CN2801069Y - Portable miniature type electrocardiograph - Google Patents

Abstract

The utility model relates to a portable miniature type electrocardiograph which comprises a microcontroller system (1), a flash memory module connected with all interfaces of the microcontroller system (1), an LCD module, a touch screen input module, an analogue quantity amplifying circuit (9), a USB module (10), a modem interface module (11) and a power supply module (12). The utility model is a device which can collect, store, display and analyze 12-lead standard body surface electrocardiograms (static electrocardiograms) and dynamic electrocardiograms (continue more than 24 hours). The utility model can be used for the monitoring and the health care of personal cardiovascular disease, can be used in family wards and can provide full and accurate different electrocardiogram data information for family doctors.

Description

The portable minisize electrocardiograph

Technical field

This utility model relates to a kind of medical health equipment, specifically be a kind of, can be used for that individual cardiovascular disease monitors, health care 12 equipment that standard surface electrocardiogram (static electrocardiogram) and ambulatory electrocardiogram (continuous more than 24 hours) gather, store, show and analyze that lead; Also can be used for family ward, provide full and accurate various ECG data data to the family doctor.

Background technology

Existing electrocardiograph or bulky and can not carry; Function singleness, the function that does not possess the synchronously real-time monitoring of multi-lead human body electrocardiosignal, record, analysis, warning, teletransmission signal and carry out diagnosis and treatment.

Summary of the invention

The purpose of this utility model just provides a kind of portable minisize electrocardiograph, with can not carrying that the solution prior art exists; Or function singleness, the problem that does not possess the synchronously real-time monitoring of multi-lead human body electrocardiosignal, record, analysis, warning, teletransmission signal and carry out diagnosis and treatment.

The technical solution of the utility model is: comprise micro controller system and the FLASH memory module that is connected with its each interface, LCD MODULE, touch screen input module, analog quantity amplifying circuit, USB module, MODEM interface module and power module.

Described high-performance microcontroller system comprises micro controller module, the configuration module that resets, data acquisition interface module and the program storage module that connects routinely.

Described micro controller module adopts the M.CORE 32 8-digit microcontroller MMC2107 of MOTOROLA, is used for carrying out the control of the collection of electrocardiosignal and analysis, system's other parts.

Described FLASH memory module is made up of storage control and FLASH memorizer, and the latter is connected with described micro controller system by the former.

Described LCD MODULE is made up of the liquid-crystal controller, liquid crystal display and the display buffer that connect routinely.

Described touch screen input module is made up of touch screen controller and touch screen.

Described analog quantity amplifying circuit is made up of lead pre-amplification circuit, chest lead pre-amplification circuit, sampling interface circuit and power circuit four parts of limb, and same being loaded on the collection plate; Described micro controller system, FLASH memory module, LCD MODULE, touch screen input module, MODEM interface module, USB module, power module are installed on the master control borad; Above-mentioned collection plate and master control borad all adopt damascene structures to be installed in the housing.

The utlity model has following advantage:

1. first embedded technology is applied to the exploitation of high-grade medical product.User terminal adopts popular embedded technology, has greatly reduced equipment cost, thereby makes expensive medical special equipment become domestic consumer's acceptable family health care equipment, has greatly widened market capacity.

2. the user terminal of native system exploitation can be used for static Electrocardiographic measurement, can be used for the record and the measurement of ambulatory electrocardiogram again, thereby reach the purpose of a tractor serves several purposes.

3. user terminal can be as the daily health caring equipment of domestic consumer, again can be as professional medical practitioner's diagnostic analysis instrument.The built-in automatic diagnostic function of user terminal both can in time have been pointed out the user to arrive specialist hospital automatically and gone to a doctor, thereby reach the purpose of timely treatment, can help specialist to carry out field diagnostic again, thereby can change the pattern that patient must go to see a doctor, thereby reach the service multiformity, improve the purpose of medical quality.

4. adopt Large Screen Display Technology, make initial data become the understandable electrocardiosignal figure of domestic consumer, strengthened the transparency of its diagnostic procedure and diagnosis basis, having changed traditional similar health promoting product is the present situation of black box to domestic consumer, has increased user's acceptable degree.

5. system is provided with conversation modes, data transfer mode and the third party multiple online modes such as adding pattern of holding a consultation, make and to carry out between the doctor and patient in time and comprehensively exchanging, increase the system diagnostics intervening mode, make the patient obtain more authoritative, treatment more accurately.

