC voltages become the specified values, respectively. Although it is desirable to control, the control circuit controls the switch timing of the switching element so that the first DC voltage has a specified value, and the second DC voltage has a specified value. And a second controller for controlling the switching timing of the switching element, and the first and second controllers may control the switching timing of the switching element in a time-division manner.

According to another aspect of the present invention, a DC having the above-described structure is provided.
And a recording device using a DC converter. This recording apparatus preferably performs recording using an ink jet recording head.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below in detail with reference to the accompanying drawings.

FIG. 1 is an external perspective view of a portable ink-jet printer which is a typical embodiment of the present invention. This inkjet printer shows a configuration that allows both color printing and black and white mono color printing,
When considered as an apparatus dedicated to black-and-white monochrome printing, only the ink cartridge containing the black ink described below is mounted on the recording head.

As shown in FIG. 1, a multi-nozzle recording head 102 having 128 nozzles and a cartridge guide 103 are mounted on a carriage 101, and the recording head 102 includes black (K) ink, Alternatively, cyan (C), magenta (M), yellow (Y), and black (K) inks are respectively discharged. At the time of printer recording operation, the recording head 102 is equipped with an ink cartridge 110 containing black ink and an ink cartridge 111 containing other three color inks. Then, magenta (M), yellow (Y), and black (K) inks are supplied from the respective ink cartridges, and each nozzle of the recording head is driven via a flexible cable (not shown) in which a large number of conductive wires are arranged. A signal is provided.

On the other hand, the carriage 101 is mounted on two guide rails 104 to 105, and
The carriage 101 is reciprocated in the X direction (hereinafter, this X direction is referred to as a main scanning direction) by driving the endless belt 109 connected to the carriage 101 with a carrier motor (described later). Further, the recording paper 106 is spread by an auxiliary roller 107 to assist in smooth transportation of the recording paper. The transport roller 108 is driven by a transport motor (described later) to feed the recording paper 106 in a Y direction (hereinafter, this Y direction is referred to as a sub-scanning direction).

FIG. 2 is a block diagram showing a configuration of a control circuit of the ink jet printer. In FIG.
Is an interface for inputting a recording signal from an external device such as a host computer, 171 is an MPU, 17
2 is a ROM for storing a control program (including a character font if necessary) executed by the MPU 171;
Is a DRAM for temporarily storing various data (such as the recording signal and recording data supplied to the recording head 102).
It is. A gate array 174 controls supply of print data to the print head 102, and also controls data transfer between the interface 170, the MPU 171 and the RAM 173. Reference numeral 179 denotes a carrier motor for moving the recording head 102 in the main scanning direction, and 178 denotes a transport motor for transporting the recording paper. Reference numeral 175 is a head driver for driving the recording head, and 176 to 177 are motor drivers for driving the transport motor 178 and the carrier motor 179, respectively.

The operation of the control circuit will be described briefly. When a recording signal is input to the interface 170, the gate array 1
The recording signal is converted into recording data for printing between 74 and the MPU 171. Then, the motor driver 17
6, 177 are driven, and the head driver 175 is driven.
The recording head 102 is driven in accordance with the recording data sent to the printer, and a recording operation is performed.

Since the ink jet printer having the above configuration is a portable type, it can be operated by a DC output from a secondary battery or an AC adapter, and a DC / D converter is provided in a part of the control circuit.
A C converter is provided. Then, a drive voltage suitable for each of the recording head 102, each motor, each driver, and a logic circuit is supplied from the DC / DC converter.

FIG. 3 shows the D used in this embodiment.
FIG. 2 is a circuit diagram illustrating a configuration of a C / DC converter.

In FIG. 3, when a DC input voltage (Vin) is applied between the terminals 1a and 1b, the main switching element Q1
Input voltage is applied to the emitter of the main switch element Q1.
Is controlled to open and close by an output drive signal Vd of the control circuit IC1. The collector output of the main switch element Q1 is connected to a voltage conversion inductance element L1, and further connected to a flywheel diode D1 provided between the main switch element Q1 and GND. The output of the inductance element L1 is connected to the switch elements SW1 and SW2,
1, SW2 is the main switching element Q1 from the control circuit IC.
It is opened and closed in synchronization with the drive signal of. Voltage smoothing capacitors C1 and C2 are connected to the other end of each switch element, respectively.
And supplies different DC output voltages Vo1 and Vo2 from the output terminals 2a and 3a to each section of the recording apparatus.

