JP2001133882A - Projection type display - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily realize optimal lighting according to various lamps by constituting a lamp lighting device of separate composition of a main block common to various lamps and individual control blocks for the various lamps. SOLUTION: A control block is selected according to lighting characteristics of lamps by separately constituting a lamp lighting device of a main block common to various lamps and individual control blocks for the various lamps.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a projection type display, and more particularly to an improvement of a high pressure discharge lamp lighting device of a liquid crystal projector.

[0002]

2. Description of the Related Art As a light source of a projection type display, a high-pressure discharge lamp such as a metal halide lamp or a high-pressure mercury lamp is used because it has a high conversion efficiency and can easily obtain a point light source. Since different types of high-pressure discharge lamps have different optimum values of the lamp current with respect to the lamp voltage, a lamp lighting device having different control characteristics for each type is provided. As a prior art relating to this type of projection type display, for example, those described in JP-A-6-163177 and JP-A-10-3996 are known.

[0003]

In the above-mentioned prior art, since the lighting characteristics are different when the lamps are different, a dedicated circuit must be provided for each lamp. In addition, since the operating voltage of the lamp cannot be accurately detected, there is a problem that the accuracy of power control is insufficient and the variation in luminance is increased. Furthermore, since the luminance of the lamp is not directly detected, there is a problem that the luminance changes largely due to the change with time.

Accordingly, a first object of the present invention is to provide a projection display capable of realizing optimum lighting according to various lamps at low cost.

A second object of the present invention is to provide a projection display having improved power control accuracy and less variation in luminance.

It is a third object of the present invention to provide a projection type display capable of maintaining a constant luminance over a long period of time and displaying an excellent image.

[0007]

In order to achieve the first object, a projection display according to the present invention comprises a discharge lamp, and a lighting device for starting and controlling the discharge lamp. In a projection type display configured to obtain an enlarged image by projecting light from a discharge lamp via an image display device, the discharge lamp lighting device includes a main block for supplying power to the discharge lamp, A control block that is detachably connected to the main block, and controls the power supplied to the discharge lamp by controlling the main block with predetermined discharge lamp control characteristics, wherein the control is performed according to the type of the discharge lamp. The present invention is characterized in that different discharge lamp control characteristics are obtained by making blocks interchangeable.

The main block is supplied with a DC voltage and controls the lighting of the discharge lamp. The DC-DC converter detects the output of the DC-DC converter and outputs a detection signal to the control block. And the control block may be configured to control the DC-DC converter according to a detection voltage of the voltage detection circuit.

In order to achieve the second object of the present invention, a projection type display according to the present invention comprises a discharge lamp, and a lighting device for starting and lighting control of the discharge lamp. In a projection-type display configured to obtain an enlarged image by projecting light from a lamp through an image display device, a lamp voltage detection circuit that detects a voltage across the discharge lamp and outputs the voltage to the discharge lamp lighting device. Wherein the discharge lamp lighting device controls the discharge lamp based on a detection output of the lamp voltage detection circuit.

Further, in order to achieve the third object of the present invention, a projection type display according to the present invention comprises a discharge lamp, and a lighting device for starting and lighting control of the discharge lamp. In a projection type display configured to obtain an enlarged image by projecting light from a lamp through an image display device, a photo sensor for detecting a light amount of the discharge lamp is provided, and an output voltage of the photo sensor is set to the discharge lamp. The discharge lamp is output to a lighting device to perform lighting control of the discharge lamp.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram of a projection display according to the present invention. In FIG. 1, 1 is a screen, 2 is an optical system, 3 is an image display device, 4 is a reflector, 5 is a high-pressure discharge lamp, 6 is an image display device drive circuit, and 7 is a lamp lighting device.

In FIG. 1, a reflector 4 and a high-pressure discharge lamp 5 constitute a light source for emitting light from the back of the image display device 3. The light transmitted through the image display device 3 is projected on the screen 1 by the optical system 2. The image display device 3 is, for example, a liquid crystal display, and is driven by the image display device driving circuit 6 to display an image.
A large screen image is obtained on the screen 1. The lamp lighting device 7 performs activation and lighting control of the high-pressure discharge lamp 5.

FIG. 2 is a block diagram of the lamp lighting device 7 of FIG. 2, 8 is an AC power supply, 9 is a rectifying and smoothing circuit, 10 is a DC-DC converter, 11 is a detection circuit, 1
2 is a start circuit, 13 is a control circuit, 71 is a main block, and 72 is a control block.