Description of drawings

Fig. 1 is the schematic perspective view of contour structures of the present utility model;

Fig. 2 is that this utility model circuit constitutes block diagram;

Fig. 3 is microprocessor circuit figure of the present utility model;

Fig. 4 is the configuration module that resets;

Fig. 5, the data acquisition interface module;

Fig. 6, the SRAM module;

Fig. 7, the FLASH memory module;

Fig. 8, LCD MODULE;

Fig. 9, the touch screen input module;

Figure 10, the MODEM interface module;

Figure 11, the USB module;

Figure 12, power module;

Figure 13, limb pre-amplification circuit that leads;

Figure 14, the chest lead pre-amplification circuit;

Figure 15, the sampling interface circuit;

Figure 16, the collection plate power circuit;

Figure 17, the main operation surface chart that liquid crystal display shows;

Figure 18, the electrocardiosignal figure of collection;

Figure 19, the demonstration of historical signal;

Figure 20, upload and long-range demonstration of uploading this locality of signal.

The specific embodiment

Referring to Fig. 1 and Fig. 2, this utility model by micro controller system 1 and with constituting that its each interface is connected with lower member: form the FLASH memory module by storage control 7 and FLASH memorizer 8, the LCD MODULE of forming by the liquid-crystal controller 2, liquid crystal display 5 and the display buffer circuit 6 that connect routinely, by the touch screen input module that touch screen controller 3 and touch screen 4 are formed, analog quantity amplifying circuit 9, USB module 10, MODEM interface module 11 and power module 12.

Described analog quantity amplifying circuit (9) is made up of lead pre-amplification circuit, chest lead pre-amplification circuit, sampling interface circuit and power circuit four parts of limb, and same being loaded on the collection plate; Described micro controller system 1, FLASH memory module 7 and 8, LCD MODULE 2,5,6, touch screen input module 3,4, MODEM interface module 11, USB module 10, power module 12 are installed on the master control borad; Above-mentioned collection plate and master control borad all adopt present popular damascene structures to be installed in the housing 01, at positive liquid crystal display 5 and operated key and the signal lamp 02 installed of this housing.

High-performance microcontroller adopts the M.CORE 32 8-digit microcontroller MMC2107 of MOTOROLA, is used for carrying out the control of the collection of electrocardiosignal and analysis, system's other parts.Signal amplification circuit leads the ecg signal acquiring network by 8 the tunnel 12 and signal amplifier is formed, and has used 16 instrumentation amplifier MAX4194 (being used to form 2 grades of signal amplification circuits) and 4 operational amplifiers (be used to form the input of electrocardiosignal high resistant and constitute the electrocardio sampling network) altogether.The high-capacity FLASH storage system has been used 2 K9K series FLASH devices and a slice FPGA device, forms the storage FLASH storage system of 256KB, can store 36 hours electrocardiogram (ECG) data.USB interface goes up load port fast as data, is used for directly connecting the center analyser, and RS-232 is the teledata delivery port, is used to connect MODEN.

Inner four layer architectures that adopt of the present utility model, liquid crystal display, collection plate, master control version and battery are installed from top to bottom successively.The critical piece physical size is:

Liquid crystal display: the long 90mm of liquid crystal display, wide 70mm, high 8mm.

Collection plate: the long 124mm of collection plate, wide 88mm.

Master control version: the long 124mm of master control version, wide 88mm.

Battery: battery uses battery of mobile phone, 1, every block length 122mm, wide 70mm, high 50mm.

Referring to Fig. 3～12, this is the electrical schematic diagram and the operation principle of master control borad:

On master control borad, comprise following circuit module: micro controller module, the configuration module that resets, data acquisition interface module, program storage module (above 4 modules are collectively referred to as micro controller system (1)), FLASH memory module (7) (8), LCD MODULE (2) (5) (6), touch screen input module (3) (4), MODEM interface module (11), USB module (10), power module (12).

Referring to Fig. 3, micro controller module of the present utility model selects to use the MMC2107 microcontroller (U1) of MOTOROLA company, and its support circuit is as follows:

Data wire: when design, adopted 16 FPDP, 16 data lines are D[31:16].

