CN105748220B - A kind of sick bed for being convenient for changing sheet - Google Patents

Abstract

The invention discloses a hospital bed for convenient bed sheet replacement, which belongs to the technical field of medical devices. In order to solve the troubles of bed sheet replacement and nursing care for patients, the hospital bed includes a footboard, a bedside board, a guardrail, a bed board and a headboard. There are two sideboards, the two bedside boards are parallel to each other, and the two ends of the bedside boards are respectively connected to the footboard and the headboard; The guardrails are respectively arranged on the upper surfaces of the two bedside boards; the bedside boards are of cuboid structure, and the two bedside boards are arranged on the same horizontal plane; the upper and lower surfaces of the bedside boards are parallel to the horizontal plane; the bed boards are composed of several Composed of bed board modules, each bed board module has the same size, multiple bed board modules are juxtaposed to each other, and the two ends of the bed board module are respectively connected to the side walls of the two bedside boards, which has the beneficial effect of being convenient, fast and without sequelae.

Description

A kind of hospital bed which is convenient for changing sheets

technical field

The invention belongs to the technical field of medical devices and relates to a sick bed, in particular to a sick bed which is convenient for changing bed sheets.

Background technique

Hospital beds can also be called medical beds, nursing beds, etc. They are beds used by patients during recuperation. They are mainly used in major hospitals, township health centers, and community health service centers. The existing hospital bed needs to move the patient when changing the bed sheet. For ordinary patients, it may be easy to move the position, but it is an extra pain and blow for those with hips, waist, back, shoulders, and fractures; for patients who cannot take care of themselves or are critically ill , especially for patients with incontinence, nursing patients to defecate is labor-intensive physical work, and uncivilized and hygienic; for those patients with fractures, especially before surgery for hip, back, waist, and shoulder fractures, changing sheets, wiping the body, buttocks, etc. Treatment and care such as injections and examinations cause pain and shock to patients. And care is difficult. It may even affect the therapeutic effect and cause some sequelae.

Contents of the invention

According to the above deficiencies in the prior art, the technical problem to be solved by the present invention is to propose a hospital bed that is convenient for changing bed sheets. By setting independently movable bed board modules, the trouble of changing bed sheets and nursing care for patients is solved, and it is convenient and fast. , the beneficial effect without sequelae.

In order to solve the problems of the technologies described above, the technical solution adopted in the present invention is:

A hospital bed for convenient bed sheet replacement, the bed includes a footboard, a bedside board, a guardrail, a bed board and a headboard, two bedside boards are parallel to each other, and the two ends of the bedside boards are respectively connected The footboard and the headboard; the guardrail and the bed board are all arranged on the bedside board, wherein there are two guardrails, and the two guardrails are respectively arranged on the upper surfaces of the two bedside boards; the bedside board is a cuboid structure, The two bedside boards are arranged on the same horizontal plane; the upper and lower surfaces of the bedside boards are parallel to the horizontal plane; the bed board is composed of several bed board modules, each of which has the same size, and multiple bed board modules are juxtaposed with each other. The two ends are respectively connected with the side walls of the two bedside boards.

The opposite sides of the two bedside boards are provided with several slideway groups, each slideway group includes three slideways, and the upper end of each slideway is provided with a square groove, and the side length of the square groove is Equal to the width of the slideway. The ends of the two ends of the bed board module are respectively provided with three protrusions; the six protrusions on each bed board module are on the same plane and the plane is parallel to the horizontal plane; among the three protrusions arranged at the same end, the middle protrusion The object is cylindrical, the cross-section of the protrusions on both sides is square, and the distance between the axes of adjacent protrusions is equal; the distance between adjacent slideways in the slideway group is equal to the distance between the axes of adjacent protrusions, The width of the slideway is equal to the diameter of the cylindrical protrusion; the axes of the three protrusions at one end of the same bed board module coincide with the axes of the three protrusions at the other end respectively. A lifting block is provided in the middle one of the three slideways in the slideway group, and the cylindrical protrusion among the three protrusions at the end of the bed board module is inserted into the middle slideway of the three slideways in the slideway group and connected with the lifting block. Vigorously connected, the cylindrical protrusion can rotate around its axis, and the lifting block is a cuboid structure whose width is equal to the width of the slideway. The sum of the length of the lifting block plus half of the width of the bed board module is less than the length of the slideway. The bottom of the lifting block is provided with an Ensen switch. The bed board module is provided with two telescopic rods, and the two ends of the telescopic rods are respectively connected to protrusions with square cross-sections at both ends of the bed board module. The bed board module is also provided with a control unit and a receiving unit. connection; the cylindrical protrusion is provided with a reset switch. A bed sheet module is provided on the upper surface of the bed board module, and the bed sheet module and the bed board module are connected by Velcro. The periphery of the bed sheet module and the part connected to the periphery of the bed sheet module on the bed board module are provided with Velcro; the bed sheet module includes a layer of cloth and a layer of sponge, and the cloth covers the sponge. Each bed board module is provided with a humidity sensor and an alarm unit; the humidity sensor and the alarm unit on each bed board module has an independent serial number. Described humidity sensor comprises semiconductor detection unit, secondary conversion unit and signal processing unit, is provided with two semiconductor strain gauges R _ε1 ( ₁₀ ) and R _ε2 (11) in the semiconductor detection unit and is installed on the diaphragm ( 9) above, the semiconductor strain gauge is changed under pressure to output a resistance response, the output end of the semiconductor detection unit is connected to the secondary conversion unit, the secondary conversion unit receives the output signal of the semiconductor detection unit, and the secondary conversion unit converts the resistance response signal into a pulse Wide signal, the output end of the secondary conversion unit is connected to the signal processing unit, the signal processing unit decouples and analyzes the output signal of the secondary conversion unit, the control module is connected to the signal processing unit to obtain the temperature of the installation point calculated by the signal processing unit, the relative Humidity and atmospheric pressure; in the semiconductor detection unit, one semiconductor strain gauge is installed at the center of the circle, and the other semiconductor strain gauge is installed at the position of a concentric circle with the center of the diaphragm as the center and a radius of _0.89r0 .

