JPH1116687A - Light source control device - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To make it possible to variably control the amount of illumination light and to prevent an increase in the size of the device configuration. SOLUTION: An inverter unit 20 for generating a high-frequency current
A DC power supply 17 for operating the inverter unit 20, an oscillating unit 18 and an oscillation driving unit 19 for driving the inverter unit 20, a secondary-side rectifying / smoothing unit 24 provided on the secondary side of the inverter unit 20, A power supply regulator for signal processing 25 for generating a DC current from the output of the secondary side rectifier / smoothing unit 24, a voltage-controlled switching element installed in parallel with the regulator 25 and symmetrically around the halogen lamp 22, and its switching It has a voltage-controlled current SW section 21 composed of a light source control section disposed on the ground side of the element, and a pulse width signal circuit 23 for generating a control signal for the light source control section.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light source control for controlling a light source used in an illumination device of an image capturing device having, for example, an image pickup device such as a linear sensor and an illumination device for illuminating a reading position thereof. The present invention relates to an apparatus, and particularly to an apparatus sharing a power source for a signal processing system and a power source for driving a light source.

[0002]

2. Description of the Related Art As a device which requires a light source control device for controlling a light source and a power source for a signal system used in a conventional lighting device, a so-called flatbed scanner or a projector using an incandescent light source is used. Etc.

FIG. 5 shows a schematic configuration of the flatbed type scanner.

In FIG. 5, a component indicated by reference numeral 1 is a DC power supply, and the current of the DC power supply 1 is supplied to the lighting inverter 2 and the power supply inverter 6. A component indicated by reference numeral 5 is an oscillation / drive unit for the lighting inverter 2, and a component indicated by reference numeral 7 is an oscillation / drive unit for the power inverter 6. The current of the DC power supply 1 is converted into a high-frequency current by the lighting inverter 2 and supplied to the lighting drive circuit 3 to drive the lighting 4. The output of the power supply inverter 6 is supplied to a power supply rectifier / smoothing unit 8 and supplied to a desired circuit block 9.

As described above, in this example of the flatbed type scanner, two power supplies, ie, a light source power supply and a signal processing power supply, that is, a lighting inverter 2 and a power supply inverter 6 are provided.
Are required.

FIG. 6 shows a schematic configuration of the projector.

[0007] In FIG. 6, a component indicated by reference numeral 10 is a DC power supply, and a current of the DC power supply 10 is supplied to an inverter 11. This inverter 11
Is connected to the oscillation / drive unit 14 for the inverter. The output of the inverter 11 is connected to the illumination 13 via an illumination relay switch 12 which is a switch for illumination and does not affect the power of the inverter. On the other hand, the output of the inverter 11 is supplied to the power supply
The output of the power supply rectifier / smoothing unit 15 is supplied to a circuit block 16 as a desired power supply.

As described above, in this example of the projector, while the power is supplied to the circuit block 16 side, that is, the signal processing side, the light source of the illumination 13 is turned off or turned on by the switching element such as the illumination relay switch 12. Switching control is performed.

[0009]

The above-mentioned conventional light source control device has the following problems.

That is, in the example of FIG. 5, in order to control the light amount of the illumination 4 while varying it, a dedicated control device (for example, an illumination inverter) separate from the signal processing inverter (power supply inverter 6). 2 and its oscillating / driving unit 5) are required, and there is a problem that the device becomes large.

In the example of FIG. 6, the illumination relay switch 12 is used to control the light source of the illumination 13, but there is a problem that it is difficult to control the amount of light with this device.

The present invention has been made in view of such circumstances, and has as its object to provide a light source control device capable of variably controlling the amount of illumination and preventing an increase in the size of the device configuration. .

[0013]

SUMMARY OF THE INVENTION The present invention relates to an inverter unit for generating a high-frequency current, a DC power supply for operating the inverter unit, a high-frequency generator for driving the inverter unit, its driving unit, and a secondary unit for the inverter unit. One or more DC regulators installed on the side, a light source control unit in which voltage-controlled switching elements are installed in parallel symmetrically around the light source, and a control signal generation unit that generates control signals for this light source control unit The above-mentioned subject is solved by providing.

