JP2009271406A - Light source device, monitoring device, projector, and driving method of light source device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a light source device, capable of further surely controlling a light quantity to be emitted when driving a plurality of laser light sources by a pulse drive system. <P>SOLUTION: The device comprises a plurality of laser light sources 10 connected in parallel to each other; and a light source drive part 12 which selects one or two or more laser light sources 10 from the plurality of laser light source 10, and supplies drive signals for pulse-driving to each of the selected one or two or more laser light sources 10. The light source drive part 12 selects a drive signal corresponding to the total number of the selected laser light sources 10 from two or more kinds of drive signals. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a light source device, a monitor device, a projector, and a driving method of the light source device.

  Projecting liquid crystal projectors using a liquid crystal panel as a light valve have been actively developed as an effective means for increasing the screen size. In this type of projector, it is essential to increase the brightness of the light source in order to reproduce vivid images. However, it is technically very difficult to completely block the light from the light source using the liquid crystal panel, and light leaking through the liquid crystal panel is likely to occur. Therefore, as the brightness of the light source increases, black floating due to light leakage or the like becomes more noticeable during black display (or dark display), and the increase in luminance of the light source is not necessarily reflected in the improvement in contrast.

  On the other hand, increasing the brightness of the light source is a negative factor in terms of heat resistance of the liquid crystal panel. Especially when the screen is generally dark, most of the light from the high-brightness light source must be blocked by the liquid crystal panel, which increases the heat absorption of the liquid crystal panel, and the constituent materials such as polarizing plates provided in the liquid crystal panel It will lead to damage due to thermal degradation.

Therefore, as a means to solve the problems such as light leakage (black floating) due to high brightness of the light source, damage due to heat absorption in the liquid crystal panel, the output of the light source is changed based on the peak signal of the image and contrast There has been proposed a method for controlling the above (for example, see Patent Document 1).
Japanese Patent Laid-Open No. 06-160811

  However, the metal halide lamp described in Patent Document 1 has problems with respect to restrictions on the illumination color temperature that changes the output of the light source, impossibility of instantaneous and intermittent lighting, short life, and the like. Accordingly, there is an expectation for a laser light source as a light source that can replace the metal halide lamp that overcomes such problems. It has been studied to use a laser array in which a plurality of laser light sources are integrated as one light source as a whole to overcome the above-described problems of the metal halide lamp. In such a laser array type light source, it is considered that the brightness of the entire light source can be adjusted, for example, by changing the total number of laser light sources to be driven.

  An object of the present invention is to provide a light source device and a driving method that use a plurality of laser light sources and can reliably control the output (the amount of light emitted) of each laser light source. Moreover, it aims at providing the monitor apparatus provided with such a light source device. It is another object of the present invention to provide a projector that realizes higher-quality image display by reliably controlling the output of a light source according to an input image signal or the like.

  As a result of various studies, the inventor has a configuration in which each laser light source of a laser array type light source including a plurality of laser light sources is driven by a modulation driving (hereinafter, pulse driving) method using a pulse signal. I came up with the idea of good. When the pulse driving method is used, since a large amount of current can be instantaneously passed, strong emission intensity can be obtained, and a high-luminance laser light source can be realized. Further, since the non-driving state is intermittently repeated, the total driving time of the laser light source can be reduced, and the life of the light source can be extended.

  However, while having various advantages as described above, it has also been clarified that a new problem arises when the pulse driving method is applied to the driving method of the laser array. This problem occurs when the total number of laser light sources to be driven is changed while pulse driving is performed to change the light amount of the laser light source.

  The laser array as described above is a parallel circuit in which a plurality of laser light sources are connected in parallel. When the number of laser light sources of a laser array driven by such a parallel circuit is increased under a condition where the applied voltage is constant, the number of conductive portions on the circuit increases and the resistance of the entire circuit decreases. Then, the influence of parasitic inductance and parasitic capacitance generated in circuit wiring and the like becomes relatively large, and the drive waveform of pulse driving changes.

  FIG. 14 shows simulation results showing the difference in the waveform of the drive signal with respect to the change in the number of light sources in a parallel circuit with a constant applied voltage. As shown in the figure, when the number of light sources is one, the drive signal is a rectangular wave. However, when the number of light sources is ten, the drive signal is distorted like a triangular wave.

  Since the amount of current flowing through the light source is represented by an integral value of the waveform, the amount of current flowing through the laser light source varies depending on the total number of light sources to be driven. In addition, since the amount of power is represented by the product of the amount of current and the applied voltage, the amount of power input to the laser light source differs depending on the total number of light sources to be driven, and the amount of light emitted from the laser light source differs. In this way, the total number of laser light sources and the amount of light do not show a linear (direct proportion) relationship, making it difficult to control the light amount of the laser array.

  Therefore, in order to solve the above problems, the light source device of the present invention selects a plurality of laser light sources connected in parallel to each other and one or more laser light sources from the plurality of laser light sources, A light source drive unit that supplies a drive signal for pulse driving the laser light source to each of the one or more laser light sources, the light source drive unit selected from a plurality of types of drive signals The drive signal corresponding to the total number of is selected.

  In the present invention, the “drive signal” is a drive signal supplied to the laser light source in order to drive the laser light source in pulses, and the “control parameter” is the duty ratio of the waveform of the drive signal (the period of the cycle relative to the width of the unit waveform). Ratio), the frequency of the drive signal, the drive voltage of the drive signal, the drive current, etc. The “plurality of drive signals” means the duty ratio of the waveform of the drive signal, the frequency of the drive signal, the drive voltage of the drive signal, the drive This is a drive signal in which control parameters such as current are changed. The light source device of the present invention changes these drive signals in accordance with the total number of laser light sources to be driven even if the number of laser light sources to be driven changes and the degree of influence of parasitic inductance or parasitic capacitance changes. By doing so, a desired amount of light can be emitted.

