JP6261792B2 - Apparatus and method for operating a discharge lamp, especially for projection - Google Patents

Description

  The invention relates to a device for operating a discharge lamp, in particular for projection, according to the superordinate concept of claim 1. The invention also relates to a method for operating a discharge lamp, in particular for projection, according to the superordinate concept of claim 17.

  The gas discharge lamp used for image projection is a so-called short arc lamp, which is usually configured for AC operation, and realizes an arc length of about 1 mm in order to achieve high optical imaging quality. This places special requirements on the stability of the electrode geometry. For such a short arc lamp, in particular, an ultrahigh pressure mercury lamp is used. Such a lamp may be referred to as, for example, a “P-VIP lamp” or a “UHP lamp” depending on the manufacturer. Due to the high current density, the electrode tip of the lamp described above is subjected to a high heat load during operation, which causes a change in shape, i.e. a change in electrode geometry, in particular electrode burnout and / or tip length or tip. A change in diameter or tip shape and / or tip movement occurs. The resulting change in arc length and position has a significant impact directly on the lamp voltage and the effective light extraction rate of the projection device, and also on the aging characteristics of the entire discharge lamp, such as devitrification or blackening. It has a significant effect.

  The usual approach to achieve a long life of the discharge lamp and, for example, a light emission of as constant quality as possible in terms of the stability of the light arc, is to select the operating mode as advantageous as possible throughout the life, in particular The focus is on the selection of the operation mode in terms of the rectification frequency for changing the polarity of the discharge current flowing in the discharge lamp, the switching of the operation periods of different frequencies, the insertion of a so-called DC phase. In this direct current phase, by eliminating the rectification of the lamp current at the electrode of the gas discharge lamp that operates as the anode at the time of rectification, which is supposed to be carried out, the melting that occurs at the tip of the existing electrode is increased. Such intervention can take place depending on the measured lamp voltage. The voltage dependency is determined at the time of manufacture of the projection device and cannot be changed during the lamp operation time.

  In this regard, European Patent No. 2168408 (EP 2 168 408 B 1) describes a driving control method for a gas discharge lamp. In this method, based on a voltage value fixed in advance. By switching the operating frequency of the lamp from the first frequency value that is fixedly set to the second frequency value that is fixedly set, the tip of the lamp electrode is formed in the first operating mode, and the second operation In the mode, at least a part of the tip of the electrode is melted.

  In the operating method of a gas discharge lamp known from DE 10 2009 0063 38 A1 (DE 10 2009 006 338 A1), the voltage limit value is set at a fixed time interval and fixedly. Based on this, the DC voltage phase is repeatedly applied.

  At this time, basically, in the case of a very low frequency in the range from 0 Hz (direct current) to 30 Hz, melting of the electrode tip occurs, the tip becomes short, and as a result, the lamp voltage increases. For moderate frequencies in the range of 30 Hz to 120 Hz, the electrode tip usually grows. For high frequencies in the range of over 120 Hz, the electrode tip grows slowly, but further material wear occurs on it. This usually occurs on both sides of the electrode tip. The frequency limit can only be roughly defined and depends inter alia on the electrode configuration, the operating current of the discharge lamp and the time-varying state of the discharge lamp.

  Certainly, the basic mechanism of the effect on the electrode tip is known, but this depends on many different factors, notably the length and diameter of the electrode tip, the condition of the electrode head and the discharge current. Depends on. Thus, for all individual products of the same lamp type, the same current waveform cannot be assumed to be predictable as being optimal for achieving a long service life, and in particular the lifespan is increased. As a result, the ramp will not change in a predictable manner.

  An object of the present invention is to realize an apparatus and a method capable of operating an AC operation type discharge lamp so that the lifetime performance can be particularly easily improved.

  The object is solved by an apparatus having the configuration of claim 1 and a method having the features of claim 17. The dependent claims describe advantageous embodiments of the invention.

  The present invention is a device for operating a discharge lamp for projection, in particular, comprising at least one discharge lamp having a first electrode and a second electrode capable of alternating current operation, and a control device, The control device is configured to provide at least two current waveforms for driving and controlling the discharge lamp, and each current waveform has an envelope curve of a lamp current to be controlled flowing through the discharge lamp, and The background is an apparatus that can be represented by each polarity transition in the direction in which the lamp current to be controlled flows. The apparatus further comprises a measuring device for determining a measured value correlated with the state quantity of the discharge lamp, the measured value being in the electrode geometry of the first electrode and / or the second electrode. This value is suitable for enabling estimation of the state.

  In the present invention, the apparatus further correlates with a change in electrode geometry of the first electrode and / or the second electrode when the discharge lamp is driven and controlled by one of the at least two current waveforms described above. It is developed by providing an evaluation device for obtaining a related evaluation index, wherein the control device determines an evaluation index obtained for the one of at least two current waveforms from among the at least two current waveforms. The corresponding one current waveform is stored, and during the first operation period, after the first operation period, of the at least two current waveforms, using the evaluation index stored for the current waveform. One for driving control in the second operation period is selected.

  The recognition that is the basis of the present invention is that the current waveform provided in the control device that is part of the device for operating the discharge lamp, in terms of the influence of the current waveform on the electrode geometry of the discharge lamp. It can be evaluated (classified), and this evaluation allows the state of the electrode geometry of the discharge lamp to be manipulated as intended. Depending on the current flowing through the electrode, the electrode head of the discharge lamp that operates with alternating current forms a local electrode tip at the attachment point of the light arc that extends between the two electrodes during gas discharge, as described above. Can be done. Thus, “change in electrode geometry” means that the electrode tip that was present on each electrode, ie, the first electrode and / or the second electrode, is burned out or the electrode tip grows. By operating the discharge lamp formed with the electrode tip in a specific superposition, the stable and uniform operation of the discharge arc can be ensured. The present invention makes it possible to more reliably maintain an appropriate electrode geometry.