In FIG. 2, a lamp lighting device 7 includes a rectifying / smoothing circuit 9, a DC-DC converter 10, and a voltage detecting circuit 1.
1. It is composed of a main block 71 composed of a starting circuit 12 and a control block 72 composed of a control circuit 13.
The main block 71 is common to various lamps, and the control block 72 has several types for various lamps, and realizes optimum lighting according to various lamps by selecting according to various lamps. The control block 72 is connected by a connector so that it can be easily attached to the main block 71.

The rectifying and smoothing circuit 9 rectifies and smoothes the AC voltage from the AC power supply 8 and supplies a DC voltage to the DC-DC converter 10. The output voltage and current of the DC-DC converter 10 are controlled by the control circuit 13 in accordance with the detection result from the detection circuit 11, and the DC-DC converter 10 supplies power to the lamp 5 via the starting circuit 12. The starting circuit 12 generates a high voltage to start the high-pressure discharge lamp 5.

FIG. 3 is a circuit diagram showing a first embodiment of the main block 71 of FIG. In FIG. 3, reference numeral 14 denotes a DC power input terminal, 15 denotes a drive circuit power input terminal, 1
6, 21 are transistors, 17 is a drive transformer, 1
8 is a diode, 19 is a choke coil, 20 is a capacitor, 22 is a constant voltage diode, 23, 24, and 25 are resistors, 26 and 27 are lamp connection terminals, 28 is a PWM input terminal, 29 is a current detection voltage output terminal, 30 is a detection voltage output terminal, and 31 is a connector.

In this embodiment, the DC-DC converter 1
Reference numeral 0 denotes a step-down chopper circuit including a transistor 16, a drive transformer 17, a diode 18, a choke coil 19, a capacitor 20, and the like. The transistor 16 is switched by a pulse from the PWM input terminal 28, and a direct current corresponding to the pulse width is applied to both ends of the capacitor 20. Voltage is generated. The detection circuit 11 includes a constant voltage diode 22 and resistors 23, 24, and 25. The terminal 29 outputs the voltage of the resistor 25, that is, the output current detection voltage of the DC-DC converter. A terminal 30 outputs a composite voltage of a voltage obtained by dividing the output voltage of the DC-DC converter by a constant voltage diode 22 by resistors 23 and 24 and an output current detection voltage.

FIG. 4 is a circuit diagram showing a first embodiment of the control block 72 corresponding to FIG. In FIG. 4, 2
8 'is a PWM output terminal, 29' is a current detection voltage input terminal, 30 'is a detection voltage input terminal, 32, 33, 34, 3
5,36,37,38,39,40,41,42,4
3, 44 are resistors, 45, 46, 47 are operational amplifiers, 4
8 is a multiplier, 49 is an error amplifier, 50 is an oscillator, 51 is a comparator, 52 is a voltage input terminal, and 53 is a reference voltage input terminal. The PWM output terminal 28 ', the current detection voltage input terminal 29', and the detection voltage input terminal 30 'are connected to the PWM input terminal 28, the current detection voltage output terminal 29, and the detection voltage output terminal 30 described in FIG. You.

When the operational amplifier 45 differentially amplifies the voltage from the detection voltage input terminal 30 'and the voltage from the current detection voltage input terminal 29', the output voltage of the DC-DC converter is level-shifted by the constant voltage diode 22. A voltage corresponding to the voltage is obtained. This voltage is applied to the operational amplifier 4
7, the level is shifted in the reverse direction.
A voltage corresponding to the output voltage of the C converter is obtained. Also,
The voltage from the current detection voltage input terminal 29 'is amplified to an appropriate amplitude by the operational amplifier 46 to obtain a voltage corresponding to the output current of the DC-DC converter. A multiplier 48 multiplies the output voltage of the operational amplifier 47 by the output voltage of the operational amplifier 46 to obtain a voltage corresponding to the output power of the DC-DC converter. This voltage and the reference voltage are compared by the error amplifier 49, and the output voltage is input to the comparator 51. The sawtooth voltage from the oscillator 50 is input to the other input of the comparator 51, and a pulse width modulated output voltage is obtained from the PWM output terminal 28 '.

Under the condition that the output voltage of the DC-DC converter is low immediately after the start of the discharge lamp and the constant voltage diode 22 does not conduct, only the voltage corresponding to the output current of the DC-DC converter is applied to the error amplifier 49 and the constant current control is performed. Increase the temperature quickly to stabilize lighting.

