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JP4562411B2 - Projection-type image display device - Google Patents

Projection-type image display device Download PDF

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JP4562411B2
JP4562411B2 JP2004087009A JP2004087009A JP4562411B2 JP 4562411 B2 JP4562411 B2 JP 4562411B2 JP 2004087009 A JP2004087009 A JP 2004087009A JP 2004087009 A JP2004087009 A JP 2004087009A JP 4562411 B2 JP4562411 B2 JP 4562411B2
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light source
temperature
led light
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duty ratio
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JP2005274884A (en
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仁志 東
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Sanyo Electric Co Ltd
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Description

この発明は、映像信号を光学信号に変換し、光学信号をレンズで拡大してスクリーンに投影する液晶プロジェクタ等の投射型映像表示装置に関する。   The present invention relates to a projection-type video display device such as a liquid crystal projector that converts a video signal into an optical signal, expands the optical signal with a lens, and projects it onto a screen.

液晶プロジェクタは、映像信号を処理する電子回路、電気信号として入力される映像信号を光学信号に変換するために用いる表示素子、光学信号の反射や屈折を行う光学回路、光源や光学回路に発生する熱を冷却するための冷却ファン等を用いた冷却回路等を備えている。光源としては、一般には、メタルハライドランプ、高圧水銀ランプ等のランプが用いられていたが、光源としてＬＥＤを用いた液晶プロジェクタも開発されている。   Liquid crystal projectors are generated in electronic circuits that process video signals, display elements used to convert video signals input as electrical signals into optical signals, optical circuits that reflect and refract optical signals, light sources and optical circuits. A cooling circuit using a cooling fan or the like for cooling heat is provided. In general, lamps such as metal halide lamps and high-pressure mercury lamps have been used as light sources, but liquid crystal projectors using LEDs as light sources have also been developed.

ＬＥＤ光源は、メタルハライドランプ、高圧水銀ランプ等のランプ光源に比べて、消費電力に対する発光効率が高い、寿命が長いといった利点がある。   The LED light source has advantages such as higher luminous efficiency with respect to power consumption and longer life compared to lamp light sources such as metal halide lamps and high-pressure mercury lamps.

しかしながら、ＬＥＤ光源は発光効率がよいとはいえ、いくらかの発熱を生じる。ＬＥＤ素子を高密度に実装して、高い照度を得ようとした場合には、ＬＥＤ光源の温度も高くなる。従来の白熱ランプや高圧水銀ランプ等のランプ光源に対してＬＥＤ光源は熱に弱く、高温環境下でＬＥＤ光源を発光させることはＬＥＤ素子の特性を低下させることになる。つまり、高温環境下ではＬＥＤ素子の照度が低下するとともに、寿命も短くなる。   However, although LED light sources have good luminous efficiency, they generate some heat. When the LED elements are mounted at a high density to obtain high illuminance, the temperature of the LED light source is also increased. An LED light source is weak against heat compared to a conventional lamp light source such as an incandescent lamp or a high-pressure mercury lamp, and causing the LED light source to emit light in a high temperature environment degrades the characteristics of the LED element. That is, under high temperature environment, the illuminance of the LED element is lowered and the lifetime is shortened.

したがって、一般的には、ＬＥＤ素子は高温となるような場所では利用できない。高温になる可能性がある場所でＬＥＤを使用する場合には、ＬＥＤ素子の保護のために、温度センサを用いて高温環境下ではＬＥＤ素子を発光させなくさせるための安全装置を設ける必要がある。   Therefore, in general, the LED element cannot be used in a place where the temperature is high. When using an LED in a place where there is a possibility of high temperatures, it is necessary to provide a safety device to prevent the LED element from emitting light in a high temperature environment using a temperature sensor in order to protect the LED element. .

この発明は、光源としてＬＥＤ光源が用いられている投射型映像表示装置において、ＬＥＤ光源の周囲温度が所定の高温とならないように、ＬＥＤ光源の発光量を制御することが可能となる投射型映像表示装置を提供することを目的とする。   The present invention relates to a projection-type image display apparatus in which an LED light source is used as a light source, and the light emission amount of the LED light source can be controlled so that the ambient temperature of the LED light source does not become a predetermined high temperature. An object is to provide a display device.