That is, in the present invention, the direction of the current flowing through the light source is reversed every half wavelength, but the voltage-controlled switching elements are connected to each other in opposite directions, and the diodes are connected in parallel and in opposite directions to the respective elements. And by controlling the falling portion of each voltage waveform by PWM (pulse width modulation), the current flowing in the forward and reverse directions can be controlled with low loss. Therefore, the same inverter unit can be used as both the high-frequency current supply unit of the signal processing circuit power supply and the high-frequency controllable type high-frequency current supply unit, and the overall size of the device can be suppressed.

[0015]

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

FIG. 1 shows a schematic configuration of a light source control device according to an embodiment of the present invention. The light source control device according to the present embodiment controls, for example, a light source used in the illumination device of an image capturing device having an image pickup device such as a linear sensor and an illumination device for illuminating a reading position thereof. It is.

In FIG. 1, the component indicated by reference numeral 17 is a DC power supply, and the current of the DC power supply 17
Supplied to The signal from the oscillating unit 18 is supplied to the inverter unit 20 by the oscillating driving unit 19. The inverter section 20 converts the output current of the DC power supply 17 into a high-frequency current according to the output signal from the oscillation drive section 19.

The high-frequency current output from the inverter unit 20 is converted into a direct current by the secondary-side rectifier / smoothing unit 24, and further used as a desired circuit power by a signal processing power regulator 25.

On the other hand, in the light source control device according to the embodiment of the present invention, a halogen lamp drive section is installed in parallel with the secondary side rectifying section / smoothing section 24, and a voltage control type A current SW unit 21 is installed in parallel with the secondary rectifier / smoothing unit and in series with the output of the inverter unit 20.

The voltage control type current SW unit 21 performs PWM (pulse width modulation) control on the output signal of the inverter unit 20 based on a control signal from the pulse width control circuit 23. The pulse width control circuit 23 generates a control signal for the PWM control based on an externally applied pulse width signal.

The voltage-controlled current SW unit 21 performs PWM
The output signal of the controlled inverter unit 20 is supplied to the halogen lamp 22 as a lamp drive current.

Next, the PWM control in the voltage-controlled current SW unit 21 will be described with reference to FIGS.

FIG. 2 shows a detailed circuit configuration of the halogen lamp drive section of the light source control device according to the present embodiment.

In FIG. 2, the parts indicated by reference symbols A and B correspond to the output terminals of the inverter unit 20. The components indicated by reference numeral 31 in FIG.

Here, the output terminals A,
The output signals φA and φB of B are signals having phases opposite to each other, and since the secondary-side rectifier / smoothing unit 24 is connected as described above, as shown in FIGS. It is a rectangular wave with no negative component.

Signals φA and φB as shown in FIGS.
Are connected to voltage-controlled switching elements 26 and 27 that constitute the voltage-controlled current SW unit 21. In this example, for example, a power MOS FFT (Metal Oxide) which is a component of the voltage-controlled switching elements 26 and 27 is used.
The connection is made such that the source side of the semiconductor field effect transistor is the ground side.

By doing so, for example, the signal φ
At the time of the phase A, the signal φA passes through the diode of the switching element 26, is input from the drain side of the FET of the switching element 27, and then returns to the inverter section 20 from the source side. At this time, a pulse signal for PWM as shown in FIG. 3E generated by the pulse width control circuit 23 of FIG. 1 is supplied to the buffer 29 as a gate signal for the signal φA. ) Will flow.

For example, when the phase of the signal φB is the same, the signal φB passes through the diode of the switching element 27 and is input from the drain side of the FET of the switching element 26, and then from the source side to the inverter section 2.
It will return to 0. At this time, FIG.
A pulse signal for PWM as shown in FIG. 3F generated by the pulse width control circuit 23 is supplied as a gate signal to the signal φB, and this pulse signal (gate signal)
The current controlled by the above flows.

As a result, the halogen lamp 30 as a light source
An intermittent current like G in FIG. 3 has flown as a lamp drive current in the (halogen lamp 22 in FIG. 1), and it is desired to change the pulse widths of E and F in FIG. It is possible to obtain a light amount. At this time, the timing of gate-off from the buffers 28 and 29 and
By controlling the timing at which the phases of the signals φA and φB are switched at the same time by the signals shown in FIGS. 3E and 3F, a reverse bias is applied between the gate and the source at the time of off-state. Can be turned off. This makes it possible to realize low-loss switching.

FIG. 4 shows a flow chart of the operation of the light source control device according to the embodiment of the present invention described above.