Address wire: used A[15:1], reason is that the SRAM space is 64KB, and the address is 16 alignment, so address A0 need not connect.A[7:3 in these address wires] link the address wire of FPGA (U5) simultaneously as FPGA, A2 is also as the A0 of liquid-crystal controller.

Chip select line: CS#0 is as the sheet choosing of FPGA, and FPGA takies the low 8MB of microcontroller external address space like this; CS#1 is as the sheet choosing of SRAM, and (U15 U16), takies the address space of 8～16MB to link 62256; CS#2 keeps; CS#3 is as the sheet choosing of liquid-crystal controller 13305 (U12), and liquid-crystal controller takies the address space of 24～32MB.

The edge interrupts the pen interruption of (INT#0～7): INT#0 as touch screen controller; INT#1 uses as the interruption of FPGA; INT#[3:2] as the input of button; INT#[7:4] be used for simulating DCD#, RI#, DSR#, the CTS# signal of MODEM;

Reset circuit: 2107 output RSTOUT# begin configuration for FPGA, FPGA, and configuration finishes back FPGA and provides CON_DONE, and CON_DONE links RESET, reset 2107 and system again, thereby have constituted the dual reset circuit.

Gather indication: driving a light emitting diode with the PE5 pin, is at present green.

Referring to Fig. 4, the configuration module that resets of MMC2107 mainly be operator scheme, clock source and clock module, chip output pin to MMC2107 output intensity, the guiding device that resets, inner FLASH module etc. be set select.

The configuration sampling of MMC2107 mainly is that 9 pins are sampled.The VDDSYN pin is the power supply of clock module, is 3.3V when resetting automatically, and other 8 pins are data wires, requires to finish the back in configuration and discharges data/address bus, so select for use ternary double buffering 74LV244 (U3) to be provided with.

(R27, R28's 0 ohmage when being configured to holotype among the R23～R210) need burn-on, and other 0 ohmage does not need welding, and the corresponding pull-up resistor of path that has welded 0 ohmage need not weld.

Referring to Fig. 5, the data acquisition of data acquisition interface module is actually by the J10 interface carries out the A/D conversion to the ECG simulator signal of sending here from collection plate, utilizes the QADC in 2107 to realize translation function.

Referring to Fig. 6, (U15 U16) constitutes the SRAM module, and U15 directly links to each other with MMC2107 with U16, expands 128K bytes of memory space by two 62256.

Referring to Fig. 7, the FLASH memory module mainly by FPGA (U5) and FLASH (U7, U9) memorizer is formed, FPGA uses as the interface between MCU and the FLASH, all need the intervention of FPGA to the operation of FLASH.What originally use is the FLASH chip of 64MB, changes the chip of 128MB now into, the pin of chip compatibility of two kinds of models.

Referring to Fig. 8, LCD MODULE by display-memory 62256 (U10, U11), display controller 13305 (U12) and 74L04 (U400) and 74L32 (U401) form.Two 62256 (64KB) comprise character generator as video memory.Attention: in print circuit pattern, added two resistance R 51 and R52 pull-up resistor as two 62256 chip select lines, attempt when 62256 do not work sheet chosen that to draw be 1 so that reduce power consumption, in fact do not reach this effect, do not have this two resistance in the schematic diagram, do not weld this two resistance on the present circuit board yet.Crystal oscillator used 8MHZ originally, and in order to reduce power consumption by reducing refreshing frequency, what use now is the crystal oscillator of 6MHZ, and effect meets the requirements.

Note selecting 13305 storage address: when design, select the D[23:16 of MMC2107] as the data/address bus of S1D13305, according to the regulation of EBI module, D[23:16] corresponding byte address is odd address (that use in the current procedure is ADDR[1:0] value be " 01 ").What S1D13305 determined that MMC2107 writes it by A0 itself is order or parameter (data), therefore when giving S1D13305 allocate memory address, should consider with any root address wire as A0, and use that chip selection signal to select as the sheet of S1D13305.Adopt the A0 of the A2 of MMC2107 as S1D13305, select the chip selection signal of 3 (CS3#) with sheet as S1D13305, therefore distribute to two storage address: 0x8,180 0005 of S1D13305 and 0x8,180 0001, the former is write order and read data address, the latter is for writing data and read states tag addresses, all read/write operation carried out in these two addresses to S1D13305 write order, parameter, data or from the S1D13305 read data.