請求項１に記載の発明は、光源としてＬＥＤ光源が用いられている投射型映像装置において、ＬＥＤ光源の周囲の温度を検出する温度検出器、および温度検出器の検出温度に基づいて、ＬＥＤ光源内のＬＥＤ素子の駆動パルスのデューティ比を制御する制御手段を備え、前記制御手段は、温度検出器の検出温度が第１の所定温度未満であるときには、ＬＥＤ光源内のＬＥＤ素子の駆動パルスのデューティ比を０より大きい予め定められた基準値となるように制御する手段、温度検出器の検出温度が第１の所定温度以上で第２の所定温度未満の範囲内であるときには、ＬＥＤ光源内のＬＥＤ素子の駆動パルスのデューティ比が０より大きく上記基準値より小さい範囲内の値となるように制御する手段、および温度検出器の検出温度が第２の所定温度以上であるときには、ＬＥＤ光源内のＬＥＤ素子の駆動パルスのデューティ比が０となるように制御する手段を備えていることを特徴とする。   According to a first aspect of the present invention, there is provided a projection type video apparatus in which an LED light source is used as a light source, a temperature detector for detecting a temperature around the LED light source, and an LED light source based on a detected temperature of the temperature detector. Control means for controlling the duty ratio of the drive pulse of the LED element in the LED element, and the control means is configured to control the drive pulse of the LED element in the LED light source when the temperature detected by the temperature detector is lower than the first predetermined temperature. Means for controlling the duty ratio to be a predetermined reference value greater than 0, and when the temperature detected by the temperature detector is within the range of the first predetermined temperature and lower than the second predetermined temperature, the LED light source Means for controlling the duty ratio of the driving pulse of the LED element to be larger than 0 and smaller than the reference value, and the temperature detected by the temperature detector is a second predetermined value. The time is at least once, wherein the duty ratio of the driving pulse of the LED elements in the LED light source is provided with means for controlling such that 0.

この発明によれば、ＬＥＤ光源の周囲温度が所定の高温とならないように、ＬＥＤ光源の発光量を制御することが可能となる。   According to the present invention, it is possible to control the light emission amount of the LED light source so that the ambient temperature of the LED light source does not become a predetermined high temperature.

以下、図面を参照して、この発明を液晶プロジェクタに適用した場合の実施例について説明する。   Embodiments in which the present invention is applied to a liquid crystal projector will be described below with reference to the drawings.

図１は、液晶プロジェクタのＬＥＤ光源およびその冷却ファンを制御するための回路の構成を示している。   FIG. 1 shows a configuration of a circuit for controlling an LED light source of a liquid crystal projector and its cooling fan.

この液晶プロジェクタは、赤（Ｒ）、緑（Ｇ）、青（Ｂ）の各色毎に用意された液晶表示素子と、赤（Ｒ）、緑（Ｇ）、青（Ｂ）の各色毎に用意されたＬＥＤ光源とを備えている。赤（Ｒ）用のＬＥＤ光源は複数の赤色ＬＥＤ素子から構成され、緑（Ｇ）用のＬＥＤ光源は複数の緑色ＬＥＤ素子から構成され、青（Ｂ）用のＬＥＤ光源は複数の青色ＬＥＤ素子から構成されている。   This liquid crystal projector is prepared for each color of red (R), green (G), and blue (B), and for each color of red (R), green (G), and blue (B). LED light source. The LED light source for red (R) is composed of a plurality of red LED elements, the LED light source for green (G) is composed of a plurality of green LED elements, and the LED light source for blue (B) is a plurality of blue LED elements. It is composed of

図１には、これら３種類のＬＥＤ光源のうちの１つのＬＥＤ光源に対する制御回路のみが示されているが、他の２つのＬＥＤ光源に対する制御回路も同様である。   FIG. 1 shows only the control circuit for one of the three types of LED light sources, but the control circuit for the other two LED light sources is the same.

