JP2002110393A - Discharge lamp lighting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a discharge lamp lighting device that enables making a clear image display without giving a faded display by trailing when used for a liquid crystal display device that may make a dynamic picture image display. SOLUTION: The driving signal generating part 100 generates plural n driving signals S1-Sn that light individually plural n discharge lamps L1-Ln. Each of the driving signals S1-Sn is generated in order having a certain phase angle within one cycle of the reference signal ϕ2 that is a row of pulse having a certain cycle. And each of the driving signals becomes a high level energy state that has an energy to light the discharge lamp L1-Ln in a timing counted backward from the end of one cycle based on its own phase angle, and maintains that high level energy state until the end of its own one cycle.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a discharge lamp lighting device mainly used as a backlight device of a liquid crystal display device.

[0002]

2. Description of the Related Art Liquid crystal display devices have the advantages of being lightweight, small, and thin, and have been conventionally used as display devices for personal computers. A liquid crystal display device has a basic structure in which liquid crystal is arranged in front of a pixel and a backlight is arranged behind the pixel. Generally,
The backlight is always lit, and the pixels are displayed by the shutter function of the liquid crystal.

However, since the liquid crystal has a response delay, so-called tailing occurs when displaying a moving image,
There is a problem that a blurred image is displayed. Japanese Patent Laying-Open No. 11-202286 discloses means for solving such a problem. JP-A-11-202286
In the liquid crystal display device disclosed in Japanese Patent Application Laid-Open Publication No. H10-157, a plurality of light emitting areas are sequentially scanned and lit in synchronization with a vertical scanning signal of the liquid crystal display section, and each of these light emitting areas is scanned with respect to the scanning line writing timing of the liquid crystal display section. Then, light is emitted with a delay time t smaller than the cycle T of the vertical scanning signal. At this time, the liquid crystal display section displays an electrochemical response waveform between the brightest state where the contrast ratio is maximized and the darkest state where the contrast ratio is minimized.
The response waveform has a time constant τ that satisfies xp (−t / τ) ≦ 0.5.

However, in this prior art document, a delay time t, which is a timing for turning on a discharge lamp (backlight) included in each light emitting region, must be determined in relation to an electrochemical response waveform of a liquid crystal display unit. There is annoyance.

[0005] In addition, this prior art merely gives an abstract description of the circuit configuration of the lighting unit, but does not disclose a specific driving circuit and a linking operation for each lighting area.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to provide a discharge lamp lighting device suitable as a backlight device for a liquid crystal display device which can display a moving image.

Another object of the present invention is to provide a liquid crystal display device which can display moving images without causing blurred image display due to tailing, which can provide a clear image display. It is to provide an electric lighting device.

Still another object of the present invention is to provide a liquid crystal display device which can display a moving image,
An object of the present invention is to provide a discharge lamp lighting device capable of easily and reliably setting the lighting timing of a discharge lamp for displaying a clear image without causing blurred image display due to tailing.

It is still another object of the present invention to provide a discharge lamp lighting device having a specific circuit configuration suitable for use in a liquid crystal display device.

[0010]

In order to solve the above-mentioned problems, a discharge lamp lighting device according to the present invention includes a drive signal generator and a plurality of output terminals, and sequentially drives a plurality of discharge lamps. .

[0011] The drive signal generator generates a plurality of drive signals for individually lighting the plurality of discharge lamps. Each of the drive signals is sequentially generated with a fixed phase angle within one cycle of a reference signal which is a pulse train having a fixed cycle, and is calculated backward from the end of one cycle based on its own phase angle. The high-level energy state having energy for lighting the discharge lamp is provided at the timed timing, and the high-level energy state is maintained toward the end.

[0012] Each of the plurality of output terminals is individually provided corresponding to each of the discharge lamps, and the drive signals generated by the drive signal generator are sequentially and individually supplied.

As described above, the discharge lamp lighting device according to the present invention includes a drive signal generation unit and a plurality of output terminals, and the drive signal generation unit controls a plurality of discharge lamps for individually lighting the plurality of discharge lamps. Generate a drive signal. Each of the plurality of output terminals is individually provided corresponding to each of the discharge lamps, and the drive signals generated by the drive signal generation unit are sequentially and individually supplied. Therefore, each of the plurality of discharge lamps is individually arranged corresponding to each light emitting area of the liquid crystal display device, and these are turned on in synchronization with vertical scanning, so that they can be used as a backlight.

