Công nghệ SMT máy DEK cảm biến sensors

Công nghệ SMT máy DEK cảm biến sensors INTRODUCTION HALL EFFECT SENSOR OPTO SENSORS Ultrasonic Sensor CAPACITIVE PROXIMITY SENSOR REED SWITCH SENSOR SAFETY SWITCH MICROSWITCH SENSOR PRESSURE SENSOR GIANT MAGNETO RESISTIVE SENSOR (GMR) STRAIN GAUGE SENSOR TEMPERATURE AND HUMIDITY SENSOR

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CHAPTER 36 SENSORS

INTRODUCTION

This chapter gives details of the various sensors used in the machine All sensors used on the machine fall within three categories, these are:

• Solid State Switch Sensors

• Conventional Switch Sensors

Solid State

Switches

The machine uses the following types of solid state sensor switches:

• Hall Effect Sensors

• Ultrasonic Sensor

• Capacitive Proximity Sensor

In all cases to initiate a logic 1 (on state) at the input, the sensor must connect the signal input to 0V This may not, however, translate to a positive condition after software processing

Figure 36-1 Typical Solid State Schematic

Testing Solid state sensors can only be tested in circuit as they require a logic supply

voltage and a pull up resistor on the sensor output

1 Check for the 12V logic supply to the sensor

2 Activate the sensor according to type and measure the voltage at the output terminal with respect to 0V The sensor output signal should change between approximately 0V and 12V (see individual sensor descriptions for more details)

Digital Input V+ (User)

12V

Opto-isolator 1K8

0V (User)

Signal I/P

Control Circuit

Solid State Sensor

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Conventional

Switches

The machine uses the following types of conventional switch sensors:

• Pressure Switch

In all cases to initiate a logic 1 (on state) at the input, the sensor must connect the signal input to 0V

Figure 36-2 Typical Conventional Switch Schematic

Testing 1 Activate the sensor according to type and measure the voltage at the output

terminal with respect to 0V The sensor signal output should change between approximately 0V and 12V

2 Remove switch from the circuit and measure continuity, when activated

In all cases check digital inputs under diagnostics at the MMI

Analogue

Sensors

The machine uses the following types of analogue sensor:

• Giant Magneto Resistive Sensor

Sensor Location Machine location for individual sensors are detailed in the respective module

chapter overview sections, ie Camera Y Home Sensor - can be found in the Camera System Module chapter

12V

Opto-isolator 1K8

0V (User)

Signal I/P

Conventional Switch

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HALL EFFECT SENSOR

Description The board stop extended Hall effect sensor is activated by a magnet fitted to

the board stop piston With power ON and the board stop extended, the output transistor is switched on and the signal voltage is pulled down to 0V When the board stop is retracted the magnet is moved out of range and the Hall effect is cancelled, switching off the output transistor and the signal is 12V via the digital input circuit

Figure 36-3 Hall Effect Schematic

Testing/

Adjustment

With Power ON and a voltmeter connected with +ve to signal (black) and -ve to 0V (blue), the following results should be obtained:

Figure 36-4 Voltage Diagram

Hall Effect Sensor

Hall Effect

Opto-isolator 1K8

0V (User) 0V

12V

12V 0V 0V

Signal

(Brown)

(Black) (Blue)

V+

Control Circuit Pin 4

Pin 5 Pin 6

Locking Screw

Sensor

Board Stop Piston and Magnet

Sensor

Digital Input

12V

0V

Hall Effect

Signal

Present

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OPTO SENSORS

Background

Suppressed

Opto

The background suppressed opto sensor is a diffuse type sensor The sensor incorporates a background suppression by triangulation capability, for precisely adjusting the sensing distance

The opto emits a pulsed red light which is reflected by a target when it enters the sensing distance, not only sensing the reflected light but also the distance

of the object to the sensor

When the beam of light hits the board or screen, some of the diffused light is reflected back and the sensor NPN transistor output state is switched ON The pulsed beam of light, which is continuously on, is accurately focused and

is able to distinguish between the target and objects outside the scan range

Setting Up

Procedure The procedures for setting up the background suppressed optos are fully detailed in the Camera System Module chapter (camera board at stop), the

Transport Rails Module chapter (board at left and board at right sensors), the Screen Change chapter (screen position sensor) and the Rising Table Module

V+ (User)

NPN

Opto-isolator 1K8

0V (User)

Pin 1 12V

Pin 3 0V Pin 2 Signal

12V 0V

Control Circuit

View on Arrow A

Sensitivity/Focal Length Adjustment

Red LED - Target Detected

Background Suppressed Opto

Emitter/Receiver

A

Digital Input

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OPTO SENSORS

Testing Procedure If the sensor fails to operate carry out the following:

1 Disconnect the opto

2 Short out the signal to earth on the socket

3 Check the relevant digital input under Diagnostics - System - Display all Digital Inputs to confirm, or otherwise, that the sensor is defective

Through Beam

Optos

The types of through beam opto used on this machine are:

Fork Sensor Type The through beam fork sensor transmits a beam across the gap in the opto

When a vane enters the gap the beam is broken and the sensors output transistor is switched high or low depending on connection (L)

Figure 36-6 Through Beam Optos

Testing Procedure If the sensor fails to operate carry out the following:

12V

0V Signal

Through Beam Fork Opto

+V (User)

Opto-isolator 1K8

0V (User) 0V

+V

Signal O/P

Vane

Control Circuit

Digital Input (L)

Pin 1 - +V Pin 2 - (L) Pin 3 - Signal O/P Pin 4 - 0V

Operation Indicator Transmitted Beam

1

12V 0V

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OPTO SENSORS

Long Throw Type The long throw opto works on the same principal as the through beam type but

uses two individual sensor devices (receiver and emitter) to cover a wider gap,

ie screen at centre indicator

Figure 36-7 Long Throw Opto

Testing/Adjustment If the sensor fails to operate, confirm the sensor is faulty as follows:

1 Disconnect the long throw opto receiver

Long Throw Optos

V+ (User)

Opto-isolator 1K8

0V (User) 0V

12V

Signal O/P

12V 0V

Control Circuit 12V

12V

Emitter

0V

Signal O/P Receiver

Receiver

12V 0V

Digital Input

12V

0V

Off Indication Light

Signal

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ULTRASONIC SENSOR

Description The ultrasonic sensor transmits a conical shaped area of ultrasonic sound

waves, some of the waves are rebounded back to the receiver in the sensor When a board passes over the sensor the amount of rebounded sound changes, switching the output of the sensor

Figure 36-9 Ultrasonic Sensor

Testing

Procedure

If the sensor fails to operate carry out the following:

V+ (User)

Opto-isolator 1K8

0V (User)

Pin 1 12V Pin 2 Control/Teach

Pin 3 0V Pin 4 Signal

+V 0V

View on Arrow A

Operation Indicator Set/Teach Button

Ultrasonic Sensor

A

Digital Input

Control Circuit

SET

12V

0V Signal

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CAPACITIVE PROXIMITY SENSOR

Description A capacitive proximity sensor consists of an RC oscillator which emits a

frequency field When the target, in this case the solder paste, moves away from the sensing range (ie paste low), the capacitance increase effectively changes the internal current which is detected by an adjustable trigger The control circuit switches the output transistor on

Figure 36-11 Capacitive Proximity Sensor

Capacitive Proximity Switch

Sensor Bracket

LED

and Indicator Sensor Bracket Sensor

Paste

Sensor

V+ (User)

Opto-isolator 1K8

0V (User)

0V 12V

RC Frequency Field

Solder Paste

12V 0V

Pin 1 Control

Circuit

Pin 2 Pin 3

Digital Input

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CAPACITIVE PROXIMITY SENSOR

Testing/

Adjustment

Setting Up

Procedure The procedure for setting up the capacitive proximity sensor is fully detailed in the Paste Dispenser System chapter of this manual, (Adjustments and Settings

section)

12V

0V

Operation Indicator

Signal

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REED SWITCH SENSOR

Description A reed switch is activated by a magnet fitted to either the piston or drive shaft

of the actuator One side of the switch is connected to the input, the other side

of the reed switch is connected to 0V The input is connected to +12V via a pull

up resistor, so under normal conditions the input is pulled high When the reed switch is activated by a magnet, the reed switch closes and pulls the input down

to 0V (low)

Figure 36-13 Reed Switch Schematic

Digital Input

V+ (User)

Opto-isolator

(Red)

(Black)

1K8

0V (User)

12V 0V N0

(normally open)

Locking Screw

Sensor Pneumatic Cylinder Reed Switch

Pneumatic Cylinder with Reed Switch

Rotary Actuator

Rotary Actuator with Reed Switch

Board Stop In Reed Switch

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REED SWITCH SENSOR

Testing/

Adjustment Setting of the sensor is necessary in order to:

• Ensure that switching takes place in the correct position

• Ensure correct sensing, ie closing when piston extended/retracted

NOTE For adjustment of ProFlow cassette low sensor refer to ProFlow chapter of this manual.