In the present invention, it is preferable that the light source driving unit includes a switch circuit connected in series to each of the plurality of laser light sources, and the switch circuit supplies the drive signal for driving the laser light source in pulses.
According to this configuration, it is possible to control the control parameter of the drive signal for driving the laser light source in pulses using the control signal for controlling the ON / OFF state of the switch circuit, so that the adjustment of the drive signal is facilitated. .

In the present invention, the light source drive unit includes storage means for storing a signal selection condition that is a correspondence relationship between the total number of the laser light sources and the drive signal corresponding to the total number of the laser light sources, and the storage means It is desirable to select a drive signal corresponding to the total number of the laser light sources based on the signal selection condition acquired from the above.
According to this configuration, signal selection conditions can be freely added, deleted, and changed, and the management of signal selection conditions is facilitated. Further, when actually driving the laser light source, a suitable drive signal can be obtained immediately in accordance with the total number of laser light sources, which can contribute to an increase in driving speed.

In the present invention, the light source driving unit stores a light source number selection condition that is a correspondence relationship between a light amount to be emitted by the plurality of laser light sources and a total number of the laser light sources according to the light amount to be emitted. It is desirable that a storage unit be provided and that the total number of the laser light sources corresponding to the amount of light to be emitted be selected based on the light source number selection condition acquired from the storage unit.
According to this configuration, the light source number selection condition can be freely added, deleted, and changed, and the management of the light source number selection condition is facilitated. Also, when actually driving the laser light source, for example, the total number of necessary laser light sources can be obtained immediately according to the amount of light to be emitted based on the input image data, which contributes to speeding up the drive. Can do.

In the present invention, it is preferable that the light source number selection condition is a correspondence relationship in which the amount of light to be emitted increases linearly with respect to an increase in the total number of laser light sources.
According to this configuration, since the total number of laser light sources and the amount of emitted light have a linear (directly proportional) relationship, it is easy to adjust the amount of light.

In the present invention, it is preferable that the light source driving unit selects a driving signal in which a duty ratio is controlled among the plurality of types of driving signals.
In the drive signal for pulse driving the laser light source, the duty ratio of the drive signal corresponds to the ratio of the ON state / OFF state of the laser light source. Therefore, the amount of light emitted can be controlled by selecting a drive signal whose duty ratio is changed.

  In the present invention, it is preferable that the light source driving unit selects a driving signal whose driving frequency is controlled from the plurality of types of driving signals.

  Normally, a circuit has a parasitic resistance (ESR), a parasitic inductance (ESL), and a parasitic capacitance (ESC) due to a wiring pattern. If the laser light source has a large circuit load impedance and a small amount of current, the influence of parasitic components such as ESR, ESL, and ESC can be ignored. However, in a laser light source having a small circuit load impedance and a large amount of current, The influence of can not be ignored. In particular, in the case of a laser light source that performs high-current pulse driving, the influence of parasitic inductance is large among the parasitic components.

  If we ignore the parasitic resistance and parasitic capacitance which have relatively little influence, and pay attention to the parasitic inductance which has a great influence, the circuit impedance due to the parasitic inductance is expressed by the following equation by the imaginary number j, the angular frequency ω of the drive signal, and the inductance L (H). It can be represented by (1).

  The period ω can be expressed by the following equation (2) using the drive frequency f.

  According to the equations (1) and (2), the influence of the parasitic inductance of the circuit can be reduced by reducing the frequency. Therefore, by selecting a drive signal having a low frequency with respect to the increase in the total number of laser light sources, The amount of light emitted can be controlled.

In the present invention, it is preferable that the light source driving unit selects a driving signal that controls a driving value that is a value of a driving voltage or a driving current from among the plurality of types of driving signals.
The laser light source emits a light amount corresponding to the amount of power input to the laser light source. Since the amount of power is determined by the product of the amount of current flowing through the laser light source and the applied voltage, the amount of light emitted by selecting the drive signal with the drive voltage or drive current changed corresponding to the change in the total number of laser light sources Can be controlled.

In the present invention, based on the drive value detection means for detecting the drive value, the detected value of the detected drive value, and the selected value of the drive value selected corresponding to the total number of the laser light sources, It is desirable to have drive value control means for controlling the drive value of the drive signal supplied to the plurality of laser light sources.
Since the drive value can be controlled so that the detected value of the drive value coincides with the detected value of the drive value, the drive value can be controlled more accurately than when the drive value is not detected. This makes it possible to control the amount of light emitted accurately.

A monitor device according to the present invention includes the light source device described above and an imaging unit that captures an image of a subject illuminated by the light source device.
According to this configuration, it is possible to provide a monitor device that can reliably control the amount of light emitted from the light source device and can perform good imaging.

According to another aspect of the invention, a projector includes the light source device described above and a modulation unit that modulates light from the light source device in accordance with an image signal.
According to this configuration, it is possible to reliably control the light amount emitted from the light source device and to modulate the light whose light amount is controlled by the modulation unit, thereby providing a projector having a wide dynamic range and excellent image expression power. it can.

The driving method of the light source device of the present invention is a driving method of a light source device that includes a plurality of laser light sources and drives each one or two or more laser light sources selected from the plurality of laser light sources. Each of the selected laser light sources is driven by a drive signal selected from a plurality of types of drive signals corresponding to the total number of light sources.
According to this method, since a drive signal corresponding to the total number of selected laser light sources is supplied to each laser light source, a change in the light amount due to a change in the total number of laser light sources is suppressed, and a reliably controlled light amount is emitted. can do.