Each of the drive signals is sequentially generated with a constant phase angle within one cycle of a reference signal which is a pulse train having a fixed cycle. When used as a backlight device of a liquid crystal display device, a reference signal is synchronized with a vertical scanning signal. Thus, in synchronization with the vertical scanning of the liquid crystal display unit, the discharge lamps are sequentially turned on within one cycle of the vertical scanning signal, and an image can be displayed.

Each of the drive signals enters a high-level energy state having energy for lighting the discharge lamp at a time timing calculated backward from the end of one cycle based on its own phase angle. When used as a backlight of a liquid crystal display device, the driving signal is synchronized with the vertical scanning signal, so that at the end of each cycle of the driving signal, the driving signal is determined according to the phase angle with respect to the vertical scanning signal. Can be That is, the temporal timing at which the drive signal enters the high-level energy state is determined according to each phase angle with reference to the vertical scanning signal. For this reason, the setting of the timing at which the discharge lamp is turned on can be extremely easily and reliably set. In this regard, in the conventional technology, which has a troublesome operation, the delay time t, which is the timing for turning on the discharge lamp (backlight) included in each light emitting region, must be determined in relation to the electrochemical response waveform of the liquid crystal display unit. On the other hand, there are obvious structural differences and operational advantages.

Each of the drive signals enters a high-level energy state having energy for lighting the discharge lamp from a time timing calculated backward from the end of one cycle. At this point, the electrochemical response of the liquid crystal has been completed, and the shutter is optically completely open. Each of the drive signals maintains a high level energy state towards the end of its one cycle.

Therefore, in each of the drive signals, 1
From the timing calculated backward from the end of the cycle, 1
At the end of the cycle, the discharge lamp is turned on to illuminate the liquid crystal in a completely open state, so that pixels can be clearly displayed.

Each of the drive signals is not in a high-level energy state in the temporal region before the time timing calculated backward from the end of one cycle. That is, the discharge lamp is not turned on. Therefore, the progress of the electrochemical reaction of the liquid crystal is not displayed, so that the image is not blurred due to the tailing.

The present invention further discloses a discharge lamp lighting device having a specific circuit configuration suitable for use in a liquid crystal display device. In this discharge lamp lighting device, the drive signal generator includes a reference signal generator, a frequency multiplier, a phase shift circuit, and an inverter.

The reference signal generation circuit generates the reference signal from an externally supplied input signal. The input signal is a pulse train signal having a fixed period. The reference signal is a signal synchronized with the input signal. The frequency multiplying circuit multiplies the frequency of the reference signal and outputs a frequency multiplied signal.

The phase shift circuit is supplied with the reference signal and the frequency-multiplied signal, and outputs a plurality of signals having a phase angle determined by the frequency-multiplied signal within one cycle of the reference signal. Generated individually and sequentially for each lamp.

The inverter unit converts each of the signals output from the phase shift circuit into a high-level energy driving signal having energy for lighting the discharge lamp, and individually supplies the driving signal to the output terminal. .

The above-described discharge lamp lighting device can further include a duty ratio control circuit. The duty ratio control circuit performs duty ratio control on each of the signals output from the phase shift circuit. By this duty ratio control, the brightness of the discharge lamp point can be adjusted.

The discharge lamp lighting device according to the present invention may further include a phase control unit. The phase control unit controls a phase angle between the signals output from the phase shift circuit.

[0025]

FIG. 1 is a block diagram showing the configuration of a discharge lamp lighting device according to the present invention. The illustrated discharge lamp lighting device includes a drive signal generator 100 and a plurality of n output terminals T1 to Tn, and sequentially drives the plurality of n discharge lamps L1 to Ln.

The drive signal generator 100 includes a plurality of n drive signals S1 to S1 for individually lighting the plurality of n discharge lamps L1 to Ln.
Generate Sn. Each of the drive signals S1 to Sn is sequentially generated with a predetermined phase angle within one cycle of the reference signal φ2 which is a pulse train having a fixed cycle. Then, at a time timing calculated backward from the end of one cycle based on its own phase angle, it becomes a high-level energy state having energy for lighting the discharge lamps L1 to Ln,
The high level energy state is maintained towards the end of one cycle of the self. The drive signal generation unit 100 can be configured by a combination of a plurality of electric circuits, or can be configured by a computer.