  Therefore, according to the present invention, which operation mode or current waveform can be used at the present time to achieve an optimum performance so that a desired change of the operation mode or current waveform can be performed when necessary during the lifetime. It becomes possible to specify continuously.

  In this way, there are other current waveforms that allow the device to continue to achieve optimal electrode behavior in the future with the current waveform being implemented using the evaluation index, or to achieve better behavior at the present time. In other words, a continuous learning process is performed. This may change the manner and magnitude of its effect on the electrode over the life of the same current waveform, for example, a current waveform that causes burnout causes growth at a later time. It takes into account the perception that it can be the opposite and vice versa. In that sense, it can also be called a “self-learning controller”. Thus, the present invention is also suitable for use with a plurality of different envelopes that can be selectively activated. However, of course, it is possible to have only one envelope used to generate all the current waveforms.

  The invention is also proposed for use in a device for operating a discharge lamp in the form of a high-pressure discharge lamp or an extra-high-pressure discharge lamp, for example for effect lighting, for vehicle floodlights, or It is also proposed for general lighting such as indoor lighting.

  Advantageously, the envelope curve can be the same for any of the at least two current waveforms. In such a case, an envelope curve that is relatively locally constant can be represented by, for example, an envelope curve vector. The polarity transition of the discharge current can also be represented by a rectification pattern in the form of a rectification vector, for example.

  In particular, the measured value can be a voltage value determined from the voltage applied across the discharge lamp. The voltage across this discharge lamp is usually referred to as the “operating voltage”. Therefore, the increase in the operating voltage is correlated with the melting of the tip of at least one of the first and second electrodes, and this relationship requires an effective extension of the distance between the electrodes. Effective extension is required. Correspondingly, the decrease in operating voltage correlates with the tip growth on at least one of the surfaces of both electrodes, and this tip growth reduces the distance between the two electrodes that is effective for the arc length. The metrics can now be used to show the effect on the electrode geometry, for example, which current waveform causes tip growth and which current waveform causes electrode tip melting. Can do.

  In an advantageous embodiment, the control device relies on the deviation between the measured value and the settable target value to select one of the at least two current waveforms used for drive control in the second operating period. It is configured to do. This settable target value is, for example, a value that achieves a stable light arc. In this embodiment, the settable target value can be subjected to follow-up control based on the evaluation of the measured value during the operation time. Advantageously, the control device has a greater influence on the shape of the electrode tip in order to be able to expedite the reapproach to the target value when the deviation between the measured value and the settable target value increases. It can be configured to select a corresponding current waveform so as to select a large current waveform.

  In an advantageous embodiment, the control device together with the measuring device and the evaluation device constitutes a control closed loop for controlling the measured value to the target value. Thereby, automatic stabilization of the light arc of the discharge lamp is achieved, and the discharge lamp can be operated in a routine operation mode.

  In an advantageous embodiment, the control device is configured to set a target value depending on the settable operating parameters of the discharge lamp. Such a setting can be made, for example, depending on the operating current or operating power of the discharge lamp. In particular, during the dimming operation of the discharge lamp that lowers the operating power below the rated power, the target value can be adaptively adjusted accordingly. Furthermore, the lamp operating time up to the present time, in other words, the lamp aging period can be taken into account when setting the target value. For example, the target value can be obtained from the characteristic curve.

  Instead of the above-described embodiment, the target value can also be obtained by analyzing the measurement value in the operation range of the measurement value that can be influenced by the setting of a plurality of different current waveforms. In that case, for example, the stability of the discharge arc can also be used. In the case of a measured value given by the operating voltage of the discharge lamp, for example, for a new discharge lamp, the target value can be set to 70V. During the operating time of such lamps, the continuous wear of the electrodes increases the effective distance between the two electrodes, which increases the operating voltage throughout the system. This increase can be determined, for example, based on a model or based on an evaluation of measured values. For example, if a sudden drop in lamp average voltage is detected after restarting the device, it can be estimated that the discharge lamp has been replaced. Thus, the target value can be reset to the initial value (default value).

   In another advantageous embodiment, the device according to the invention comprises a device for determining a temporal change in the measured value, wherein the evaluation device determines the evaluation index depending on the temporal change in the measured value. It is configured. Thus, for example, the rate of change can be obtained as an evaluation criterion.

  In an advantageous embodiment, the device for determining the temporal change of the measurement values is configured to apply a non-linear time scale in the acquisition and evaluation of the measurement values. An advantageous technique for determining the temporal change of the measured value is to determine the time elapsed until the measured value changes in the positive or negative direction by a settable step width. This time required to change as described above by a settable step width can be determined by a counter, in particular by a counter performing a logarithmic time evaluation. In this way, the measurement, preferably the voltage measurement, is started at a certain point in time to determine continuously whether a predetermined step width has been exceeded, in which case the counter is always new. It is restarted so that it can be continuously determined whether the rate of change has changed, in particular whether the sign has changed.

  In another advantageous embodiment, the evaluation index is correlated with the magnitude of the change in state of the electrode geometry. Such an embodiment allows the current waveform to be selected in direct consideration of the suitability of the current waveform that has the desired effect on the electrode geometry state.

  In another advantageous embodiment, at least the respective polarity transitions of the at least two current waveforms mentioned above are stored in a table together with an evaluation index corresponding to each current waveform in the control device. In this case, it is advantageous that entries including at least each polarity transition and each corresponding evaluation index in the table are sorted and arranged according to the evaluation index. Such an arrangement allows for particularly easy access to select a current waveform suitable for a predetermined influence on the electrode shape. For example, one end portion of the table may store a current waveform that causes significant tip growth of the electrode, and the other end of the table may store a current waveform that causes significant melting of the electrode tip. A current waveform that does not affect the shape of the electrode tip at all or significantly can be arranged in the middle part of the table.