[First Embodiment]
Hereinafter, the light source device according to the first embodiment of the present invention will be described with reference to FIGS. In the present embodiment, an example in which the light source device according to the present invention is applied to a semiconductor laser (LD) light source device (hereinafter referred to as a laser light source device) which is a semiconductor laser array will be described. In all the drawings below, the film thicknesses and dimensional ratios of the constituent elements are appropriately changed in order to make the drawings easy to see.

  FIG. 1 is a schematic configuration diagram of a laser light source device according to the present embodiment. The laser light source device 2 includes a plurality (ten in this embodiment) of laser light sources 10 that emit laser light, and a light source driving unit 12 that drives the laser light sources 10.

  In the present embodiment, the laser light source 10 is a VCSEL (Vertical-Cavity Surface-Emitting Laser) type in which the direction in which light resonates is perpendicular to the substrate surface 10a and the laser light is emitted perpendicular to the substrate surface 10a. Use what is called.

  The plurality of laser light sources 10 have, for example, an array structure regularly arranged on the same substrate. In the present embodiment, a plurality of laser light sources 10 have a one-dimensional array structure arranged in one array axis direction, and the distance between adjacent laser light sources 10 is a constant distance. Since the plurality of laser light sources 10 have such an array structure, the light emission amount can be made uniform. Further, by reducing the gap between the laser light sources, the plurality of laser light sources 10 can be used as one light source as a whole, and can be used as a light source having a wide light emitting area.

  The laser light source 10 is not necessarily limited to one in which a plurality of light emitting portions are formed on the same substrate, but is an array in which a plurality of individually manufactured laser light sources are mounted on a support substrate. It may be. Alternatively, a two-dimensional array structure may be used in which two laser light sources 10 are arranged in the direction of two arrangement axes.

  FIG. 2 is a schematic circuit diagram of the laser light source device according to the present embodiment. As shown in the figure, in the laser light source device 2, a plurality of laser light sources 10 constitutes a parallel circuit and is connected to a light source driving unit 12. The light source drive unit 12 supplies drive signals to all 10 laser light sources 10, and all the laser light sources 10 are pulse-driven. The light source drive unit 12 applies a voltage to the entire circuit and supplies a predetermined drive current, and the laser light source drive circuit 14 pulse-drives each laser light source 10 based on the control signal, and lasers emitted from the plurality of laser light sources 10 A light source control circuit 16 that controls the total amount of light, and a drive signal selection that calculates the outputs of a plurality of laser light sources 10 based on input image data and the like, and selects appropriate driving conditions for driving the laser light sources 10 in pulses. And a circuit 20.

  In the present embodiment, the drive signal selection circuit 20 constitutes a part of the light source drive unit 12, but a circuit having part or all of the functions of the drive signal selection circuit 20 is separated from the laser light source device 2. It is good also as preparing and connecting to the light source drive part 12. FIG.

  The light source control circuit 16 controls the amount of laser light emitted by switching the number of laser light sources 10 to be driven. As described above, the laser light source device 2 is a parallel circuit, and each laser light source 10 can be independently controlled.

  The light source control circuit 16 is connected to each of the switch circuits 18 connected in series to each of the plurality of laser light sources 10 and each switch circuit 18, and supplies individual control signals to each switch circuit 18. And a switch control circuit 17 for controlling.

  The switch control circuit 17 supplies a signal (control signal) for controlling (switching) whether each switch circuit 18 is turned ON or OFF. Based on the control signal supplied from the switch control circuit 17, the switch circuit 18 supplies a current corresponding to the ON / OFF state of the switch circuit 18 to the laser light source 10 to drive the laser light source 10.

  The switch circuit 18 selects driving / non-driving for each of the plurality of laser light sources 10 and generates a driving signal for driving the laser light source 10 selected based on the control signal supplied from the switch control circuit 17. And supplied to the laser light source 10. As the switch circuit 18, a three-terminal element such as a transistor that is a semiconductor element that performs a switch operation can be used. In this case, the switch control circuit 17 outputs a drive signal to the gate terminal of the transistor of each switch circuit 18. A corresponding driving potential is supplied. In the present embodiment, an FET (Field effect transistor) is used as the switch circuit 18.

  The laser light source device 2 of the present embodiment combines the number of laser light sources 10 to be driven with the gradation output obtained by driving each of the laser light sources 10 to be pulse-driven, thereby allowing the emitted laser light to be emitted. Control the total amount.

  The drive signal selection circuit 20 calculates outputs of the plurality of laser light sources 10 based on input image data and the like, and selects an appropriate drive signal for driving the laser light sources 10 in pulses. The drive signal selection method performed by the drive signal selection circuit 20 will be described in detail later.

  FIG. 3 is an explanatory diagram for explaining the driving of each laser light source 10. FIG. 3A is a diagram showing a relationship between an input current to one laser light source 10 and a laser light quantity, which is a so-called output characteristic curve, where the horizontal axis is current I (no unit) and the vertical axis is light quantity L ( Unitless). When the current is increased from zero, light emission does not start to a certain extent, but when it exceeds a certain value, light emission starts, and thereafter, the amount of light increases as the current increases (referred to as a transition region). Continues for a while. Then, the light amount becomes maximum at a certain value, and after that, even if the current is increased, the light amount is rather decreased. The laser light source 10 generally exhibits the above output characteristics.

  On the other hand, FIG. 3B shows the relationship between the current I (no unit) on the horizontal axis and the light amount / current (dL / dI, no unit) on the vertical axis. In the present embodiment, the current value when the light amount / current value is maximum, that is, the gradient of the output characteristic curve is maximum is defined as “threshold value”.

  When driving a plurality of laser light sources 10, the difference in the amount of light emission due to the individual difference of each laser light source 10 becomes remarkable in the vicinity of the threshold value of the laser light, and even if the same current is applied, the output is different for each laser light source. Makes a big difference. Therefore, a value that avoids the threshold value of the laser light source, which is greatly influenced by individual differences, is set as the drive current value that is pulse-driven and flows to the laser light source 10, and the first and second current values that avoid the threshold value are set. If the laser light source 10 is driven by this, the output can be controlled more reliably.

