1305441 九、發明說明： 【發明所屬之技術領域】 本發明有關於驅動電路，特別有關一種可用於鐳射相 位測距之鐳射二極體的驅動電路。 " 【先前技術】 \ 目前鐳射二極體(laser diode ; LD)由於其體積小、償格 ' 低廉與使用方便的優點，已被廣泛地應用在資訊的光存儲 φ 與讀取、光通信和距離量測等眾多領域中，但根據用途的 不同，對鐳射二極體之驅動電路的要求，也相對的有所改 變0 如第1圖中所示，只有在驅動電流大於臨界電流Ith 時，鐳射二極體所發出的才是有效的鐳射光，並且溫度對 鐳射二極體輸出之光功率有很大影響，在同樣的驅動電流 之下，溫度越高，輸出的光功率越小。然而，大多數的應 用（如：CD、DVD或距離量測）皆要求鐳射二極體能夠輸出 • 穩定的鐳射光。換言之，鐳射二極體皆需要一適當之驅動 電路能夠提供恰當的驅動電流，使得其能夠工作在輸出有 . 效鐳射光的狀態。 【發明内容】 本發明係提供一種可應用於鐳射相位測距之驅動電 %，包括光發射元件，用以產生光信號；偏壓電路，用以 產生驅動電信號，致使光發射元件操作於預定的工作區間 中；光電轉換元件，用以感測光發射元件之光輸出功率的 大小，產生對應之電信號；功率控制電路，用以根據電信 6 1305441 號，調整驅動 於一既定值；，，使得光發射元件之光輸出功率趨近 號源之間，用、X及父流通路，耦接於光發射元件與外部信 件產生至少一 X接收至少一交流調製信號，致使光發射元 已調製之光信號。 為了讓本於明 、、 明顯易懂，下=之上述和其他目的、特徵、和優點能更 詳細說明如下：特舉一較佳實施例，並配合所附圖示，作 【實施方式） 隨著電f 4» 位測距儀和半導體雷射器的發展，掌上型雷射和 勘測與室内’且廣泛地應用在建築、交通、地开」 :備有光發射器用以發出雷射光束用 束，以便能夠對準量測點(目標物)。由對準被：Μ之为 束會散射’並且被測距儀中所内建之接故=物體之为 藉由相較於發射ϋ所料之光束與所接彳^錢下來， 位變化量，即可求出與被測物之間的距離。光束間之才丨 一般而言，相位式測距儀中之偵測器係使 二極體或崩潰光電二極體(APD)將所對準之被ΡΙΝ光電 反^回來之光束，轉換成電性信號。f見的相=物敢射或 係藉由測量相位作為判定距離的標準，在這種式測姖儀 接收到的電性信號會疊加上一混波頻率，以產2置中，所 里/則4號，直測此低頻量測信號之相位，再今〜A彳口低頻 之相位作比較。藉由低頻量測信號之相位與參t考信鞔 位間之相位差，即可作為被測物之距離的量剛。彳相 1305441 本發明係提供一種可應用於鐳射相位測距之驅動電 路。第2圖為本發明之驅動電路之一實施例。如圖所示， 驅動電路100包括一光發射元件10、一光接收元件20、一 功率控制電路30、一偏壓電路40以及一交流通路50。 一般而言，光發射元件10可為鐳射二極體（Laser - Diode ; LD)，用以產生光信號。光接收元件20，用以感測 ' (監控）光發射元件10之光輸出功率的大小，並產生對應之 電信號（輸出信號）。一般而言，光信號的接收裝置常使用 ® 光電轉換元件作為接收端，特別是使用崩潰光電二極體 (Avalanche Photo Diode ; APD)或光二極體（Photo Diode ; PD)，並根據所接收到光信號的強度，產生對應之輸出信號。 偏壓電路40用以產生驅動電信號，致使光發射元件 10操作在恰當的工作範圍中，以減少信號失真；於本實施 例中，偏塵電路40會產生驅動電信號，使光發射元件10 操作於預定的工作區間中。於本實施例中，偏壓電路40包 括二電阻R2與R3、一電晶體Q1以及一電感L1。舉例而 言，電晶體Q1為NPN型之放大電晶體，但不限定於此。 電阻R2與R3係作為限流電阻，防止通過光發射元件10 的電流過大，而電感測L1為一隔離電感，用以將交流信號 限制在交流通路50。 功率控制電路30用以根據來自光接收元件20之電信 號，控制偏壓電路40以調整驅動電信號，使得光發射元件 10之光輸出功率趨近於一既定值。簡言之，功率控制電路 30與偏壓電路40共同組成了驅動電路100中之直流驅動 1305441 部分。 由此可知，當由於自身發熱或者環境改變等因素造成 鐳射二極體之光輸出功率發生改變時，本發明之驅動電路 100可藉由光接收元件20、功率控制電路30與偏壓電路 40，將可根據所採集到之光輸出功率的大小，自動地調整 光發射元件10之驅動電信號的大小，使光發射元件10輸 出之光功率等於(趨近）一既定值。其中，上述偏壓電路40 所產生之驅動電信號可為電流信號或電壓信號。 此外，交流通路50耦接於光發射元件10與外部信號 源（未圖示）之間，用以接收至少一交流調製信號（INH與 INL)，致使光發射元件10產生至少一已調製之光信號。於 本實施例中，交流通路50由二電容C1與C2、一電感L2 與一電阻R1所組成，用以接收交流調製信號INH與INL， 但不限定於此。 在一般的測距系統中，為了獲得較大的量測距離和較 高的準確度，通常需要多個相位量測信號，因此也就需要 多個調製頻率，範圍由幾MHz至幾百MHz不等。所以測 距系統中之頻率合成器（未圖示）會根據處理單元之控制信 號，產生對應之交流調製信號(如INH與INL)，交流通路 50會被耦接至頻率合成器，用以將頻率合成器所輸出之交 流調製信號，載入到光發射元件10之輸入端（陽極）。 一般而言，電容C1與電感L2可用於將具有較高頻率 之交流調製信號INH載入至光發射元件10，而電容C2與 電阻R1可用於將具有較低頻率之交流調製信號INL載入 1305441 至光發射元件10，於是光發射元件10會根據所載入之交 流調製信號，輸出與調製信號相同頻率之明暗變化的光信 號。舉例而言，交流調製信號INH之頻率會比交流調製信 號來的得高，且兩個之間約有幾KHz之頻率差，但不限定 . 於此。 - 由於本發明之驅動電路在鐳射二極體由於自身發熱或 者環境改變等因素，而造成其光輸出功率發生改變時，可 根據所採集到之光輸出功率的大小，自動地調整光發射元 _ 件10之驅動電流的大小使光發射元件10輸出之光功率 等於（趨近）一既定值，並同時可藉由交流通路載入交流調 製信號，因此本發明之驅動電路不僅可應用於距離量測系 統中，亦可應用於資訊的光存儲與讀取和光通信等眾多領 域中。 雖然本發明已以較佳實施例揭露如上，然其並非用以 限定本發明，任何熟知技藝者，在不脫離本發明之精神和 範圍内，當可作些許更動與潤飾，因此本發明之保護範圍 B 當視後附之申請專利範圍所界定者為準。 10 1305441 【圖式簡單說明】 第1圖所示係為習知鐳射二極體於不同溫度下，順向 電流與光輸出功率之關係曲線。 第2圖所示係為本發明之驅動電路之一實施例。 【主要元件符號說明】1305441 IX. Description of the Invention: [Technical Field] The present invention relates to a driving circuit, and more particularly to a driving circuit for a laser diode that can be used for laser phase ranging. " [Prior technology] \The current laser diode (LD) has been widely used in information optical storage φ and reading, optical communication due to its small size, low cost and easy to use. And distance measurement and many other fields, but depending on the application, the requirements for the driving circuit of the laser diode are also relatively changed. 0 As shown in Fig. 1, only when the driving current is greater than the critical current Ith The laser diode emits effective laser light, and the temperature has a great influence on the optical power output of the laser diode. Under the same driving current, the higher the temperature, the smaller the output optical power. However, most applications (such as CD, DVD, or distance measurement) require the laser diode to output • stable laser light. In other words, the laser diode requires a suitable drive circuit to provide the proper drive current so that it can operate in the state of output laser light. SUMMARY OF THE INVENTION The present invention provides a driving power % that can be applied to laser phase ranging, including a light emitting element for generating an optical signal, and a bias circuit for generating a driving electrical