  In an advantageous embodiment, the control device generates, inter alia, a new table, depending on the configurable update signal, so that all the evaluation indices stored in the table are newly determined and stored in the table. Is configured to do. In such an embodiment, the table contents can be stored in a non-volatile memory. For example, the update signal can be configured to start to newly obtain an evaluation index of the current waveform stored in the table at predetermined time intervals. In addition, a new evaluation of the current waveform stored in the table can be performed each time the device is turned on again after the lamp operation is stopped.

  A so-called commutation pattern, which is an array of polarity alternations (zero crossings) of each polarity transition for each current waveform, is advantageously controlled at the stage of the device manufacturing process, ie in the form of, for example, a so-called electronic ballast (EVG) Set during device programming. During operation, the evaluation index is continuously updated. This can be done, for example, by updating at regular intervals during one mode of operation, preferably between 0.1 seconds and 30 minutes. It is particularly advantageous to select the length of this interval as a function of the current rate of change of the measured value which is correlated with the state quantity of the discharge lamp. Specifically, a short interval is selected when the change rate is fast, and a long interval is selected when the change rate is slow. The regular interval can be adaptively adjusted depending on the rate of change, in particular the interval can be reduced when the rate of change is increased and / or the interval can be increased when the rate of change is reduced. Particularly preferably, the possible range variation of the regular intervals is from 10 seconds, in particular from 30 seconds to 3 minutes, in particular up to 10 minutes. That is, the advantageous range is any of 10 seconds to 10 minutes, 10 seconds to 3 minutes, 30 seconds to 3 minutes, 30 seconds to 10 minutes.

  It may also be advantageous to activate each such operating mode over an additional test phase in order to update the evaluation of the currently not optimal operating mode. At that time, only the instantaneous value of the evaluation index and / or the temporal transition of the evaluation index including the past value (history) of each evaluation index obtained in each case is stored in a volatile and / or non-volatile manner in the table. It is also possible to memorize. For example, when the evaluation index changes significantly due to natural occurrence, a new evaluation of all current waveforms can be started.

  In another advantageous embodiment, the control device also selects the current waveform used in the second operating period, further depending on the effectiveness index, so that in addition to the evaluation index, an additional effectiveness index is provided: In particular, the evaluation index is stored in the form of display of the time period. This has the advantage that all current waveforms can be kept up-to-date so that the most suitable current waveform can be selected to have the desired effect on the electrodes. Several different scenarios are possible for this, one of which is to provide a time period display that represents a current waveform for which there is no corresponding latest evaluation index since it has not been used for a long time. Further, in a specific operation mode such as when the discharge lamp is dimmed, an exclusion of a specific current waveform can be provided. Furthermore, it is also possible to set one current waveform as a setpoint current waveform (Default-Waveform), which is activated, for example, under specific operating conditions.

  In another advantageous embodiment, the control device is configured to use together the past value of the evaluation index in order to reduce the influence of the measurement value including noise when determining the evaluation index. In such an embodiment, an existing old value can be taken into a new value and calculated, or one or more values can be maintained as a history followed by a new entry, eg, in a ring buffer fashion. is there. To incorporate one or more old values into a new value and calculate, for example, form a moving average value, eg record the median of 20 values, or new and old values Can be added at a settable ratio. For example, 80% of the old value and 20% of the new value can be integrated, and thereby the effect of the low-pass filter can be realized. This eliminates high frequency noise, such as glitches. This can alleviate, among other things, the memory usage requirements for storing the corresponding values.

  In another advantageous embodiment, the control device is for all at least two current waveforms after initial operation of the device and / or after shut-off and subsequent restart, in particular after replacement of the discharge lamp in the device. A new value for each corresponding evaluation index is determined. In such an embodiment, the control device can be configured to determine that the lamp has been replaced when a noticeable steep change occurs in the operating voltage of the lamp. Furthermore, it is also possible to implement a configurable initialization process, for example taking into account the evaluation index obtained with the replaced old lamp. It is possible to newly construct a table having an evaluation index by periodically testing all the obtained current waveforms without depending on the evaluation table existing at the present time.

  In another advantageous embodiment, each of the at least two current waveforms described above comprises an unsigned envelope curve as a function of time, at least one first square wave signal having a constant absolute value, and an absolute value. Can be represented by multiplication with at least one second square wave signal of which is constant. Here, the first square wave signal has a first fundamental frequency, and the second square wave signal has a second fundamental frequency different from the first fundamental frequency. In the simplest case, such an embodiment is specifically that a square wave signal has only one square wave fundamental frequency. That is, the periodicity of the signal is obtained by congruent overlapping when each square wave signal is further shifted by two zero crossings. When the duty ratio is 50%, shifting by the interval of two zero crossings, that is, shifting by a half cycle, the square wave signal is just inverted, that is, has the opposite sign. However, a square wave signal can also have a superimposed periodicity, for example the polarity change from -1 to +1 or the edge of a polarity change from +1 to -1, for example normally used in a DLP projector. Such a periodicity can be obtained by shifting with respect to the period length determined by each square wave fundamental frequency for synchronization with the segment transition part of the color wheel. For example, a square wave signal can be generated whose (exact) periodicity corresponds to 1/3 or 1/4 of its fundamental frequency.

  In an advantageous embodiment, each function transition of the at least two current waveforms suitably defines a first temporal shift of the first square wave signal relative to the envelope curve and a second relative to the envelope curve. Can be expressed by appropriately defining the second time shift of the square wave signal.

  In a particularly advantageous embodiment, the parameter set representing at least one first square wave signal, at least one second square wave signal, and a temporal relationship between each of these square wave signals and the envelope curve is provided. Is stored in the control device. In such an embodiment, the control device is configured to generate a rectification pattern representing each polarity transition depending on the stored parameter set. The envelope curve can be set for each customer in the case of a device that can be used for installation in a DLP projector, for example, depending on the color wheel used in such projection technology. At that time, a reference point is defined in the temporal flow of the envelope curve. Based on this defined reference point, a time shift for the first square wave signal and a time shift for the second square wave signal are represented. Therefore, each current waveform can be defined by using the designation of the first fundamental frequency and the second fundamental frequency together. If more than two square wave signals are used to synthesize one current waveform, multiple parameter pairs are supplemented accordingly. Usually, the reference point on the envelope curve is defined at the transition from high current to low current.

