Centrifuge

Abstract

To provide a centrifuge in which over-rotation of a rotor is doubly monitored by software and an electric circuit, and a protection mechanism for maintaining a door lock state during rotation of the rotor is also doubled.SOLUTION: In addition to a function of monitoring over-rotation of a rotor 11 by software executed by a microcomputer 50, speed monitoring is performed by a rotation signal processing circuit 51 realized by a circuit configuration. When the over-rotation of the rotor is generated, an over-rotation signal for stopping the rotation of the motor 13 is transmitted to a motor driving circuit by an over-rotation detecting circuit 60. The set value of the monitoring speed is set in the data output holding circuit 53, and can be arbitrarily set from the control device 50. Further, a door lock control circuit 70 is provided to maintain the locked state of the door lock 20 until the rotor 11 stops. Even if the operation of the software falls into an abnormal state, the rotation signal processing circuit 51 ensures the protection function from overspeed and the maintenance of the door lock state during the rotation of the rotor 11.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a centrifuge that performs centrifugal separation by rotating a sample placed in a rotor at high speed, and in particular to an improved circuit and control for detecting over-rotation of the rotor. [Background technology]

[0002] In conventional centrifuges, a control device monitors the rotational state of the rotating rotor in real time and controls the rotor to prevent unexpected overspeeding. Such overspeeding monitoring and suppression is often performed by the control device using software, but it is important to be able to protect the rotor from overspeeding even if the control device breaks down for some reason or the software stops running.

[0003] Patent Document 1 discloses a centrifuge that monitors rotor speed using an analog circuit separate from a processor-equipped control device and cuts off power to the motor when rotor overspeed is detected. Specifically, the rotor shaft is provided with an overspeed detection disk, and a counter and CPU are used to monitor whether the frequency of the signal emitted from the disk exceeds a predetermined allowable rotation frequency (e.g., 15.5 kHz). The signal emitted from the disk is also sent to an analog circuit, where the signal frequency is F / V converted and compared with a reference voltage (9.8 V, equivalent to 15.5 kHz) using a comparator. Thus, Patent Document 1 provides dual monitoring by separately detecting and determining the occurrence of overspeed using a processor-equipped control device and an analog circuit, and by configuring a circuit that cuts off power to the motor when either circuit detects overspeed. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 10-174903 [Patent Document 2] Patent Publication No. 2021-28068 Summary of the Invention [Problem to be solved by the invention]

[0005] According to the technology of Patent Document 1, monitoring of whether the rotor's rotational speed exceeds the allowable limit is performed using independent circuits, a CPU and an analog circuit, and power supply to the motor can be stopped using separate means, thereby improving the reliability of monitoring for rotor overspeed in the event of a malfunction. This technology prevents damage to the rotor due to overspeed, and in other words, monitors whether the rotor's rotational speed has exceeded the allowable upper limit. Therefore, the speed at which overspeed is determined is uniquely set for each rotor installed.

[0006] According to the technology in Patent Document 1, for example, a rotor with an allowable rotation speed of 60,000 rpm is pre-mounted with a disk that generates 15 pulses per rotation, while a rotor with an allowable rotation speed of 70,000 rpm is pre-mounted with a disk that generates 13 pulses per rotation. The reason for providing overspeed detection disks with different pulse counts for rotors with different allowable rotation speeds is that the frequency for determining the allowable rotation speed is fixed at 15.5 kHz. Furthermore, the analog circuit also uses a potentiometer to adjust the frequency so that it becomes 9.8 V at 15.5 kHz, which is used as the reference voltage for determining overspeed.

[0007] When using a centrifuge, the rotation speed must be set to a value below the rotor's allowable speed and the required centrifugation time before operation begins. Depending on the sample being centrifuged, rotating at a speed exceeding the specified rotation speed (the set rotation speed or the sample's upper limit) can result in greater than expected centrifugal load, potentially destroying the sample itself (e.g., red blood cells). Therefore, it is desirable not only to monitor operation beyond the set rotation speed entered via an input device (not shown), but also to continuously monitor whether the set rotation speed exceeds the maximum allowable rotation speed for each sample, both before and during centrifugation operation. Possible causes of operation exceeding the set rotation speed or the maximum allowable rotation speed include processor failure, software malfunction, or runaway, and the loss of motor rotation control is also a potential event that must be anticipated. To address these issues, a possible approach is to install a separate processor in the control device and monitor the motor rotation speed using multiple software programs. However, because multiplexing the same software may result in software malfunctions, it is preferable to prepare different computer programs, but this would significantly increase development costs.

[0008] The determination of rotor stoppage is made by a software-implemented control device. The control device also locks the door to prevent it from being easily opened during centrifugation operation, but unlocks it once rotation has stopped, allowing the user to open the door. If the door could be unlocked while the rotor is still rotating, a user could open the door and come into contact with the rotating rotor, potentially resulting in a dangerous situation where they could be injured or have their clothing caught. To address this issue, the control device detects the rotor rotation signal to accurately determine the rotor's rotation state. For example, the control device acquires two types of rotation signals, one for the rotor and one for the motor. However, in conventional centrifuges, the control of door unlocking upon rotor stoppage determination has not been multiplexed using a software-independent method.

[0009] The present invention has been made in view of the above-mentioned background, and an object of the present invention is to provide a centrifuge that can accommodate various rotors and objects to be centrifuged by allowing the judgment value of the speed monitored by the rotation signal processing circuit to be set arbitrarily. Another object of the present invention is to provide a centrifuge in which, in addition to the door lock control by the control device, a control that prevents the doors from being unlocked while the rotor is rotating is multiplexed by a signal processing circuit, thereby making it possible to reliably maintain the door locked state during rotation. [Means for solving the problem]