signal, so that the light emitting element operates a predetermined operating range; a photoelectric conversion component for sensing a magnitude of an optical output power of the light emitting component to generate a corresponding electrical signal; and a power control circuit for adjusting the driving to a predetermined value according to the telecommunications number 6 1305441; The optical output power of the light emitting element is brought closer to the source, and the X and the parent flow path are coupled to the light emitting element and the external letter to generate at least one X to receive at least one AC modulated signal, so that the light emitting element is modulated. Optical signal. The above and other objects, features, and advantages of the present invention will be described in more detail in the light of the appended claims. Development of electric f 4» position rangefinders and semiconductor lasers, handheld lasers and surveys and indoors - and widely used in construction, transportation, and ground opening: equipped with light emitters for emitting laser beams Beam so that it can be aligned with the measurement point (target). By aligning: Μ 为 束 会 散射 并且 并且 并且 并且 被 被 被 被 被 被 = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = , the distance to the object to be measured can be found. Between the beams, in general, the detector in the phase range finder causes the diode or the collapsing photodiode (APD) to convert the beam that is directed to the photoreactor to be converted into electricity. Sexual signal. f see the phase = object dare to shoot or by measuring the phase as the criterion for determining the distance, the electrical signal received by the meter in this type of meter will superimpose the previous mixing frequency, to produce 2 in the middle, in / On the 4th, directly measure the phase of the low-frequency measurement signal, and then compare the phase of the low-frequency of the A-port. By measuring the phase difference between the phase of the low-frequency measurement signal and the reference signal, it can be used as the distance of the distance of the object to be measured.彳 phase 1305441 The present invention provides a drive circuit that can be applied to laser phase ranging. Figure 2 is an embodiment of the drive circuit of the present invention. As shown, the driving circuit 100 includes a light emitting element 10, a light receiving element 20, a power control circuit 30, a bias circuit 40, and an AC path 50. In general, the light-emitting element 10 can be a laser diode (LD-diode) to generate an optical signal. The light receiving element 20 senses the magnitude of the light output power of the (monitoring) light emitting element 10 and generates a corresponding electrical signal (output signal). In general, optical signal receiving devices often use the ® photoelectric conversion element as the receiving end, especially using a crash photodiode (APD) or photodiode (PD), and according to the received The intensity of the optical signal produces a corresponding output signal. The biasing circuit 40 is configured to generate a driving electrical signal, such that the light emitting component 10 operates in an appropriate operating range to reduce signal distortion. In the present embodiment, the dusting circuit 40 generates a driving electrical signal to cause the light emitting component 10 Operates in a predetermined work area. In this embodiment, the bias circuit 40 includes two resistors R2 and R3, a transistor Q1, and an inductor L1. For example, the transistor Q1 is an NPN type amplifying transistor, but is not limited thereto. The resistors R2 and R3 serve as current limiting resistors to prevent excessive current flow through the light emitting element 10, and the inductance meter L1 is an isolated inductor for limiting the AC signal to the AC path 50. The power control circuit 30 is operative to control the bias circuit 40 to adjust the drive electrical signal based on the electrical signal from the light receiving element 20 such that the optical output power of the light emitting element 10 approaches a predetermined value. In short, power control circuit 30 and bias circuit 40 together form part of the DC drive 1305441 in drive circuit 