ＬＥＤ光源１内の複数のＬＥＤ素子は、例えば、格子状に配されている。ＬＥＤ光源１の周辺には、ＬＥＤ光源１の周囲温度が所定温度Ｔ４以上になったときに駆動停止信号を出力するサーモスタット３と、ＬＥＤ光源１の周囲温度を検出するための温度センサ４とが配されている。また、ＬＥＤ光源１の周辺には、ＬＥＤ光源１を冷却するための冷却ファン２が設けられている。   The plurality of LED elements in the LED light source 1 are arranged in a grid, for example. Around the LED light source 1, there are a thermostat 3 that outputs a drive stop signal when the ambient temperature of the LED light source 1 becomes equal to or higher than a predetermined temperature T4, and a temperature sensor 4 for detecting the ambient temperature of the LED light source 1. It is arranged. A cooling fan 2 for cooling the LED light source 1 is provided around the LED light source 1.

ＬＥＤ光源１は、光源駆動回路１１によって駆動（パルス駆動）される。冷却ファン２はファン駆動回路１２によって駆動される。光源駆動回路１１およびファン駆動回路１２は、マイクロコンピュータ１０によって制御される。マイクロコンピュータ１０には、温度センサ４によって検出された検出温度ｔが送られる。光源駆動回路１１は、サーモスタット３によっても制御される。   The LED light source 1 is driven (pulse driven) by a light source driving circuit 11. The cooling fan 2 is driven by a fan drive circuit 12. The light source drive circuit 11 and the fan drive circuit 12 are controlled by the microcomputer 10. The detected temperature t detected by the temperature sensor 4 is sent to the microcomputer 10. The light source driving circuit 11 is also controlled by the thermostat 3.

マイクロコンピュータ１０は、制御を行うのに必要な複数の基準温度値を保持している。基準温度値には、Ｔ１，Ｔ２，Ｔ３（Ｔ１＜Ｔ２＜Ｔ３）がある。なお、サーモスタット３の作動温度Ｔ４は、Ｔ３より大きい値である。   The microcomputer 10 holds a plurality of reference temperature values necessary for performing control. The reference temperature values include T1, T2, and T3 (T1 <T2 <T3). The operating temperature T4 of the thermostat 3 is a value higher than T3.

マイクロコンピュータ１０は、検出温度ｔに応じて以下のような制御を行う。   The microcomputer 10 performs the following control according to the detected temperature t.

（ａ）検出温度ｔがＴ１未満の場合
検出温度ｔがＴ１未満の場合には、マイクロコンピュータ１０は、ＬＥＤ光源１内の各ＬＥＤ素子に与えられる駆動パルスのデューティ比が１となるように、光源駆動回路１１を制御する。この場合には、冷却ファン２は駆動されていない。 (A) When the detected temperature t is less than T1 When the detected temperature t is less than T1, the microcomputer 10 causes the duty ratio of the drive pulse applied to each LED element in the LED light source 1 to be 1. The light source driving circuit 11 is controlled. In this case, the cooling fan 2 is not driven.

（ｂ）検出温度ｔがＴ１以上の場合
検出温度ｔがＴ１以上の場合には、マイクロコンピュータ１０は、冷却ファン２を駆動させるように、ファン駆動回路１２を制御する。 (B) When the detected temperature t is equal to or higher than T1 When the detected temperature t is equal to or higher than T1, the microcomputer 10 controls the fan drive circuit 12 so as to drive the cooling fan 2.

（ｃ）検出温度ｔがＴ２以上でＴ３未満の場合
検出温度ｔがＴ２以上でＴ３未満の場合には、マイクロコンピュータ１０は、ＬＥＤ光源１内の各ＬＥＤ素子に与える駆動パルスのデューティ比が０より大きくかつ１より小さい範囲内の所定値（例えば、０．５）となるように、光源駆動回路１１を制御する。なお、検出温度ｔがＴ２以上でＴ３未満の場合には、ＬＥＤ光源１内の各ＬＥＤ素子に与える駆動パルスのデューティ比が、０より大きくかつ１より小さい範囲内において、検出温度ｔが高くなるほどデューティ比が小さくなるように、光源駆動回路１１を制御してもよい。 (C) When the detected temperature t is equal to or higher than T2 and lower than T3 When the detected temperature t is equal to or higher than T2 and lower than T3, the microcomputer 10 has a duty ratio of a drive pulse applied to each LED element in the LED light source 1 of 0. The light source driving circuit 11 is controlled so as to be a predetermined value (for example, 0.5) that is larger and smaller than 1. When the detected temperature t is equal to or higher than T2 and lower than T3, the detected temperature t increases as the duty ratio of the drive pulse given to each LED element in the LED light source 1 is larger than 0 and smaller than 1. The light source drive circuit 11 may be controlled so that the duty ratio becomes small.