[0010] Representative features of the invention disclosed in this application will be described as follows. According to one aspect of the present invention, a centrifuge includes a rotor for holding a sample, a rotor chamber for accommodating the rotor, a motor having a rotating shaft for driving the rotor, an input unit (operation panel) for inputting a set rotation speed of the rotor, a housing for accommodating the rotor, the motor, and the rotor chamber, a door attached to the housing for opening and closing the rotor chamber, an electric door lock device for keeping the door closed, a rotation detection device for generating a signal indicating the rotation speed of the rotor, and a control unit including a processor for executing a program and controlling the rotation speed of the motor according to the set rotation speed set via the input unit. The centrifuge is provided with a rotation signal processing circuit that operates independently of the control unit. When the rotation signal processing circuit determines that the rotation speed of the motor exceeds an allowable rotation speed, the circuit stops the motor and prevents the door lock device from unlocking, thereby keeping the door locked while the rotor is rotating. The centrifuge also includes an encoder circuit that outputs a first pulse indicating the rotation speed of the motor's rotating shaft and / or an ID sensor circuit that reads an identifier attached at a predetermined position circumferentially of the rotor during rotation and outputs a second pulse. The rotation signal processing circuit is composed of an over-rotation detection circuit section that counts the first and second pulses output from the encoder circuit and the ID sensor circuit to detect an over-rotation state and output an over-rotation signal, and a door lock control circuit section that monitors the output first and second pulses and issues a drive control signal to prevent the door lock device from being driven while the rotor is rotating.

[0011] According to another feature of the present invention, a control device having a processor sets a parameter corresponding to the maximum allowable rotation speed for the sample set in the rotor in a data output holding circuit section of a rotation signal processing circuit, and the rotation signal processing circuit detects an over-rotation state of the rotor by counting the first and / or second pulses using the set parameter. Also provided are drive sources for a plurality of door lock devices, a motor control device for controlling the operation of the drive sources, and a lock motor drive circuit for opening and closing the motor door lock devices to their locked and unlocked states, and the control device outputs a drive signal to the lock motor drive circuit, and the output from the lock motor drive circuit to the door lock device is transmitted after an AND circuit performs an AND operation with the drive permission signal from the rotation signal processing circuit.

[0012] According to yet another feature of the present invention, the control device calculates a determination value for the time it takes for the rotor to make one rotation from a set rotation speed input from an operation panel, and writes the calculated value to the data output hold circuit unit. The over-rotation detection circuit unit includes a one-pulse conversion circuit that outputs one pulse per rotation from a signal detecting rotor rotation or a plurality of pulse signals detecting motor rotation, a divide-by-two circuit that divides the output signal of the one-pulse conversion circuit by two, a first countdown circuit that loads data output from the data output hold circuit unit with an inverted signal from the divide-by-two circuit and performs a countdown operation with an output signal from an OR circuit that receives as inputs a clock generated by an oscillator and a divider and the output signal from the divide-by-two circuit, a second countdown circuit that loads a detection count value with a borrow output signal from the first countdown circuit and performs a countdown operation with an inverted signal from the divide-by-two circuit, and an over-rotation detection hold circuit that uses the borrow output signal from the second countdown circuit as a trigger to output an over-rotation signal when the countdown exceeds the determination value.

[0013] According to yet another feature of the present invention, the door lock control circuit section is configured to include a first edge detection circuit that uses a clock generated by an oscillator and a frequency divider to detect the rising and falling edges of the output signal of the ID sensor circuit; a second edge detection circuit that uses the clock to detect the rising and falling edges of the output signal of the encoder circuit; a third countdown circuit that loads a timer value with the output signal of an AND circuit that receives the output signals of the first edge detection circuit and the second edge detection circuit as inputs and counts down with the clock output from the frequency divider; and a stop signal output circuit that is cleared with the output signal of the AND circuit and outputs a drive control signal triggered by the borrow output signal of the third countdown circuit. [Effects of the Invention]

[0014] According to the present invention, in addition to control for detecting rotor overspeed by executing a computer program, the overspeed state is monitored by electrical control using a circuit configuration called a rotation signal processing circuit, and the door is kept locked during rotation. As a result, even if program execution in the control device is inhibited, the overspeed state can be monitored and the door can be kept locked during rotation. Furthermore, instead of using a fixed value for each rotor as in the prior art, the rotation signal processing circuit's overspeed determination criterion can be set by the control device to an arbitrary determination value tailored to the sample. Therefore, in addition to preventing overspeed due to the rotor's destruction limit, it is also possible to monitor overspeed so as not to destroy the sample, resulting in a centrifuge that is easy to use and even safer.

[0015] Furthermore, according to the present invention, the rotation signal processing circuit uses two types / two systems of rotation signals from the rotor and the motor to determine the rotation speed and rotor stop, thereby further improving the accuracy of overspeed detection. Also, since the rotation signal processing circuit outputs an electrical signal (lock motor drive stop signal) to prevent the door from being unlocked when locked while the rotor is rotating, multiplexing has been achieved by adding control by the rotation signal processing circuit to control for maintaining door lock in addition to control executed by software. [Brief explanation of the drawings]

[0016] [Figure 1] 1 is a partial perspective view of a centrifuge 1 according to an embodiment of the present invention. [Figure 2] 1 is a diagram showing the structure of a centrifuge 1 according to the present embodiment. [Figure 3] 1A and 1B are diagrams showing the door lock mechanism 20 of the centrifuge 1 of this embodiment, in which (A) shows the unlocked state, (B) shows the state during driving from the unlocked state to the locked state, and (C) shows the locked state. [Figure 4] 1 is an overall control block diagram of a centrifuge 1 according to the present embodiment. [Figure 5] 10 is a flowchart showing the procedure for monitoring excessive rotation speed and controlling door locking by the main control device 50. [Figure 6] FIG. 2 is a block diagram of an over-rotation detection circuit 60 of the centrifuge 1 of the present embodiment. [Figure 7] FIG. 2 is a block diagram of a door lock control circuit 70 of the centrifuge 1 of the present embodiment. DETAILED DESCRIPTION OF THE INVENTION [Example]

[0017] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In the following drawings, the same parts are given the same reference numerals, and repeated explanations will be omitted. In addition, in this specification, the front, back, left, right, and up and down directions will be described as the directions shown in FIG.

