JPH08258282A - Ink jet recording apparatus - Google Patents

Abstract

PURPOSE: To detect an amt. of ink at the time of the running of a carriage at a constant speed or the deceleration/acceleration thereof by operating the amt. of the ink in an ink tank at a time of inspection from the voltage and current in a standard state of a DC motor, the amt. of ink and the voltage and current of the motor at a time of inspection. CONSTITUTION: A control part 1 performs the control of the whole and a motor control part 2 generates the waveform controlling a DC motor 3 allowing a carriage to run to supply power to the DC motor 3. A voltage source 4 is the drive power supply of the DC motor 3. A differential amplifier 5 detects the difference between the terminal voltage of the DC motor 3 and reference voltage and a reference power supply 6 applies reference voltage to the differential amplifier 5 and an amplifier 7 amplifies the output of the differential amplifier 5 to n-times. An A/D converter 8 converts an analogue signal to a digital signal. Power is supplied to the DC motor 3 to rotate the motor. The motor control part 2 rotates the motor slowly at the beginning and rotates the same at a constant speed finally.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet recording apparatus used in facsimiles, printers and the like, and more particularly to an ink jet recording apparatus for measuring the amount of ink.

[0002]

2. Description of the Related Art FIG. 14 is a diagram showing an example of an ink jet recording apparatus. As shown in FIG. 1, the ink jet type recording apparatus includes a removable cassette 101 and a cassette 10.
The recording paper 102 stored in 1 and a pickup roller 103 for feeding the recording paper 102 one by one, a feed roller 104 for conveying the fed recording paper 102, a feed motor 105 for rotating the feed roller 104, and the recording paper 102.
First pinch roller 10 for pressing the feed roller 104 against the feed roller 104
6, a second pinch roller 107 for preventing the recording paper 102 from floating at the recording position, a gear box 108 for switching the rotation transmission of the feed motor 105, and a position sensor 109 for detecting the leading end of the conveyed recording paper 102. A carriage 110 having a plurality of ink ejection nozzles and an ink tank, a guide shaft 111 provided for moving the carriage 110 in a direction traversing the recording paper 102 (this direction is referred to as a main scanning direction), and a guide shaft 111. A belt 112 that reciprocates along the carriage 112, a carriage motor 113 that rotates the belt 112 forward and backward, and a carriage sensor 114 that is provided on the carriage 110 and detects an initial position of the carriage 110 (a detected member is shown in this figure). Is not provided) and is provided in the initial position of the carriage 110 A cleaning unit 115 for cleaning and capping the paper, a first conveying roller 116 and a first pressing roller 117 for nipping and carrying the recording paper 102 on which recording has been completed, a second conveying roller 118 and a second pressing roller. Roller 119 and recording paper 10
The first recording paper guide 120, the second recording paper guide 121, and the third recording paper guide 122 which guide the second sensor 10, and the respective sensors 10
Each motor 10 receives signals from 9, 114
5, 113 and the control circuit section 123 for controlling the drive of the carriage 110.

The carriage 110 is provided with a container for storing ink and a device for detecting the presence or absence of ink. FIG.
Is a diagram showing an example of this. In the figure, 131 is an ink cartridge that stores ink, 132 is an ejection head having a large number of nozzles that eject ink, 133 is provided below the ejection head 132, and ink droplets 13 that pass through
5 is a light emitting diode that emits light, and 134 is a phototransistor that receives the light emitted from the light emitting diode 133 to detect ink droplets 135.

To detect ink, first, an ink droplet 135 is ejected from the ejection head 132 one nozzle at a time. The change in the output of the phototransistor 134 as it passes between the light emitting diode 133 and the phototransistor 134 is examined. FIG. 16 shows an ink droplet 135
17 shows a continuous signal output from the phototransistor 134 when there is no light, and FIG. 17 shows a state in which the light from the light emitting diode 133 is blocked by the passage of the ink droplet 135 and the output of the phototransistor 134 changes.

[0005]

However, the above method has the following drawbacks. When the ejection nozzle is clogged with ink for some reason, it is determined that there is no ink. That is, it is not possible to distinguish between ink clogging and no ink. The nozzle arrangement of the actual discharge nozzles is shown in FIG.
As shown in (B), since it is configured with a certain width and length, it is difficult to align the light emitting diode 133 and the phototransistor 134 with the nozzle position, and ink droplets cannot be detected unless they are aligned correctly. The above method can detect only whether or not ink is present, and cannot detect how much ink is present.

The present invention has been made in view of the above problems, and an object of the present invention is to provide an apparatus capable of detecting the amount of ink present in a carriage. More specifically, it is an object of the present invention to provide an apparatus capable of detecting the ink amount when the carriage is traveling at a constant speed when detecting the ink amount. Another object of the present invention is to provide a device that can detect the amount of ink when the carriage decelerates. Another object of the present invention is to provide a device that can detect the amount of ink while the carriage is accelerating.

[0007]

In order to achieve the above object, according to the invention of claim 1, a carriage equipped with a recording head for recording an image on a recording medium and an ink tank for supplying ink to the recording head, and the carriage. A DC motor that reciprocates in the main scanning direction, a constant speed circuit that rotates the DC motor at a predetermined rotation speed, a voltage measuring unit that measures the voltage of the DC motor in the constant speed circuit, and an ink tank A calculation means for calculating the ink amount of the ink tank at the time of inspection from the voltage or current and the ink amount of the DC motor in the reference state and the voltage or current of the DC motor at the time of inspection, when the predetermined amount of ink is used as the reference state. And.