  In another advantageous embodiment, the control device provides a configurable bandwidth of at least two current waveform metrics, and in the case of equalization of the at least two current waveform metrics, up to the present time It is configured to generate another current waveform having a polarity transition that is not present in any of the at least two current waveforms provided. In such a case, a new fundamental frequency is generated based on an existing parameter set for generating a current waveform, for example, by using at least one time shift and using the first and second fundamental frequencies. can do. Alternatively, at least one of the two fundamental frequencies can be adaptively adjusted.

  As an alternative to this, an existing current waveform can be replaced with a new current waveform instead of inserting another current waveform. This is performed especially when substantially the same evaluation index is given to a plurality of current waveforms. The same principle can be applied when deviating from a set bandwidth, for example, one current waveform shifts the operating voltage of the discharge lamp to an excessively low region by rapidly growing the tip. This can be applied in cases where the electrode tip shape is greatly affected by the fact that it can adversely affect arc stability by completely dissolving the electrode tip.

  The advantageous range of the first frequency is in the range from 5 Hz to 500 Hz, and the lower limit is preferably at least 15 Hz, 40 Hz, 50 Hz, 60 Hz in ascending order, and the lower limit is increased in this order. It is 500 Hz, 350 Hz, 250 Hz, and 180 Hz that are advantageous as the upper limit without depending on the above, in descending order, and the advantage increases in this order. The advantageous range of the second frequency can be in the range from 0 Hz to 500 Hz. The lower limit of the advantageous range of the second frequency is preferably at least 0.1 Hz, 1 Hz, 5 Hz, and 10 Hz in ascending order. The advantage increases in this order, and the second frequency is not dependent on this. In the descending order, 500 Hz, 350 Hz, 250 Hz, 180 Hz, 150 Hz, 120 Hz, and 90 Hz are advantageous as the upper limit of the advantageous range of the frequency, and the advantage increases in this order. In particular, a frequency that is very low in the vicinity of 0 Hz but different from 0 Hz can be used. Advantageously, a fixed relationship is selected between both frequencies. For example, the first frequency can be twice, four times, or six times the second frequency.

  The invention further provides a method for operating a discharge lamp, in particular a projection, having a first electrode and a second electrode, in alternating current, wherein at least two current waveforms are provided for driving and controlling the discharge lamp. Therefore, each current waveform can be represented by each envelope curve of the lamp current to be controlled flowing in the discharge lamp and each polarity transition in the direction in which the lamp current to be controlled flows. The method further includes determining a measurement that is correlated with the state quantity of the discharge lamp. The measured value is a value suitable to allow estimation of the state of the electrode geometry of the first electrode and / or the second electrode.

  In the present invention, the method further correlates with a change in electrode geometry of the first electrode and / or the second electrode when the discharge lamp is driven and controlled by one of the at least two current waveforms described above. Obtaining a related evaluation index and storing the evaluation index obtained for the one of the at least two current waveforms in correspondence with the corresponding one current waveform of the at least two current waveforms And, during the first operation period, using the evaluation index stored corresponding to the current waveform, of the at least two current waveforms, the drive control in the second operation period after the first operation period. Developed by selecting one for.

  The advantages, features and embodiments described for the apparatus according to the invention apply equally well to the corresponding method and vice versa. Therefore, the features of the corresponding method can be used as the features of the device and vice versa.

  The features and combinations of features mentioned in the above description and the features and feature combinations listed in the following description of the drawings and / or features and combinations of features shown only in the drawings are in the combinations described. It can be used in other combinations or alone without departing from the scope of the present invention. Thus, embodiments that are not explicitly illustrated or described in the drawings, and that become apparent and achievable by dividing combinations of features of the described embodiments, are also included in the present invention. Should be considered as disclosure.

  Other advantages and features will become apparent when reference is made to the following description of embodiments with reference to the accompanying drawings. In the drawings, the same reference numerals indicate the same components and the same functions.

Fig. 2 is a schematic diagram illustrating a method according to an advantageous embodiment of the present invention. It is the schematic which shows simply the time transition of the measured value correlated with the state quantity of a discharge lamp. It is the schematic which shows the 1st method of determining a current waveform simply. It is the schematic which shows the 2nd method of determining a current waveform simply.

  The projection device of the present invention includes a control device for driving and controlling the discharge lamp. The controller is configured to provide at least two current waveform functions for driving and controlling the discharge lamp. Each current waveform function includes an envelope curve (hereinafter also referred to as “envelope information” (for example, a correlation with current amplitude)) and polarity information (rectification pattern). Multiple different rectification patterns can be combined with the same envelope information. The envelope information is expressed by, for example, an intensity vector. The commutation pattern is likewise defined by a commutation vector, or by one square wave signal, or by other alternative representations. At least two different commutation patterns can be used.

  The measurement device of the projection device is used to obtain a measurement value correlated with the state quantity of the discharge lamp, and from such measurement value, the electrode burnout at the electrode tip of the first electrode and / or the second electrode and / or Or an estimate of growth can be derived. The distance between the two electrodes that determines the length of the light arc of the discharge lamp that ignites between the two electrode tips is not directly measurable by the control device of the projection device, for example by an electronic ballast. In order to indirectly measure the distance between the electrode and the second electrode, the lamp voltage across the discharge lamp can be used as a measured value. The lamp voltage is influenced by the so-called cathode drop, anode voltage, and voltage drop in the original discharge arc. The cathode drop and anode voltage do not depend on the distance between the electrodes in a good approximation when the current is the same, and the voltage drop in the discharge arc is proportional to the distance in a good approximation. Therefore, the lamp voltage can be used as a control variable for the interelectrode distance. When the tip grows in the electrode, the voltage decreases and the protruding portion dissolves. The voltage change rate, that is, the difference between the initial value and the final value of the voltage within the settable measurement period divided by the width of the settable measurement period affects the electrode tip as desired. It is a scale that represents the effectiveness of each operation mode.