In FIG. 4, in step S1, a DC current is supplied from the DC power supply 17 of FIG. In step S2, the high frequency oscillator 18 for the inverter is used.
Starts the oscillating operation. In step S3, the oscillation unit 18
The oscillating signal from the oscillating driver 19 for the inverter 20
Supplied to In step S4, the inverter unit 2
The DC current supplied to 0 is converted into a high-frequency current by the inverter drive signal from the oscillation drive unit 19.

Next, in step S6, the pulse width control circuit 23 receives a pulse width modulation pulse width signal for determining the modulation width from the outside, and receives the pulse width modulation pulse width signal as shown in FIGS. To generate a control signal.

In step S5, the control signal for pulse width modulation is supplied to the voltage-controlled switching elements 26 and 27 shown in FIG. 2, and the output signals of the inverter 20 are supplied to the voltage-controlled switching elements 26 and 27. To generate a desired modulated lamp drive signal.

In step S7, the inverter output signal subjected to the PWM control as described above is supplied to the halogen lamp 30, so that the lamp 30 is driven at a desired luminance as shown in FIG.

In step S8, the inverter unit 2
The output of 0 is supplied to a signal processing two-dimensional rectifier / smoothing unit 24 installed in parallel with the halogen drive unit. Then, in step S9, the smoothed DC current is supplied to a signal processing power supply regulator. The power is sent to the circuit 25 and the desired power is supplied to the circuit.

As described above, in the light source control device according to the embodiment of the present invention, the light amount control of the illumination light source and the inverter of the circuit power supply can be shared, and the power supply unit can be reduced in space. In addition, low-loss modulation can be realized by performing modulation such that the falling portion is left in the pulse width control section of the high-frequency current.

[0037]

According to the present invention, an inverter for generating a high-frequency current, a DC power supply for operating the inverter, a high-frequency generator for driving the inverter, a driving unit thereof, and a secondary side of the inverter are provided. One or more DC regulators, a light source control unit in which voltage-controlled switching elements are installed in parallel with the light source around the light source, and a control signal generation unit that generates a control signal for the light source control unit are provided. With this configuration, the amount of illumination light can be variably controlled, and an increase in the size of the device configuration can be prevented. That is, according to the present invention, the light amount control of the illumination light source and the inverter of the circuit power supply can be shared, and the power supply unit can be reduced in space. In addition, low-loss modulation can be realized by performing modulation such that the falling portion is left in the pulse width control section of the high-frequency current.

[Brief description of the drawings]

FIG. 1 is a block circuit diagram illustrating a schematic configuration of a light source control device according to an embodiment of the present invention.

FIG. 2 is a circuit diagram showing a specific configuration of a halogen lamp drive unit of the light source control device according to the embodiment of the present invention.

FIG. 3 is a waveform diagram used to describe the operation of a halogen lamp drive unit.

FIG. 4 is a flowchart illustrating a flow of an operation of the light source control device according to the embodiment of the present invention.

FIG. 5 is a block circuit diagram showing a schematic configuration of a light source control device having a light source control device and a signal processing power supply device as seen in a conventional scanner or the like.

FIG. 6 is a block circuit diagram showing a schematic configuration of a light source control device in which a conventional light source control device and a signal processing power supply device are shared by one inverter.

[Explanation of symbols]

17 DC power supply, 18 oscillation part, 19 oscillation drive part, 20 inverter part, 21 voltage control type current S
W section, 22 halogen lamp, 23 pulse width control circuit, 24 secondary side rectification section / smoothing section, 25 signal processing power supply regulator A, B inverter output terminal, 26 voltage control switching element for terminal B side control, 27 Voltage controlled switching element drive signal buffer for terminal A side control, 28 Voltage controlled switching element drive signal buffer for terminal B side control, 29 Voltage controlled switching element drive signal buffer for terminal A side control

Claims (2)

[Claims] 1. An inverter for generating a high-frequency current, a DC power supply for operating the inverter, a high-frequency generator for driving the inverter, and a secondary-side rectifying / smoothing unit provided on a secondary side of the inverter. One or more DC regulators provided on the secondary side of the inverter section; a voltage-controlled switching element installed in parallel with the DC regulator and symmetrically around a light source; A light source control device comprising: a light source control unit disposed on the ground side of an element; and a control signal generation unit that generates a control signal of the light source control unit. 2. The apparatus according to claim 1, further comprising a modulating means for modulating a high-frequency current signal output from said inverter section from a falling portion of a drive current waveform when performing pulse width modulation. Light source control device.