The beneficial effect of the present invention is: it solves the trouble of changing the bed sheet and nursing for the patient, has the beneficial effect of being convenient, fast, and has no sequelae; it greatly alleviates the pain caused by the changing of the bed sheet for the patient, and can remind the nursing staff in time and effectively Changing the patient's bed sheet provides a comfortable environment for the patient to recuperate.

Description of drawings

The following is a brief description of the content expressed in the drawings of this specification and the marks in the drawings:

Fig. 1 is a schematic diagram of installation of strain gauges in a sensor according to a specific embodiment of the present invention.

Fig. 2 is a schematic structural diagram of a sensor according to a specific embodiment of the present invention.

Fig. 3 is a strain distribution diagram of a strain gauge according to an embodiment of the present invention.

Fig. 4 is a structural block diagram of the working principle of the sensor according to the specific embodiment of the present invention.

Fig. 5 is a block diagram of the signal flow of the sensor according to the specific embodiment of the present invention.

Fig. 6 is a circuit diagram of a pulse width signal conversion in a specific embodiment of the present invention.

Fig. 7 is a front view of a hospital bed that facilitates bed sheet replacement according to a specific embodiment of the present invention.

Fig. 8 is a top view of a hospital bed that facilitates bed sheet replacement according to a specific embodiment of the present invention.

Fig. 9 is a side view of a bedside board of a hospital bed that facilitates bed sheet replacement according to a specific embodiment of the present invention.

Fig. 10 is a top view of a bed board module according to a specific embodiment of the present invention.

Fig. 11 is a bottom view of the bed board module according to the specific embodiment of the present invention.

In the figure 1. Footboard, 2. Side board, 3. Guardrail, 4. Bed board, 5. Headboard, 6. Lifting block, 7. Cup support, 8. Air seal chamber, 9. Diaphragm, 10. Semiconductor strain gauge R _ε1 , 11, semiconductor strain gauge R _ε2 .

detailed description

Referring to the accompanying drawings, through the description of the embodiments, the specific embodiments of the present invention include the shape, structure, mutual position and connection relationship of each part, the function and working principle of each part, and the manufacturing process of the various components involved. And the method of operation and use, etc., are described in further detail to help those skilled in the art have a more complete, accurate and in-depth understanding of the inventive concepts and technical solutions of the present invention.

The invention relates to a hospital bed which is convenient for changing bed sheets. The hospital bed comprises a footboard 1 , a bedside board 2 , a guardrail 3 , a bed board 4 and a headboard 5 . The footboard 1 and the headboard 5 are parallel to each other and have equal lengths. There are two sideboards 2, the two sideboards 2 are parallel to each other, and the two ends of the sideboards 2 are respectively connected to the footboard 1 and the headboard 5. , the distance between the two bedside boards 2 is less than the length of the footboard 1 and the headboard 5 .

Both the guardrail 3 and the bed board 4 are arranged on the bedside board 2, wherein there are two guardrails 3, and the two guardrails 3 are arranged on the upper surfaces of the two bedside boards 2 respectively. The bedside board 2 is a cuboid structure, and the two bedside boards 2 are arranged on the same horizontal plane. The upper and lower surfaces of the bedside board 2 are parallel to the horizontal plane.

The bed board 4 is composed of several bed board modules, each of which has the same size, and a plurality of bed board modules are juxtaposed with each other, and the two ends of the bed board modules are respectively connected with the side walls of the two bedside boards 2 . The length of the bed board module is equal to the distance between the opposite sides of the two bed side boards 2 .