When used as a backlight device of a liquid crystal display device, a reference signal generation unit 101 generates a reference signal φ2 from a vertical scanning signal φ1 for scanning the liquid crystal display unit in the vertical direction. The reference signal φ2 is a pulse train signal having the same frequency synchronized with the vertical scanning signal φ1. The reference signal φ2 has a pulse waveform suitable for signal processing in the signal processing unit 102.

Each of the plurality of n output terminals T1 to Tn is individually provided corresponding to each of the discharge lamps L1 to Ln, and the drive signal S1 generated by the drive signal generator 100 is provided.
To Sn are sequentially and individually supplied.

Next, regarding the above-described discharge lamp lighting device,
A more specific description will be given, taking as an example the case where the device is used as a backlight device of a liquid crystal display device.

FIG. 2 is a diagram schematically showing a configuration of a liquid crystal display device using the discharge lamp lighting device shown in FIG. In the figure, a liquid crystal display unit 400 has a well-known structure in which liquid crystal is arranged on the front surface of an optical filter unit. The optical filter unit and the liquid crystal are arranged in the vertical direction X in a plurality of n light-emitting regions
Pn are arranged. Liquid crystal display section 40
Behind 0, a backlight device 200 in which a plurality of n discharge lamps L1 to Ln are vertically arranged is arranged. Each of the plurality n of discharge lamps L1 to Ln is
The light emitting regions P1 to Pn of 0 are individually associated with each other.

Light emitting areas P1 to Pn of liquid crystal display section 400
Is a vertical scanning signal φ supplied from the liquid crystal driving circuit 300.
1 sequentially scans in the vertical direction X. The drive signal generation unit 100 is supplied with the vertical scanning signal φ1 from the liquid crystal driving circuit 300, and individually supplies drive signals S1 to Sn synchronized with the vertical scanning signal φ1 to the discharge lamps L1 to Ln constituting the backlight device 200. I do.

As described above, the discharge lamp lighting device according to the present invention includes the driving signal generation unit 100 and the plurality of n output terminals T.
1 to Tn. The drive signal generator 100 generates a plurality of n drive signals S1 to Sn for individually lighting the plurality of n discharge lamps L1 to Ln. N output terminals T1 to T
n are individually provided corresponding to the discharge lamps L1 to Ln, respectively, and the drive signals S1 to Sn generated by the drive signal generator 100 are sequentially and individually supplied. Therefore, each of the plurality of n discharge lamps L1 to Ln can be individually arranged in each of the light emitting areas P1 to Pn of the liquid crystal display device, and these can be scanned in the vertical direction X and turned on to be used as a backlight. .

Next, details of the circuit operation when the liquid crystal display device shown in FIG. 2 is constructed using the discharge lamp lighting device shown in FIG. 1 will be described with reference to FIGS.
For simplicity and specificity of the description, the vertical scanning signal φ1 and the reference signal φ2 are pulse train signals having a frequency of 60 Hz, and the driving signals S1 to Sn, the discharge lamps L1 to Ln, and the light emitting area P1
ＰPn is set to n = 4. However, these are numerical values adopted only for specific description, and it goes without saying that the present invention does not involve such numerical limitations.

FIG. 3A shows a time axis at 60 Hz. FIG. 3B shows a pulse train of the reference signal φ2 synchronized with the vertical scanning signal φ1. The reference signal φ2 is t0
With 0:00 as the starting point 0 (ms), t04 at an interval of 16.6 (ms) is the end of one cycle. Here, it is assumed that the four discharge lamps L1 to L4 are driven, and respective time points obtained by equally dividing one cycle of the reference signal φ2 into four are displayed. Specifically, in the first cycle of the reference signal φ2, at time t01 delayed by 4.15 (ms) with respect to the starting point 0 (ms), time t02 delayed by 8.3 (ms)
At time t03, which is delayed by 12.5 (ms), and 1
The time t04, which is delayed by 6.6 (ms), is displayed.