According to another aspect of the present invention, in the constant speed circuit, a bridge circuit provided with the DC motor on one side of four sides is connected to a collector, and two points of the DC circuit on the side of the DC circuit having the same potential are connected to each other. It is composed of a PNP type transistor in which the positive side input of the dynamic amplifier is the other side negative input, the output is input to the base, and the power source is connected to the emitter.

According to another aspect of the present invention, a recording head for recording an image on a recording medium, a carriage equipped with an ink tank for supplying ink to the recording head, a DC motor for reciprocating the carriage in the main scanning direction, A resistance circuit for connecting a brake resistance to the DC motor so that the first resistance value and the second resistance value can be switched, and a constant current according to the resistance value is applied to the brake resistance while the DC motor is decelerating by the brake resistance. A constant current circuit for generating a constant brake torque, a clocking means for measuring a deceleration time for the DC motor to reach a predetermined second rotation speed from a predetermined first rotation speed, and a first deceleration at a brake resistance having a first resistance value. The first angular velocity change and the second angular velocity change during deceleration are obtained from the time and the second deceleration time at the second resistance value, and the constant brake torque at each brake resistance value is obtained. There calculated the moment of inertia from equations of motion for the DC motor, the ink comprises a calculating means for calculating the amount of ink in comparison with the load moment of inertia upon entering a predetermined amount.

According to another aspect of the present invention, the constant current circuit comprises an NPN transistor having the resistor circuit connected to the emitter, the DC motor connected to the collector, and the constant voltage power supply connected to the base.

According to another aspect of the present invention, there is provided a recording head for recording an image on a recording medium, a carriage having an ink tank for supplying ink to the recording head, and a DC motor for reciprocating the carriage in the main scanning direction. A voltage application circuit for switching the first voltage and the second voltage to the DC motor and applying the voltage, and a constant current according to the voltage during acceleration of the voltage applied by the DC motor to the DC motor. A constant torque circuit for generating a voltage, a time measuring means for measuring an acceleration time until the DC motor reaches a predetermined rotation speed, and a first acceleration time at a first voltage and a second acceleration time at a second voltage as a power supply voltage. The first angular velocity change and the second angular velocity change during acceleration are obtained, and the load inertia moment is obtained from the equation of motion of the DC motor using the constant motor torque at each voltage. , Ink and a calculating means for calculating the amount of ink in comparison with the load moment of inertia upon entering a predetermined amount.

According to a sixth aspect of the present invention, in the constant torque circuit, a bridge circuit in which the DC motor is provided on one side of four sides is connected to an emitter, and two points having the same potential of the bridge circuit are connected to a first differential amplifier. And a second differential amplifier in which the output is set to the voltage of the counter electromotive force of the DC motor by the amplification factor of the first differential amplifier and this voltage is set to the negative input side and the constant voltage source is set to the positive input side. It is composed of an NPN type transistor whose output is input to the base.

[0013]

According to the first aspect of the invention, the voltage applied to the DC motor for moving the carriage at a constant speed varies depending on the amount of ink. The voltage difference of the DC motor between the reference state when the ink amount is a predetermined amount and the two states at the time of inspection is proportional to the difference between the two states of the load torque under a constant motor rotation speed condition (constant speed condition). The difference in ink weight is proportional to the load torque difference between the two states. As a result, the difference between the ink amounts in the two states is obtained by obtaining the voltage difference between the two states, and the ink weight in the inspection state can be known from the ink weight in the reference state.

Further, the voltage difference of the DC motor may be the current difference. Since the load torque of the DC motor is proportional to the current of the DC motor, the current difference between the reference state and the two states during inspection is 2
It is proportional to the ink weight difference of the state. Thus, the ink weight can be obtained by measuring the current of the DC motor when the carriage is traveling at a constant speed.

According to the second aspect of the present invention, in the constant speed circuit of the first aspect, when the rotation of the DC motor is increased, the balance of the bridge is lost and the output of the differential amplifier becomes +, so that When the output is reduced and the rotation speed drops, the output of the differential amplifier becomes negative and the output of the transistor increases. This causes the DC motor to rotate at a constant speed.

According to the invention of claim 3, a constant current circuit is provided in which a constant brake current flows according to the brake resistance value. When the brake resistance value is determined by this, the predetermined first
The deceleration time from the rotation speed to the predetermined second rotation speed changes according to the magnitude of the moment of inertia of the load. The equation of motion during deceleration of the DC motor is roughly expressed as follows. T + TL = (JM + JL) / g * (dw / dt) (1) Where, T: Torque generated by brake resistance TL: Load torque JM: Moment of inertia of motor itself JL: Moment of inertia of load (inertia moment of carriage 110) ) G: Gravitational acceleration dw / dt: Rate of change of motor angular velocity with time

In the equation (1), T has a constant value due to the constant current circuit. Then, since TL, JM, JL, and g are constant values during the movement, dw / dt is also a constant value, that is, constant acceleration, and the relationship between the angular velocity w and the time t is a straight line. Brake torque T1 when the brake resistance is the first resistance, brake torque T2 when the brake resistance is the second resistance value, and a predetermined first rotation speed N0
The time required to decelerate to a predetermined second rotation speed N1 is t1 for the brake torque T1 and t2 for the brake torque T2, and dw / dt for each brake torque is Δ.
Let w1 and Δw2 be: T1 + TL = (JM + JL) / g * Δw1 ... (2) T2 + TL = (JM + JL) / g * Δw2 ... (3) Subtracting the expression (2) from the expression (3) gives T2-T1 = (JM + JL). ) / G * (Δw2-Δw1) ... (4) ∴JL = (T2-T1) * g / (Δw2-Δw1) -JM ... (5) where Δw2 = (2π * (N0-N1) * 60 ) / T2 ... (6) Δw1 = (2π * (N0-N1) * 60) / t1 ... (7) (when the unit of w is rad / s and the unit of rotation speed is r.pm).