In order to control the plurality of output voltages to specified DC voltages, the control circuit IC1 controls the internal reference voltages Vref1, Vref2, the outputs from the differential amplifiers 5, 6 and the triangular wave Using signals,
A square wave signal is generated by the comparators 8 and 9;
Further, the rectangular wave signal is frequency-divided by に よ っ て by the frequency divider 7. The outputs from the frequency divider 7 and the outputs from the comparators 8 and 9 are ANDed by the AND circuits 10 and 11 and input to the NOR circuit 12. The output from the NOR circuit 12 is output to the switch elements SW1 and SW2 via the D-type flip-flop 13.

With such a configuration, the drive timing of the main switch element Q1 is controlled according to the plurality of output voltages detected, and the switch elements SW1 and S
The opening and closing of W2 is also controlled.

Next, the operation of the control circuit IC1 and the drive timing of the main switching element Q1 and the switching elements SW1 and SW2 will be described with reference to a time chart shown in FIG.

As can be seen from FIG. 3, the output voltage Vo1 is divided by the resistors R3 and R4 and input to the voltage detection terminal 301 of the control circuit IC1. This input voltage is applied to the differential amplifier 5
Is compared with the internal reference voltage Vref1 and the differential signal (d)
Is input to the comparator 8. A triangular wave signal (a) generated by the triangular wave oscillation circuit 4 is input to one input terminal of the comparator 8, and a pulse signal (e) having a pulse width corresponding to the voltage value of the difference signal is output. The pulse signal (e) is input to one terminal of the AND circuit 10, and is also input to the frequency divider 7, and the pulse signal (b) obtained by doubling the cycle of the PWM pulse signal is output to the AND circuit 10. It is input to the other terminal. As a result, the AND circuit 10 outputs a pulse signal (f) at half the triangular wave oscillation frequency, that is, a pulse signal (e) in which one pulse signal is skipped.

Control circuit IC divided by resistors R5 and R6
The same signal operation is performed by the triangular wave oscillation circuit 4, the difference amplifier 6, the comparator 9, and the AND circuit 11 on the output voltage Vo2 input to the first voltage detection terminal 302, and the AND circuit 11 outputs a pulse signal (i). Is done. If these pulse signal (f) and pulse signal (i) are NO
The pulse signal (j) is input to the R circuit 12 and output.

The pulse signal (j) is a drive signal for the main switch element Q1 for controlling a plurality of output voltages.
It is a serial signal whose pulse width is adjusted in a time-division manner every other cycle so that each of the two output voltages Vo1 and Vo2 is controlled to a specified value.

In other words, the pulse signal (j) has a pulse width for controlling the output voltage Vo1 in the section A shown in FIG. 4, and has a pulse width for controlling the output voltage Vo2 in the section B. Thereby, the switch elements SW1,
SW2 is a control signal (k) whose logic switches at the timing when the main switch element Q1 is turned on, and its inverted signal (l).
Is opened and closed by The control signal (k) and the control signal (l) are obtained by inputting the pulse signal (j) to the inverted CK terminal of the D-type flip-flop 13 and inputting the inverted output to the D terminal.

The pulse signal (j) output as a driving signal of the main switching element Q1 and the control signal (k) of each of the switching elements SW1 and SW2 output by the above operation.
And the control signal (l), the switch element SW1 is turned on in the section A, and the output 2
The current is supplied to the smoothing capacitor C1 on the a side, and becomes the specified value voltage Vo1. Next, in the section B, the switch element SW
2 is turned on, a current is supplied from the inductance element L1 to the smoothing capacitor C2 on the output 3a side, and the voltage becomes the specified value voltage Vo2.

The signal (m) in FIG. 4 is the voltage waveform at the point VA in FIG. 3, and the signal (n) is the voltage waveform V in FIG.
The voltage waveform at point B, signal (o) is the inductance element L1
3 shows a current waveform.

Therefore, according to the embodiment described above, the main switching element Q1, the flywheel diode D
1 and the voltage conversion inductance element L1 can be shared to form a DC / DC converter that outputs a plurality of different DC voltages. Further, the output voltage value can be freely set without depending on the mutual output voltage by changing the voltage dividing ratio of the voltage dividing resistors R3, R4 and R5, R6 which determine the detection voltage of the output voltage. On the other hand, a circuit for detecting the output voltages obtained from the two output terminals and controlling the switch timing of the main switching element so that the output voltages become a specified value is provided independently in the control circuit corresponding to the two output voltages. These circuits drive the main switching element in a time-division manner.