FIG. 3C shows the operating characteristics of the liquid crystal included in the light emitting region P1 in the liquid crystal display section 400 (see FIG. 2). The operating characteristics of a liquid crystal follow its electrochemical response characteristics. In the time domain before the starting point 0 (ms) to which the reference signal φ2 is given, the liquid crystal included in the light emitting area P1 is in an optically closed state, and from the starting point 0 (ms), the liquid crystal is closed according to its electrochemical response characteristics. Transition from the state to the open state. At some point, it will be optically open. FIG.
In the illustration of (c), the liquid crystal included in the light emitting region P1 is in the middle of the electrochemical reaction from the starting point 0 (ms) to 4.15 (ms), and has passed 8.3 (ms). t
It is assumed that an optically open state occurs at around 02:00. However, the electrochemical response characteristics of the liquid crystal differ individually depending on the liquid crystal used. The illustrated electrochemical response characteristics are shown for illustrative purposes only.

FIG. 3D shows the timing at which the drive signal S1 supplied to the discharge lamp L1 reaches a high energy level for lighting the discharge lamp L1. The first cycle of the drive signal S1 starts at time t00 when the start point is 0 (ms),
At t04 when 16.6 (ms) has elapsed from t00,
The first cycle ends. The drive signal S1 starts from time t04, which is the end of one cycle assigned to itself, from time Ton.
At time t11, which is calculated backward by 1 (ms), the discharge lamps L1 to L
The state becomes a high-level energy state having energy for lighting n, and the high-level energy state is held toward time t04, which is the end of one cycle allocated to the self. In the case shown in the figure, the drive signal S1 keeps the high energy level until t04, and at the moment when the drive signal S1 arrives at t04, it becomes the low energy level.

FIG. 3E shows the timing at which the drive signal S2 supplied to the discharge lamp L2 reaches a high energy level for lighting the discharge lamp L2. The timing at which the drive signal S2 supplied to the discharge lamp L2 goes to a high energy level is illustrated in more detail in FIG.

Referring to FIG. 3E and FIG. 4, the drive signal S2 is obtained by setting the reference signal φ2 to t0 at the starting point 0 (ms).
Phase shift by 4.15 (ms) from 0:00 (phase angle θ
2) The first cycle starts at t01, and ends at t05, which is 16.6 (ms) after t01. The drive signal S2 starts from time t05, which is the end of one cycle assigned to itself, from time Ton1 (m
At t21, which is calculated backward by s), the state becomes a high-level energy state having energy for lighting the discharge lamp L2, and the high-level energy state is held toward t05, which is the end of one cycle of the self. In the case shown, the drive signal S
2 holds the high energy level until t05,
At 5 o'clock the low energy level is reached.

FIG. 4C shows the operating characteristics of the liquid crystal included in the light emitting region P2 in the liquid crystal display section 400 (see FIG. 2). In the drive signal S2, in a time region before time t01, which is the start point of one cycle, the liquid crystal included in the light emitting region P2 is in an optically closed state.
According to its electrochemical response characteristics, transitioning from the closed state to the open state, and at some point, becoming optically open,
This is the same as the illustration in FIG. The liquid crystal included in the light emitting region P2 is in the middle of the electrochemical reaction until 4.15 (ms) has elapsed from the time t01, and 8.3 from the time t01.
It is assumed that an optically opened state is obtained at about t03 when (ms) has elapsed.

FIG. 3F shows the timing at which the drive signal S3 supplied to the discharge lamp L3 reaches a high energy level for lighting the discharge lamp L3. The timing at which the drive signal S3 supplied to the discharge lamp L3 goes to a high energy level is illustrated in more detail in FIG.

Referring to FIG. 3F and FIG. 5, the drive signal S3 is obtained by setting the reference signal φ2 to t0 at which the starting point is 0 (ms).
From 0:00, a phase shift of 8.3 (ms) (phase angle θ
3) The first cycle starts at time t02, and ends at t06 when 16.6 (ms) has elapsed from time t02. The drive signal S3 starts at time t06, which is the end of one cycle assigned to itself, from time Ton1 (m
At t31, which is calculated back by s), the state becomes a high-level energy state having energy for lighting the discharge lamp L3, and the high-level energy state is held toward t06, which is the end of one cycle of the self. Specifically, the drive signal S
3 holds the high energy level until t06, and t0
The moment you reach 6 o'clock, you have a low energy level.