[0018] FIG. 1 is a partial perspective view showing the door structure of a centrifuge (centrifuge) 1 according to an embodiment of the present invention. As shown in FIGS. 1 and 2, centrifuge 1 has a bowl 3 provided inside a box-shaped housing 2 made of sheet metal or the like, and a rotor chamber 5 is defined by the bowl 3 and a door (LID) 4. Door 4 can rotate up and down around hinge 6 as shown by the arrow in FIG. 1, and this rotation is maintained by gas springs 19a and 19b. Door packing 7 is provided on the outside of the opening of rotor chamber 5, and when door 4 is closed, rotor chamber 5 is sealed. When door 4 is opened, the biasing force of gas springs 19a and 19b assists in reducing the strain required to open door 4.

[0019] The housing 2 is provided with multiple door lock mechanisms for locking the door 4. Specifically, through-holes 2a and 2b are provided on the front left and right sides of the top surface of the housing 2, and door lock mechanisms 20 and 30 are provided below the through-holes 2a and 2b. Door hooks 9 and 10 are provided on the bottom surface of the door 4 at positions that pass through the through-holes 2a and 2b. The door lock mechanisms 20 and 30 have movable door lock hooks 22 and 32 (described later in FIGS. 2 and 3), which are engaged with the elongated holes 9a and 10a of the door hooks 9 and 10 to lock the door 4, and are unlocked when the hooks are released. The door lock mechanisms 20 and 30 are electrically driven by two LID lock motors (drive units), which will be described later. The two LID lock motors are driven by a lock motor drive circuit 35.

[0020] FIG. 2 is a vertical cross-sectional view of the centrifuge 1 of this embodiment with the door 4 closed. This partial cross-sectional view is a vertical cross-sectional view looking leftward from near the center, and shows the rotor 11 and motor 13 in a side view rather than a cross-section. The rotor 11 holds the sample to be centrifuged and rotates at high speed. For example, it is an angle rotor or a swing rotor with multiple holes (not shown) for inserting sampling tubes or the like for the sample. The rotor 11 is fixed to the tip of the rotating shaft 12 of the motor 1 and rotated by the motor 13. The motor 13 is, for example, a well-known brushless motor driven by a commercial power source via a converter circuit and an inverter circuit (not shown). However, any type of motor can be used. The starting, acceleration / deceleration, constant-speed rotation, and stopping of the motor 13 are controlled by a motor control device 80 (see FIG. 4 ), which will be described later. The motor 13 is mounted on a partition plate 2d, which is part of the housing 2, via multiple dampers 8.

[0021] When the door 4 is closed, the rotor chamber 5 is sealed when the door 4 and door packing 7 are closed to a position where they are in full contact, and the air inside the rotor chamber 5 is compressed, causing an air spring action that exerts a reaction force on the door 4 in the opening direction. Therefore, when the door 4 is closed to a certain extent, the control device 80 drives the LID lock motors 21, 31 (31 is not visible in the figure) to retract the door hooks 9, 10 (see Figure 1). A pipe (not shown) is wrapped around the outer periphery of the bowl 3 to circulate a refrigerant that cools the rotor 11 in the rotor chamber 5, and a heat insulating material 43 is also provided around the outer periphery of that pipe.

[0022] In the centrifuge 1, it is important to prevent the rotor 11 from rotating at an excessive speed, i.e., exceeding the maximum allowable rotation speed preset for each rotor 11. Typically, in the centrifuge 1, the main control device 50 monitors the rotation speed of the rotor 11 and controls the rotation of the motor 13. This monitoring is performed using at least one, preferably both, of a first pulse signal (MPG signal) that detects the rotation of the motor 13 and a second pulse signal (RPG signal) that detects the rotation of the rotor 11. If the rotation speed of the rotor 11 exceeds the maximum allowable rotation speed for some reason during centrifugation operation, the control devices 50, 80 send an over-rotation signal #1 to the device that controls the rotation of the motor 13 to stop the motor 13. After the rotor 11 has completely stopped rotating, the control devices 50, 80 drive the lid lock motors 21, 31 of the door lock mechanisms 20, 30, which are in the locked state, to allow the user to open the door 4.

[0023] The LID lock motors 21, 31 are controlled by sending drive control signals from the control devices 50, 80 (described later in FIG. 4). The main control device 50's monitoring of overspeed is not limited to monitoring whether the rotor 11 exceeds its physically maximum rotational speed. It can also be used to monitor the set rotation speed for separating the sample set in the rotor 11 and the maximum rotor rotation speed required to prevent sample damage. For example, the maximum rotation speed required to prevent sample damage can be set as the monitoring value for the overspeed condition. If an overspeed condition occurs during centrifugation that requires the rotor 11 to be stopped, the control devices 50, 80 stop the centrifuge motor 13 and output a drive control signal #1 to prohibit the LID lock motors 21, 31 from being driven until the motor 13 stops rotating.

[0024] In this embodiment, the function of monitoring the overspeed state is duplicated, and in addition to monitoring by software performed by the control devices 50, 80, monitoring is also duplicated by a separate rotation signal processing circuit 51. In other words, even in some cases where the operating software of the main control device 50 or the motor control device 80 (described later in FIG. 4) is not running normally, the separate rotation signal processing circuit 51 reliably stops the rotation of the motor 13. Furthermore, the rotation signal processing circuit 51 maintains the locked state of the electrically driven door lock mechanisms 20, 30 until the rotation of the rotor 11 has completely stopped.

[0025] When the rotor 11 experiences an overspeed condition, the rotation signal processing circuit 51 (1) outputs an "overspeed signal #2" to the centrifugal motor drive circuit 59 (described later in FIG. 4) to stop the rotation of the centrifugal motor 13, and (2) sends a "drive control signal #2" to inhibit the operation of the door lock mechanisms 20 and 30. An overspeed detection circuit 60 is provided to output the "overspeed signal #2" (1). A data output hold circuit (unit) 53 is also provided to enable the overspeed detection setting value of the overspeed detection circuit 60 to be changed. The data output hold circuit 53 acquires data on the rotation speed to be determined as an overspeed from the control device 50 and sets parameters in the counter of the overspeed detection circuit (unit) 60. The data output hold circuit 53 can set a determination value for the time required for one rotation of that rotation speed. When the overspeed condition is maintained by comparing the time required for one rotation from the actual rotation pulse signal, an "overspeed signal #2" indicating an overspeed is output.