Referring to Fig. 9, the touch screen input module: the touch screen input module is put forward interrupt requests by 7846 (U4) to 2107, then in interrupt handling routine 2107 to 7846 measuring command, obtain contact coordinate.

Measure the touch point coordinate time and must select suitable SPI clock frequency could cooperate the sequential of ADS7846, proper when the external clock (SPI clock) of discovery ADS7846 is 50KHz～60KHz in measuring process.

In measuring process, need disappear to the touch process and tremble processing, when pen interrupts taking place, do not measure coordinate immediately but postpone 300ms and read interrupt identification again, if interrupt identification still is 1 (has and interrupt taking place), carry out measurement of coordinates this moment again.

When measuring, earlier at the coordinate figure of the equidistant several points of measurement on the basic vertical straight line and on the straight line of a basic horizontal, no matter from table, be that vertical direction or horizontal direction are all linear basically as can be known.Can get Y changes in coordinates slope is 46.33/mm, and the slope of X coordinate is 64.25/mm.According to application need touch screen is divided into the touch piece of 8 * 16 pixel sizes, totally 40 * 15=600 touches piece, thereby the granularity chap is more conducive to practical application.The size of utilizing the touch piece to adjust slope again makes it be more suitable for the needs of practical application.

The contact coordinate formula:

Row-coordinate: 15-(ADS7846 (0xD1)-100)/233

Row coordinate: (ADS7846 (0x91)-150)/89

Wherein: ADS7846 (0xD1) and ADS7846 (0x91) are the return of values that ADS7846 measures subprogram, and 0xD1 and 0x91 are the measuring command words.

Referring to Figure 10, the MODEM interface module mainly is to utilize 2107 I/O port to simulate 16550, and level translator MAX3243 (U2) is used for finishing the voltage transitions between Transistor-Transistor Logic level and the MODEN interface level, and J3 is the connector with MODEN.

Referring to Figure 11, USB module: when FPGA (U5) detects USB100 (U17) module TXE when low, the inner relief area that sends of expression allows to send data to USB port, data can be issued the USB100 module by the eight bit data bus, the transmission data latch by WR to be controlled, when USB100 module TXE is high, forbid sending data.When FPGA (U5) detects USB100 module RXF when low, expression is inner to receive relief area data from USB port, can data be read in by the eight bit data bus and issue the USB100 module, receives data and latchs by RD and controls.

Referring to Figure 12, power module: total system has 6 groups of power supply :+3.3V (the master control borad digital circuit is used) ,+3.6V ,-3.6V ,+5V ,-5V (the collection plate analog circuit is used) ,+20.8V (liquid crystal display is used).All power supplys from a chargeable lithium cell (+3.6V), the power supply of 3.3V is uploaded from collection plate.

On master control borad, utilize MAX629 (U14) that 3.3V voltage is changed into the needed 20.8V voltage of liquid crystal display.

System power supply is subjected to the control of SHDN# pin, when SHDN#=1, and the system power supply operate as normal, when SHDN#=0, the system power supply Close All.The switch SW DPDT (J12) of control SHDN# signal is positioned on the master control borad.When this switch ground connection, the SHDN# signal is a low level; When this switch met lithium battery source output terminal VBAT, the SHDN# signal was a high level.Socket J8 on the master control borad docks with the J101 on the collection plate, and the SHDN# signal is introduced U100, the U101 of collection plate and the SHDN# leads ends of U103 chip.In addition, be provided with a power supply indicator D61 on the master control borad.

Figure 13～16 are the electrical schematic diagram and the operation principle of collection plate:

Collection plate is formed (being collectively referred to as analog quantity amplification module (9)) by lead pre-amplification circuit, chest lead pre-amplification circuit, sampling interface circuit and power circuit four parts of limb.

Figure 13 is the limb pre-amplification circuit that leads, this circuit is by signal follower U300, U301 (TL072), difference amplification appliance U302, U303 (MAX4194), back level amplifying circuit U312, U313 (MAX4194) and peripheral Resistor-Capacitor Unit thereof constitute, and are used to form extraction and amplification that limb leads electrocardiosignal I and II.Wherein R316, R317, R318 constitute an electrocardio equilibrium point, are used as the reference point that forms the chest lead ecg signal acquiring.U301A and peripheral Resistor-Capacitor Unit thereof constitute right lower limb wobble circuit and are used to drive the screen layer of connection cord.