JM is a value peculiar to the DC motor, and T2,
Since T1 is a value determined by the brake resistance value,
The moment of inertia of the carriage can be obtained from the equation (5). By comparing this moment of inertia with the moment of inertia of the carriage when a predetermined amount of ink has entered, the amount of ink in the carriage can be known.

According to the invention of claim 4, in the constant current circuit of claim 3, the brake resistor is used as the load of the emitter terminal and the constant voltage power source is connected to the base to form the emitter follower. The flowing current is almost constant.

According to the fifth aspect of the present invention, a constant torque circuit is provided which generates a constant motor torque by causing a constant current to flow in the DC motor according to the voltage applied to the DC motor. When the applied voltage is determined by this, the time to accelerate to the predetermined rotation speed N changes according to the magnitude of the moment of inertia of the load. The equation of motion during acceleration of the DC motor is roughly expressed as follows. T-TL = (JM + JL) / g * (dw / dt) (8) Here, T: torque generated by the DC motor The meanings of the other symbols are the same as those in the equation (1). The difference between the expressions (1) and (8) is that the sign of TL is different.
In equation (8), the torque generated by the motor is controlled by the constant torque circuit so as to have a constant value by the applied voltage. As a result, TL, JM, JL, and g are constant values during the movement, so that dw / dt is a constant value and the relationship between the angular velocity w and the time t is a straight line.

Predetermined rotation speed N at motor torques T1 and T2 generated by applied voltages E1 and E2 to the DC motor.
Rise times t1 and t2 are calculated. As a result, assuming that dw / dt at each torque is Δw1 and Δw2, T1-TL = (JM + JL) / g * Δw1 ... (9) T2-TL = (JM + JL) / g * Δw2 ... (10) (10) Subtracting the expression (9) from the expression, T2-T1 = (JM + JL) / g * (Δw2-Δw1) ... (11) ∴JL = (T2-T1) * g / (Δw2-Δw1) -JM ... (12) Here, Δw2 = (2π * N * 60) / t2 (13) Δw1 = (2π * N * 60) / t1 (14) (The unit of w is rad / s and the unit of rotation speed is r.p.) .M)

In the equation (12), JM is a value peculiar to the DC motor, and T2 and T1 can be calculated from the constant torque circuit as constant values according to the applied voltages E2 and E1. As a result, the moment of inertia of the carriage can be obtained from the equation (12). By comparing this moment of inertia with the moment of inertia of the carriage when a predetermined amount of ink has entered, the amount of ink in the carriage can be known.

According to the sixth aspect of the present invention, in the constant torque circuit, two points having the same potential of the bridge circuit are input to the first differential amplifier, and the amplification factor of the first amplifier is set to a predetermined value. The output is the back electromotive force −Ec of the DC motor. When this voltage is set to the negative input side of the second differential amplifier and a constant voltage source is input to the positive input side, the output of the second differential amplifier becomes the sum E + Ec of the constant voltage E and the counter electromotive force Ec, and this voltage is applied to the transistor. The voltage is applied from the base to the bridge circuit connected to the emitter terminal and becomes the drive voltage Es of the bridge circuit. The current Ia flowing through the motor in the bridge circuit is the total resistance R on the motor side of the bridge, and the drive voltage Es and the counter electromotive force −E
Since it is a value obtained by dividing the sum of c, Ia is a constant voltage E as follows.
Since E is a constant value, Ia is also a constant value. Ia = (Es-Ec) / R = (E + Ec-Ec) / R = E / R (15) Since the motor torque T is proportional to this motor current Ia, if the voltage applied to the DC motor is E, then E The motor torque T can be calculated.

[0024]

Embodiments of the present invention will be described below with reference to the drawings. The first embodiment is an apparatus that calculates the weight of ink from the voltage of a DC motor that drives the carriage 110 at a constant speed. FIG. 1 is a block diagram showing the configuration of the first embodiment. The control unit 1 controls the whole, and the motor control unit 2 generates a waveform for controlling the DC motor 3 (corresponding to the carriage motor 113 in FIG. 14) that drives the carriage 110 and supplies electric power to the DC motor 3. The voltage source 4 is a drive power source for the DC motor 3. The differential amplifier 5 detects the difference between the terminal voltage of the DC motor 3 and the reference voltage, and the reference power source 6
Applies a reference voltage to the differential amplifier 5. The amplifier 7 amplifies the output of the differential amplifier 5 by n times. The AD converter 8 converts an analog signal into a digital signal.

Next, the operation will be described. First, a START signal is output from the control unit 1 to the motor control unit 2 and electric power is supplied to the DC motor 3 to rotate the motor. The motor control unit 2 controls so that the motor control unit 2 starts slowly and finally rotates at a constant speed. FIG. 2 is a diagram showing the rotation speed of the DC motor 3 and shows the relationship between the rotation speed and time.

FIG. 3 shows a constant speed circuit provided in the motor controller 2. In this circuit, a bridge circuit is connected to the collector of the PNP transistor 9, the voltage at the point where the bridge has an equal potential is input to the differential amplifier 10, and the output thereof is input to the base. The bridge circuit is R1,
It is composed of R2, R3 and the internal resistance ra of the DC motor. The DC motor 3 constitutes one side of the bridge and generates a counter electromotive force Ec. The voltage of the voltage source 4 of FIG. 1 is applied as Vs to the emitter of the transistor 9.