[0026] As the "drive control signal #2" in (2) above, a signal indicating inhibition is continuously output while the motor 13 is rotating. When it is detected that the rotor 11 has stopped, the "drive control signal #2" indicating inhibition is released. As described above, in the centrifuge 1 of this embodiment, the control device 50 detects an overspeed state using software, and the rotation signal processing circuit 51, which uses a hardware circuit configuration, is provided, allowing for highly accurate detection of an overspeed state. Furthermore, the rotation signal processing circuit 51 can cut off the power supply to the motor 13 by outputting the overspeed signal #2, thereby preventing valuable samples from being damaged by the centrifugal load. Furthermore, the rotation signal processing circuit 51 uses two types / two systems of rotation signals (RPG, MPG) from the rotor 11 and the motor 13 to determine whether the rotor 11 is rotating or stopped and output a drive / stop signal for the lid lock motors 21 and 31. This reliably prevents the unlocking operation from being performed while the rotor 11 is rotating, and allows the door to be unlocked only when the rotor 11 is stopped.

[0027] Next, the structure by which the door lock mechanism 20 retracts and holds the door hook 9 will be described with reference to Figure 3. For ease of understanding, Figure 3 shows the door lock holder 24, which is the outer shell of the door lock mechanism 20, in a cutaway state so that the interior can be seen. Figure 3(A) shows the door lock hook 22 in an open state (unlocked state), and when an operator manually moves the door 4 in the closing direction, the tip of the door hook 9 descends as shown by arrow 17. When the door hook 9 descends to the position shown in Figure 3(B), it is positioned opposite the LID closing sensor 25, and the LID closing sensor 25 outputs a detection signal indicating "door hook present" to both control devices (the main control device 50 and the motor control device 80, which will be described later with reference to Figure 4).

[0028] When the door hook detection signal is input, the control device 80 drives and rotates the LID lock motor 21 of the door lock mechanism 20, and moves the link bar 23 attached to the rotation shaft of the LID lock motor 21 in the direction of arrow 19, causing the door lock hook 22 to rotate about the hook rotation shaft 22a and engage with the elongated hole 9a of the door hook 9. The inner periphery 22b of the door lock hook 22 is arc-shaped, and the closer it is to the locked position, the closer the hook rotation shaft 22a and the inner periphery 22b are formed. Therefore, if the door lock hook 22 continues to rotate in this state, the door hook 9 is pulled further downward. As a result, the door 4 is pulled in together with the door, and the door 4 further compresses the door gasket 7, improving airtightness.

[0029] The rotation state of the hook position detection board 27 attached to the rotation shaft of the LID lock motor 21 is detected by two LID lock sensors 26a, 26b. The LID lock sensors 26a, 26b are transmission-type photosensors such as photointerrupters, with a light-emitting element and a light-receiving element arranged opposite each other, and the hook position detection board 27, which serves as a detection object, rotates between them. When a detection object (hook position detection board 27) is present between the light-emitting element and light-receiving element of the LID lock sensors 26a, 26b, it blocks the light, thereby detecting the presence or absence of the detection object. When the door lock hook 22 is in the positions shown in Figures 3(A) and (B), both LID lock sensors 26a, 26b issue a signal indicating that an object is detected. When the door lock hook 22 is in the position shown in Figure 3(C), both LID lock sensors 26a, 26b issue a signal indicating that an object is not detected. In this way, when the lock completion position (the state of Figure 3(C)) of the door lock hook 22 is detected, the detection signals are input to the control device (50, 80 in Figure 4 described later), and the motor control device 80 interrupts the driving of the LID lock motor 21 and stops the door lock hook 22 at a predetermined position.

[0030] The motor control device 80 transmits a signal to the main control device 50 that the door 4 has been locked by the door lock mechanism 20. Although only the door lock mechanism 20 has been described in FIG. 3, the door lock mechanism 30 is also a common component and has the same configuration and control. Therefore, reference numerals 30 to 37 indicate mechanisms corresponding to reference numerals 20 to 27, respectively. The LID lock motors 21 and 31 (not shown) of the door lock mechanisms 20 and 30 are controlled by the motor control device 80. Many types of structures and drive sources for the door lock mechanisms 20 and 30 are known, and in addition to rotary motors, solenoids and other electrically controllable drive sources may also be used.

[0031] FIG. 4 is an overall control block diagram of the centrifuge 1 of this embodiment. The control unit of the centrifuge 1 is mainly controlled by two control devices (50, 80). The main control device 50 performs overall control of the centrifuge 1, including input from the operation panel 15, displaying the operating status on the operation panel 15, setting conditions for centrifugation operation and monitoring the centrifugation operation, controlling the rotation of the centrifuge motor, managing the temperature of the rotor chamber 5, monitoring the open state of the door 4, and monitoring the door lock when closed. The motor control device 80 controls the drive of various motors included in the centrifuge 1, including controlling the drive and stop of the centrifuge motor 13 for rotating the rotor 11, monitoring the rotation speed, driving the cooling device 66 for cooling the rotor chamber 5 to a predetermined temperature, and driving the door lock mechanisms 20 and 30. The main control device 50 and the motor control device 80 are connected to each other by a communication line 54, allowing for bidirectional serial communication.

[0032] The main control device 50 is configured by a microcomputer having a CPU (Central Processing Unit) or MPU (Micro-Processing Unit), not shown, and receives input from the user from the operation panel 15 via the operation section circuit 16, and displays information to inform the user on the operation panel 15. The operation panel 15 can be configured, for example, by a touch-type liquid crystal display, but it may also be configured by combining input devices such as multiple switches and buttons with known output devices such as LEDs and matrix displays.

[0033] Since the rotation speed of the centrifugal motor 13 is equal to the rotation speed of the rotor 11, by reading the ID (not shown) provided on the bottom surface of the rotor 11, the ID sensor circuit 41 generates a signal with one pulse per rotation as a "pulse signal (hereinafter referred to as RPG) detecting the rotation of the rotor 11," and outputs it to the main control device 50, the motor control device 80, and the door lock control circuit 70.