  The first current value is set to a value less than the smallest threshold value Ithmin among the plurality of threshold values Ith of the plurality of laser light sources 10, and the largest threshold value Ithmax is set to the second current value. It is preferable to set a value exceeding. In the present embodiment, the current value in a state where all the laser light sources 10 do not substantially emit laser light (OFF state) is set to the first current value, and all the laser light sources 10 substantially emit laser light. By setting the current value in the state where the gas is injected (ON state) to the second current value and driving the pulse with the binary current value of the first and second current values, the output is easy and reliable To control.

  Subsequently, a driving method of the laser light source device 2 of the present embodiment will be described with reference to FIGS.

  FIG. 4 is a schematic diagram illustrating the overall configuration of the laser light source device 2 of the present embodiment. The light source drive unit 12 of this embodiment includes a drive signal selection circuit 20 and a light source control circuit 16. The drive signal selection circuit 20 includes a light source number selection unit 22, a drive signal selection unit 24, and a storage unit 26. The light source control circuit 16 includes a switch control circuit 17 and a switch circuit 18.

  Input data such as image data input to the light source device 2 input from the outside is input to a drive signal selection circuit 20 provided in the light source drive unit 12, and a drive signal corresponding to the input data is selected and then selected. When the drive signal is input to the light source control circuit 16, the laser light source 10 is driven according to the drive signal. Hereinafter, each configuration will be described in detail.

  The light source number selection means 22 provided in the drive signal selection circuit 20 calculates the amount of light to be emitted from the maximum luminance of the input data, and selects the total number of laser light sources to be driven according to the amount of light to be emitted. Further, the drive signal selection unit 24 selects a suitable drive signal according to the total number of selected laser light sources. An integrated circuit such as a DSP (Digital Signal Processor), a PLD (Programmable Logic Device), a CPLD (Complex PLD), or an FPGA (Fielf Programmable Gate Alley) can be used for the light source number selection means 22 and the drive signal selection means 24. .

  Further, the storage means 26 stores a light source number selection condition that is a correspondence relationship between the amount of light to be emitted and the total number of laser light sources, and a signal selection condition that is a correspondence relationship between the total number of laser light sources and a drive signal. Yes. The light source number selection unit 22 and the drive signal selection unit 24 can acquire each selection condition from the storage unit 26. The light source number selection condition and the signal selection condition may be stored as a calculation formula indicating the corresponding relationship, and the corresponding value may be calculated, or a plurality of data indicating the previously calculated corresponding relationship is accumulated. A lookup table may be stored and a corresponding value may be selected.

  When data is input to the drive signal selection circuit 20 having such a configuration, first, the light source number selection unit 22 selects the amount of light to be emitted obtained from the maximum luminance of the input data and the number of light sources stored in the storage unit 26. The total number of laser light sources to be driven is calculated using the conditions.

  Next, the drive signal selection unit 24 selects a drive signal for the total number of laser light sources by using the total number of laser light sources calculated by the light source number selection unit 22 and the signal selection conditions stored in the storage unit 26. The drive signal selected by the drive signal selection circuit 20 in this way is input to the light source control circuit 16.

  The light source control circuit 16 supplies a switch control signal for driving the laser light source 10 in pulses from the switch control circuit 17 based on the drive signal selected by the drive signal selection circuit 20. In the switch circuit 18, a drive potential is applied to the gate electrode in accordance with the switch control signal. Then, the switch circuit 18 supplies a pulse current, which is a drive signal, to the laser light source 10 according to the switch control signal, and the laser light source 10 is turned on (emits light) to emit laser light. The laser light source device 2 of this embodiment processes the input data in this way and emits laser light.

  Next, a drive signal selection method will be described with reference to FIGS. In the present embodiment, the laser light source device 2 is driven by selecting a drive signal in which the duty ratio or drive frequency of the drive waveform is controlled from among a plurality of types of drive signals. In the following description of FIGS. 5 to 8, description will be made using the reference numerals of the components shown in FIG. 4.

[1] Selection of Drive Signal with Controlled Duty Ratio The laser light source device 2 of the present embodiment emits a necessary amount of light by selecting a drive signal with a controlled duty ratio of the drive signal supplied to the laser light source 10. Can be made. FIG. 5 is an explanatory diagram for explaining drive signals having different duty ratios. FIG. 5A shows a drive signal when the present invention is not applied and the duty ratio is not changed, and FIG. 5B shows a drive signal when the present invention is applied and the duty ratio is changed.

  As shown in FIG. 5A, the drive signal P is composed of a plurality (two in the figure) of unit drive signals having a period T and a width τ. In the laser light source device 2 of the present embodiment, since a plurality of laser light sources 10 are connected in parallel, when the total number of the laser light sources 10 to be driven increases, the influence of the parasitic inductance and parasitic capacitance of the circuit increases. Therefore, the drive signal P supplied to the laser light source 10 is affected by the impedance of the circuit, and becomes a drive signal P that looks like a triangular wave as shown in the figure. Therefore, compared with an ideal rectangular wave drive signal, no current is supplied to the laser light source by the lost current amount d1 shown as the hatched portion in the figure, and the amount of power becomes insufficient.

  Therefore, the laser light source device 2 of the present embodiment compensates for the lost part and eliminates the shortage of the current amount by controlling the duty ratio r (ratio of the width τ to the period T, τ / T) of the drive signal P. It is said. That is, the drive signal P supplied to the laser light source 10 is switched from the drive signal P1 having the duty ratio r1 (r1 = τ1 / T1) to the switch control signal having the duty ratio r2 (r2 = τ2 / T2) shown in FIG. Change to P2 (where r1 <r2).