100. Therefore, when the optical output power of the laser diode is changed due to factors such as self-heating or environmental changes, the driving circuit 100 of the present invention can be provided by the light receiving element 20, the power control circuit 30, and the bias circuit 40. The size of the driving electrical signal of the light emitting element 10 can be automatically adjusted according to the magnitude of the collected optical output power, so that the optical power outputted by the light emitting element 10 is equal to (approached) a predetermined value. The driving electrical signal generated by the bias circuit 40 may be a current signal or a voltage signal. In addition, the AC path 50 is coupled between the light emitting element 10 and an external signal source (not shown) for receiving at least one AC modulated signal (INH and INL), such that the light emitting element 10 generates at least one modulated light. signal. In the present embodiment, the AC path 50 is composed of two capacitors C1 and C2, an inductor L2 and a resistor R1 for receiving the AC modulated signals INH and INL, but is not limited thereto. In a general ranging system, in order to obtain a larger measurement distance and higher accuracy, multiple phase measurement signals are usually required, and thus multiple modulation frequencies are required, ranging from several MHz to several hundred MHz. Wait. Therefore, the frequency synthesizer (not shown) in the ranging system generates corresponding AC modulated signals (such as INH and INL) according to the control signals of the processing unit, and the AC path 50 is coupled to the frequency synthesizer for The AC modulated signal output from the frequency synthesizer is loaded to the input terminal (anode) of the light emitting element 10. In general, the capacitor C1 and the inductor L2 can be used to load the AC modulation signal INH having a higher frequency into the light emitting element 10, and the capacitor C2 and the resistor R1 can be used to load the AC modulation signal INL having a lower frequency into the 1305441. To the light-emitting element 10, the light-emitting element 10 then outputs an optical signal of the same frequency as the modulated signal according to the loaded AC modulated signal. For example, the frequency of the AC modulated signal INH is higher than that of the AC modulated signal, and there is a frequency difference of a few KHz between the two, but is not limited thereto. - Since the driving circuit of the present invention changes its optical output power due to factors such as self-heating or environmental change, the light-emitting element can be automatically adjusted according to the magnitude of the collected light output power_ The driving current of the device 10 is such that the optical power output from the light emitting element 10 is equal to (near) a predetermined value, and at the same time, the AC modulation signal can be loaded through the AC path, so that the driving circuit of the present invention can be applied not only to the distance amount In the measurement system, it can also be applied to many fields such as optical storage and reading of information and optical communication. While the present invention has been described above in terms of the preferred embodiments thereof, it is not intended to limit the invention, and the invention may be modified and modified without departing from the spirit and scope of the invention. Scope B is subject to the definition of the scope of the patent application. 10 1305441 [Simple description of the diagram] Figure 1 shows the relationship between the forward current and the light output power of the conventional laser diode at different temperatures. Figure 2 shows an embodiment of the drive circuit of the present invention. [Main component symbol description]
Ith :臨界電流； 10 :光發射元件； 20 :光接收元件； 30 :功率控制電路； 40 :偏壓電路； 50 :交流通路； R1-R3 :電阻； L1〜L2 :電感； C1-C2 :電容； Q1 :電晶體； INH、INL :交流調製信號 Vcc :電源電壓。 11Ith: critical current; 10: light emitting element; 20: light receiving element; 30: power control circuit; 40: bias circuit; 50: AC path; R1-R3: resistance; L1 to L2: inductance; C1-C2 : Capacitance; Q1: Transistor; INH, INL: AC modulation signal Vcc: Supply voltage. 11