In this circuit, if the number of rotations of the DC motor 3 is increased for some reason, the counter electromotive force Ec becomes large and the balance of the bridge is lost, the output of the differential amplifier 10 becomes +, and the collector voltage of the transistor 9 is changed. It works in a decreasing direction, the voltage of the DC motor 3 decreases, and the number of rotations decreases, so that the rotation speed becomes constant. When the rotation speed decreases for some reason, the collector voltage rises due to the opposite action, and the rotation speed increases, maintaining constant speed rotation.

At constant speed rotation, the terminal voltage of the DC motor 3 stabilizes at a certain value determined by the rotation speed and the load torque (torque generated by the DC motor 3). The reason for this will be described later. The reference voltage of the reference power supply 6 is subtracted from this stable voltage using the differential amplifier 5. As this reference voltage, the terminal voltage of the DC motor 3 when the ink in the ink cartridge 131 is empty is measured in advance and the voltage is set. The reason will be described below, but the reason is as follows. As a result, the output of the differential amplifier 5 under a certain load is obtained when the ink in the ink cartridge 131 is present to some extent (the state of the ink under that load).
The voltage is proportional to the difference when the first ink is empty. This voltage difference is multiplied by n by the amplifier 7. The value of n is set so that the voltage difference when the ink cartridge 131 is completely filled with ink is the full input range of the AD converter 8. By the above operation, the output of the AD converter becomes a value proportional to the weight of the ink in the ink cartridge 131, so that the control unit 1 can know the remaining amount of the ink as a ratio with respect to 100%.

Next, the reason why the voltage difference in the differential amplifier 5 is proportional to the weight of ink will be described. DC motor 3
The terminal voltage of is expressed by the following equation. E = I * R + Ec (16) However, E: Motor terminal voltage I: Current flowing in the motor R: Internal resistance of the motor Ec: Back electromotive force generated when the motor is rotating Here, Ec is the rotation speed of the motor If N, then Ec = Kn * N (Kn is a proportional constant) (17), so this value will be a constant value if the rotation speed is controlled to be constant.

When the torque of the load (DC motor) is T, it is expressed by T = Ki * I, (Ki is a proportional constant), and the current I becomes I = T / Ki (18). Proportional to the magnitude of load torque. (1
Substituting (7) and (18) into (16), E = Kn * N + T / Ki ... (19)

Here, the voltage when the ink cartridge 131 is empty is E1, and the torque is T1. Further, assuming that the voltage when the ink is in the cartridge 131 to some extent is E2 and the torque T2, E1 = Kn * N + T1 / Ki ... (20) E2 = Kn * N + T2 / Ki ... (21) From equation (21), equation (20) is changed to Subtracting gives the following formula. E2-E1 = (T2-T1) / Ki ... (22) and the voltage difference is proportional to the load torque difference.

The torque T is generally expressed by the following equation. T = K (F + μ (Wk + W)) (23) where T: Torque required to rotate the motor K: Constant determined by gear ratio etc. μ: Friction coefficient determined by mechanical system F: Motor determined by mechanical system Force to move the system in the circumferential direction of the shaft (may be 0) Wk: total weight of ink cartridge, head, etc. W: weight of ink

Therefore, the torque T1 when the ink is empty and the torque T2 when there is a certain amount of ink are represented by the following equations, where Wi is the weight of the ink. T1 = K (F + μ (Wk + 0)) ... (24) T2 = K (F + μ (Wk + Wi)) ... (25) ∴T2-T1 = K * μ * Wi ... (26) The torque difference is proportional to the ink weight Wi. Because (22)
From the equation, the voltage difference E2-E1 is also proportional to the weight of the ink.

The voltage difference E2-E1 is 100%
Let Ef be the voltage in some cases, and the voltage difference E from the empty voltage E1.
When divided by f-E1, (E2-E1) / (Ef-E1) *
100 represents the ratio of a certain amount of ink to 100% time. The control unit 1 receives each voltage as an output value of the AD converter 8 as a digital value and calculates the above.

Further, the torque Tf when the ink is 100% and the torque T2 when there is a certain amount of ink are 10 times the weight of the ink.
Wf is represented by 0%, and Wi is represented by Wi in some cases, and is represented by the following equation. Tf = K (F + μ (Wk + Wf)) ... (27) T2 = K (F + μ (Wk + Wi)) ... (28) ∴T2-Tf = K * μ * (Wi-Wf) ... (29) Torque difference is ink weight Since it is proportional to the difference, the voltage difference E2-Ef is also proportional to the ink weight difference from the equation (22). If this value is divided by the voltage difference E1-Ef when the ink is empty and when it is 100%, (1- (Ef-E2) / (Ef-E1)) * 100 ... (30) is a certain amount of ink. And the amount of 100%. However, in this case, Ef becomes the maximum value, so the differential amplifier 5 in FIG. From the above, the current amount of ink can be obtained as a ratio when 100% ink is present.

In the above description, the ink amount is obtained from the voltage difference between the voltage of the DC motor 3 in the state where the ink amount is obtained and the voltage of the DC motor 3 when the ink amount is 100% or empty. However, as is clear from the equation (16), the voltage difference of the DC motor 3 is proportional to the current difference. Therefore, the ink amount can be obtained by taking the current difference of the DC motor 3.

