โฟโต้สวิตช์แบบทรงสี่เหลี่ยม
Square Photo Switch
รุ่น T18
คุณลักษณะ
สามารถใช้ในงานอุตสาหกรรมได้ทุกประเภท เช่น ตรวจนับวัตถุที่ถูกมีการเคลื่อนไหวโดยรอก,ใช้ในการกันประตูลิฟท์หนีบ,งานล้างรถหรือล้างขวด,ลอกป้ายฉลาก,ตรวจนับห่อสินค้า,กำหนดรถยนต์อยู่ตรงตำแหน่งที่จะพ่นสี,ตรวจดูสินค้าว่ามีจุกฝาปิดทุกขวดหรือเช็คฝากล่องปิดทุกกล่องหรือไม่,ตรวจดูว่าแก้วพลาสติกคว่ำหรือหงาย เป็นต้น
รายละเอียด||โฟโต้สวิตช์แบบทรงสี่เหลี่ยม รุ่น T18
- Featuring EZ-BEAM® technology, the specially-designed optics and electronics provide reliable sensing without the need for adjustments (most models)
- “T” style plastic housing with 18 mm threaded lens mount
- Models available in opposed, retroreflective, diffuse and fixed-field modes
- Completely epoxy-encapsulated to provide superior durability, even in harsh sensing environments to IP69K
- Innovative dual-indicator system takes the guesswork out of sensor performance monitoring
- 20 to 250V ac (3-wire hookup); SPST solid-state switch output, maximum load 300 mA
Models
Fixed-Field Mode Overview
T18 Series self-contained fixed-field sensors are small, powerful, infrared diffuse mode sensors with far-limit cutoff (a type of background suppression). Their high excess gain and fixed-field technology allow them to detect objects of low reflectivity, while ignoring background surfaces.
The cutoff distance is fixed. Backgrounds and background objects must always be placed beyond the cutoff distance.
Fixed-Field Sensing – Theory of Operation
The T18FF compares the reflections of its emitted light beam (E) from an object back to the sensor’s two differently aimed detectors, R1 and R2 (see Figure 1). If the near detector (R1) light signal is stronger than the far detector (R2) light signal (see object A, closer than the cutoff distance), the sensor responds to the object. If the far detector (R2) light signal is stronger than the near detector (R1) light signal (see object B, beyond the cutoff distance), the sensor ignores the object.
The cutoff distance for model T18FF sensors is fixed at 25, 50 or 100 millimeters (1", 2", or 4"). Objects lying beyond the cutoff distance usually are ignored, even if they are highly reflective. However, it is possible to falsely detect a background object, under certain conditions (see Background Reflectivity and Placement).
In the drawings and discussion on these pages, the letters E, R1, and R2 identify how the sensor’s three optical elements (Emitter “E”, Near Detector “R1”, and Far Detector “R2”) line up across the face of the sensor. The location of these elements defines the sensing axis (see Figure 2). The sensing axis becomes important in certain situations, such as those illustrated in Figures 5 and 6.
Sensor Setup
Sensing ReliabilityFor highest sensitivity, position the target object for sensing at or near the point of maximum excess gain. The excess gain curves for these products are shown on page 5. They show excess gain vs. sensing distance for sensors with 25 mm, 50 mm, and 100 mm (1", 2", and 4") cutoffs. Maximum excess gain for the 25 mm models occurs at a lens-toobject distance of about 7 mm; for 50 mm models, at about 10 mm; and for the 100 mm models, at about 20 mm. Sensing at or near this distance will make maximum use of each sensor’s available sensing power. The background must be placed beyond the cutoff distance. (Note that the reflectivity of the background surface also may affect the cutoff distance.) Following these two guidelines will improve sensing reliability.
Background Reflectivity and Placement
Avoid mirror-like backgrounds that produce specular reflections. False sensor response will occur if a background surface reflects the sensor’s light more strongly to the near detector, or “sensing” detector (R1), than to the far detector, or “cutoff” detector (R2). The result is a false ON condition (Figure 3). To cure this problem, use a diffusely reflective (matte) background, or angle either the sensor or the background (in any plane) so the background does not reflect light back to the sensor (see Figure 4). Position the background as far beyond the cutoff distance as possible.
An object beyond the cutoff distance, either stationary (and when positioned as shown in Figure 5), or moving past the face of the sensor in a direction perpendicular to the sensing axis, can cause unwanted triggering of the sensor if more light is reflected to the near detector than to the far detector. The problem is easily remedied by rotating the sensor 90° (Figure 6). The object then reflects the R1 and R2 fields equally, resulting in no false triggering. A better solution, if possible, may be to reposition the object or the sensor.
Color Sensitivity
The effects of object reflectivity on cutoff distance, though small, may be important for some applications. It is expected that at any given cutoff setting, the actual cutoff distance for lower reflectance targets will be slightly shorter than for higher reflectance targets (see Figure-of-Merit information on page 5). This behavior is known as color sensitivity.
For example, an excess gain of 1 (see page 5) for an object that reflects 1/10 as much light as the 90% white card is represented by the horizontal graph line at excess gain = 10. An object of this reflectivity results in a far limit cutoff of approximately 20 mm (0.8"), for the 25 mm (1") cutoff models for example; thus 20 mm represents the cutoff for this sensor and target.
These excess gain curves were generated using a white test card of 90% reflectance. Objects with reflectivity of less than 90% reflect less light back to the sensor, and thus require proportionately more excess gain in order to be sensed with the same reliability as more reflective objects. When sensing an object of very low reflectivity, it may be especially important to sense it at or near the distance of maximum excess gain.
Specifications||โฟโต้สวิตช์แบบทรงสี่เหลี่ยม รุ่น T18
Performance Curves
Dimensions
Hookups
Quick-Disconnect (QD) Cables