Referring to Figure 14, the chest lead pre-amplification circuit is by signal follower U400, U401, U402 (TL072), difference amplification appliance U403, U404, U405, U503, U504, U505 (MAX4194), back level amplifying circuit U406, U407, U408, U506, U507, U508 (MAX4194) and peripheral Resistor-Capacitor Unit thereof constitute, and are used to form chest lead electrocardiosignal V1, V2, V3, V4, V5 and V6 extraction and amplification.

Referring to Figure 15, the sampling interface circuit is made of the extremely peripheral resistive element of J200, is mainly used in electrocardiosignal transmission and coupling with master control borad.

Referring to Figure 16, it is needed various running voltages in the equipment that power circuit is used for mile 3.6V voltage transitions of battery output.

Wherein: it is the 3.3V running voltage that U100 (MAX1685) and peripheral Resistor-Capacitor Unit thereof are used for the 3.6V voltage transitions.

It is the 5V running voltage that U101 (MAX1674) and peripheral Resistor-Capacitor Unit thereof are used for the 3.6V voltage transitions.

U102 (MAX764) and peripheral Resistor-Capacitor Unit thereof are used for.

U103 (MAX1921) and U104 (MAX764) and peripheral Resistor-Capacitor Unit thereof are used for.

Main operating process of the present utility model is as follows:

1, the machine open/close of equipment

Press device power supply (DPS) switch J12, device power-up.Press the device power supply (DPS) switch once more at open state, the equipment shutdown.

After the device power-up, enter the main operation interface.The main operation interface shows the content of Figure 17 under liquid crystal display.

2, the collection of signal, demonstration, storage and disease detection (referring to Figure 18)

Gather switch or J13 or click that to click beginning on the touch screen after " collections " function under the collection menu that ejects regional by pressing equipment, promptly begin the collection of electrocardiosignal, electrocardiosignal shows on screen when gathering, and in automatic storage and the FLASH memorizer.In gatherer process,, press switch J14 if do not need signal to show; Under the state that no signal shows, press switch J14 once more, then opening signal shows not.

In the procedure for displaying of signal, can open (by gathering " interpolation " function choosing-item under the menu) or (closing) a certain road electrocardiosignal arbitrarily by gathering " hiding " function choosing-item under the menu.

In the gatherer process of signal, ecg analysis software moves automatically, and the signal that collects is carried out real-time analysis,, then shows " anomalous ecg, suggestion is gone to a doctor " printed words and flicker automatically on screen if find that electrocardiosignal is unusual.

3, the demonstration of historical signal and measurement (referring to Figure 19)

After equipment is opened, under non-signals collecting mode, choose " demonstration " function under the main operation interface, then the demonstration of entering signal and measuring operation interface.Can show according to the historical electrocardiosignal that the time is chosen in this machine of being stored in, in procedure for displaying, can select to open arbitrarily (by gathering " interpolation " function choosing-item under the menu) or (closing) a certain road electrocardiosignal by gathering " hiding " function choosing-item under the menu.

Can signal be amplified and dwindle in the procedure for displaying, the synchronous signal bottom with the scale of the grid of time of shows signal and amplitude also in company with changing.Heart beating correspondence is each time put, and then the screen below shows " normal/abnormal " printed words.

4, upload and long-range uploading (referring to Figure 20) this locality of signal

Under the device power-up state, click " uploading " function choosing-item under the main interface, " long-range " or " this locality " transmission mode is selected according to connected mode in entering signal upload operation interface.Connect by MODEN under the remote transmission pattern, connect by USB port under the local transmission mode.

Can signal be amplified and dwindle in the procedure for displaying, the synchronous signal bottom with the scale of the grid of time of shows signal and amplitude also in company with changing.Heart beating correspondence is each time put, and then the screen below shows " normal/abnormal " printed words.