  A method implemented on an apparatus for operating a discharge lamp, according to an advantageous embodiment of the invention, is shown in FIG. By using this method, a control closed loop for controlling the distance between the first electrode and the second electrode is realized. The method starts at step S0 and starts with an execution index i = 1. If the device is already in operation and re-entered after a pause, the execution index i can preferably take on the value it had at the end of the previous operating cycle. In step S1, the projection apparatus is operated with the rectification pattern Ki. In step S2, the measurement amount X is measured. The measurement quantity X can be measured continuously or at discrete time points that can be set. Such measurement value detection can be performed, for example, by a microprocessor / microcontroller incorporating an analog-to-digital converter.

  Thereafter, the measured quantity X is manipulated by the lamp voltage (operating voltage) U, for example.

  For example, the measurement signal can be filtered to remove noise due to voltage signal noise floor, voltage change due to change in discharge arc attachment point, or lamp current change due to necessary power control, etc. .

  In the third step S3, the change rate dX / dt is obtained based on the obtained measurement value. For example, a settable change width dX is set, and a counter can be used to obtain the time elapsed from the settable start time until one change width dX of the measured value X changes. Such a change can occur in both positive and negative directions. That is, the measurement value X can be increased or the measurement value X can be decreased.

  In order to evaluate the change rate dX / dt, a counter that performs nonlinear time scale evaluation can be used. For that purpose, a logarithmic scale can be used in particular.

  Depending on the obtained change rate dX / dt, the evaluation value Yi is generated based on the temporal change of the measurement value X during the operation using the rectification pattern Ki. This evaluation value Yi represents the size of the burning or growth of the electrode tip of the first electrode and / or the second electrode during operation using the rectification pattern. When obtaining the evaluation value Yi, other factors can be used together. For example, when the rectification pattern is used, a steady transition without a steep change and / or a monotonous transition without a turning point is achieved. A factor can be used together. The obtained evaluation value Yi is stored in the evaluation table Tab together with the rectification pattern Ki. The evaluation table Tab can be arranged so that the entries are sorted and arranged according to the evaluation value Yi. Furthermore, the evaluation table Tab may have an entry indicating the time when the corresponding rectification pattern Ki was last evaluated, that is, an entry indicating information about the lifetime of the evaluation value Yi, for each element.

  In a fifth step S5, a calculated value of the measured value deviation ΔX is obtained from the difference between the measured value X correlated with the interelectrode distance and the target value XZ. Therefore, the target value-actual value comparison of the distance between the electrodes of the discharge lamp is based on an indirect evaluation of the measured value correlated with the distance between the electrodes, which can be obtained during the operation of the projection apparatus. Therefore, this can be obtained based on a model and based on a so-called observer. The model parameters can be statistically determined by performing systematic measurements in advance on the type of discharge lamp that is intended to be used in the device, for example using the discharge current flowing in the discharge lamp. Thus, it can be obtained using an arc projection method for obtaining a relationship between the voltage applied to the lamp and the arc length of the discharge lamp light arc between the first electrode and the second electrode of the discharge lamp. This discharge current can also be obtained in the control device. Therefore, in order to obtain the deviation between the interelectrode distance X or the interelectrode distance X and the settable target value, it is based on the voltage of the discharge lamp and the current flowing in the discharge lamp, or the voltage of the discharge lamp Based on the power supplied to the discharge lamp.

  In the sixth step S6, based on the obtained deviation between the interelectrode distance and the settable target value XZ, it depends on at least the measured value deviation ΔX and the evaluation values Y1, Y2 to YN existing in the evaluation table Tab. Then, a new rectification pattern Ki is selected. In order to obtain a new rectification pattern Ki, it is also possible to take into account the measured value X itself and / or the time t which are correlated with the distance between the electrodes. Therefore, for a new rectification pattern Ki, for example, i = f (t, X, ΔX, Y1, Y2,..., YN).

  After a new rectification pattern Ki is selected, the process jumps back to the first step S1, and is executed with the rectification pattern Ki having the index i updated accordingly.

  Of course, instead of the rectification pattern Ki (i = 1... N), the complete current waveform Wi (i = 1... M) is stored in the table Tab, in particular a plurality of sets of current waveforms. These current waveforms are selectively activated for selection each time. In such a case, in the evaluation table Tab, the rectification patterns K1, K2,... KN are replaced with the current waveforms W1, W2,. N can be equal to M. This is true, for example, when using the same envelope curve IL for all current waveforms. When all the rectification patterns Ki (i = 1... N) are combined with all the stored envelopes IL, the number of current waveforms WM obtained is M = N × L.

FIG. 2 shows how the method works, based on an example of a simplified curve 21 comprising individual curve sections 21a, 21b, 21c, 21d, 21e. This curve 21 represents the transition of the measured value X at time t. In the graph shown in FIG. 2, the time t is shown on the horizontal axis, and further on the horizontal axis at the first switching time T1, the second switching time T2, and the third switching time T3. Three highlighted points are also shown. On the vertical axis, the voltage U of the discharge lamp is shown. This is representative of the measured value X which is correlated with the distance between the electrodes of the discharge lamp. Here, for simplification, it is assumed that the voltage U corresponds to the measured value X.

  On the vertical axis, the target value Z, the lower limit UG, and the upper limit OG are shown. The target value Z is between the lower limit UG and the upper limit OG. In the first time interval 22a up to the first switching time T1, the transition of the voltage U follows the first curve interval 21a with a negative slope. The distance between the electrodes is initially reduced from the initial voltage exceeding the upper limit OG in a direction toward the target value Z with a gradient of −0.5 in an arbitrary unit. If the first time interval 22a further shifts, the target value Z falls below, and finally the lower limit UG is reached at the first switching time T1.