[0034] The rotor 11 attached to the rotating shaft 12 is driven by a centrifugal motor 13 located at the lower end of the rotating shaft 12. The centrifugal motor 13 receives a motor drive signal 63 sent from a motor control device 80 via a centrifugal motor drive circuit 59, which then supplies a predetermined excitation current to an inverter circuit (not shown) to rotate the brushless motor 13. A three-input AND circuit 58 is provided between the drive signal 63 from the motor control device 80 and the centrifugal motor drive circuit 59, with the drive signal 63 being one of its inputs. The AND circuit 58 allows the motor 13 to rotate only when it receives the drive signal 63 from the motor control device 80 under conditions where the output of the rotor chamber high temperature detection circuit 56 indicates normal and the over-speed signal 61 indicates a "not over-speed" state.

[0035] An encoder circuit 14 is provided at the end of the rotating shaft 12 of the centrifugal motor 13 away from the rotor 11. The encoder circuit 14 generates a pulse signal (hereinafter referred to as MPG) that detects the rotation of the motor 13, with one pulse per rotation, and outputs the signal to the main control device 50 and the motor control device 80. The output of the encoder circuit 14 is also simultaneously output to the overspeed detection circuit 60 and the door lock control circuit 70. A determination value indicating the time it takes for the rotor 11 to make one rotation at a threshold (rotation speed) that constitutes an overspeed is written from the main control device 50 to the data output holding circuit 53, and the data output holding circuit 53 outputs the value to the overspeed detection circuit 60. The determination value can also be read from the motor control device 80. The overspeed detection circuit 60 has a circuit that determines whether or not the rotation pulse signal from the encoder circuit 14 is an overspeed by comparing it with the time required for one rotation, and outputs an overspeed signal 61 when the overspeed state is maintained. The overspeed signal 61 is a signal for stopping the rotation of the motor 13 (overspeed signal #2 in FIG. 2), and is output to the AND circuit 58 and also to the motor control device 80 via the buffer circuit 62.

[0036] The temperature sensor circuit 42 measures the temperature inside the rotor chamber 5 and outputs an output signal corresponding to the temperature to the main control device 50 and the motor control device 80. The rotor chamber high temperature detection circuit 56 is a circuit made up of, for example, a thermal guard that operates at high temperatures, and outputs a high signal if the condition is normal and a low signal if the condition is abnormal to the main control device 50. One output of the rotor chamber high temperature detection circuit 56 is also output to the motor control device 80 via a buffer circuit 57, and the other output is output to an AND circuit 58.

[0037] The cooling device 66 is a known device including, for example, a compressor, and cools the rotor chamber 5 by supplying a refrigerant through a pipe wound around the bowl 3. The compressor of the cooling device 66 is driven by a motor (not shown), which is driven by the cooling device drive circuit 65 under the control of the motor control device 80. The vibration detection circuit 52 includes a sensor for detecting whether the rotating rotor 11 is vibrating due to sample imbalance or other reasons, and a means for determining the vibration. In this embodiment, two vibration detection circuits 52 are provided, and their outputs are sent to the main control device 50 and the motor control device 80. If the magnitude of vibration detected by the vibration detection circuit 52 during forest separation operation exceeds the allowable value, the motor control device 80 switches the drive signal 63 to the motor 13 to low, thereby stopping the motor 13.

[0038] The two LID lock motors 21, 31 are driven by a lock motor drive circuit 35. They can be controlled simultaneously or individually and precisely. The lock motor drive circuit 35 is controlled by a motor control device 80 in response to operational instructions from the main control device 50. An AND circuit 69 is interposed between the motor control device 80 and the lock motor drive circuit 35, and an output from a door lock control circuit 70 (a drive control signal for stopping the motor) is input to the AND circuit 69. The output of the door lock control circuit 70 is high when operation of the LID lock motors 21, 31 is permitted, and low when operation is prohibited (unlocking is inhibited). The output of the door lock control circuit 70 is also output to the motor control device 80 via a buffer circuit 68.

[0039] Figure 5 is a flowchart showing the control procedure for monitoring the overspeed of the rotor 11 and locking the door by the main control device 50. The control procedure in Figure 5 is executed by software as the main control device 50 executes a computer program. First, the user attaches the rotor 11 with the sample set to the rotating shaft 12 and closes the door 4. Next, the user inputs the necessary operating conditions, such as the set rotation speed, centrifugation time, and rotor chamber temperature, from the touch-type operation panel 15 (step 101).

[0040] Next, the computer program acquires the value of the allowable rotation speed (the rotation speed at which an overspeed state is determined) for the installed rotor 11 and the sample to be centrifuged set in the rotor 11 (step 102). This acquisition method may be achieved by reading from data previously stored in a memory (not shown) of the centrifuge 1, calculating by calculation, inputting by a user via the operation panel 15, reading from the rotor 11, or any other method. Next, when the operator issues a command to start operation via the operation panel 15, the door 4 is locked to the door-locked state shown in FIG. 3(C), the cooling device 66 (see FIG. 4) is started, and the centrifuge motor 13 begins to rotate (step 103). Note that steps 101 to 103 can be performed in any order. For example, in step 102, the computer program may identify or calculate the allowable rotation speed at which an overspeed state is determined after the rotor 11 starts rotating and the ID sensor circuit 41 reads the rotor ID.

[0041] When the rotor 11 starts to rotate, the main control device 50, which executes a computer program, continuously acquires MPG and RPG and constantly monitors the rotation speed of the rotor 11 (step 104). This detection function corresponds to a rotation detection device executed by software. The main control device 50 controls the rotation of the motor 13 that rotates the rotor 11 according to the obtained rotation speed (step 105). In addition, the motor control device 80 maintains the door locked state to prevent the door 4 from opening during centrifugation operation, and prevents the door from transitioning from the locked state to the unlocked state until the rotor 11 decelerates and completely stops. Furthermore, the main control device 50 controls the cooling device 66 to maintain the rotor chamber 5 at a set temperature.