  When the duty ratio r of the drive signal P is changed in this way, the amount of current flowing through the laser light source 10 changes per unit time, so that a larger amount of current can be supplied to the laser light source 10 by the difference d2 shown in the figure. . Therefore, by selecting the drive signal P with the duty ratio r that makes the lost current amount d1 and the difference d2 equal, it is possible to make up for the amount of power input to the laser light source 10. As described above, the laser light source device 2 can emit the necessary amount of light by selecting the drive signal P with the duty ratio r controlled.

  In order to realize the above-described driving by a suitable driving signal, the light source driving unit 12 included in the laser light source device 2 performs the following processing. That is, based on the input data input to the light source drive unit 12, the maximum light quantity to be emitted is calculated by the light source number selection means 22, and the total number of laser light sources capable of emitting the calculated light quantity to be emitted is calculated. Next, the drive signal selection means 24 calculates the duty ratio of the drive signal corresponding to the total number of laser light sources, and selects a suitable drive signal that enables the amount of light to be emitted by the total number of laser light sources. Next, the selected laser light source 10 is driven with a drive signal having the selected duty ratio, and a desired light amount is emitted. This will be described in detail below.

  FIG. 6 is an explanatory diagram showing a method of selecting a drive signal whose duty ratio is controlled.

  FIG. 6A is a diagram for explaining processing performed by the light source number selecting unit 22. The figure shows the correspondence between the total number of light sources and the amount of light when the applied voltage is constant, with the total number of selected laser light sources (total number of light sources) on the horizontal axis and the amount of laser light to be emitted from the laser light source on the vertical axis. It is a graph which shows (light source number selection conditions LC).

As described above, when the drive signal corresponding to the total number of light sources is not selected, for example, when the total number of light sources increases, the amount of power input to the laser light source 10 decreases. Therefore, as shown in the graph G in the figure, the correspondence relationship gradually deviates from the light source selection condition LC as the total number of light sources N increases. With such a correspondence, the control of the light amount becomes complicated. Therefore, in order to easily control the light quantity, it is preferable to set a relationship in which the light quantity increases linearly as the total number of light sources increases as the light source number selection condition LC. Such light source selection conditions LC, for example, based on the graph G ₀ showing the injectable amount when obtained by pulsing a single laser light source, as comprising direct proportion, the injection quantity of the plurality of laser light sources Can be calculated and set.

  The light source number selection means 22 first obtains the necessary light quantity L based on the input data, and obtains the total number N of light sources that can emit the necessary light quantity L based on the light source selection condition LC.

  FIG. 6B is a diagram for explaining processing performed by the drive signal selection unit 24. In the figure, the horizontal axis represents the total number of light sources, and the vertical axis represents the duty ratio of the drive signal corresponding to the total number of light sources. The correspondence relationship between the total number of light sources and the duty ratio under the condition of constant applied voltage (drive signal selection condition DC1). It is a graph which shows.

  The drive signal selection condition DC1 can be calculated by obtaining a resistance value and an impedance value from the laser light source and circuit configuration to be used. Alternatively, the resistance value and the impedance value may be measured in advance, and the drive signal selection condition DC1 may be set based on the measured value.

  The drive signal selection means 24 calculates the duty ratio r of the drive signal P that can drive the total number of light sources N and obtain the required light quantity L based on the drive signal selection condition DC1.

  FIG. 6C is a diagram showing the amount of light when the laser light sources 10 having the total number of light sources N are driven by the drive signal P with the duty ratio r. Since the drive signal P for driving the laser light source 10 has a duty ratio r suitable for driving the total number of light sources N, it is possible to drive the light source selection condition LC and to emit the necessary light quantity L. Can do. In this way, by applying the present invention and selecting the drive signal P suitable for the total number N of light sources, a suitable drive in which the light quantity is reliably controlled by filling the gap between the light source selection condition LC and the graph G is realized. can do.

[2] Selection of Drive Signal with Controlled Drive Frequency The laser light source device 2 according to the present embodiment is required by selecting the drive signal with the drive frequency controlled of the drive signal supplied to the laser light source 10. The amount of light can be emitted. FIG. 7 is a diagram illustrating the drive frequency of the drive signal P. 7A shows a drive signal when the present invention is not applied and the drive frequency is not changed, and FIG. 7B shows a drive signal when the present invention is applied and the drive frequency is changed.

  When the drive signal P3 having the drive frequency f1 shown in FIG. 7A is changed to the drive signal P4 having the drive frequency f2 shown in FIG. 7B (where f1> f2), the above-described equations (1) and (2) ), The impedance of the circuit changes to f2 / f1 times. The drive frequency f can be controlled, for example, by controlling the frequency of the switch control signal supplied from the switch control circuit 17. Therefore, the circuit impedance can be reduced by changing the drive frequency f. As a result, more current can be supplied to the laser light source 10 and more power can be supplied to the laser light source 10. As described above, the laser light source device 2 can emit the necessary amount of light by selecting the drive signal P with the drive frequency f controlled.

  In order to realize the above-described driving by a suitable driving signal, the light source driving unit 12 included in the laser light source device 2 performs the following processing. That is, the laser light source device 2 calculates the drive frequency of the drive signal corresponding to the total number of laser light sources in the drive signal selection means 24, and selects a suitable drive signal that enables the total number of laser light sources to emit light. To do. Next, the selected laser light source 10 is driven with a drive signal having the selected duty ratio, and a desired light amount is emitted. This will be described in detail below.

  FIG. 8 is a diagram for explaining processing performed by the drive signal selection unit 24. In the figure, the horizontal axis represents the total number of light sources, and the vertical axis represents the driving frequency of the driving signal corresponding to the total number of light sources. The correspondence relationship between the total number of light sources and the driving frequency under the condition of constant applied voltage (driving signal selection condition DC2). It is a graph which shows.