  At the first switching time point T1, the first rectification pattern K1 is switched to the second rectification pattern K2, so that the gradient of the second curve section 21b in the second time section 22b becomes +2 in an arbitrary unit. Thereby, after the tip of the electrode of the discharge lamp grows first and the voltage U between the two electrodes is reduced, the tip melts and moves backward, whereby the first switching time T1 and the second switching time T2 During the second time interval 22b between and the lamp, the voltage U of the lamp rises continuously, and the voltage U reaches the value of the upper limit OG at the second switching time T2.

  By switching back to the first rectification pattern K1 at the second switching time point T2, the gradient of the third curve section 21c following the second switching time point T2 becomes −0.5 of an arbitrary unit again.

  During the operation with the first rectification pattern K1, the change of the voltage change direction occurs. This alternation can be caused by changes in electrode geometry. Thus, the third curve segment 21c is followed by a fourth curve segment 21d characterized by an increase in voltage. At the third switching time T3, a change in the voltage change direction of K1 is detected. In response to this, the fourth time interval 22d following the third time interval 22c ends at the third switching time T3. Subsequent to the fifth time interval 22e, the change to the rectification pattern K4 is performed, and the rectification pattern K4 causes a voltage drop with a gradient of −0.06 level in arbitrary units. The fifth curve section corresponding to this is denoted by reference numeral 21e.

Hereinafter, the transition of the curve 21 composed of the curve sections 21a, 21b, 21c, 21d, and 21e displayed in a graph in FIG. 2 is collectively shown in a compact table format. Each row of the table shows the state of the table Tab (N = 4) at the time points T1, T2 or T3, and the action taken at each time point as a result.

  Therefore, this is a list of tables Tab at different points in time. In addition, the column “Action” also describes what happens at each point in time.

  By the above, the control device realizes a control loop that can maintain the state of the electrode geometry of the first electrode and / or the second electrode within a set range.

  Hereinafter, another method for describing the current waveform, in particular, a method for synthesizing the current waveform, which is an alternative to the above method, will be described. The control device is configured to generate a current waveform function for driving and controlling the discharge lamp. Each current waveform function is composed of envelope information (current amplitude) and polarity information (rectification pattern). The envelope information can be represented by an intensity vector or by an envelope curve IL as described below. The rectification pattern KN is set by multiplying a plurality of square wave signals Rj having different frequencies. This square wave signal includes the frequency fj of the square wave signal, the phase angle φ1 of the first square wave signal with respect to the envelope curve, and the phase angles φj of the other remaining square wave signals with respect to the first square wave signal. And is represented by

  Hereinafter, referring to FIGS. 3a, 3b, 3c, and 3d, current waveform synthesis in the case of a specific case where the projection device is, for example, in the form of a 3LCD projection device (Liquid Crystal Display) or a 3-chip DLP (Digital Light Processing). Will be described. In FIG. 3a, the envelope information is represented by a constant envelope curve IL at time t. Here, the unit 1 is arbitrarily selected and can represent 100% operation, and this 100% operation represents, for example, the operation of the discharge lamp at the rated output. FIG. 3b shows the temporal transition of the first square wave signal R1. FIG. 3c shows the time course of the second square wave signal R2. Both the first square wave signal R1 and the second square wave signal R2 are zero average and each have a duty ratio of 50%. Furthermore, both square wave signals each have only one square wave frequency. In other words, the double wave signals R1 and R2 are inverted in sign after exactly half a cycle. Thus, the interval between the two zero crossings of each square wave signal R1 and R2 is always constant and a half cycle. That is, it is half the reciprocal of the first frequency f1 or the second frequency f2. Both frequencies f1, f2 of the both-wave signals R1, R2 can be freely selected. The advantageous range of the first frequency f1 is from 5 Hz to 500 Hz, and the advantageous range of the second frequency f2 is from 0 Hz to 500 Hz. FIG. 3d shows the product of the envelope curve IL, the first square wave signal R1, and the second square wave signal R2. The characteristics of the signal generated in this way (referred to as “current waveform WM”) appear complex, but this signal is represented by a simple coefficient set, ie the respective frequencies f1, f2 of the underlying square wave signals R1, R2. And the above-described phase angle of the square wave signals R1 and R2 with respect to the envelope curve IL, whereby the phase relationship between the two wave signals R1 and R2 is also obtained.

  In the illustrated embodiment, the first square wave signal R1 has a first frequency f1 = 130 Hz and the second square wave signal R2 has a second frequency f2 = 60 Hz. Therefore, the frequency ratio of f2 to f1 is about 0.46. The phase difference between the two wave signals or the time shift between them is about 1.28 ms. Since the envelope curve is constant in time, the time shift with respect to the envelope curve can be selected arbitrarily in principle.

  For example, a current waveform suitable for a one-chip DLP projector (Digital Light Processing) needs to satisfy other conditions in contrast to the above-described current waveform. In a one-chip DLP projector, it is necessary to accurately synchronize with a commonly used color wheel. The color wheel rotates on the optical path of the projector and has a plurality of color segments, and each color segment is assigned to a different color and can have a different length. That is, the angle ratio of 360 ° as a whole for each color sector may be settable. With such a color wheel, a plurality of different colors of one video image are sequentially projected in time. Modern DLP projectors are further provided with adjusting means for individually setting the magnitude of the lamp current of each color segment. This makes it possible to improve the color reproducibility by, for example, making the luminance higher by excessive increase of the white segment or by appropriately adjusting each color. Typically, a customer using the apparatus of the present invention in a projection apparatus, specifically a manufacturer, for example, has multiple current curves (current amplitude envelope information) for multiple different brightness sets in each segment, For example, three to six current curves can be defined, and these current curves can be stored in the non-volatile memory of the projection device, mostly in the EEPROM memory.