[0042] Next, the main control device 50 determines whether the rotation speed of the rotor 11 exceeds the allowable rotation speed set in step 102 (step 106). If, in step 106, it is determined that the rotor 11 cannot maintain rotation at the set rotation speed for some reason and that the allowable rotation speed has been exceeded, the main control device 50 determines that the rotor 11 is in an "over-rotation state," and stops the power supply to the centrifugal motor 13, thereby stopping the rotation of the rotor 11 (step 109). Furthermore, the main control device 50 prohibits the door unlocking operation until the motor 13 stops rotating, and then allows the door unlocking operation after the rotation has stopped.

[0043] If the over-rotation state is not present in step 106, the main control device 50 determines whether the centrifugation operation for the set time has finished, and if not, returns to step 104 (step 107), and if finished, brakes the centrifuge motor 13 to stop its rotation (step 108). At this time, the main control device 50 prohibits the door unlocking operation until the motor 13 stops rotating, and allows the door to be unlocked after the rotation has stopped.

[0044] As described above, the processor of the main control device 50 executes a computer program to control the rotation of the rotor 11 of the centrifuge 1, permit the opening and closing of the door lock mechanisms 20 and 30, detect an overspeed state, and perform control after the overspeed state. In this way, the determination of whether the rotor 11 has stopped is performed by software, but to further enhance the safety of management by the computer program, in this embodiment, the detection of an overspeed state (steps 104 and 106), the reliable stopping control of the rotor 11 in the event of overspeed, and the control to maintain the door locked state while the rotor 11 is rotating (step 109) executed by the processor of the main control device 50 are also controlled by means other than the device that executes the software, i.e., the rotation signal processing circuit 51 shown in Figure 2, thereby doubling the monitoring of the overspeed state and the countermeasures.

[0045] FIG. 6 is a detailed block diagram of the overspeed detection circuit 60 shown in FIGS. 2 and 4. When the user inputs the set rotation speed and centrifugation time from the operation panel 15 (see FIG. 4), the main control device 50 acquires the speed deemed to be an overspeed and writes the threshold value, which is the time required for one rotation at the rotation speed deemed to be an overspeed, to the data output / hold circuit 53 via the data bus 55. The threshold value may be the maximum permissible rotation speed of the rotor 11, the set rotation speed input from the operation panel 15, or the upper limit rotation speed at which the sample placed in the rotor 11 will not be damaged. The rotation speed, which serves as the threshold value, is written to memory via the OR circuit 64 using the chip select signal CS and write signal WR of the microcomputer in the main control device 50. The data output / hold circuit 53 can output 16-bit data LD0 to LD15 by using, for example, two 74HC374 general-purpose logic ICs. The threshold value for judgment can be determined by adding a rotation speed to the set rotation speed so that the sample is not destroyed, taking into account the overshoot of the rotation speed when switching from acceleration to constant speed. For example, if the added amount is 200 rpm, then Overspeed N over = set rotation speed + 200 (Equation 1) The judgment value is the clock φ1 and the over-rotation speed N over It is calculated using the following formula 2. Judgment value = 60 x 1000 x 1000 / (φ1 x N over )...(Formula 2)

[0046] A signal (RPG) detecting the rotation of the rotor 11 or a signal (MPG) detecting the rotation of the motor is input, and a one-pulse conversion circuit 610 generates and outputs a signal 613 with one pulse per rotation. If the RPG signal 612 is one pulse per rotation, no conversion circuit is required, but if it is four pulses per rotation, a divider or the like can be used to divide it by four and convert it to one pulse. The 1 / 2 frequency divider circuit 611 toggles the output with each rotation. That is, as shown in waveform 614, a Hi (High) output is produced at the first rotation and a Lo (Low) output is produced at the second rotation, repeating alternately. In other words, odd-numbered rotations result in a Hi signal, and even-numbered rotations result in a Lo signal.

[0047] When the output signal of the 2-divider circuit 611 is Hi, the first countdown circuit 601 loads data from the data output / hold circuit 53 using the inverted signal Lo inverted by the inverter 608. This operation is performed once every two rotor revolutions. When the output signal of the 2-divider circuit 611 is Lo, the clock φ1 generated by the oscillator 607 and the frequency divider 606 is output from the OR circuit 605, and the countdown circuit 601 performs a countdown operation. This operation is also performed once every two rotor revolutions. The first countdown circuit 601 performs a countdown operation based on the loaded decision value, and if the rotation speed is slow, it enters a borrow state and outputs a one-pulse signal from the borrow terminal BO. This first countdown circuit 601 corresponds to 16-bit data LD0 to LD15 using, for example, four 74HC193 general-purpose logic ICs.

[0048] The second countdown circuit 602 loads the value of the detection count value 603 with the Lo signal output from the borrow terminal BO of the first countdown circuit 601. over When the rotation speed is lower than N, a 1-pulse Lo signal is input to the LD terminal. overWhen the rotation speed reaches this level, the LD terminal of countdown circuit 602 goes into a Hi signal state, and the countdown operation is performed using a rotation signal of one pulse per two rotor rotations output from 2-frequency divider circuit 611. When the countdown exceeds the set value of detection count value 603, the signal output from borrow terminal BO of countdown circuit 602 triggers an over-rotation signal to be output from over-rotation detection holding circuit 604. The second countdown circuit 602 can be configured using one 74HC193 general-purpose logic IC, and the over-rotation detection holding circuit 604 can be configured using one 74HC74 general-purpose logic IC.

[0049] Although not shown, this overspeed signal can be used to operate a relay to cut off the power supply to the motor or to cut off the drive signal to the inverter, allowing the rotor to naturally decelerate. This method can also be used to detect overspeed when operating at the maximum rotation speed of the rotor 11.

[0050] According to the experiment conducted by the inventor, the oscillator 607 is set to 16 MHz, the divider 606 is set to a general-purpose logic IC 74HC4040, the clock φ1 is set to 1 μsec, and the over-rotation speed N over When the rotational speed is 22,200 rpm, the judgment value is 2702 in decimal and A8E in hexadecimal. When a frequency was applied to the experimental circuit using a pulse generator, it was detected at 370.1 Hz (22,206 rpm) and an overspeed signal was output. Compared to conventional rotational signal processing circuits for overspeed detection, this method enables more accurate and stable overspeed detection.