As described above, the main switching element, the rectifying element, and the inductor element for voltage conversion are shared, and this inductance element is connected in a time-division manner by the switch to take out two different DC voltages.

Thus, a desired DC voltage can be obtained without using a transformer, which contributes to downsizing of a DC / DC converter and downsizing of a portable electronic device. Further, sharing the main switching element Q1, the flywheel diode D1, and the inductance element L1 for voltage conversion also contributes to downsizing of the DC / DC converter.

Although the above embodiment has been described with respect to an example in which two different DC outputs are obtained, a similar configuration may be used when three or more different DC outputs are to be obtained.

In the above embodiment, the description has been made assuming that the droplets ejected from the recording head are ink, and that the liquid stored in the ink tank is ink. It is not limited. For example, an ink tank may contain a processing liquid discharged to a recording medium in order to improve the fixability and water resistance of the recorded image or to improve the image quality.

The above-described embodiment is particularly provided with a means (for example, an electrothermal converter or a laser beam) for generating thermal energy as energy used for performing ink ejection even in an ink jet recording system. By using a method in which a change in the state of the ink is caused by energy, it is possible to achieve higher density and higher definition of recording.

The typical configuration and principle are described in, for example, US Pat. Nos. 4,723,129 and 4,740.
It is preferable to use the basic principle disclosed in the specification of Japanese Patent No. 796. This method can be applied to both the so-called on-demand type and continuous type. In particular, in the case of the on-demand type, liquid (ink)
By applying at least one drive signal corresponding to the recorded information and providing a rapid temperature rise exceeding the nucleate boiling to an electrothermal transducer arranged corresponding to the sheet or the liquid path holding the Since thermal energy is generated in the electrothermal transducer and film boiling occurs on the heat-acting surface of the recording head, bubbles in the liquid (ink) corresponding to this drive signal on a one-to-one basis can be formed. It is valid. By discharging the liquid (ink) through the discharge opening by the growth and contraction of the bubble, at least one droplet is formed. When the drive signal is formed into a pulse shape, the growth and shrinkage of the bubble are performed immediately and appropriately, so that the ejection of the liquid (ink) having particularly excellent responsiveness can be achieved, which is more preferable.

As the pulse-shaped drive signal, those described in US Pat. Nos. 4,463,359 and 4,345,262 are suitable. Further, if the conditions described in US Pat. No. 4,313,124 relating to the temperature rise rate of the heat acting surface are adopted, more excellent recording can be performed.

As the configuration of the recording head, in addition to the combination of the discharge port, the liquid path, and the electrothermal converter (linear liquid flow path or right-angle liquid flow path) as disclosed in the above-mentioned respective specifications, A configuration using U.S. Pat. No. 4,558,333 or U.S. Pat. No. 4,459,600, which discloses a configuration in which a heat acting surface is arranged in a bent region, is also included in the present invention. In addition, for multiple electrothermal transducers,
JP-A-59-123670 which discloses a configuration in which a common slot is used as a discharge part of an electrothermal transducer, and JP-A-59-123670 which discloses a configuration in which an opening for absorbing a pressure wave of thermal energy corresponds to a discharge part. A configuration based on 138461 may be adopted.

Further, as a full-line type recording head having a length corresponding to the width of the maximum recording medium that can be recorded by the recording apparatus, the length is determined by combining a plurality of recording heads as disclosed in the above-mentioned specification. This may be either a configuration satisfying the above requirements or a configuration as a single recording head formed integrally.

In addition, not only the cartridge type recording head in which the ink tank is provided integrally with the recording head itself described in the above-described embodiment but also the apparatus main body can be electrically connected to the apparatus main body. A replaceable chip-type recording head, which enables a simple connection and supply of ink from the apparatus main body, may be used.

It is preferable to add recovery means for the printhead, preliminary auxiliary means, and the like to the configuration of the printing apparatus described above, since the printing operation can be further stabilized. Specific examples thereof include capping means for the recording head, cleaning means, pressurizing or suction means, preheating means using an electrothermal transducer or another heating element or a combination thereof. It is also effective to provide a preliminary ejection mode for performing ejection that is different from printing, in order to perform stable printing.

Further, the recording mode of the recording apparatus is not limited to the recording mode of only the mainstream color such as black, but may be a single recording head or a combination of plural recording heads. Alternatively, the apparatus may be provided with at least one of full colors by color mixture.