Two sideboards 2 opposite sides are provided with several slideway groups, each slideway group comprises three slideways, and the upper end of each slideway inside is provided with a square groove, and the side length of the square groove is equal to The width of the slide. The ends of the two ends of the bed board module are respectively provided with three protrusions. The six protrusions on each bed board module are on the same plane and the plane is parallel to the horizontal plane. Among the three protrusions arranged at the same end, the protrusion in the middle is cylindrical, the cross-section of the protrusions on both sides is square, and the distances between the axes of adjacent protrusions are equal. The distance between adjacent slideways in the slideway group is equal to the distance between the axes of adjacent protrusions, and the width of the slideway is equal to the diameter of the cylindrical protrusion. The axes of the three protrusions at one end of the same bed board module coincide with the axes of the three protrusions at the other end respectively. The number of slideway groups on the bedside board 2 is equal to the number of bedside modules, and the slideway groups on each bedside board 2 correspond to the bedside modules one by one, ensuring that the protrusions at both ends of each bedside module can be inserted into the corresponding slideways. In the Tao group.

The protrusions at both ends of the bed board module are inserted into the slideways of the slideway group on the bedside board 2 . A lift block 6 is provided in the middle slideway among the three slideways in the slideway group, and the cylindrical protrusion among the three protrusions at the end of the bed board module is inserted into the slideway in the middle of the three slideways in the slideway group to connect with the lifting block. Block 6 is flexibly connected, and the cylindrical protrusion can rotate around its axis. The lifting block 6 is a cuboid structure, and its width is equal to the width of the slideway.

A bed sheet module is provided on the upper surface of the bed board module, and in order to facilitate quick separation and connection between the bed board module and the bed board module, the bed sheet module and the bed board module are connected by Velcro. Velcro fasteners are provided on the periphery of the bed sheet module and the parts connected to the periphery of the bed sheet module on the bed board module. In order to allow the patient to lie on the bed comfortably, the bed sheet module includes a layer of cloth and a layer of sponge, and the cloth is covered on the sponge.

In order to make the lifting block 6 drop to the bottom of the slideway, the bed board module will not interfere with the patient on the hospital bed when it rotates, that is, it will not affect the patient, the length of the lifting block 6 plus the sum of half the width of the bed board module less than the length of the slideway.

The bed board module is provided with two telescopic rods, and the two ends of the telescopic rods are respectively connected to protrusions with square cross-sections at both ends of the bed board module. When the telescopic rod stretches, it can drive the movement of the square protrusion. The bed board module is also provided with a control unit and a receiving unit, the control unit is used to control the expansion and contraction of the telescopic rod, and the receiving unit is used to receive signals. The control unit and the receiving unit are connected by wires.

The cylindrical protrusion is provided with a reset switch, and when the cylindrical protrusion rotates 360 degrees, the reset switch sends a reset signal.

In order to facilitate the replacement of the bed sheet module arranged on the bed board module, the bottom of the lifting block 6 is provided with an Ensen switch. When the lifting block 6 descends to the bottom of the slideway, the bottom of the lifting block 6 contacts the bottom of the slideway. The Ensen switch is squeezed and the Ensen switch sends a signal. After the receiving unit receives the signal from the Ensen switch, the control unit controls the telescopic rod to shrink, the square protrusion retracts into the bed board module, the bed board module can rotate around the axis of the cylindrical protrusion, and the bed board module turns over 180 degrees, The bed sheet module on the bed board module can be replaced manually; after the bed sheet module is replaced, the bed board module can be turned 180 degrees again, so that the cylindrical protrusion rotates 360 degrees, the reset switch sends out a reset signal, and the receiving unit receives the reset signal, the control unit Control the extension of the telescopic rod, and the square protrusion extends out of the bed board module and inserts it into the slideway of the slideway group on the bedside board 2; after the telescopic rod is stretched in place, the lifting block 6 drives the bed board module to rise until the bed board module returns to its original position, Complete the replacement of a bed board module, and then proceed to the replacement of the next bed board module. In this way, gradually replacing the bed sheet modules on the bed board module can minimize the sequelae brought to the patient by changing the bed sheet modules, and greatly reduce the pain of the patient.

The top of the lifting block 6 is provided with a second Ensen switch. When the lifting block 6 rises to make the bed board module return to its original position, the top of the lifting block 6 will contact the top of the slideway, triggering the second Ensen switch. The second Ensen switch is transmitted to the control unit, and the control unit controls the secondary extension of the telescopic rod,

The diameter of the cylindrical protrusion is equal to the side length of the cross section of the square protrusion.