FIG. 5 shows a second control block corresponding to FIG.
FIG. 3 is a circuit diagram showing an example of the embodiment. The input voltage from the output voltage input terminal 30 ′ is compared with the reference voltage by the error amplifier 49 and the output voltage is input to the comparator 51. The sawtooth voltage from the oscillator 50 is input to the other input of the comparator 51, and a pulse width modulated output voltage is obtained from the PWM output terminal 28 '.

Under the condition that the output voltage of the DC-DC converter is low immediately after the discharge lamp is started and the constant voltage diode 22 is not conducting, only the voltage corresponding to the output current of the DC-DC converter is applied to the error amplifier 49 and the constant current control is performed. The lamp temperature rises quickly to stabilize lighting.

FIG. 6 shows the DC-
FIG. 3 is a diagram illustrating control characteristics of a DC converter. (A) is an output current characteristic with respect to the output voltage, and (b) is an output power characteristic with respect to the output voltage.

The characteristics of the control block shown in FIG.
3 and is controlled by the error amplifier so that the power becomes equal to the reference voltage, so that the constant power characteristic is shown above the voltage Vs at which the Zener diode is turned on, and the constant current characteristic is shown below it.

The characteristics of the control block shown in FIG.
In the error amplifier, the output voltage and the output current are controlled so that the sum of the output voltage and the output current becomes equal to the reference voltage. Therefore, when the Zener diode is turned on at a voltage Vs or higher, the power has a maximum value at a specific voltage. Below that, it has a constant current characteristic. Since the separately provided overvoltage protection circuit operates at the voltage Vn, the characteristics are shown up to Vn.

FIG. 7 is a circuit diagram showing a second embodiment of the main block 71 of FIG. In 7, 54 and 55 are resistors, 561 and 562 are resistor connection terminals, 57 and 58 are lamp voltage output terminals, and 59 is a connector. In the first embodiment of the main block 71, the output voltage of the DC-DC converter is used as the detection voltage. Error occurred and control accuracy had to be improved. In the second embodiment, since the resistors 54 and 55 are provided in parallel with the lamp 5 and the lamp voltage is directly detected, the control accuracy can be improved. As a result, there is an effect that variations in lamp luminance can be reduced.

FIG. 8 is a circuit diagram showing an embodiment of a control block corresponding to FIG. In FIG. 8, 57 ', 58'
Is a detection voltage input terminal, and 60 is a constant voltage diode.
The voltage corresponding to the lamp voltage is obtained by differentially amplifying the voltage from the detection voltage input terminals 57 ′ and 58 ′ with the operational amplifier 45. This output voltage is input to the operational amplifier 47 via the constant voltage diode 60. Other operations are the same as those in FIG. Further, under the condition that the output voltage of the DC-DC converter is low immediately after the discharge lamp is started and the constant voltage diode 60 does not conduct, only the voltage corresponding to the output current of the DC-DC converter is applied to the error amplifier 49, and the constant current control is performed. Increase the temperature quickly to stabilize lighting.

FIG. 9 is a circuit diagram showing a third embodiment of the main block 71 of FIG. In FIG. 9, 61 is a photo sensor, 62 is a photo sensor connection terminal, 63 is a voltage output terminal, and 64 is a connector.

In the first and second embodiments of the main block 71, the output voltage of the DC-DC converter and the lamp voltage are used as the detection voltage. There was a problem that the change in luminance due to the change was large. In the third embodiment, since the amount of light of the lamp is directly detected and controlled, there is a feature that the brightness is kept constant over a long period of time and a good image can be displayed.

FIG. 10 is a circuit diagram showing an embodiment of a control block corresponding to FIG. In FIG. 10, 63 'is a sensor voltage input terminal, 65, 66, 67 are resistors, 68 is an operational amplifier, 69 is a comparator, 80 is a multiplexer, and 81 is a voltage input terminal.

The voltage from the sensor voltage input terminal 63 ′ is amplified by the operational amplifier 68 to a voltage of an appropriate magnitude and applied to one input of the multiplexer 80. Multiplexer 8
A voltage obtained by amplifying the voltage of the current detection voltage input terminal 29 'to an appropriate level by the operational amplifier 46 is applied to the other input of 0. The output voltage of the comparator 69 is applied to the control terminal of the multiplexer, and when the voltage of the operational amplifier 68 is higher than the voltage applied to the voltage input terminal 81, the output voltage of the operational amplifier 68 is selected.