Next, a second embodiment will be described. In the present embodiment, when the DC motor that is decelerating due to the brake resistance decelerates from the steady rotation speed to the predetermined rotation speed, the deceleration time varies depending on the amount of ink. To calculate.

FIG. 4 is a block diagram showing the configuration of the second embodiment. The control unit 21 controls the whole, and the motor control unit 22
Generates a signal for driving the motor. Based on this signal, the driver circuit 23 supplies electric power to the DC motor 24. The DC motor 24 runs a carriage 110 having ink and nozzles for ejecting this ink. The encoder 25 converts the rotation state of the DC motor 24 into a pulse signal train. The voltage source 26 supplies electric power to the motor driver 23 that drives the DC motor 24. The switch 27 switches the DC motor 24 between the motor driver 23 and the brake resistor. Switch 28 selects whether resistor 29 is alone or in series with resistor 30. The resistors 29 and 30 are brake resistors for stopping the braking of the DC motor 24. The switch 31 switches between a case where a constant current flows through the resistors 29 and 30, and a case where a normal braking operation is performed. The voltage source 32 determines a current for flowing a constant current through the resistors 29 and 30, and the NPN transistor 33 functions to flow a constant current.

The flip-flop 34 operates the counter 35 in synchronization with the signal of the encoder 25, and the counter 35
Counts the pulse width of the encoder 25 and creates data on the number of revolutions of the DC motor 24. The latch 36 temporarily holds the output of the counter 35. The comparator 37 compares the output of the counter 35 with the reference value 18. Reference value 18
Is a reference value corresponding to the reference rotation speed of the DC motor 24. The counter 39 counts the total time until the DC motor 24 decreases from the constant speed to the reference number of revolutions, that is, until the comparator 37 operates. AND gate 40
Is a gate for controlling the operation stop timing of the counter 39.

FIG. 5 is a time chart showing the operation of the block diagram shown in FIG. The operation will be described with reference to this chart. First, from the control unit 21 to the motor control unit 22, START
One signal is output, power is supplied to the DC motor 24 via the motor driver 23, and the DC motor 24 rotates. At this time, the contact of the switch 27 and the contact of the switch 31 are tilted to the left side in the figure. Also, the START2 signal is OF
It is F. Normally, the recording operation is performed in this state, and when stopped, the switch 27 is tilted to the right and the resistor 29,
Resistor 30 brakes and stops. When performing the remaining ink amount detecting operation, the switch 31 is tilted to the right at the start time or an appropriate time during recording. Next, the switch 27 is tilted to the right at an appropriate timing such as when one-page recording is completed, and the resistor 29 and the resistor 30 apply a brake to forcibly stop. At this point, the switch 31 is tilted to the right, so the DC motor 24, the voltage source 32, the transistor 33,
An emitter follower is formed by the resistors 29 and 30. Therefore, the current flowing through the resistors 29 and 30 is almost constant.

At the same time when the forced stop is started, the control unit 21
When the START1 signal is turned off and the START2 signal is turned on, the counter 39 that counts the total time until the reference speed is reduced starts to operate. The flip-flop 34 repeats the operation of operating the counter 35 in synchronization with the rising edge of the encoder signal and clearing it in the LOW section. The output of the counter 35 is temporarily held by the latch 36 at the fall of the encoder signal,
The comparator 37 compares it with the reference value 38. Control unit 2
1 outputs the START3 signal at an appropriate timing and waits for the rotation speed of the motor to drop to the reference rotation speed.

Since the rotation speed of the DC motor 24 is initially high, the HIGH section t of the encoder signal in FIG. 5 is small,
Since the input clock of the counter 35 is counted less, the counter output of the counter 35 is <reference value 38, but when the speed is lower than the reference rotation speed N, the output of the counter 35> = reference value 38. At that time, the comparator 37 notifies the control unit 21 of the result by the A> = B signal and stops counting the total time of the counter 39 via the AND gate 40.

The control unit 21 reads the output D1 of the counter 39 and the brake resistance is R1 (= resistance 29 + resistance 30).
At the time of, the total time from the start of the motor stop operation to the decrease to the reference rotation speed N is t1 = D1 / (counter 39
The clock frequency f) is calculated. Then switch 2 again
7 is tilted to the left to start the DC motor 24, and the above operation is repeated. At this time, the switch 28 is closed. From this operation, the time t2 from the start of the motor stop operation for the brake resistance R2 (= only the resistance 29) to the arrival of the reference rotation speed N is obtained. This t1, t2 and R1,
The load inertia moment JL is calculated from the value of R2 by the method described below, and then the ratio of the weight of the ink is estimated.

The calculation of the load inertia moment JL at the time of deceleration by the brake resistance has been described in the section "Operation", but will be described in more detail. The equation of motion during deceleration due to the brake resistance is roughly expressed by equation (1). In the equation (1), T is a switch 27, 28, 31, a resistor 29, 30,
The constant value is obtained by the constant current circuit composed of the voltage source 32 and the transistor 33. The reason will be described later. Then TL, JM, JL, g are constant during exercise, so dw / d
t also becomes constant, and the relationship of the angular velocity w time t becomes a straight line as shown in a of FIG. When the brake resistance is a fixed resistance, that is, when the constant current circuit is not used, 1
It has the next-delay characteristic. The reason will be described later.