Since the bed board 4 is composed of several bed board modules, and each bed board module is provided with a bed sheet module, when the patient's incontinence causes local contamination of the hospital bed, it is only necessary to replace the bed sheet module on the bed board module of the contaminated part, and it is not necessary to remove the bed sheet. Change them all or put diapers on the sheets. In order to find out whether the patient wets the bed early, each of the bed board modules is provided with a humidity sensor and an alarm unit. The humidity sensor and alarm unit on each deck module has an individual number. In order to prevent the alarm unit from causing too much interference, the alarm unit includes two light alarm modules and an acoustic alarm module; the two light alarm modules are respectively arranged on the bed board module and the nurse's duty room, and the alarm of the light alarm module is optical. The alarm and the brightness of the light are very small; the acoustic alarm module is arranged in the nurse's duty room, and the alarm of the acoustic alarm module is an acoustic alarm but the alarm sound is louder. The humidity sensor and the alarm unit are connected with the control unit through wires. After the humidity sensor detects that the humidity of the bed sheet exceeds the standard, the humidity sensor will send an exceeding signal to the control unit, and the control unit will judge the position of the contaminated bed board module through the number of the humidity sensor, and then the control unit will control the alarm unit of the corresponding bed board module to give an alarm , that is, the optical alarm is issued by the light alarm module, and the acoustic alarm is issued by the acoustic alarm module.

The humidity sensor includes a semiconductor detection unit, a secondary conversion unit and a signal processing unit, and the semiconductor detection unit is provided with two semiconductor strain gauges R _ε1 10 and R _ε2 11 installed on a diaphragm 9 whose radius is r ₀ , and the semiconductor strain gauge When the pressure resistance of the chip changes, the output resistance responds. The output terminal of the semiconductor detection unit is connected to the secondary conversion unit. The secondary conversion unit receives the output signal of the semiconductor detection unit. The secondary conversion unit converts the resistance response signal into a pulse width signal. The output end of the conversion unit is connected to the signal processing unit, the signal processing unit decouples and analyzes the output signal of the secondary conversion unit, the receiving unit is connected to the signal processing unit, and the control unit processes the temperature, relative humidity and atmospheric pressure of the installation point calculated by the signal processing unit.

In the semiconductor detection unit, the resistance changes of the two semiconductor strain gauges are equal, one semiconductor strain gauge is installed at the center of the circle, and the other semiconductor strain gauge is installed at the concentric circle with a radius of 0.89r ₀ . The secondary conversion unit includes two identical pulse signal conversion circuits, and a semiconductor strain gauge is correspondingly connected to a pulse signal conversion circuit. The pulse signal conversion circuit includes a 555 timer, a resistor R and a capacitor C, and the resistor R is connected to the 555 timer Between pin 2 and pin 3, the capacitor C is connected to pin 2 of the 555 timer, pin 2 and pin 6 are short-circuited, pin 3 and pin 7 are short-circuited , 555 timer pin 7 output pulse width signal is connected to the signal processing unit. The pulse width conversion formula of described pulse signal conversion circuit is τ=ln2 C R, and τ is output pulse width in the formula, and R is the resistance in the circuit, and C is mica standard capacitance, and pulse width outputs τ and connected resistance respectively R is directly proportional. The diaphragm is divided into a positive strain gauge region and a negative strain gauge region according to the strain change of the two semiconductor strain gauges in the semiconductor detection unit, bounded by a concentric circle with a radius of 0.63r ₀ . The signal processing unit is provided with a GPS unit and an atmospheric pressure gauge, and the GPS unit is connected to the signal processing unit to locate the latitude and longitude of the installation point of the sensor and query the atmospheric pressure value of the installation point. The signal processing unit is provided with a temperature-saturated water vapor partial pressure gauge, and the signal processing unit uses the temperature to call the corresponding saturated water vapor partial pressure value. Described humidity sensor is arranged on the cylindrical cup-shaped support 7, and diaphragm 9 is arranged on the upper surface of cup-shaped support 7, and diaphragm 9 selects brass diaphragm for use, between cup-shaped support 7 and brass diaphragm There is an air-tight cavity 8 between them, and two semiconductor strain gauges 10 and 11 are installed on the surface of the brass diaphragm.

The signal processing unit uses the difference between the partial pressure of water vapor in the atmosphere and the sensitive resistance, and the pulse width after the second transformation and the difference between the counts of the total frequency are proportional to the sum of the ambient temperature of the atmosphere and the count of the sensitive element. The value corresponds to the functional relationship, and the differential pressure value, water vapor partial pressure value and temperature value of the strain gauge are calculated. The signal processing unit uses the temperature saturated water vapor partial pressure gauge, uses the temperature value to call the corresponding saturated water vapor partial pressure value, and calculates the relative humidity according to the relative humidity formula.