This utility model can be whenever and wherever possible, in unlimited time ground carry out continuously 12 lead the monitoring in real time synchronously of human body electrocardiosignal, record, analyze, report to the police, being sent to 24 hours cardiovascular disease diagnosis and treatment centers on duty by network system diagnoses, and can be synchronously and doctor's conversation description pathological characters, the guidance of obtaining medical practitioner, the miniature electrocardiograph of portable personal also can be used as the analytical tool at the scene of professional practitioner simultaneously and carries out medical diagnosis on disease.The major function of the miniature electrocardiograph of Portable, personal comprises:

1. the collection of electrocardiosignal and storage: can correctly gather 12 ambulatory electrocardiograms that lead and static electrocardiogram, guarantee 24 hours uninterrupted collections, storage signal is not lost.

2. uploading fast of electrocardiogram (ECG) data: by USB interface and the interconnection of center analyser.This interface meets the USB1.1 communication specification, the big 1MB/S of effective speed.

3. the long-range of electrocardiogram (ECG) data uploaded: realize the user terminal dial-up by public switched telephone network, the call function of center analyser, can correctly set up connection between the two.Under the second best in quality situation of circuit, the message transmission rate between user terminal and the center analyser is not less than 28.8Kb/s.

4. electrocardiosignal is automatically analyzed and abnormal alarm: can discern automatically stop winning, leak rich, tachycardia, bradycardia, room early, early rich on the chamber, chamber morning, premature ventricular beat, premature ventricular beat, insertion early rich, RonT, the chamber of taking place frequently early, chamber disease and prompting prescription on individual diagnosis such as quiver.

5. the demonstration of electrocardiosignal, measurement and auxiliary diagnosis: provide functions such as information is located, scans, fixed, measurement, convergent-divergent to support specialist to carry out medical diagnosis on disease, and can provide ST section trendgram, 24 hours analysis reports, auxiliary medical practitioner carries out disease and judges.

6. online electrocardio expertise: provide 12 shape, form and the relevant parameters that lead the standard cardioelectric signal and supply online query.

7. do not examined person's information record: can write down at any time the person of being examined kinestate and feel.

8. real-time clock: calendar and time accurately are provided.

9. equipment Online Help: online operation instructions, guides user correctly use this equipment.

The key technical indexes of the present utility model is as follows:

Built-in collection and memory circuit can correctly be gathered 12 ambulatory electrocardiograms that lead, and guarantee 24 hours uninterrupted collections, and storage signal is not lost, and can correctly gather 12 lead ECG electrocardiograms;

The 320*240 lattice lcd shows and touch screen;

Built-in 256MB FLASH data warehouse;

Internal USB 1.1 interfaces;

Built-in diagnostic analysis software can be reported to the police automatically to 16 kinds of anomalous ecg diseases.

Claims (7)

1, a kind of portable minisize electrocardiograph is characterized in that: comprise micro controller system (1) and the FLASH memory module that is connected with its each interface, LCD MODULE, touch screen input module, analog quantity amplifying circuit (9), USB module (10), MODEM interface module (11) and power module (12).

2, portable minisize electrocardiograph according to claim 1 is characterized in that: described high-performance microcontroller system (1) comprises micro controller module, the configuration module that resets, data acquisition interface module and the program storage module that connects routinely.

3, portable minisize electrocardiograph according to claim 2, it is characterized in that: described micro controller module adopts the M.CORE 32 8-digit microcontroller MMC2107 of MOTOROLA, is used for carrying out the control of the collection of electrocardiosignal and analysis, system's other parts.

4, portable minisize electrocardiograph according to claim 1 is characterized in that: described FLASH memory module is made up of storage control (7) and FLASH memorizer (8), and the latter is connected with described micro controller system by the former.

5, portable minisize electrocardiograph according to claim 1 is characterized in that: described LCD MODULE is made up of the liquid-crystal controller (2) that connects routinely, liquid crystal display (5) and display buffer (6).

6, portable minisize electrocardiograph according to claim 1 is characterized in that: described touch screen input module is made up of touch screen controller (3) and touch screen (4).

7, according to any one described portable minisize electrocardiograph of claim 1～6, it is characterized in that: described analog quantity amplifying circuit (9) is made up of lead pre-amplification circuit, chest lead pre-amplification circuit, sampling interface circuit and power circuit four parts of limb, and same being loaded on the collection plate; Described micro controller system (1), FLASH memory module (7) (8), LCD MODULE (2) (5) (6), touch screen input module (3) (4), MODEM interface module (11), USB module (10), power module (12) are installed on the master control borad; Above-mentioned collection plate and master control borad all adopt damascene structures to be installed in the housing.

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