The brake resistance is R1 (resistance 29 + resistance 3
0), the constant braking torque generated at T1, R
When the braking torque of a constant value generated when the resistance is 2 (resistance 29) is T2, the times t1 and t2 during which the braking speed decreases from the rotation speed during constant speed operation to the reference rotation speed N at each brake resistance.
Ask for. FIG. 7 is a diagram showing the relationship between t1 and t2 and the angular velocity, showing the time required to decelerate from the angular velocity w0 at the constant speed operation to the angular velocity w1 at the reference rotational speed N, and the brake resistance R1.
In the case of, it becomes t1, and in the case of R2, it becomes t2. In this case, the load (amount of ink) has the same value. Thus, if dw / dt at each torque is Δw1 and Δw2, (2)-
Expression (7) is obtained. In the equation (5), g is a gravitational acceleration and is a constant, and JM is a value specific to the DC motor 24 and is obtained from a catalog or the like. Brake torque T1, T2
Is calculated by the method described later. By substituting the brake torques T1 and T2 into the equation (5), the inertia moment JL of the load at that time (the load in the state of the ink amount at that time) can be obtained. The reason for measuring twice, T1 and T2, may be changed depending on the operating environment, and is to eliminate the load torque TL, which has to be actually measured to obtain an accurate value, from the calculation formula to improve accuracy.

Next, a method for estimating the weight of the ink from the load inertia moment JL thus obtained will be described. As the load inertia moment JL, the inertia moment Jf when ink is 100% in the ink cartridge, the inertia moment Je when there is no ink, and the inertia moment Jx when there is ink to some extent are obtained by the above method. Since the moment of inertia J is proportional to the sum of the weight of the ink at that time and the weight of the carriage 110 such as the ink cartridge and the nozzle, the proportional constant is K, the weight of the carriage 110 is Mk, the weight of the ink is 100% If, and If Ix at the time of inspection, the following formula is established.

Jf = K (Mk + If) (31) Je = KMk (32) Jx = K (Mk + Ix) (33) ∴If = (Jf-Je) / K ... (34) Ix = (Jx-Je) ) / K (35) Here, the ratio of the weight of the ink at the time of inspection to the weight when 100% ink is present is obtained by the following formula. Ix / If = (Jx−Je) / (Jf−Je) (36) Therefore, from the formula (36), the weight of the ink at the time of inspection is 1
It can be calculated as a ratio with respect to the case where it is 00%.

Next, the control for keeping the torque T generated by the brake resistance constant will be described. The following relational expression holds when the DC motor 24 is moving toward the stop while operating the brake. Ec = Ia * (ra + R) (37) However, Ia: Current flowing in the motor ra: Winding resistance of the motor R: Brake resistance value Ec Back electromotive force of the motor

Here, the brake torque T generated by the motor
Can be written as T = Ki * Ia ... (38) where Ki is the proportional constant. (Ki is a unique value of the motor) Further, it is possible to write Ec = Kn * N where Ec is the counter electromotive force, N is the number of revolutions, and Kn is the proportional constant. (Kn is an eigenvalue of the motor) Since the angular velocity w is proportional to the rotation speed N, w = Kw * N
Then, Ia = Ec / (R + ra) = Kn * Kw * w /
Since it becomes (R + ra), the torque generated by the motor is proportional to the angular velocity w from the equation (38). In this case, the graph of the time t and the angular velocity w is "1" as shown by the curve b in FIG.
Second-order lag characteristic. ”On the other hand, in the present invention, the current flowing through the brake resistor is controlled to a constant value, and as a result, the brake torque is maintained at a constant value.

FIG. 8 shows the switches 27, 28 and 3 shown in FIG.
It is a figure explaining operation | movement of the constant current circuit comprised by 1, resistance 29, 30, voltage source 32, and transistor 33.
R is R1 (resistor 29 + resistor 30) or R2 (resistor 2
9) is represented. In this case, the current flowing through the load resistance R is IR,
When the base-emitter voltage of the transistor is VBE, IR = (E-VBE) / R, so E >>
If VBE, IR≈E / R, which is a constant value regardless of the collector voltage V + of the transistor 33. Therefore, the brake torque also becomes constant according to the equation (38). As described above, it is possible to measure the ink amount during deceleration using the brake resistance.

Next, a third embodiment will be described. In this embodiment, the time required for the accelerating DC motor to reach a predetermined speed is calculated, and the ink amount is calculated from this time. This time varies depending on the applied voltage when the ink amount is constant. When the torque generated by the DC motor is kept constant, the applied voltage is proportional to this time. Therefore, this relationship is used in the kinetic equation of the DC motor to calculate the ink amount.

FIG. 9 is a block diagram showing the structure of the third embodiment. The control unit 51 controls the entire system, and the motor control unit 52 supplies power for driving the DC motor 54 to the motor driver 53. The DC motor 54 reciprocates the carriage 110 having ink and ejection nozzles in the main scanning direction. The encoder 55 converts the rotation state of the DC motor 54 into a pulse signal train. The power supply 56 is a reference voltage source that generates the voltage Ea, and the power supply 57 is a reference voltage source that generates the voltage Eb. The switch 58 switches between the voltage Ea and the voltage Ea + Eb and applies it to the DC motor 54. The power supply 59 is a power supply for the motor control unit 52 and supplies driving power for the motor driver 53. The flip-flop 60 specifies the pulse width of the encoder 55 counted by the counter 61. Counter 6
1 counts the pulse width of the encoder 55 and calculates the DC motor 54
To get the rotation speed data. The latch 62 temporarily holds the output of the counter 61. The comparator 63 compares the value of the latch 16 with the reference value 18. Reference value 18 is DC motor 5
With the value corresponding to the reference rotation speed of 4, the ink amount is calculated when this rotation speed is reached. Counter 65 is START1
The operation is started by the signal, and the total time from the start of the DC motor 54 to the operation of the comparator 63 is counted. That is, the time for accelerating to the standard number of revolutions is counted. The AND gate 66 controls the timing of stopping the counter 65.