[0051] FIG. 7 is a block diagram of a door lock control circuit 70 for a centrifuge 1 according to an embodiment of the present invention. Oscillator 704 generates a 16 MHz clock, and divider 705 uses a general-purpose logic IC, 74HC4040, to form a two-stage frequency divider circuit. For example, clock φ2 is 1 μsec and clock φ3 is 262 msec. First edge detection circuit 701 detects the rising and falling edges of the RPG signal, and second edge detection circuit 702 detects the rising and falling edges of the MPG signal. These edge detection circuits 701 and 702 are configured using, for example, general-purpose logic ICs, 74HC175 and 74HC86, and output a 1 μsec-wide Lo signal during rotation.

[0052] The output signals of the first edge detection circuit 701 and the second edge detection circuit 702 are input to an AND circuit 703, and either of the Lo signals is output from the AND circuit 703. This AND output signal 720 is connected to the LD terminal of a third countdown circuit 707 and the CLR terminal of a stop signal output circuit 708. The third countdown circuit 707 loads a timer value 706 each time a Lo signal is input to the LD terminal. When rotation stops, no Lo signal is input to the LD terminal, so the countdown operation is performed by clock φ3. For example, if the timer value 706 is set to "8," the circuit determines that rotation has stopped if no RPG or MPG signals are input during approximately two seconds from the time of clock φ3.

[0053] When the countdown exceeds the timer value of "8", the third countdown circuit 707 outputs a signal from the borrow terminal BO. This signal triggers a "drive stop signal" to be output from the stop signal output circuit 708. The third countdown circuit 707 can be configured using one general-purpose logic IC, 74HC193, and the stop signal output circuit 708 can be configured using one general-purpose logic IC, 74HC74.

[0054] The stop signal output circuit 708 outputs a Hi signal while the rotor 11 is rotating and outputs a Lo signal when the rotor 11 stops. These outputs are input to an OR circuit 712. The other input of the OR circuit 712 is the output of an AND circuit 711. The outputs of the lid lock detection sensor A (26) and the lid lock detection sensor B (36) are input to the AND circuit 711. The outputs of the lid lock detection sensors A and B are High in the unlocked state and Low in the locked state. Therefore, the output of the AND circuit 711 is Hi when both the lid lock detection sensors A and B are in the unlocked state and Lo otherwise. The OR circuit 712 outputs a Lo signal when both the signals of the stop signal output circuit 708 and the AND circuit 711 are Lo, and is Hi otherwise. The inverter 713 inverts the input signal and outputs it to the AND circuit 69. The lock motor drive signal 81 controls the lock motor drive circuit 35 with an ON or OFF signal. The lock motor drive circuit 35 supplies a signal (PWM (Pulse Width Modulation) or DC power supply, etc.) for driving the LID motors 21 and 31.

[0055] The centrifuge 1 begins operation after the door 4 is closed and locked. The drive stop signal 730 for the operating door lock mechanisms 20 and 30 outputs a high signal during rotation. The LID lock sensors 26 and 36 output a low signal to detect that the door 4 is locked when it is closed. The two door lock mechanisms 20 and 30 (see FIGS. 2 and 4) and the LID lock sensors 26 (see FIG. 2) and 36 (not shown) are provided to prevent malfunction even if one of them fails. Even if the signal from either of the two LID lock sensors 26 and 36 is a low signal indicating lock, if the drive stop signal is a high signal while the rotor 11 is rotating, the inverter 713 outputs a low signal, and the AND circuit 69 cuts off the lock motor drive signal 81 to the lock motor drive circuit 35. As a result, the LID lock motors 21 and 31 are prevented from switching from locked to unlocked.

[0056] As described above, by using the LID lock sensors 26, 36 and the drive stop signal 730, even if the processor of the main control device 50 malfunctions, the door lock control circuit 70 operates normally, and the door 4 remains locked until the rotor 11 completely stops. As a result, the user does not come into contact with the rotating rotor 11, eliminating the risk of clothing getting caught in it. In this invention, in addition to the conventional software-based overspeed monitoring, an overspeed monitoring device realized by circuit configuration is provided, and in the event of overspeed, a protection mechanism is implemented that stops the rotation of the centrifuge motor 13 and prevents the door from being unlocked, thereby achieving a centrifuge 1 with even greater reliability.

[0057] While the present invention has been described above based on the embodiments, it is not limited to the above-described embodiments and various modifications are possible without departing from the spirit of the present invention. For example, the door 4 shown in Figures 1 and 2 can be a sliding door with a door lock mechanism, as well as a pivoting door supported by hinges 6. In addition, in this embodiment, the control of the centrifuge 1 is separated into the main control device 50 and the motor control device 80, and software is executed by multiple processors for control. However, the configuration of software control, whether centralized or distributed, is optional, and a centralized control configuration in which all software control is performed by the main control device 50 alone, may also be used. [Explanation of symbols]

[0058] 1 centrifuge 2. Case 2a, 2b through hole 2d partition board 3 bowls 4 Doors (LID) 5. Rotor chamber 6 hinges 7 Door gasket 8 Damper 9, 10 Door hook 9a, 10a long hole 11 rotor 12 Rotation axis 13 Motor 14 Encoder circuit 15 Operation panel 16 Operation circuit 19a, 19b gas springs 20 Door lock mechanism 21 LID lock motor 22 Door lock hook 22a Hook rotation axis 22b Inner and surrounding areas 23 Link Bar 24 Door lock holder 25 LID closed sensor 26 LID lock detection sensor 26a, 26b LID lock sensor 27 Hook position detection board 30 Door lock mechanism 31 LID lock motor 35 Lock motor drive circuit 36 LID lock detection sensor 38 LID Closed Lock Sensor Circuit 39 LID lock sensor circuit 41 ID sensor circuit 42 Temperature sensor circuit 43 Insulation 50 Main control device 51 Overspeed detection circuit 52 Vibration detection circuit 53 Data output hold circuit 54 Communication lines 55 Data Bus 56 Rotor chamber high temperature detection circuit 57, 62 Buffer circuit 58 AND Circuit 59 Centrifugal motor drive circuit 60 Overspeed detection circuit 61 Overspeed signal 63 Drive signal 64 OR Circuit 65 Cooling device drive circuit 66 Cooling device 68 Buffer Circuit 69 AND Circuit 70 Door lock control circuit 80 Motor control device 81 Lock motor drive signal 601 First Countdown Circuit 602 Second Countdown Circuit 603 Detection count 604 Overspeed detection and holding circuit 605 OR Circuit 606 Frequency divider 607 Oscillator 608 Inverter 610 1-pulse conversion circuit 611 2 divider circuit 612 RPG signal 701 First Edge Detection Circuit 702 Second Edge Detector Circuit 703 AND circuit 704 Oscillator 705 frequency divider 706 Timer Value 707 Third Countdown Circuit 708 Stop signal output circuit