In the above-described embodiment, the description is made on the assumption that the ink is a liquid. However, even if the ink solidifies at room temperature or lower, it is possible to use an ink that softens or liquefies at room temperature. Or, in the ink jet method, generally, the temperature of the ink itself is controlled within a range of 30 ° C. or more and 70 ° C. or less to control the temperature so that the viscosity of the ink is in a stable ejection range.
It is sufficient that the ink is in a liquid state when the use recording signal is applied.

In addition, in order to positively prevent temperature rise due to thermal energy as energy for changing the state of the ink from the solid state to the liquid state,
Alternatively, in order to prevent evaporation of the ink, an ink which solidifies in a standing state and liquefies by heating may be used. In any case, the application of heat energy causes the ink to be liquefied by application of the heat energy according to the recording signal and the liquid ink to be ejected, or to start to solidify when reaching the recording medium. The present invention is also applicable to a case where an ink having a property of liquefying for the first time is used. In such a case, as described in JP-A-54-56847 or JP-A-60-71260, the ink is held in a liquid state or a solid state in the concave portion or through hole of the porous sheet. It is good also as a form which opposes an electrothermal transducer. In the present invention, the most effective one for each of the above-mentioned inks is to execute the above-mentioned film boiling method.

In addition to the above, the recording apparatus according to the present invention may be provided not only as an image output terminal of an information processing apparatus such as a computer but also integrally or separately, a copying apparatus combined with a reader, etc. It may take the form of a facsimile machine having functions.

Even if the present invention is applied to a system including a plurality of devices (for example, a host computer, an interface device, a reader, a printer, etc.), an apparatus including one device (for example, a copier, a facsimile machine) Etc.).

[0054]

As described above, according to the present invention, an expensive main switching element, a rectifying element, and a voltage converting inductance element having a large circuit area can be provided without using a transformer as in the prior art. There is an effect that a plurality of DC voltages can be obtained in common. Further, it is a great advantage that the output voltage can be freely set without being limited by the output ratio of the transformer as in a multi-output DC / DC converter using a conventional transformer-type transformer.

Further, the present invention can reduce the mounting area of the components constituting the DC / DC converter, and at the same time contribute to the realization of the cost reduction.

The use of such a DC / DC converter also contributes to a reduction in size and weight of a portable electronic device such as a portable recording device.

[Brief description of the drawings]

FIG. 1 is an external perspective view of a portable inkjet printer as a typical embodiment of the present invention.

FIG. 2 is a block diagram illustrating a configuration of a control circuit of the inkjet printer.

FIG. 3 is a circuit diagram showing a configuration of a DC / DC converter.

4 is a time chart illustrating an operation of the DC / DC converter shown in FIG.

FIG. 5 is a circuit diagram showing a conventional DC / DC converter.

[Explanation of symbols]

 1a, 1b Input terminal 2a, 2b Output terminal 3a, 3b Output terminal C1-C2 Capacitor R1-R6 Resistance L1 Inductance element D1 Diode Q1 Main switch element SW1, SW2 Switch element IC1 Control circuit

Claims (7)

[Claims] An input terminal for inputting a DC voltage, a first output terminal for outputting a first DC voltage, and a second output terminal for outputting a second DC voltage different from the first DC voltage A shared circuit including a switching element used for voltage conversion for obtaining the first and second DC voltages, a rectifier element, and an inductor element; A first switch connected between the first and second output terminals; a second switch connected between the inductor element and the second output terminal; and opening and closing of the first and second switches. And a control circuit for controlling the DC / DC in a time-division manner. 2. The control circuit according to claim 1, wherein the control circuit outputs the first DC voltage from the first output terminal by closing the first switch during a first time interval, and outputs the first DC voltage from the first output terminal during a second time interval. 2. The DC / DC converter according to claim 1, wherein control is performed such that the second switch is closed to output the second DC voltage from the second output terminal. 3. The DC / DC converter according to claim 1, further comprising first and second smoothing capacitors connected in parallel to each of the first and second output terminals. 4. The control circuit detects voltages output from the first and second output terminals, and controls the switching elements so that the first and second DC voltages become specified values, respectively. 2. The DC / DC converter according to claim 1, wherein switch timing is controlled. 5. The control circuit, comprising: a first control unit that controls a switch timing of the switching element so that the first DC voltage has a specified value; and the second DC voltage has a specified value. And a second control unit for controlling the switch timing of the switching element, wherein the first and second control units control the switch timing of the switching element in a time-division manner. 4. The DC / DC converter according to 4. 6. A recording apparatus using the DC / DC converter according to claim 1. 7. The recording apparatus according to claim 6, wherein recording is performed using an ink jet recording head.