FIG. 10 is a time chart showing the operation of the block diagram of FIG. First, the START1 signal is output from the control unit 51 to the motor control unit 52, and the motor driver 5
Electric power is supplied to the DC motor 54 via 3 to rotate the motor. At this time, in the motor driver 53, the torque generated by the DC motor 54 is controlled to have a constant value, as will be described later. At this time, the switch 58 has the left contact closed and the right contact opened. That is, the DC motor 54 is operated in a low voltage state. At the same time that the DC motor 54 is operated, the counter 65 and the flip-flop 60 are started. Since the flip-flop 60 sets the counter 61 to ACTIVE in synchronization with the rising edge of the encoder signal, the counter 61 counts the CK input during the HIGH section of the encoder signal,
The operation of clearing the OW section is repeated.

The output of the counter 61 is latched by the latch 62 at the trailing edge of the encoder signal and compared with the reference value 64 by the comparator 63. The control unit 51 outputs the START2 signal at an appropriate timing, and the DC motor 5
Wait for the 4 rpm to rise to the reference rpm. Since the rotation speed of the DC motor 54 is low at first, the HIGH section t of the encoder signal in FIG. 10 is large and the clock of the counter 61 is counted more, so that the counter output of the counter 61> reference value 64, When the speed becomes higher than the reference number of revolutions N, the counter output of the counter 61 <= the reference value 64. At that time, the comparator 63 notifies the control unit 51 of the result by an A <= B signal and stops counting the total time of the counter 65 via the AND gate 66.

The control unit 51 reads the output D1 of the counter 65, and the total time from the start of the motor at the motor operating voltage E1 (= Ea) to the increase to the reference rotation speed N is t1 = D1 / ( Calculation is performed using the clock frequency f) of the counter 65.

Next, the DC motor 54 is once stopped, the contact on the left side of the switch 58 is opened and the contact on the right side is closed, and the above operation is repeated. By this operation, the motor operating voltage E2
When (= Ea + Eb), the time t2 from when the motor starts rotating to when it reaches the reference rotation speed N is obtained. This t
1, t2 and the voltages Ea, Eb are used to calculate the load inertia moment JL by the method described below, and this is used to estimate the ink weight ratio.

The moment of inertia JL of the load has been described in the section of "Operation", but will be described in more detail. The equation of motion during acceleration of the DC motor is roughly expressed by equation (8). Here, the torque T generated by the DC motor 54
Is controlled by a constant torque circuit described later so as to have a constant value according to the applied voltage. That is, if the applied voltage is E1, the torque is a constant value represented by T1 if it is E1, and if it is E2, the torque is fixed if the voltage is determined. When controlled in this way, the acceleration dw / dt becomes a straight line as indicated by a in FIG. FIG. 11 shows a change in the angular velocity w of the DC motor 54 with time t. When a constant voltage is applied and the motor torque T is kept constant, a
As shown in the above, the curve becomes a straight line, and in the normal case where such control is not performed, the curve becomes a curve b. This shows a first-order lag characteristic. Further, when a high voltage is applied, it becomes substantially straight as shown by c.

The rising times t1 and t2 up to the reference rotational speed N when the motor torques T1 and T2 are generated by the voltages E1 and E2 are obtained. FIG. 12 shows this relationship. The angular velocity w0 is the angular velocity at the reference rotation speed N. If dw / dt at each torque is Δw1 and Δw2, (9)-
Equation (14) is obtained, g is the gravitational acceleration, and JM is a value specific to the DC motor 54.

The torques T2 and T1 generated by the motor are T = Ki * Ia (39) where Ki is a proportional constant and Ki is a value peculiar to the motor. Ia is a current of the DC motor 54 and is represented by the following equation by a constant torque circuit described later. Ia = E / (R3 + ra) (40) where E is the applied voltage, R3 is the resistance of one side of the bridge in the constant torque circuit, ra is the winding resistance of the DC motor 54, and R3 and ra are constants. . Substituting this Ia into the equation (39), the following equation is obtained. T = Ki * E / (R3 + ra) (41) The voltages E2 and E1 applied to the DC motor 54 according to the equation (41).
By substituting for, the torques T2, T1 at that time can be calculated, and therefore the inertia moment JL of the load can be obtained from the equation (12). The reason for measuring T2 and T1 twice is the same as the case of calculating the ink amount during deceleration.
This is because the precision is eliminated by excluding from the formula.

Next, the method of calculating the ink amount from the moment of inertia JL is exactly the same as the method described in the second embodiment. That is, also in the present embodiment, the expressions (31) to (36) are established, and the weight of the ink at the time of the inspection can be calculated from the expression (36) as a ratio with respect to the case where the ink is 100%.

Next, the constant torque circuit will be described. FIG.
Reference numeral 3 shows an example of a constant torque circuit provided in the motor driver 53. In the figure, ra: winding resistance of the DC motor 54 Ec: back electromotive force of the DC motor AMP1: gain (R3 + ra) / R3 differential amplifier AMP2: gain 1 differential amplifier Tr: NPN transistor Vs: FIG. Voltage applied from power supply 59 R1, R2, R3: Bridge resistance

In FIG. 13, R1, R2 and R3, ra form a bridge, and R1: R2 = R3: ra. Therefore, when the motor is not rotating, A when Vb = Va
The output of MP1 is 0 and the output of AMP2 is E.
This voltage is applied to the bridge and becomes Es. The current Ia flowing through the motor while the motor is rotating is Ia = (Es-Ec) / (R3 + ra) ... (42), and this I is required to keep the torque generated by the motor constant.
It is sufficient to make a constant.