  The drive signal selection condition DC2 can be calculated by obtaining a resistance value and an impedance value from the laser light source and circuit configuration to be used. Alternatively, the resistance value and the impedance value may be measured in advance, and the drive signal selection condition DC2 may be set based on the measured value.

  The drive signal selection means 24 calculates the drive frequency f of the drive signal P that can drive the total number N of light sources and obtain the required light quantity L based on the drive signal selection condition DC2. In this manner, by selecting the drive signal P suitable for the total number N of light sources by applying the present invention, a suitable drive can be realized.

  According to the laser light source device 2 configured as described above, it is necessary by changing the duty ratio r and the drive frequency f of the drive signal P of the laser light source 10 corresponding to the total number N of the light sources 10 to be driven. The light quantity L can be emitted.

  In the present embodiment, the switch circuit 18 connected in series to each of the plurality of laser light sources 10 is provided, and the pulse drive signal is supplied to the laser light source 18 by the switch circuit 18. Since the drive signal P can be controlled using the switch control signal for controlling the ON / OFF state of the switch circuit 18, the adjustment of the drive signal P is facilitated.

  In the present embodiment, the light source driving unit 12 includes a storage unit 26 that stores a signal selection condition DC that is a correspondence relationship between the total number of light sources N and the drive signal P corresponding to the total number of light sources N. Based on this, the drive signal P corresponding to the total number N of light sources is selected. Therefore, addition, deletion, and change of the signal selection condition DC can be freely performed, and management of the signal selection condition DC becomes easy. Further, when the laser light source 10 is actually driven, a suitable drive signal P can be obtained immediately according to the total number N of light sources, which can contribute to speeding up the drive.

  In the present embodiment, the light source driving unit 12 includes a storage unit 26 that stores a light source number selection condition LC that is a correspondence relationship between the required light quantity L and the total number N of light sources corresponding to the required light quantity L, and the light source number selection condition The total number N of light sources is selected based on the LC. Therefore, addition, deletion, and change of the light source number selection condition LC can be freely performed, and management of the light source number selection condition LC is facilitated. Further, when the laser light source 10 is actually driven, for example, the necessary total number N of light sources can be obtained immediately in accordance with the required light quantity L based on the input image data, which contributes to speeding up the drive. it can.

  Further, in the present embodiment, the light source number selection condition LC has a correspondence relationship in which the required light amount L increases linearly with respect to the increase in the total number N of light sources, so that the light amount can be easily adjusted.

  Further, according to the driving method of the laser light source device 2 as described above, the drive signal P corresponding to the total number N of the selected laser light sources 10 is supplied to each laser light source 10. A change in the amount of light can be suppressed and a controlled amount of light can be emitted.

  In the present embodiment, the switch circuits 18 are connected in series to all the laser light sources 10 and all the laser light sources 10 are pulse-driven. However, a laser light source that does not connect the switch circuits 18 is provided, A laser light source that is continuously driven and a laser light source that is pulse-driven may be mixed.

  Further, in the present embodiment, the light source number selection condition LC has a correspondence relationship in which the required light amount L increases linearly with respect to the increase in the total number N of light sources. The total number of light sources N can be selected satisfactorily based on the required light quantity.

[Second Embodiment]
FIG. 9 is an explanatory diagram of the laser light source device 4 according to the second embodiment of the present invention. The laser light source device 4 of this embodiment is partly in common with the first embodiment. Therefore, in this embodiment, the same code | symbol is attached | subjected about the component which is common in 1st Embodiment, and detailed description is abbreviate | omitted.

  As shown in the figure, the laser light source device 4 includes a drive value detection unit 32 that detects a drive value of the circuit, a detection value of the drive value detected by the detection unit 32, and a drive signal selected by the drive signal selection circuit 20. Drive value control means 34 for controlling the drive value of the circuit based on the selected value. Here, the “drive value” refers to the value of the drive voltage or drive current applied to the laser light source 10 by the power supply drive circuit 14 among the control parameters of the drive signal.

  FIG. 10 is a schematic diagram illustrating the overall configuration of the laser light source device 4 of the present embodiment. The drive signal data selected by the drive signal selection circuit 26 is supplied to the switch control circuit 17 and also to the drive value control means 34. The drive value controller 34 compares the detected value of the drive value detected by the drive value detector 32 with the selected value of the selected drive signal, and matches the detected value and the selected value with the light source drive circuit 14. To control.

  11A and 11B are diagrams for explaining processing performed by the drive signal selection unit 24. FIG. 11A shows a case where the drive value to be controlled is a drive voltage, and FIG. 11B shows a case where the drive value to be controlled is a drive current. The case is shown. FIG. 11A is a graph showing a correspondence relationship (drive signal selection condition DC3) between the total number of light sources and the drive voltage, with the total number of light sources on the horizontal axis and the drive voltage of the drive signal corresponding to the total number of light sources on the vertical axis. FIG. 11B shows the correspondence between the total number of light sources and the drive current (drive signal selection condition DC4) where the total number of light sources is plotted on the horizontal axis and the drive current of the drive signal corresponding to the total number of light sources is plotted on the vertical axis. The graph which shows is shown.

  In the present embodiment, the amount of current flowing through the laser light source 10 decreases due to the influence of the impedance of the circuit, and the drive value for driving the laser light source 10 is controlled in order to compensate for the amount of power that decreases. Since the amount of electric power can be obtained from the product of the amount of current and the applied voltage, the amount of input power can be controlled by controlling the applied voltage or the amount of current.

  The drive signal selection conditions DC3 and DC4 can be calculated by obtaining a resistance value and an impedance value from the laser light source and circuit configuration to be used. Alternatively, the resistance value or impedance value may be measured in advance and set based on the measured value.