FIG. 5C shows the operating characteristics of the liquid crystal included in the light emitting region P3 in the liquid crystal display section 400 (see FIG. 2). In the time domain of the drive signal S3 before time t02, which is the start point of one cycle, the liquid crystal included in the light emitting area P3 is in an optically closed state.
According to its electrochemical response characteristics, transitioning from the closed state to the open state, and at some point, becoming optically open,
This is the same as the illustration in FIG. The liquid crystal included in the light emitting region P3 is in the middle of the electrochemical reaction until 4.15 (ms) has elapsed since t02, and 8.3 from t02.
It is assumed that an optically opened state is obtained at about t04 when (ms) has elapsed.

FIG. 3 (g) shows the timing at which the drive signal S4 supplied to the discharge lamp L4 reaches a high energy level for lighting the discharge lamp L4. The timing at which the drive signal S4 supplied to the discharge lamp L4 reaches a high energy level for lighting the discharge lamp L4 is illustrated in more detail in FIG.

Referring to FIG. 3G and FIG. 6, the drive signal S4 changes the reference signal φ2 from the start point 0 (ms) to t0.
From 0:00, a phase shift of 12.5 (ms) (phase angle θ
4) The first cycle starts at time t03, and ends at time t07 when 16.6 (ms) has elapsed from time t03. The drive signal S4 starts from time t07, which is the end of one cycle assigned to itself, from time Ton1 (m
At t41, which is calculated backward by s), the state becomes a high-level energy state having energy for lighting the discharge lamp L4, and the high-level energy state is held toward t07, which is the end of one cycle of the self. Specifically, the drive signal S
4 holds the high energy level until t07, and
The moment you reach 7 o'clock, you have a low energy level.

FIG. 6C shows the operating characteristics of the liquid crystal included in the light emitting area P4 in the liquid crystal display section 400 (see FIG. 2). In the drive signal S4, in a time region before time t03, which is the start point of one cycle, the liquid crystal included in the light emitting region P4 is in an optically closed state.
According to its electrochemical response characteristics, transitioning from the closed state to the open state, and at some point, becoming optically open,
This is the same as the illustration in FIG. The liquid crystal included in the light emitting region P4 is in the middle of the electrochemical reaction until 4.15 (ms) has elapsed since t03, and 8.3 from t03.
It is assumed that an optically opened state is obtained at about t05 when (ms) has elapsed.

As described above, each of the drive signals S1 to S4 has a constant phase angle (0, θ2,...) Within one cycle of the pulse train reference signal φ2 having a fixed cycle of 16.6 (ms). θ3 or θ4). When used as the backlight device 200 of the liquid crystal display device, as described above, by synchronizing the reference signal φ2 with the vertical scanning signal φ1, one cycle of the vertical scanning signal φ1 is synchronized with the vertical scanning of the liquid crystal display unit 400. Among them, the discharge lamps L1 to L4 can be sequentially turned on to display an image.

Each of the drive signals S1 to S4 is at time t04, t05, t06 at the end of its own one cycle,
Or, the timing t11 calculated backward from t07.
Hour, t21, t31 or t41, the discharge lamp L1
To a high-level energy state having energy to light L4.

As described above, the drive signals S1 to S4
Are synchronized with the vertical scanning signal φ1, the driving signals S1 to
At time t04, time t05, time t06, or time t07, which is the end of one cycle assigned to each of S4, t is the start point of the reference signal φ2 (or the vertical scanning signal φ1).
With reference to 00 hours, the respective phase angles 0, θ2, θ3
Alternatively, it can be determined according to θ4. That is, the driving signals S1 and S2 enter the high-level energy state t11.
Time, t21, t31 or t41, the reference signal φ
2 (or the vertical scanning signal φ1) is determined according to each phase angle (0, θ2, θ3, or θ4).

Therefore, the timing for turning on the discharge lamps L1 to L4 can be set very easily and reliably. In this regard, a delay time t for turning on the discharge lamps L1 to L4 (backlight) included in each light emitting region has to be determined in relation to the electrochemical response waveform of the liquid crystal display unit 400. This is a clear difference in configuration and operation and effect from the related art.