  It is preferred to perform rectification at the transitions between the color segments of the color wheel, so-called spokes. As a result, a drop in luminance due to current rectification is not perceived by the user. This is because the color mixture caused by the spoke is inherently shielded by the projector or used, for example, to increase the white light component.

  In this regard, FIG. 4a shows an envelope curve IL representing an amplitude transition of a desired luminance of each color segment of the color wheel as another embodiment. Shown in the figure is an envelope curve IL of a color wheel having six segments as an example. In the figure, the rotational speed of the color wheel is constant, that is, the rotational speed is constant. Assuming that, segment durations or percentages of angles are summarized in the following table:

White W 70 °
Cyan C 30 °
Blue B 90 °
Green G 30 °
Red R 65 °
Yellow (Yellow) Y 75 °

  Each broken line in the vertical direction in FIGS. 4a, 4b, 4c, and 4d indicates a segment boundary.

  FIG. 4b shows the first square wave signal R1, the period duration of each pulse being slightly different. Here, the “pulse” is each section extending between the first zero crossing (for example, G → R) and the third zero crossing (for example, Y → W) of the first square wave signal R1, Each interval in which the polarity change of the first square wave signal R1 is made at a second zero crossing (eg, C → B) located as the only zero crossing between the first zero crossing and the third zero crossing. Say. Specifically, in contrast to the embodiment of FIG. 3b described above, the duty ratio in FIG. 4b is not always 50%, but rather the first square wave signal shown in FIG. 4b. In consideration of the segmentation determined by the color wheel of the DLP projector, the zero crossing of R1 is stored in a ready-made mold that has a finite number of zero crossing positions. In other words, the width of each square is rounded up or down in both the negative direction (-1) and the positive direction (1) depending on non-equal spacing rasterization.

  The same applies to the second square wave signal R2 of the embodiment shown in FIG. 4c. In the case of the second square wave signal R2, the period duration of each pulse is also slightly different. Thus, one rotation of the color wheel correlates with one round of white W, cyan C, blue B, green G, red R and yellow Y segments. That is, its duration is combined with a complete rotation (360 °) of the color wheel via the number of rotations of the DLP color wheel.

  Therefore, the product of the envelope curve IL, the first square wave signal R1, and the second square wave signal R2 is a curve waveform of the current waveform WM as shown in FIG. 4d.

  The first square wave signal R1 and the second square wave signal R2 of the present embodiment that can be used for DLP projection also apply that the both square wave signals have zero average as described above. .

  In the case described above, the possible zero crossings are limited to a predetermined rectification position, so that the instantaneous value of the frequency of the square wave signal fluctuates around the average value f1 or f2, respectively. In the example shown in FIGS. 4b and 4c, these average values are f1 = 45 Hz and f2 = 25.7 Hz. The ratio of both frequencies is 0.57. In this embodiment, the time shift of both the square wave signals is 0 ms between the envelope curve IL and the first square wave signal R1, and the first square wave signal R1 and the second square wave signal R2 Is about 3.2 ms.

  The same applies to the second square wave signal R2.

  In particular, the frequency and the phase angle are appropriately selected by using the above-described method for synthesizing a plurality of rectification patterns Ki by taking in a settable intensity vector representing a locally constant intensity transition of the envelope curve IL. In particular, it is possible to generate a current waveform WM that also satisfies the requirements for a zero-average current waveform in a particularly simple manner.

  This current waveform synthesis technique does not depend on the above-described use with the present invention, and can be installed and used without depending on any type of AC operation type discharge lamp. It can also be used advantageously as an alternative to the method of changing the commutation vector characterizing the appropriate current waveform as described in later published application 102014142275.2.

  The above examples are provided only for illustrating the present invention and are not intended to limit the present invention. In particular, both the number of square wave functions used for synthesizing the current waveform and the number of current waveforms provided for the implementation of the present invention can be arbitrarily changed. There is no limitation on how to store or store an appropriate parameter set or signal in an appropriate device.

  Therefore, the above description shows how the operating mode of an AC operation type ultrahigh pressure discharge lamp having two electrodes, particularly a lamp for a projection apparatus, can be optimized.

S0 start S1 first step S2 second step S3 third step S4 fourth step S5 fifth step S6 sixth step Tab evaluation table i index W1 first current waveform W2 second current waveform K1 1st rectification pattern K2 2nd rectification pattern KN Nth rectification pattern Y1 1st evaluation index Y2 2nd evaluation index YN Nth evaluation index IL envelope curve X measured value dX / dt change speed dX change width t Time ΔX Measured value deviation XZ Target value U Operating voltage OG Upper limit Z Target value UG Lower limit T1 First switching point T2 Second switching point T3 Third switching point 21a First curve section 21b Second curve section 21c 3rd curve section 21d 4th curve section 21e 5th curve section 22a 1st time section 22b 2nd time section 22 The third time interval 22d fourth time interval 22e fifth time interval I envelope curve R1 first square wave signal R2 the second square-wave signal WM current waveform (generally)

Claims (17)