A control method for a humidity sensor, the method steps comprising: step 1, connecting and installing a sensor circuit, setting two semiconductor strain gauges to collect temperature and air pressure; step 2, adjusting the installation positions of the two semiconductor strain gauges, and confirming that the two semiconductor strain gauges are The resistance change of the strain gauge is equal; Step 3, the resistance change of the semiconductor strain gauge is input to the secondary conversion unit for pulse width conversion, and the pulse width signal is output; Step 4, the signal processing unit receives the pulse width signal output by the secondary conversion unit , use Dalton's law, strain gauge principle and analytical method to analyze the variation of semiconductor strain gauge, analyze the information of temperature and water vapor partial pressure, and calculate the relative humidity and atmospheric pressure of the point to be measured; step five, signal processing unit connection control module, the control module receives the temperature, relative humidity and air pressure information of the point to be measured.

The signal processing unit uses the difference between the partial pressure of water vapor in the atmosphere and the semiconductor strain gauge of the sensitive resistor, and the difference between the pulse width after the second conversion and the count of the constant frequency is proportional to the difference between the ambient temperature of the atmosphere and the count of the sensitive resistor. The logarithm of the sum is inversely proportional to the relationship, and the differential pressure value ΔP, the water vapor partial pressure P _W and the temperature value t of the strain gauge are calculated. The signal processing unit uses the temperature saturated water vapor partial pressure meter to call the corresponding saturated water vapor partial pressure value according to the temperature value, and according to the relative humidity formula Calculate the relative humidity, where is relative humidity, and P _WS is the saturated water vapor partial pressure at a certain temperature in atmospheric pressure.

1. Atmospheric state parameters

Dalton's law states that the total pressure of the mixed atmosphere is equal to the sum of the partial pressures of the constituent gases, as shown in formula (1):

P _M =P _d +P _W (Pa) (1)

In the formula, P _M (Pa) is the total pressure of the mixed gas, P _d (Pa) is the partial pressure of the dry atmosphere, P _W (Pa) is the partial pressure of water vapor contained in the air, and P _{W accounts} for the largest share in PM , is only about 5%, so the _PM and P _d pressures are relatively close to the standard atmospheric pressure.

Relative humidity (RH%) formula is:

In the formula Indicates relative humidity, P _WS is atmospheric pressure at a certain temperature, saturated water vapor pressure (Pa), which changes with temperature, can be obtained by looking up the table with known temperature or by regression fitting curve equation. From the formula (1), if the differential pressure P _M –P _d can be measured by the instrument, P _W can be calculated, and then the measured temperature can be found in the comparison table of wet air density, water vapor pressure, and moisture content P _WS , the relative humidity can be calculated by formula (2) (RH%).

2. Strain gauge and its conversion characteristics

The installation diagram of the strain gauge in the sensor is shown in Figure 1, the structural diagram of the sensor is shown in Figure 2, and the conversion characteristics and strain distribution of the strain gauge are shown in Figure 3. The temperature integration relative humidity air pressure sensor is a cylindrical shell as a whole, the shell includes a cup-shaped support 7 and a brass diaphragm, the brass diaphragm covers the cup-shaped support 7, and an air-tight cavity 8 is formed between the two , two semiconductor strain gauges are installed on the brass diaphragm, and the temperature, relative humidity and atmospheric pressure data in the installation environment of the humidity sensor are calculated by measuring the resistance change of the semiconductor strain gauges. The secondary conversion unit and signal processing unit required for the analysis and calculation of temperature, relative humidity and atmospheric pressure can be installed on the brass diaphragm or on the side of the cup-shaped support to transmit signals through line connections.

The mixed atmospheric pressure P _M evenly acts on the outer surface of the elastic diaphragm, so the differential pressure on both sides of the diaphragm is:

ΔP＝P _M –P _re ＝P _W +P _d -P _re (Pa) (3)

In the formula, P _re ＝4·10 ⁴ (Pa) is the reference pressure set in the sealed cavity, P _d ＝101325 (Pa) is the standard atmospheric pressure, so the water vapor pressure in the atmosphere can be calculated P _W (Pa)

Under the action of differential pressure ΔP, the distribution of stress and strain on the surface of the diaphragm is as follows:

Radial stress:

Radial Strain:

In the formula, the elasticity of the brass diaphragm is better in the present invention, E (Pa) is the modulus of elasticity of the diaphragm, about 7 ^* 10 ¹⁰ Pa, μ is about 0.33, which is Poisson's ratio, and r ₀ is the diaphragm 9 The outer radius of 40 (mm), h is the diaphragm thickness 0.1 (mm) of the diaphragm 9, b is the thickness of the cup-shaped support 5 (mm), the height of the cup-shaped support is 10 (mm), ΔP acts on the membrane The differential pressure (Pa) on both sides of the sheet, r (mm) is the radius of the observation point.