  When the drive voltage is controlled, the drive signal selection unit 24 obtains the drive voltage v of the drive signal P that can drive the total number of light sources N and obtain the necessary light amount L based on the drive signal selection condition DC3. When controlling the drive current, the drive signal selection means 24 calculates the drive current j of the drive signal P that can drive the total number of light sources N and obtain the required light quantity L based on the drive signal selection condition DC4. In this manner, by selecting the drive signal P suitable for the total number N of light sources by applying the present invention, a suitable drive can be realized.

  According to the laser light source device 4 configured as described above, the amount of light emitted can be controlled by selecting the drive signal P in which the drive voltage v or the drive current j is changed in response to the change in the total number N of light sources. Can do.

  Further, based on the detection value of the drive value measured using the drive value detection means 32 for the laser light source device 4 being driven and the selection value of the drive value selected by the drive signal selection means 24, the drive value control means 34 is used to control the drive value so that the detected value matches the selected value. Therefore, it is possible to control the drive value more accurately and control the amount of light emitted.

  Although the laser light source device 4 of the present embodiment generates a pulse drive signal for pulse driving the laser light source 10 using the switch circuit 18, the pulse drive for causing the light source drive circuit 14 to pulse drive the laser light source 10 is used. A signal may be generated.

[Monitor device]
FIG. 12 is a schematic configuration diagram of a monitor device according to the present invention. The monitor device 50 according to the present embodiment includes a device main body 52 and an optical transmission unit 54. The apparatus main body 52 includes the laser light source apparatus 2 of the first embodiment described above, and further includes an optical wavelength conversion element 56 and a reflection mirror 58.

  The light transmission unit 54 includes two light guides 60 and 62 on the light sending side and the light receiving side. Each of the light guides 60 and 62 is a bundle of a large number of optical fibers, and can send laser light to a distant place. The laser light source device 2 is disposed on the incident side of the light guide 60 on the light transmitting side, and the diffusion plate 64 is disposed on the emission side thereof. Laser light emitted from the laser light source device 2 travels through the light guide 60 and is sent to the diffusion plate 64 provided at the tip of the light transmission unit 54, and is diffused by the diffusion plate 64 to irradiate the subject.

  An imaging lens 66 is also provided at the tip of the light transmission unit 54, and reflected light from the subject can be received by the imaging lens 66. The received reflected light travels through the light guide 62 on the receiving side and is sent to a camera 68 as an imaging unit provided in the apparatus main body 52. As a result, an image based on the reflected light obtained by irradiating the subject with the laser light emitted from the laser light source device 2 can be captured by the camera 68.

  According to the monitor device 50 configured as described above, it is possible to provide the monitor device 50 that can reliably control the amount of light emitted from the laser light source device 2 and can perform good imaging.

[projector]
FIG. 13 is a schematic configuration diagram of a projector according to the present invention. In the drawing, the casing constituting the projector 70 is omitted for simplification. The projector 70 according to the present embodiment includes a red laser light source device 72R that emits red light, a green laser light source device 72G that emits green light, and a blue laser light source device 72B that emits blue light.

  The red laser light source device 72R has the same configuration as the laser light source device 2 of the first embodiment described above. This is a semiconductor laser array that emits red laser light LBr. The green laser light source device 72G has the same configuration as that of the laser light source device 2 of the first embodiment described above, and further includes a light wavelength conversion element 56 and a reflection mirror 58. In this optical wavelength conversion element 56, wavelength conversion is performed so as to emit laser light LBg having a green wavelength. The blue laser light source device 72B has the same configuration as the laser light source device 2 of the first embodiment described above, and further includes a light wavelength conversion element 56 and a reflection mirror 58. In this optical wavelength conversion element 56, wavelength conversion is performed so as to emit laser light LBb having a blue wavelength.

  The projector 70 also includes liquid crystal light valves (modulation units) 74R, 74G, and 74B, a cross dichroic prism (color light synthesis unit) 76, and a projection lens (projection unit) 78. The liquid crystal light valves 74R, 74G, and 74B modulate the laser beams LBr, LBg, and LBb of the respective colors emitted from the laser light source devices 72R, 72G, and 72B of the respective colors according to image signals sent from a personal computer or the like. The cross dichroic prism 76 combines the light emitted from the liquid crystal light valves 74R, 74G, and 74B and guides it to the projection lens 78. The projection lens 78 enlarges and projects the image formed by the liquid crystal light valves 74R, 74G, and 74B onto the screen 80.

  Further, the projector 70 makes the illuminance distribution of the laser light emitted from each of the laser light source devices 72R, 72G, 72B uniform so that the homogenizing optical system is located downstream of the laser light source devices 72R, 72G, 72B in the optical path. 82R, 82G, and 82B are provided. The liquid crystal light valves 74R, 74G, and 74B are illuminated by the light whose illuminance distribution is made uniform by these. For example, the uniformizing optical systems 82R, 82G, and 82B are configured by holograms or field lenses.

  The three color lights modulated by the liquid crystal light valves 74R, 74G, and 74B are incident on the cross dichroic prism 76. This prism is formed by bonding four right-angle prisms, and a dielectric multilayer film that reflects red light and a dielectric multilayer film that reflects blue light are arranged in a cross shape on the inner surface thereof. These dielectric multilayer films combine the three color lights to form light representing a color image. The synthesized light is projected onto the screen 80 by the projection lens 78 which is a projection optical system, and an enlarged image is displayed.

  According to the projector 70 configured as described above, the amount of light emitted from the laser light source devices 72R, 72G, and 72B is reliably controlled, and the light whose amount is controlled is modulated by the liquid crystal light valves 74R, 74G, and 74B. As a result, it is possible to provide the projector 70 having a wide dynamic range and excellent image display power.