Each of the drive signals S1 to S4 is t11, t21, t3 which is calculated backward from t04, t05, t06, or t07, which is the end of one cycle.
From 1 o'clock or t41 o'clock, a high-level energy state having energy for lighting the discharge lamps L1 to L4 is established. At this point, the electrochemical response of the liquid crystal has been completed,
The liquid crystal as the shutter is completely open. Each of the drive signals S1 to S4 changes the high-level energy state to a time t04, t05 at the end of each cycle.
At time t06 or t07.

Accordingly, at time t04, t05, which is the end of one cycle assigned to each of the drive signals S1 to S4.
Hour, the discharge lamps L1 to L1 end at the end of one cycle from the temporal timing calculated backward from t06 or t07.
By turning on L4 and illuminating the liquid crystal in a fully opened state as a shutter, pixels can be clearly displayed.

Each of the drive signals S1 to S4 is calculated as t11 calculated from the end of one cycle assigned to itself.
At the time, at the time t21, the time t31, or the time t41, the region before the time is not in the high level energy state having the energy for lighting the discharge lamps L1 to L4. That is, the discharge lamps L1 to L4 are not turned on. Therefore, the progress of the electrochemical reaction of the liquid crystal is not displayed, so that the image is not blurred due to the tailing.

In the case of the embodiment, the drive signal S1 is t
The high energy level is maintained until 04:00, and at the moment when the time reaches t04, the energy level becomes low, and the discharge lamp L1
Turns off. Therefore, in the time region after the time t04 when the driving of the liquid crystal is completed, the progress of the electrochemical reaction of the liquid crystal is not displayed, so that the image is not blurred due to the tailing. The same applies to the drive signals S2 to S4.

FIG. 7 is a block diagram showing a more specific configuration of the discharge lamp lighting device according to the present invention. In the discharge lamp lighting device shown in FIG.
It includes a reference signal generation circuit 101, a phase shift circuit 4, and an inverter unit 8. In the embodiment, an external signal input circuit 1, a duty ratio control circuit 5, and a phase adjustment circuit 9 are further provided.

The reference signal generation circuit 101 generates a reference signal φ2 based on an input signal φ1 supplied from the outside. The reference signal φ2 is a signal synchronized with the input signal φ1. The input signal φ1 is a pulse train signal having a fixed period, and is a digital signal. Therefore, the reference signal generation circuit 1
01 is also configured as a digital circuit. In particular,
It is configured as a digital pulse oscillation circuit. When used as a backlight device of a liquid crystal display device, the input signal φ
1 is the above-described vertical scanning signal φ1. Hereinafter, the input signal will be described as a vertical scanning signal φ1.

The reference signal generator 101 includes an external signal input circuit 111, a pulse oscillation circuit 112, and a frequency multiplication circuit 113. The external signal input circuit 111 is a circuit for interfacing with an external circuit.

The frequency multiplying circuit 113 multiplies the frequency of the reference signal φ2 by a multiple m, and outputs a frequency multiplied signal φ3. The vertical scanning signal φ1 and the reference signal φ2 are digital signals, and the external signal input circuit 111 and the pulse oscillation circuit 112 are also digital circuits.
3 is configured as a digital circuit. The multiplication number m is selected so that, for example, 128 pulses and 256 pulses are generated within one cycle of the reference signal φ2.

The phase shift circuit 4 is supplied with a reference signal φ2 and a frequency multiplied signal φ3. Phase shift circuit 4
Is a frequency-multiplied signal φ within one cycle of the reference signal φ2.
3 (0, θ2, θ3 or θ)
4), the plurality of n signals S11 to S1n are transmitted to the discharge lamp L1.
ＬLn. Frequency multiplied signal φ3
Is carved at a period smaller than the period of the reference signal φ2, so that the phase angle (0, θ2, θ3 or θ4)
Can be set with high accuracy.

The inverter unit 8 generates high-level energy driving signals S1 to Sn having energy for lighting the discharge lamps L1 to Ln based on the signals S11 to S1n output from the phase shift circuit 4, respectively. The drive signals S1 to Sn are individually supplied to the output terminals T1 to Tn.
The inverter unit 8 includes n number of inverter circuits 81 to 8n equal to the number n of the discharge lamps L1 to Ln. Each of the inverter circuits 81 to 8n includes a discharge lamp L1 to Ln.
Are connected in a one-to-one relationship.