If the known constants are substituted into formula (4), the stress at the center of the circle σ _r＝0 ＝8*10 ⁴ *ΔP (Pa) (6)

The sensitivity coefficient K _ε and conversion characteristics of the strain gauge are shown in formula (7):

In the formula, R ₀ is the resistance of the strain gauge (Ω) when t=0°C and ε _r =0, K _ε is about 125, and ΔR _ε is the resistance change (Ω) of the strain gauge under the excitation of ε _r , and the (6 ) into (7) to get:

If E=7*10 ¹⁰ Pa is substituted into the formula, it can be seen that the relative resistance change that the strain gauge can output is only on the order of 10 ^-2 in the maximum range, so it is necessary to add a secondary conversion and signal processing circuit to the device to Get the sensitivity and resolution you need.

3. Secondary conversion and signal transmission process

The structure block diagram of the working principle is shown in Figure 4. The humidity sensor includes a semiconductor detection unit, a secondary conversion unit, and a signal processing unit. There are two semiconductor strain gauges in the semiconductor detection unit. The output terminal of the semiconductor detection unit is connected to the secondary conversion unit, the secondary conversion unit receives the output signal of the semiconductor detection unit, the secondary conversion unit converts the resistance response signal into a pulse width signal, and the output terminal of the secondary conversion unit is connected to the signal processing unit, The signal processing unit decouples and analyzes the output signal of the secondary conversion unit, and the control module is connected to the signal processing unit to receive the temperature, relative humidity and atmospheric pressure of the installation point calculated by the signal processing unit.

The signal flow block diagram is shown in Figure 5. The secondary conversion unit includes two identical pulse signal conversion circuits. The pulse signal conversion circuit is composed of 555 timers C1 and C2. The secondary conversion unit and the signal processing unit are also equipped with a strobe switch. , select the C3 switch, and the signal processing unit is mainly composed of a C4 single-chip microcomputer. In Fig. 5, R _ε1 and R _ε2 produce different R ₁ and R ₂ responses respectively under the excitation of P _W and t, and after they are transformed by the C1 and C2 chips 555 of two identical pulse signal conversion circuits, each generates τ ₁ and τ ₂ (S) pulse width output, the pulse width signal is gated by the C3 switch and then sent to the C4 microcontroller for signal processing. The pulse signal conversion circuit is shown in Figure 6. The resistor R is connected between the pin 2 and pin 3 of the C timer 555, the capacitor C is connected to the pin 2 of the 555 timer, and the pin 2 and the Pin 6 is short-circuited, pin 3 and pin 7 are short-circuited, and the output pulse width signal of pin 7 of the 555 timer is connected to the signal processing unit. Due to the difference of strain gauges, the resistance and output pulse width in the two pulse circuits can be represented by R ₁ and R ₂ , τ ₁ and τ ₂ .

Pulse width conversion formula: τ=ln2 C R (S) corresponding to two pulse signal conversion circuits is:

τ ₁ = ln2·C ₀ ·R ₁ (S) (9)

τ ₂ ＝ln2·C ₀ ·R ₂ (S) (10)

In the formula, τ ₁ and τ ₂ are two pulse width output signals corresponding to two semiconductor strain gauges, R ₁ and R ₂ are resistance change values of semiconductor strain gauges, and the unit of measurement is Ω, C ₀ (F) is mica standard capacitance, It is about 0.72×10 ^-6 F. The above formula shows that the pulse width output is directly proportional to the respective connected resistors R ₁ and R ₂ .

4. When multiple factors are input, the decoupling processing of the composite response

In τ ₁ and τ ₂ , there are two kinds of information, the water vapor partial pressure P _W and the temperature t. How to separate them in the subsequent data processing requires data decoupling technology to realize information separation and restoration.

The _formula for the resistance change _of R1 and R2 is:

In the formula, R ₀ =1000Ω is the reference resistance; B=4850(K) is the temperature resistance coefficient of the semiconductor strain gauge; T ₀ =273(K) is the reference temperature; T(K) is the input temperature; ΔR _ε1 and ΔR _ε2 are respectively is the resistance increment produced by R1 and R2 _respectively under the excitation _of atmospheric pressure. It can be seen from the above two formulas that if the values of ΔR _ε1 and ΔR _ε2 are the same, but the positive and negative are opposite, that is, the formulas (11) and (12) can be changed into:

By subtracting or adding the above two formulas, two kinds of input information, P _W and t, can be separated, that is, R1+R2=f _t (T) when adding, and R1-R2=f _ε (P _W ), that is, the result of the sum and difference only corresponds to a single input information, ΔR _ε1 ＝-ΔR _ε2 ＝ΔR _ε .

Referring to Figure 2, under the action of differential pressure ΔP, the outer surface of the entire diaphragm is divided into positive and negative strain zones with radius r = 0.63r ₀ as the boundary. The inner circle near the center is a positive ε area, while the outer circle near the periphery is a negative ε area. In the appropriate positions of these two areas, two points with equal ε values but opposite polarities can be found, one of which is at the center of the circle , r ₁ =0, and the other point is calculated as r ₂ =0.89r ₀ by formula (5). Two semiconductor strain gauges with the same performance are arranged on these two points, and their centers coincide with the reference point on the diaphragm, so the quantitative relationship of (13) and (14) is realized.