The output voltage of the multiplexer 80 is compared with the reference voltage by the error amplifier 49, and the output voltage is input to the comparator 51. The sawtooth voltage from the oscillator 50 is input to the other input of the comparator 51, and a pulse width modulated output voltage is obtained from the PWM output terminal 28 '. Since the output voltage of the multiplexer 80 selects the output voltage of the operational amplifier 68 when the output voltage of the operational amplifier 68, that is, the light amount of the lamp is equal to or more than a certain value, constant brightness control is performed in a steady state. Conversely, under the condition that the light amount immediately after the discharge lamp is started is low, the output voltage of the operational amplifier 46 is selected, so that constant current control is performed, and the lamp temperature is quickly increased to stabilize the lighting.

[0033]

As described above, in the projection type display of the present invention, the lamp lighting device is divided into a main block common to various lamps and a control block for each lamp, so that optimum lighting according to various lamps can be easily performed. There are effects that can be realized.

Further, since the operating voltage of the lamp can be accurately detected, there is an effect that the accuracy of power control is improved and the life can be extended.

Further, since the power control is performed by detecting the luminance of the lamp, there is an effect that the luminance can be kept constant for a long period of time and the image quality can be improved.

[Brief description of the drawings]

FIG. 1 is a block diagram of a projection display according to the present invention.

FIG. 2 is a block diagram of the lamp lighting device of FIG. 1;

FIG. 3 is a circuit diagram showing a first embodiment of a main block in FIG. 2;

FIG. 4 is a circuit diagram showing a first embodiment of a control block corresponding to FIG. 3;

FIG. 5 is a circuit diagram showing a second embodiment of the control block corresponding to FIG. 3;

FIG. 6 is a diagram showing characteristics of a control block.

FIG. 7 is a circuit diagram showing a second embodiment of the main block in FIG. 2;

FIG. 8 is a circuit diagram showing an embodiment of a control block corresponding to FIG. 7;

FIG. 9 is a circuit diagram showing a third embodiment of the main block in FIG. 2;

FIG. 10 is a circuit diagram showing an embodiment of a control block corresponding to FIG. 9;

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Screen, 2 ... Optical system, 3 ... Image display device,
5 high-pressure discharge lamp, 6 drive circuit, 7 lamp lighting device, 8 AC power supply, 9 rectifying and smoothing circuit, 10 DC-D
C converter, 11 detection circuit, 12 startup circuit, 13
... Control circuit, 14 ... DC power input terminal, 15 ... Drive circuit power input terminal, 16, 21 ... Transistor, 17 ...
Drive transformer, 18 ... diode, 19 ... choke coil, 20 ... capacitor, 22, 60 ... constant voltage diode, 23, 24, 25 ... resistor, 26, 27 ... lamp connection terminal, 28 ... PWM input terminal, 28 '... PWM output terminal, 29 ... current detection voltage output terminal, 29 '... current detection voltage input terminal, 30 ... detection voltage output terminal, 30' ... detection voltage input terminal, 31 ... connector, 32, 33, 34, 3
5,36,37,38,39,40,41,42,4
3, 44 ... resistor, 45, 46, 47 ... operational amplifier, 4
8 Multiplier, 49 Error amplifier, 50 Oscillator, 51
Comparator, 52: Voltage input terminal, 53: Reference voltage input terminal, 54, 55: Resistor, 561, 562: Resistance connection terminal, 57, 58 ... Detection voltage output terminal, 57 ', 5
8 ': detection voltage input terminal, 59: connector, 61: photo sensor, 62: photo sensor connection terminal, 63: voltage output terminal, 63': voltage input terminal, 64: connector, 6
5, 66, 67: resistor, 68: operational amplifier, 69: comparator, 71: main block, 72: control block, 80: multiplexer, 81: voltage input terminal.