（ｄ）検出温度ｔがＴ３以上の場合
検出温度ｔがＴ３以上の場合には、マイクロコンピュータ１０は、ＬＥＤ光源１内の各ＬＥＤ素子に与える駆動パルスのデューティ比が０となるように、光源駆動回路１１を制御する。これにより、ＬＥＤ光源１内の各ＬＥＤ素子は発光を停止することになる。 (D) When the detected temperature t is equal to or higher than T3 When the detected temperature t is equal to or higher than T3, the microcomputer 10 causes the light source so that the duty ratio of the drive pulse applied to each LED element in the LED light source 1 becomes zero. The drive circuit 11 is controlled. Thereby, each LED element in the LED light source 1 stops light emission.

なお、ＬＥＤ光源１の周囲温度が所定温度Ｔ４（Ｔ４＞Ｔ３）以上になったときには、サーモスタット３から駆動停止信号が出力され、この駆動停止信号は光源駆動回路１１に与えられる。光源駆動回路１１は、駆動停止信号が与えられると、その動作を停止する。このように、サーモスタット３は、マイクロコンピュータ１０が発熱等の原因で正常に動作しない場合等を考慮して、ＬＥＤ光源１を保護するために設けられている。   When the ambient temperature of the LED light source 1 becomes equal to or higher than a predetermined temperature T4 (T4> T3), a drive stop signal is output from the thermostat 3, and this drive stop signal is given to the light source drive circuit 11. The light source drive circuit 11 stops its operation when given a drive stop signal. Thus, the thermostat 3 is provided to protect the LED light source 1 in consideration of a case where the microcomputer 10 does not operate normally due to heat generation or the like.

図２は、マイクロコンピュータ１０による処理手順を示している。   FIG. 2 shows a processing procedure by the microcomputer 10.

電源が入れられると（ステップＳ１）、ＬＥＤ光源１内の各ＬＥＤ素子に与えられる駆動パルスのデューティ比Ｄが１となるように、光源駆動回路１１を制御する（ステップＳ２）。この後、検出温度ｔがＴ１以上であるか否かを判別する（ステップＳ３）。検出温度ｔがＴ１未満である場合には、冷却ファン２が駆動されていれば冷却ファン２を停止させるようにファン駆動回路１２を制御するとともに（ステップＳ４）、ＬＥＤ光源１内の各ＬＥＤ素子に与える駆動パルスのデューティ比が１未満であればデューティ比が１となるように光源駆動回路１１を制御した後（ステップＳ５）、ステップＳ３に戻る。   When the power is turned on (step S1), the light source drive circuit 11 is controlled so that the duty ratio D of the drive pulse given to each LED element in the LED light source 1 becomes 1 (step S2). Thereafter, it is determined whether or not the detected temperature t is equal to or higher than T1 (step S3). If the detected temperature t is less than T1, the fan drive circuit 12 is controlled to stop the cooling fan 2 if the cooling fan 2 is driven (step S4), and each LED element in the LED light source 1 is controlled. If the duty ratio of the drive pulse applied to is less than 1, the light source drive circuit 11 is controlled so that the duty ratio becomes 1 (step S5), and the process returns to step S3.

上記ステップＳ３において、検出温度ｔがＴ１以上であると判別した場合には、冷却ファン２を駆動させるように、ファン駆動回路１２を制御する（ステップＳ６）。そして、検出温度ｔがＴ２以上であるか否かを判別する（ステップＳ７）。検出温度ｔがＴ２未満である場合には、ステップＳ３に戻る。   If it is determined in step S3 that the detected temperature t is equal to or higher than T1, the fan drive circuit 12 is controlled to drive the cooling fan 2 (step S6). Then, it is determined whether or not the detected temperature t is equal to or higher than T2 (step S7). If the detected temperature t is less than T2, the process returns to step S3.