Add (13) to (14) to get

The interference of ε information on the quantity of (R ₁ + R ₂ ) has been eliminated in the above formula. However, R ₁ and R ₂ are respectively connected to the charging and discharging circuit of the 555 chip, so it is no longer possible to directly add R ₁ and R ₂ , at this time, it needs to be realized through data operation processing. If the pulse width τ ₁ and τ ₂ are counted to the clock frequency f ₀ in the microcontroller, then the count values N ₁ and N ₂ are:

N ₁ =τ ₁ ·f ₀ (16)

N ₂ =τ ₂ ·f ₀ (17)

τ ₁ +τ ₂ =(N ₁ +N ₂ )/f ₀ (S) (18)

Combining the above formulas and sorting out:

Celsius temperature: t=T-273(℃)(20)

The constant coefficients in the formula are calculated under the conditions of R ₀ =1000Ω, C ₀ =7.2*10 ^-6 F and f ₀ =10MHZ. Separate information such as strain and water vapor partial pressure P _W from the secondary conversion information of R ₁ and R ₂ , and subtract (14) from (13) to get

R1-R2＝2ΔRε＝2R _{0 Kε} · _ε (Ω) (21)

Then use τ ₁ -τ ₂ =(N ₁ -N ₂ )/f ₀ and formulas (5), (9) and (10) to combine, after finishing, we can get,

ΔP=10·(N ₁ -N ₂ )(Pa) (22)

Formulas (19) and (22) are the two input-output characteristic equations of the sensor, both of which have sufficient sensitivity and resolution. A known In the formula, P _WS can be calculated by looking up the table or the following regression equation through the temperature t,

P _WS = a·EXP(b·t)(Pa) (23)

In the formula, a is 6.16 (Pa), b is 0.064 (1/℃) as the fitting constant, so we get

P _WS ＝6.16·EXP(0.064·t)(Pa) (24)

Atmospheric pressure is not a constant value, it varies with the altitude of the region, and it also changes slightly with seasonal temperature changes. The calculation of P _W can be approximately described by the following formula:

P _W ＝ΔP+P _re -Bf(T)+h·8.76(Pa) (25)

In the formula, h is the local altitude (m), the coefficient 8.76 (Pa/m) is the atmospheric pressure attenuation slope, and f(T) is the temperature correction coefficient, which can be estimated through the fitting curve of the experimental measurement data. Because the change ratio of air pressure in winter and summer in coastal areas is 1.02, but in Qinghai area, the ratio of winter to summer pressure is only 1.0026. Both increased slightly with decreasing temperature. Therefore, when the slight influence of temperature is not considered, and in coastal areas, formula (25) can be simplified as:

P _w =ΔP+(P _re -B)=10(N ₁ -N ₂ )+(P _re -B)(Pa) (26)

One of the theoretical foundations of the analysis process in this paper is that the standard atmospheric pressure is a constant, and the actual atmospheric pressure changes with the local altitude. When the altitude of the device’s operating area differs greatly from the reference altitude, Pd in _formula (3) should be corrected by software , in order to maintain the data conversion accuracy of water vapor partial pressure. Therefore, the present invention is provided with a GPS unit and an atmospheric pressure value table in the signal processing unit. The GPS unit is connected to the signal processing unit to locate the longitude and latitude of the installation point of the sensor. Combined with the partial pressure value of water vapor in the atmosphere calculated by the signal processing unit, the formula (1): PM = P _{d +} P _W (Pa) is used to calculate the pressure value of the mixed atmosphere, that is, the pressure value of the installation point.

So far, the values of temperature, relative humidity and atmospheric pressure can be calculated and solved. The humidity sensor provided by the invention has a simple structure and is easy to implement. In the present invention, it is obtained by analytical method: the difference between the partial pressure of water vapor in the atmosphere and the sensitive resistance, that is, the difference between the pulse width after the secondary transformation and the counting of the constant frequency, is proportional, and the ambient temperature of the atmosphere is proportional to the sensitive element The logarithm of the sum of counts is inversely proportional. The theoretical basis of the analysis process in this paper is that the physical atmospheric pressure is a constant, and the actual atmospheric pressure changes with the local altitude. When the altitude of the device is used is greatly different from the reference altitude, it should be corrected by software to maintain the data conversion of the water vapor partial pressure. precision.

The present invention has been exemplarily described above in conjunction with the accompanying drawings. Obviously, the specific implementation of the present invention is not limited by the above methods, as long as various insubstantial improvements are adopted in the method concept and technical solutions of the present invention, or there is no improvement Directly applying the conception and technical solutions of the present invention to other occasions falls within the protection scope of the present invention. The protection scope of the present invention should be determined by the protection scope defined in the claims.