In particular, a device for operating a discharge lamp for projection,
At least one discharge lamp capable of alternating current operation comprising a first electrode and a second electrode;
In order to drive and control the discharge lamp, each envelope curve (IL) of the lamp current to be controlled flowing in the discharge lamp and each polarity transition (K1, K2) in the direction in which the lamp current to be controlled flows A controller configured to provide at least two current waveforms (W1, W2) each represented;
A measuring device for obtaining a measured value (X) correlated with the state quantity of the discharge lamp,
The measured value (X) is a value suitable for enabling an estimation of the state of the electrode geometry of the first electrode and / or the second electrode, for operating the discharge lamp In the device
An apparatus for operating the discharge lamp is:
Electrode geometry of the first electrode and / or the second electrode when the discharge lamp is driven and controlled using one of the at least two current waveforms (W1, W2) And an evaluation device for obtaining evaluation indices (Y1, Y2) that are correlated with changes in
The controller is
The evaluation index (Y1, Y2) obtained for one of the at least two current waveforms (W1, W2) is used as the corresponding one of the at least two current waveforms (W1, W2). Memorize the current waveform,
During the first operation period (22a), the first operation of the at least two current waveforms (W1, W2) is performed using the evaluation index (Y1, Y2) stored for the current waveform. An apparatus for operating a discharge lamp, characterized in that it is configured to select one current waveform for drive control in a second operating period (22b) after the period. The control device selects one of the at least two current waveforms (W1, W2) for driving control in the second operation period as a target value that can be set with the measured value (X). (XZ) is configured to be performed depending on a deviation (ΔX),
Apparatus for operating a discharge lamp according to claim 1. The control device, together with the measurement device and the evaluation device, constitutes a control closed loop for controlling the measurement value (X) to the target value (XZ).
Apparatus for operating a discharge lamp according to claim 2. The control device is configured to set the target value (XZ) depending on a settable operating parameter of the discharge lamp.
Apparatus for operating a discharge lamp according to claim 2 or 3. An apparatus for operating the discharge lamp is:
A device for determining a temporal change of the measured value (X),
The evaluation device is configured to obtain the evaluation index (Y1, Y2) depending on a temporal change of the measurement value.
An apparatus for operating a discharge lamp according to any one of claims 1 to 4. The apparatus for determining the temporal change of the measurement value (X) is configured to apply a non-linear time scale in acquiring and evaluating the measurement value.
6. An apparatus for operating a discharge lamp according to claim 5. The evaluation index (Y1, Y2) is correlated with the magnitude of change in the state of the electrode geometry.
A device for operating a discharge lamp according to any one of claims 1-6. At least the polarity transitions (K1, K2) of the at least two current waveforms (W1, W2) are stored in the table (Tab) together with the corresponding evaluation indexes (Y1, Y2) in the control device,
Advantageously, entries in the table that include at least each polarity transition and each corresponding evaluation index are arranged sorted according to the evaluation index,
A device for operating a discharge lamp according to any one of claims 1-7. The control device is configured to newly generate all the evaluation indexes stored in the table and store them in the table, in particular, depending on a settable update signal, and particularly to generate the table. Being
9. An apparatus for operating a discharge lamp according to claim 8. In addition to the evaluation index (Y1, Y2), the control device further stores an effectiveness index, particularly in the form of a time period display of the evaluation index, and the current waveform used in the second operation period ( W1, W2) is further selected depending on the validity index,
A device for operating a discharge lamp according to any one of the preceding claims. The controller is configured to use the past value of the evaluation index together in order to reduce the influence of the measurement value (X) including noise when determining the evaluation index (Y1, Y2).
Device for operating a discharge lamp according to any one of the preceding claims. The control device may be configured to provide the at least two currents after initial operation of the device and / or after shut-off and subsequent re-operation, in particular after replacement of the discharge lamp in a device for operating the discharge lamp. It is configured to obtain a new value of each corresponding evaluation index (Y1, Y2) for all the waveforms (W1, W2).
Device for operating a discharge lamp according to any one of the preceding claims. The at least two current waveforms (W1, W2) are respectively an unsigned envelope curve (IL) as a time function, at least one first square wave signal (R1) having a constant absolute value, and absolute Represented by multiplication with at least one second square wave signal (R2) having a constant value;
The first square wave signal has a first fundamental frequency (f1), and the second square wave signal (R2) has a second fundamental frequency (f2) different from the first fundamental frequency. Have
Device for operating a discharge lamp according to any one of the preceding claims. Each function transition of the at least two current waveforms (W1, W2) suitably defines a first temporal shift of the first square wave signal (R1) relative to the envelope curve (IL), and It is expressed by appropriately defining the second time shift of the second square wave signal (R2) with respect to the envelope curve (IL).
An apparatus for operating a discharge lamp according to claim 13. The at least one first square wave signal (R1), the at least one second square wave signal (R2), and a parameter representing a temporal relationship between each square wave signal and the envelope curve (IL) A set is stored in the control device;
The control device is configured to generate a rectification pattern (K1, K2) representing each polarity transition depending on the stored parameter set.
Device for operating a discharge lamp according to claim 13 or 14. The control device provides a configurable bandwidth of the evaluation index (Y1, Y2) of the at least two current waveforms (W1, W2), and the evaluation index of the at least two current waveforms is equalized Is configured to generate another current waveform having a polarity transition that is not present in any of the at least two current waveforms (W1, W2) provided to date.
Device for operating a discharge lamp according to any one of the preceding claims. In particular, a method for operating a discharge lamp having a first electrode and a second electrode with alternating current for projection,
In order to drive and control the discharge lamp, each envelope curve (IL) of the lamp current to be controlled flowing in the discharge lamp and each polarity transition (K1, K2) in the direction in which the lamp current to be controlled flows Providing at least two current waveforms (W1, W2) each represented;
Determining a measured value (X) that is correlated with a state quantity of the discharge lamp,
In the method, the measured value (X) is a value suitable to allow an estimation of the state of the electrode geometry of the first electrode and / or the second electrode,
Electrode geometry of the first electrode and / or the second electrode when the discharge lamp is driven and controlled using one of the at least two current waveforms (W1, W2) Obtaining evaluation indices (Y1, Y2) correlated with changes in
The evaluation index (Y1, Y2) obtained for one current waveform of the at least two current waveforms (W1, W2) is used as the one current corresponding to the at least two current waveforms (W1, W2). Remembering the waveform,
During the first operation period (22a), the first operation of the at least two current waveforms (W1, W2) is performed using the evaluation index (Y1, Y2) stored for the current waveform. Selecting one current waveform for drive control in a second operating period (22b) after the period.

Images