The discharge lamp lighting device shown in the embodiment has a duty ratio control circuit 5 between the phase shift circuit 4 and the inverter section 8. The duty ratio control circuit 5 performs duty ratio control on each of the signals S11 to S1n output from the phase shift circuit 4. By this duty ratio control, the brightness of the discharge lamps L1 to Ln can be adjusted.

The illustrated duty ratio control circuit 5 includes sawtooth wave generation circuits 51 to 5n, comparators 71 to 7n,
And a DC voltage generation circuit 10. Sawtooth wave generation circuit 5
1 to 5n and the comparators 71 to 7n are provided in the same number as the number n of the discharge lamps L1 to Ln to be driven. r-th sawtooth wave generation circuit 6r and comparator 7r out of n
Constitutes a duty ratio control circuit for the r-th discharge lamp Lr. For example, the first sawtooth wave generation circuit 61 and the comparator 71 constitute a duty ratio control circuit for the discharge lamp L1.

FIG. 8 is a diagram showing the duty control operation of the duty ratio control circuit 5. The phase shift circuit 4 shifts the phase of the reference signal φ2 shown in FIG.
The reset pulse shown in (b) is generated. With this reset pulse, the sawtooth wave generating circuit 5
The frequency-multiplied signals S11 to S1n shown in FIG. 8C are supplied to each of 1 to 5n.

The sawtooth wave generating circuits 51 to 5n are provided with a frequency multiplied signal (digital signal) S supplied from the phase shift circuit 4.
11 to S1n are converted into analog signals to generate sawtooth signals S21 to S2n shown in FIG. Sawtooth signal S2
1 to S2n are synchronized with the vertical scanning signal φ1 and the reference signal φ2.

The sawtooth wave signals S21 to S2n generated by the sawtooth wave generation circuits 51 to 5n are output from comparators 71 to S2n, respectively.
7n (+) terminals are individually supplied. Comparator 7
DC voltage generation circuit 10 supplies D-
A C voltage signal S40 is supplied. Therefore, as shown in FIG.
Pulse signals S31 to S3n having an ON time width Ton corresponding to the level of the voltage signal S40 are output. The signals S31 to S3n output from the comparators 71 to 7n are
Synchronous with the vertical scanning signal φ1 and the reference signal φ2.

The ON time width Ton of the signals S31 to S3n
(Or OFF time width) is obtained from the DC voltage generation circuit 10
DC voltage signal S4 supplied to comparators 71 to 7n
Controlled by zero level adjustment. That is, the signal S31
To S3n can be controlled.

FIG. 9 shows drive signals S1 to S4 to which duty ratio control has been applied. In FIG. 9, the same display as the display in FIGS. 3 to 6 is used. As is clear when the illustration in FIG. 9D is compared with the illustration in FIG. 3D, the period during which the drive signal S1 has a high energy level is changed from the time Ton1 in FIG. 3D to the time Ton2. It is enlarged (Ton2> Ton1). Other drive signal S
The same applies to 2 to S4. On the contrary, the driving signals S1 to S1
In S4, the period during which the high energy level is achieved can be controlled to be reduced.

Further, the illustrated discharge lamp lighting device includes a phase control unit 9. The phase control unit 9 is provided to shift the phase of the reference signal φ2 to obtain drive signals S1 to Sn with adjusted phase angles (0, θ2, θ3, or θ4). The phase control section 9 includes a plurality of n phase control circuits 91 to 9n corresponding to the plurality of n discharge lamps L1 to Ln, respectively.

[0068]

As described above, according to the present invention, the following effects can be obtained. (A) It is possible to provide a discharge lamp lighting device suitable as a backlight device of a liquid crystal display device that can display a moving image. (B) It is possible to provide a discharge lamp lighting device capable of performing clear image display without causing blurred image display due to tailing when used in a liquid crystal display device that may perform moving image display. . (C) When used in a liquid crystal display device that may display moving images, the lighting timing of the discharge lamp for displaying clear images can be easily and reliably performed without causing blurry image display due to tailing. It is possible to provide a discharge lamp lighting device that can be set to: (D) A discharge lamp lighting device having a specific circuit configuration suitable for use in a liquid crystal display device can be provided.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a discharge lamp lighting device according to the present invention.

FIG. 2 is a diagram schematically showing a configuration of a liquid crystal display device using the discharge lamp lighting device shown in FIG.