Claims

1. a rotor for holding the sample; a rotor chamber that accommodates the rotor; a motor having a rotary shaft that rotates and drives the rotor; an input unit for inputting a set rotation speed of the rotor; a housing that houses the rotor, the motor, and the rotor chamber; a door provided on the housing to open and close the rotor chamber; an electric door lock device that holds the door in a closed state; a rotation detector that generates a signal indicative of the rotation speed of the rotor; a control device configured to include a processor that executes a program and controls the rotation speed of the motor in accordance with a set rotation speed set from the input unit, a rotation signal processing circuit that operates independently of the control device; When the rotation signal processing circuit determines that the rotation speed of the motor exceeds an allowable rotation speed, the rotation signal processing circuit stops the rotation of the motor and prevents an unlocking operation of the door lock device, thereby keeping the door locked until the rotation of the rotor stops.

2. an encoder circuit that outputs a first pulse indicating the rotation speed of the rotary shaft of the motor, and / or an ID sensor circuit that reads an identifier provided at a predetermined position in the circumferential direction of the rotor during rotation and outputs a second pulse; The rotation signal processing circuit includes: an over-rotation detection circuit unit that counts the first pulse and / or the second pulse to detect an over-rotation state and outputs an over-rotation signal; 2. The centrifuge according to claim 1, further comprising a door lock control circuit that monitors the first pulse and / or the second pulse to be output and issues a drive control signal to prevent the door lock device from being driven while the rotor is rotating.

3. the control device sets a parameter corresponding to the maximum allowable rotation speed of the sample set in the rotor in a data output holding circuit unit of the rotation signal processing circuit; 3. The centrifuge according to claim 2, wherein the rotation signal processing circuit detects an over-rotation state of the rotor by counting the first pulses and / or the second pulses using the set parameters.

4. a lock motor drive circuit for performing an opening and closing operation of the door lock device to a locked state and an unlocked state; the control device outputs a drive signal to the lock motor drive circuit, 4. The centrifuge according to claim 3, wherein an output from the lock motor drive circuit to the door lock device is transmitted after an AND operation is performed by an AND circuit with the drive permission signal from the rotation signal processing circuit.

5. the control device calculates a determination value for the time it takes for the rotor to make one rotation from the set rotation speed input from the operation panel, and writes the value into a data output / hold circuit section; The overspeed detection circuit unit a one-pulse conversion circuit that outputs one pulse per rotation from a signal that detects the rotation of the rotor or a plurality of pulse signals that detect the rotation of the motor; a frequency divider circuit that divides the frequency of the output signal of the one-pulse conversion circuit by two; a first countdown circuit that loads data output from the data output holding circuit unit using an inverted signal from the 2-divider circuit, and performs countdown operation using an output signal from an OR circuit that receives as input a clock generated by an oscillator and a frequency divider and the output signal from the 2-divider circuit; a second countdown circuit that loads a detection count value using a borrow output signal from the first countdown circuit and counts down using an inverted signal from the 2-frequency divider circuit; 5. The centrifuge according to claim 4, further comprising an over-rotation detection and holding circuit that is triggered by a borrow output signal from the second countdown circuit and outputs an over-rotation signal when the countdown exceeds the detection number.

6. The door lock control circuit unit a first edge detection circuit that detects rising and falling edges of an output signal of the ID sensor circuit using a clock generated by the oscillator and the frequency divider; a second edge detection circuit for detecting rising and falling edges of the output signal of the encoder circuit using a clock; a third countdown circuit that loads a timer value with an output signal of an AND circuit that receives output signals from the first edge detection circuit and the second edge detection circuit as inputs, and that counts down with a clock output from the frequency divider; 6. The centrifuge according to claim 5, further comprising a stop signal output circuit that is cleared by the output signal of the AND circuit and that outputs the drive control signal using a borrow output signal of the third countdown circuit as a trigger.

7. a rotor for holding the sample; a rotor chamber that accommodates the rotor; a motor having a rotary shaft that rotates and drives the rotor; an input unit for inputting a set rotation speed of the rotor; a housing that houses the rotor, the motor, and the rotor chamber; a door provided on the housing to open and close the rotor chamber; an electric door lock device that holds the door in a closed state; a rotation detector that generates a signal indicative of the rotation speed of the rotor; A centrifuge having a controller configured to include a processor that executes a program and that controls the rotation speed of the motor by software, a rotation signal processing circuit that operates independently of the control device; The control device monitors whether the rotation speed of the rotor during centrifugal operation exceeds a maximum allowable rotation speed by using software executed by the processor, and The rotation signal processing circuit counts the outputs from an encoder circuit that detects the rotation speed of the rotating shaft of the motor and an ID sensor circuit that reads an identifier provided at a predetermined position around the circumference of the rotor while the rotor is rotating, and when it detects that the maximum permissible rotation speed has been exceeded, it outputs a drive control signal that prohibits operation of a drive unit of the door lock device, thereby maintaining the locked state of the door lock device until the rotation of the rotor stops.

8. 8. The centrifuge according to claim 7, wherein the rotation signal processing circuit has an over-rotation detection circuit unit that stops rotation of the motor by issuing an over-rotation signal when the rotation speed of the motor exceeds an allowable rotation speed in the count.

9. the control device has a data output holding circuit unit that holds a set value indicating the maximum rotation speed monitored by the rotation signal processing circuit, 9. The centrifuge according to claim 8, wherein the over-rotation detection circuit detects the over-rotation state by performing the counting in accordance with the set value.

Images