Claims (8)

1. A sick bed for conveniently changing bed sheets, characterized in that: the sick bed comprises a footboard (1), a bedside board (2), a guardrail (3), a bed board (4) and a headboard (5), and the bedside There are two boards (2), the two bedside boards (2) are parallel to each other, and the two ends of the bedside boards (2) are respectively connected to the footboard (1) and the headboard (5); the guardrail (3) and The bed boards (4) are all arranged on the bedside boards (2), wherein there are two guardrails (3), and the two guardrails (3) are respectively arranged on the upper surfaces of the two bedside boards (2); (2) is a cuboid structure, two bedside boards (2) are arranged on the same horizontal plane; the upper and lower surfaces of the bedside boards (2) are parallel to the horizontal plane; the bed board (4) is composed of several bed board modules, each The size of the bed board modules is the same, a plurality of bed board modules are juxtaposed with each other, and the two ends of the bed board modules are respectively connected with the side walls of the two bed side boards (2); Several slideway groups, each slideway group includes three slideways, the upper end of each slideway is provided with a square groove, the side length of the square groove is equal to the width of the slideway; the ends of the two ends of the bed board module There are three protrusions each; the six protrusions on each bed board module are on the same plane and the plane is parallel to the horizontal plane; among the three protrusions at the same end, the middle protrusion is cylindrical, and the protrusions on both sides are cylindrical. The cross-section of the object is square, and the distance between the axes of adjacent protrusions is equal; the distance between adjacent slideways in the slideway group is equal to the distance between the axes of adjacent protrusions, and the width of the slideways is equal to that of cylindrical protrusions The diameter of the three protrusions on one end of the same bed board module coincides with the axes of the three protrusions on the other end respectively; the bed board module is provided with two telescopic rods, and the two ends of the telescopic rods are respectively connected to the two ends of the bed board module. The end cross-section is a square protrusion, the bed board module is also provided with a control unit and a receiving unit, and the control unit and the receiving unit are connected by wires; the cylindrical protrusion is provided with a reset switch. 2. The hospital bed for convenient bed sheet replacement according to claim 1, characterized in that: a lifting block (6) is provided in the middle of the three slideways in the slideway group, and three protrusions at the end of the bed board module The cylindrical protrusion is inserted into the slideway in the middle of the three slideways of the slideway group and is flexibly connected with the lifting block (6). The cylindrical protrusion can rotate around its axis. The lifting block (6) is a cuboid structure. The width is equal to the width of the slideway. 3. The hospital bed for convenient bed sheet replacement according to claim 2, characterized in that: the sum of the length of the lifting block (6) plus half of the width of the bed board module is less than the length of the slideway. 4. The hospital bed for convenient bed sheet replacement according to claim 2, characterized in that: the bottom of the lifting block (6) is provided with an Ensen switch. 5 . The hospital bed for convenient bed sheet replacement according to claim 1 , wherein a bed sheet module is provided on the upper surface of the bed board module, and the bed sheet module and the bed board module are connected by Velcro. 6. The hospital bed for convenient replacement of sheets according to claim 5, characterized in that: Velcro fasteners are provided on the periphery of the sheet module and the parts connected to the periphery of the sheet module on the bed board module; the sheet module includes A layer of fabric and a layer of sponge, with the fabric covering the sponge. 7. According to any one of claims 1-6, the hospital bed for conveniently changing bed sheets is characterized in that: each of the bed board modules is provided with a humidity sensor and an alarm unit; the humidity sensor and the alarm unit on each bed board module Each has an individual number. 8. according to the described hospital bed of claim 7 convenient replacement bed sheet, it is characterized in that: described humidity sensor comprises semiconductor detection unit, secondary conversion unit and signal processing unit, is provided with two semiconductor strain gauges R _ε1 ( 10) and R _ε2 (11) are installed on the diaphragm (9) with a radius of r ₀ , the semiconductor strain gauge changes output resistance response under pressure, the output terminal of the semiconductor detection unit is connected to the secondary conversion unit, and the secondary conversion unit receives The output signal of the semiconductor detection unit, the secondary conversion unit converts the resistance response signal into a pulse width signal, the output of the secondary conversion unit is connected to the signal processing unit, the signal processing unit decouples and analyzes the output signal of the secondary conversion unit, and the control module is connected The signal processing unit is used to obtain the temperature, relative humidity and atmospheric pressure of the installation point calculated by the signal processing unit; in the semiconductor detection unit, one semiconductor strain gauge is installed at the center of the circle, and the other semiconductor strain gauge is installed at the center of the circle of the diaphragm. Center, the position of the concentric circle with radius 0.89r ₀ .