Magnetic Piston Retracted Extended Retracted

12V

0V

Closed Open Closed Reed Switch

Signal

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SAFETY SWITCH

Description The safety switch is a device fitted to the printhead cover designed to provide

operator safety

The design of the internal anti-tamper cams also act as a latch A 6mm movement of the switch activator 'open circuits' the safety contacts There are

3 sets of contacts in the switch but only 2 of the sets, both normally open (NO), are used by the machine One set of contacts is used as a digital input to inform the PC that a cover has been opened, the other set is used as part of the system safety loop to cut the system power

The cover interlock signal is pulled low when the front cover is opened

Figure 36-15 Safety Switch Schematic

Safety Switch

Digital Input

V+ (User)

Opto-isolator 1K8

0V (User)

12V 0V

14 22

Part of System Safety Loop

13 14

21

33 34 22

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SAFETY SWITCH

Testing/

Adjustment

To adjust the safety switch, physically move the body of the switch to ensure that 6mm of cover movement activates the switch

12V

0V

Closed Circuit

Open Circuit Continuity

Signal

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MICROSWITCH SENSOR

Description The microswitch sensor used is a solid state microswitch with no mechanical

contacts The plunger operates a Hall effect sensor triggering the transistorized output

Figure 36-17 Microswitch Sensor and Schematic

Testing/

Adjustment

Testing can be carried out with the microswitch in circuit by measuring the voltage between pin 2 (signal) and pin 3 (0V), Voltage Diagram figure below, refers

Digital Input

V+ (User)

Opto-isolator 1K8

0V

Squeegee/ProFlow Home Microswitch

Voltage Regulator

Trigger Circuit and Amplifier

Hall Effect Sensor

Block Diagram of Microswitch

1

2

3

Switch Position

Released Depressed Released

12V

0V

Voltage Output at Pin 2 (signal)

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PRESSURE SENSOR

Description The pressure sensor switch is wired as a normally open (NO) switch which is

closed by the air pressure exceeding the set point

Figure 36-19 Pressure Sensor Schematic

Opto-isolator 1K8

0V (User)

12V 0V

Pressure Sensor Symbol

Pressure Sensor and Gauge

P

Common

NC NO

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PRESSURE SENSOR

Testing/

Adjustment

For adjustment refer to the Pneumatic Module Chapter

The sensor may be tested either in circuit or disconnected:

In circuit

-• Monitor the voltage at signal DIG IN 0 whilst increasing the pressure from zero using the main regulator As the air pressure exceeds the set point value the voltage is pulled down to 0V

Disconnected

-• Measure continuity across the switch whilst increasing the pressure from zero using the main regulator As the air pressure exceeds the set point value the contacts close

Figure 36-20 Pressure Diagram

Indicated Pressure

12V

0V

Open Circuit

Closed Circuit

Open Circuit

Set Point

Contact Continuity

Digital I/P Signal

5

3 bar

0

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GIANT MAGNETO RESISTIVE SENSOR (GMR)

Description The sensor reacts to the magnetic field produced by the magnetic end of the

cylinder piston This produces an analogue signal proportional to the piston position, ie the closer the piston to the sensor the larger the analogue signal This analogue signal is fed to the Analogue to Digital Converter (ADC) on the print carriage I/O Node 3 PCB and the digital output is fed via the CAN bus to the NextMove ES card

Figure 36-21 Giant Magneto Resistive Schematic

Testing/

Adjustment

The sensor does not require adjustment In use the assembly is calibrated - see the ProFlow Module Chapter for details

+12V

Print Carriage I/O Node 3

0V Sig

0V +12V

M36 Machine Control

M37 Power Supply Crate

NextMove

ES Card Paste

Level Amplifier

GMR Sensor

Paste Level Amplifier

Pneumatic Actuator and GMR Sensor

Pneumatic Actuator

GMR Sensor

15

30

Output 0.5V - 5V Digital

Out Analog

In ADC

CAN Bus

Power Distribution PCB

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STRAIN GAUGE SENSOR

Description The sensors are produced in a full resistive Wheatstone bridge configuration

that is temperature and creep compensated It uses a thin foil as one of the resistive elements of the bridge If a force is applied (weight) such that the measuring foil is stretched, the lengthening of the foil causes its resistance to vary This change in resistance is detected and passed to a high gain DC amplifier

Testing/

Adjustment

The sensors do not require adjustment In use the assemblies are calibrated - see the Squeegee chapter or the relevant underscreen cleaner chapter for details

Solvent Level Strain Gauge Squeegee Strain Gauge

M36 Machine Control Enclosure

USB

PC

Single Board Computer (SBC)

NextMove ES (I/O Node 1)

I/Ps O/Ps

NextMove Interface

AN IN0

-AN IN0 +

Solvent Load Cell

Solvent Level Amp

-V +V -IN +IN

0V USR +12V -12V

Print Carriage I/O Node 3

CAN Bus CAN

In

0V +V -IN +IN

Squeegee Pressure Load Cell

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TEMPERATURE AND HUMIDITY SENSOR

The temperature and humidity sensor is an integral part of the print carriage I/O Node 3 PCB and as such there is no adjustment and setting available for this sensor

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TEMPERATURE AND HUMIDITY SENSOR

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