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Yasuhiro Tomioka 1410 Inada, Hitachinaka-shi, Ibaraki F-term (reference) 2H088 EA13 HA06 HA28 MA20 3K072 AA11 AB09 AC20 DE01 DE02 DE04 EB05 EB06 GB01 5C058 AA06 BA05 BA26 BA29 BB25 EA01 EA26 EA51 5G435 AA16 BB12 DD04 EE26 GG23 GG28 LL15

Claims (14)

[Claims] 1. A projection system comprising: a discharge lamp; and a lighting device for starting and controlling the lighting of the discharge lamp, wherein an enlarged image is obtained by projecting light from the discharge lamp via an image display device. In the type display, the discharge lamp lighting device is a main block for supplying power to the discharge lamp, and is detachably connected to the main block, and controls the main block with predetermined discharge lamp control characteristics. And a control block for controlling the power supplied to the discharge lamp, wherein the control block can be replaced according to the type of the discharge lamp to obtain different discharge lamp control characteristics. Projection display. A main block to which at least a DC voltage is supplied and which controls lighting of the discharge lamp;
A DC converter, and a detection circuit that detects an output of the DC-DC converter and outputs the output to the control block, wherein the control block controls the DC-DC converter according to a detection signal of the detection circuit. The projection display according to claim 1, wherein: 3. A detection signal output from the detection circuit to the control block includes an output current detection voltage of the DC-DC converter and a composite voltage of the output current detection voltage and an output voltage detection voltage of the DC-DC converter. The projection display according to claim 2, comprising: 4. A subtraction circuit for subtracting a combined voltage of an output current detection voltage of the DC-DC converter and an output voltage detection voltage of the DC-DC converter from the output current detection voltage, 4. The projection display according to claim 3, further comprising a multiplication circuit that multiplies an output voltage of the subtraction circuit by a detection voltage of the discharge lamp current. 5. A projection device comprising: a discharge lamp; and a lighting device for starting and controlling the lighting of the discharge lamp, wherein an enlarged image is obtained by projecting light from the discharge lamp via an image display device. In the type display, a lamp voltage detection circuit that detects a voltage between both ends of the discharge lamp and outputs the voltage to the discharge lamp lighting device is provided, and the discharge lamp lighting device controls the discharge lamp based on a detection output of the lamp voltage detection circuit. A projection display characterized by being controlled. 6. The discharge lamp lighting device includes a main block for supplying power to the discharge lamp, the main block being detachably connected to the main block, and based on a detection output of the lamp voltage detection circuit. A control block that controls power supplied to the discharge lamp by controlling the discharge lamp with predetermined discharge lamp control characteristics, and that the control block can be replaced in accordance with the type of the discharge lamp, thereby providing different discharge lamp control. 6. The projection display according to claim 5, wherein characteristics are obtained. 7. The main block detects the lamp voltage detection circuit, a DC-DC converter supplied with a DC voltage and controlling lighting of the discharge lamp, and an output of the DC-DC converter. The projection display according to claim 6, further comprising a converter output detection circuit that supplies a signal to the control block. 8. The main block outputs detection signals of the lamp voltage detection circuit and the converter detection circuit to the control block, and the control block controls the DC-DC converter based on the two detection signals. The projection type display according to claim 7, wherein: 9. The projection display according to claim 8, wherein said control block includes a multiplication circuit for multiplying a detection signal of said lamp voltage detection circuit by a detection signal of said converter detection circuit. . 10. A projection system comprising: a discharge lamp; and a lighting device for starting and controlling the lighting of the discharge lamp, wherein an enlarged image is obtained by projecting light from the discharge lamp via an image display device. In the type display, a photo sensor for detecting the light amount of the discharge lamp is provided,
A projection-type display configured to output an output voltage of the photosensor to the discharge lamp lighting device to control lighting of the discharge lamp. 11. A discharge lamp lighting device, comprising: a main block for supplying power to the discharge lamp; a main block for detachably connecting to the main block; and a predetermined block based on a detection output of the photosensor. A control block for controlling the power supplied to the discharge lamp by controlling the discharge lamp control characteristics of the discharge lamp, wherein the control block can be replaced in accordance with the type of the discharge lamp, thereby providing different discharge lamp control characteristics. The projection display according to claim 10, wherein the projection display is obtained. 12. The main block detects the photo sensor, a DC-DC converter to which a DC voltage is supplied, and controls lighting of the discharge lamp, and detects an output of the DC-DC converter, and outputs a detection signal. 2. A detection circuit for supplying a signal to the control block.
2. The projection display according to 1. 13. The projection type display according to claim 12, wherein said main block supplies a detection signal of said photosensor and a detection signal of said detection circuit to said control block. 14. A projection type display according to claim 13, wherein said control block further includes a switch circuit for selecting one of a detection signal of said photosensor and a detection signal of said detection circuit. And projection type display.