上記ステップＳ７において、検出温度ｔがＴ２以上であると判別した場合には、ＬＥＤ光源１内の各ＬＥＤ素子に与える駆動パルスのデューティ比Ｄが０より大きくかつ１より小さい範囲内の所定値（例えば、０．５）となるように、光源駆動回路１１を制御する（ステップＳ８）。そして、検出温度ｔがＴ３以上であるか否かを判別する（ステップＳ９）。検出温度ｔがＴ３未満である場合には、ステップＳ３に戻る。   When it is determined in step S7 that the detected temperature t is equal to or higher than T2, the duty ratio D of the drive pulse applied to each LED element in the LED light source 1 is a predetermined value (within a range larger than 0 and smaller than 1). For example, the light source driving circuit 11 is controlled so as to be 0.5) (step S8). Then, it is determined whether or not the detected temperature t is equal to or higher than T3 (step S9). If the detected temperature t is less than T3, the process returns to step S3.

上記ステップＳ９において、検出温度ｔがＴ３以上であると判別した場合には、ＬＥＤ光源１内の各ＬＥＤ素子に与える駆動パルスのデューティ比Ｄが０となるように、光源駆動回路１１を制御する（ステップＳ１０）。そして、ステップＳ３に戻る。   If it is determined in step S9 that the detected temperature t is equal to or higher than T3, the light source drive circuit 11 is controlled so that the duty ratio D of the drive pulse applied to each LED element in the LED light source 1 becomes zero. (Step S10). Then, the process returns to step S3.

液晶プロジェクタのＬＥＤ光源およびその冷却ファンを制御するための回路の構成を示すブロック図である。It is a block diagram which shows the structure of the circuit for controlling the LED light source and its cooling fan of a liquid crystal projector. マイクロコンピュータ１０による処理手順を示すフローチャートである。3 is a flowchart showing a processing procedure by the microcomputer 10;

符号の説明Explanation of symbols

１ ＬＥＤ光源
２ 冷却ファン
３ サーモスタット
４ 温度センサ
１０ マイクロコンピュータ
１１ 光源駆動回路
１２ ファン駆動回路 DESCRIPTION OF SYMBOLS 1 LED light source 2 Cooling fan 3 Thermostat 4 Temperature sensor 10 Microcomputer 11 Light source drive circuit 12 Fan drive circuit

Claims (1)

光源としてＬＥＤ光源が用いられている投射型映像装置において、
ＬＥＤ光源の周囲の温度を検出する温度検出器、および
温度検出器の検出温度に基づいて、ＬＥＤ光源内のＬＥＤ素子の駆動パルスのデューティ比を制御する制御手段、を備え、
前記制御手段は、
温度検出器の検出温度が第１の所定温度未満であるときには、ＬＥＤ光源内のＬＥＤ素子の駆動パルスのデューティ比を０より大きい予め定められた基準値となるように制御する手段、
温度検出器の検出温度が第１の所定温度以上で第２の所定温度未満の範囲内であるときには、ＬＥＤ光源内のＬＥＤ素子の駆動パルスのデューティ比が０より大きく上記基準値より小さい範囲内の値となるように制御する手段、および
温度検出器の検出温度が第２の所定温度以上であるときには、ＬＥＤ光源内のＬＥＤ素子の駆動パルスのデューティ比が０となるように制御する手段、
を備えていることを特徴とする投射型映像装置。 In a projection type video apparatus in which an LED light source is used as a light source,
A temperature detector for detecting the ambient temperature of the LED light source, and a control means for controlling the duty ratio of the drive pulse of the LED element in the LED light source based on the detected temperature of the temperature detector;
The control means includes
Means for controlling the duty ratio of the drive pulse of the LED element in the LED light source to be a predetermined reference value greater than 0 when the temperature detected by the temperature detector is lower than the first predetermined temperature;
When the temperature detected by the temperature detector is within the range of the first predetermined temperature or more and less than the second predetermined temperature, the duty ratio of the drive pulse of the LED element in the LED light source is greater than 0 and less than the reference value. Means for controlling to be a value of, and means for controlling the duty ratio of the drive pulse of the LED element in the LED light source to be 0 when the temperature detected by the temperature detector is equal to or higher than the second predetermined temperature,
A projection type video apparatus comprising:
JP2004087009A 2004-03-24 2004-03-24 Projection-type image display device Expired - Fee Related JP4562411B2 (en)

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