FIG. 3 is a time chart showing a timing at which a drive signal S1 supplied to a discharge lamp L1 attains a high energy level in the discharge lamp lighting device shown in FIG. 1 and the liquid crystal display device shown in FIG.

4 is a time chart showing a timing at which a drive signal S2 supplied to a discharge lamp L2 attains a high energy level in the discharge lamp lighting device shown in FIG. 1 and the liquid crystal display device shown in FIG.

FIG. 5 is a time chart showing the timing at which the drive signal S3 supplied to the discharge lamp L3 attains a high energy level in the discharge lamp lighting device shown in FIG. 1 and the liquid crystal display device shown in FIG.

FIG. 6 is a time chart showing a timing at which a drive signal S4 supplied to a discharge lamp L4 attains a high energy level in the discharge lamp lighting device shown in FIG. 1 and the liquid crystal display device shown in FIG.

FIG. 7 is a block diagram showing a more specific configuration of the discharge lamp lighting device according to the present invention.

8 is a diagram illustrating a duty control operation of the duty ratio control circuit 5. FIG.

FIG. 9 is a diagram illustrating duty ratio control.

[Explanation of symbols]

 Reference Signs List 111 External signal input circuit 113 Frequency multiplication circuit 4 Phase shift circuit 5 Duty ratio control circuit 8 Inverter section 9 Phase adjustment circuit 100 Drive signal generation section 101 Reference signal generation section 102 Signal processing circuit 200 Backlight device 300 Liquid crystal drive circuit 400 Liquid crystal display Part T1 to Tn Output terminal L1 to Ln Discharge lamp

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Yasuta Domon 1-13-1 Nihombashi, Chuo-ku, Tokyo TDK Corporation F-term (reference) 2H091 FA41Z FD03 FD21 GA12 LA16 2H093 NA43 NC44 NC49 ND01 NE06 NH18 3K098 CC21 DD44 EE18 EE28 EE32

Claims (6)

[Claims] 1. A discharge lamp lighting device including a drive signal generation unit and a plurality of output terminals for sequentially driving a plurality of discharge lamps, wherein the drive signal generation unit separates the plurality of discharge lamps from each other. A plurality of drive signals to be lit are generated, and each of the drive signals is sequentially generated with a predetermined phase angle within one cycle of a reference signal which is a pulse train having a fixed cycle, and a reference is made to its own phase angle. A high-level energy state having energy to turn on the discharge lamp at a temporal timing calculated backward from the end of the one cycle, the high-level energy state is held toward the end, and the plurality of outputs are output. A discharge lamp lighting device in which each of the terminals is individually provided corresponding to each of the discharge lamps, and the drive signals generated by the drive signal generation unit are sequentially and individually supplied. 2. The discharge lamp lighting device according to claim 1, wherein the reference signal is generated from an input signal of a pulse train supplied from the outside. 3. The discharge lamp lighting device according to claim 1, wherein the drive signal generator includes a reference signal generator, a frequency multiplier, a phase shift circuit, and an inverter. The reference signal generation circuit is a circuit that generates the reference signal from an externally supplied input signal, wherein the input signal is a pulse train signal having a fixed period, and the reference signal Is a signal synchronized with the input signal, the frequency multiplying circuit multiplies the frequency of the reference signal and outputs a frequency multiplied signal, and the phase shift circuit is supplied with the reference signal and the frequency multiplied signal. Generating, in one cycle of the reference signal, a plurality of signals having a phase angle determined by the frequency-multiplied signal for each of the discharge lamps; Each of the signals output from the bets circuit, is converted into the drive signal of the high level energy states with energy for lighting the discharge lamp, the discharge lamp lighting device supplies separately to the output terminal. 4. The discharge lamp lighting device according to claim 3, further comprising a duty ratio control circuit, wherein the duty ratio control circuit is configured to control each of the signals output from the phase shift circuit. And a discharge lamp lighting device for adding duty ratio control. 5. The discharge lamp lighting device according to claim 3, further comprising a phase control unit, wherein the phase control unit outputs a phase of the signal output from the phase shift circuit. A discharge lamp lighting device that controls the angle. 6. The discharge lamp lighting device according to claim 1, wherein the discharge lamp lighting device is used as a backlight device of a liquid crystal display device.