  Although a transmissive liquid crystal light valve is used as the light modulation device, a light valve other than liquid crystal may be used, or a reflective light valve may be used. Examples of such a light valve include a reflective liquid crystal light valve and a digital micro mirror device. The configuration of the projection optical system is appropriately changed depending on the type of light valve used.

  Note that the present invention is not limited to the above-described embodiment, and can be implemented in various modes without departing from the gist thereof.

  In the above embodiment, the VCSEL type is used as the semiconductor laser array, but instead of this, an edge emitting semiconductor laser array in which the direction of light resonance is parallel to the substrate surface is used. Also good. Furthermore, the laser light source may be another type of laser such as a solid-state laser, a liquid laser, a gas laser, or a free electron laser instead of the semiconductor laser.

The projector 70 of the above embodiment is a so-called three-plate type liquid crystal projector. Instead of this, the laser light source device is turned on in a time-sharing manner for each color so that color display is performed with only one light valve. A single-plate liquid crystal projector having a possible configuration may be used.
Further, a scanning projector may be used.

  The preferred embodiments of the present invention have been described above with reference to the accompanying drawings, but it goes without saying that the present invention is not limited to such examples. Various shapes, combinations, and the like of the constituent members shown in the above-described examples are examples, and various modifications can be made based on design requirements and the like without departing from the gist of the present invention.

1 is a schematic configuration diagram of a laser light source device according to a first embodiment of the present invention. It is a schematic circuit diagram of the laser light source apparatus which concerns on this embodiment. It is explanatory drawing about the drive of each laser light source. It is the schematic explaining the whole structure of the laser light source apparatus of 1st Embodiment. It is the figure which showed the duty ratio of the drive signal. It is a figure explaining the process performed with a drive signal selection circuit. It is a figure which shows the drive frequency of a drive signal. It is a figure explaining the process performed by a drive signal selection means. It is explanatory drawing of the laser light source apparatus which concerns on 2nd Embodiment of this invention. It is the schematic explaining the whole structure of the laser light source apparatus of 2nd Embodiment. It is a figure explaining the process performed by a drive signal selection means. It is a schematic block diagram of the monitor apparatus which concerns on this invention. It is a schematic block diagram of the projector which concerns on this invention. It is explanatory drawing which shows the difference in the waveform of the drive signal with respect to the change of the number of light sources.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 2,4 ... Light source device, 10 ... Laser light source, 12 ... Light source drive part, 18 ... Switch circuit, 26 ... Memory | storage means, 32 ... Drive value control means (voltage control means, current control means), 34 ... Drive value detection means (Voltage detection means, current detection means), 50 ... monitor device, 68 ... camera (imaging unit), 70 ... projector, 74R, 74G, 74B ... liquid crystal light valve (modulation unit), DC ... driving signal selection condition (signal selection) Condition), f ... drive frequency, j ... drive current, L ... required light quantity (light quantity to be emitted), LC ... light source number selection condition, N ... total number of light sources (total number of laser light sources), P ... drive signal, r ... duty Ratio, v ... drive voltage,

Claims (12)

A plurality of laser light sources connected in parallel to each other;
A light source drive unit that selects one or more laser light sources from the plurality of laser light sources, and supplies a drive signal for pulse driving the laser light sources to each of the selected one or more laser light sources; Prepared,
The light source drive unit selects a drive signal corresponding to the total number of selected laser light sources from a plurality of types of drive signals having different control parameters. The light source driving unit includes a switch circuit connected in series to each of the plurality of laser light sources,
The light source device according to claim 1, wherein the driving signal is supplied by the switch circuit. The light source drive unit includes storage means for storing a signal selection condition that is a correspondence relationship between the total number of the laser light sources and the drive signal corresponding to the total number of the laser light sources,
3. The light source device according to claim 1, wherein a drive signal corresponding to the total number of the laser light sources is selected based on the signal selection condition acquired from the storage unit. The light source driving unit includes storage means for storing a light source number selection condition that is a correspondence relationship between the light amount to be emitted by the plurality of laser light sources and the total number of the laser light sources according to the light amount to be emitted,
4. The light source according to claim 1, wherein the total number of the laser light sources corresponding to the light amount to be emitted is selected based on the light source number selection condition acquired from the storage unit. 5. apparatus.   The light source device according to claim 4, wherein the light source number selection condition is a correspondence relationship in which the amount of light to be emitted increases linearly with respect to an increase in the total number of the laser light sources.   6. The light source according to claim 1, wherein the light source drive unit selects a drive signal whose duty ratio is controlled among the control parameters from the plurality of types of drive signals. apparatus.   6. The light source according to claim 1, wherein the light source driving unit selects a driving signal whose driving frequency is controlled from among the plurality of types of driving signals. 6. apparatus.   6. The light source drive unit selects a drive signal that controls a drive value that is a value of a drive voltage or a drive current among the control parameters from the plurality of types of drive signals. The light source device according to any one of the above. Driving value detecting means for detecting the driving value;
Based on the detected value of the detected drive value and the selected value of the drive value selected corresponding to the total number of the laser light sources, the drive value of the drive signal supplied to the plurality of laser light sources is determined. The light source device according to claim 8, further comprising drive value control means for controlling. The light source device according to any one of claims 1 to 9,
An image pickup unit for picking up an image of a subject illuminated by the light source device. The light source device according to any one of claims 1 to 9,
And a modulation unit that modulates light from the light source device in accordance with an image signal. A driving method of a light source device comprising a plurality of laser light sources, wherein one or more laser light sources selected from the plurality of laser light sources are pulse-driven,
A method of driving a light source device, wherein each of the selected laser light sources is driven by a drive signal selected from a plurality of types of drive signals corresponding to the total number of selected laser light sources.

Images