When the motor is rotating, the input voltage of AMP1 is: Va = Es * R2 / (R1 + R2) Vb = Es-R3 * Ia = Es-R3 * (Es-Ec) / (R3 + ra) = (ra * Es + R3 * Ec) / (R3 + ra) Here, from the bridge condition, R2 / (R1 + R2) = ra / (R3 + ra), so Vb−Va = R3 * Ec / (R3 + ra) (43) and proportional to the motor electromotive force. To do. This voltage is AMP1
By multiplying (R3 + ra) / R3, the input of AMP2 becomes E on the + side and Ec on the − side, and the drive voltage Es of the bridge circuit is always kept at E + Ec. Therefore, Ia of (42) becomes constant as Ia = (E + Ec−Ec) / (R3 + ra) = E / (R3 + ra) (40), and the torque becomes constant.

When the method of keeping the torque constant is not used, the relationship between the time t and the angular velocity w has a first-order lag characteristic as shown in FIG. 11b, but when rotated at a high voltage, it has a characteristic like c. Can be regarded as a straight line. Also, since there is a portion such as b that can be regarded as a substantially straight line even in the normal operation, dw / dt can be detected using that portion.

[0065]

As is apparent from the above description, the present invention detects the ink amount from the voltage value when the DC motor for driving the carriage having the ink tank is driven at a constant speed. In addition, the amount of ink is detected from the time during which the brake resistance decelerates to a predetermined speed during deceleration. Further, the amount of ink is detected from the time it takes to accelerate to a predetermined speed. In this way, the amount of ink can be detected at any time, so it is possible to prevent recording from being interrupted due to a shortage of ink, and it is also possible to know when ink should be replenished.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a first embodiment.

FIG. 2 is a diagram showing a relationship between the number of revolutions of the DC motor of the first embodiment and time.

FIG. 3 is a constant speed circuit diagram of the first embodiment.

FIG. 4 is a block diagram showing a configuration of a second embodiment.

FIG. 5 is a time chart of the second embodiment.

FIG. 6 is a diagram showing a temporal change in angular velocity in each state.

FIG. 7 is a diagram illustrating a method of obtaining a time change rate of angular velocity according to a second embodiment.

FIG. 8 is a diagram illustrating a constant current circuit according to a second embodiment.

FIG. 9 is a block diagram showing the configuration of a third embodiment.

FIG. 10 is a time chart of the third embodiment.

FIG. 11 is a diagram showing a relationship between angular velocity and time in each state.

FIG. 12 is a diagram showing a relationship between angular velocity and time according to the third embodiment.

FIG. 13 is a constant torque circuit diagram of the third embodiment.

FIG. 14 is a diagram showing an example of an inkjet recording apparatus.

FIG. 15 is a diagram illustrating a configuration of a carriage and an ink detection method.

FIG. 16 is a diagram showing the output of a transistor when ink does not pass through.

FIG. 17 is a diagram showing an output of a transistor when ink passes.

FIG. 18 is a diagram showing a nozzle arrangement.

[Explanation of symbols]

 1 Control Unit 2 Motor Control Unit 3 DC Motor 5 Differential Amplifier 21 Control Unit 22 Motor Control Unit 23 Motor Driver 24 DC Motor 25 Encoder 29, 30 Resistor 33 Transistor 34 Flip Flop 35, 39 Counter 37 Comparator 51 Control Unit 52 Motor Control Part 53 Motor driver 54 DC motor 55 Encoder 60 Flip-flop 61,65 Counter 63 Comparator

Claims (6)

[Claims] 1. A recording head for recording an image on a recording medium, a carriage having an ink tank for supplying ink to the recording head, a DC motor for reciprocating the carriage in the main scanning direction, and a predetermined DC motor. Constant speed circuit for rotating at a rotational speed of, a voltage measuring means for measuring the voltage of the DC motor in the constant speed circuit, and a DC motor in the reference state when the ink amount in the ink tank is a predetermined amount as a reference state. Voltage or current and ink amount of
An ink jet recording apparatus comprising: a calculation unit that calculates the ink amount of an ink tank at the time of inspection from the voltage or current of a DC motor at the time of inspection. 2. The constant speed circuit has a bridge circuit, in which the DC motor is provided on one side of four sides, connected to a collector, and two points of the DC circuit having the same potential of the bridge circuit are connected to the + side of the differential amplifier. 2. The ink jet recording apparatus according to claim 1, wherein the ink jet recording apparatus comprises a PNP type transistor in which the other is used as the negative input, the output is input to the base, and the power source is connected to the emitter. 3. A recording head for recording an image on a recording medium, a carriage on which an ink tank for supplying ink to the recording head is mounted, a DC motor for reciprocating the carriage in the main scanning direction, and a DC motor for the DC motor. 1 resistance and 2nd
A resistance circuit that connects the brake resistance so that the resistance value can be switched, and the DC motor is decelerating by the brake resistance,
A constant current circuit for supplying a constant current according to the resistance value to the brake resistor to generate a constant brake torque; and a time measuring means for measuring a deceleration time at which the DC motor becomes a predetermined second rotation speed from a predetermined first rotation speed. , A first angular velocity change and a second angular velocity change during deceleration are obtained from the first deceleration time of the brake resistance at the first resistance value and the second deceleration time of the second resistance value, and a constant brake torque at each brake resistance value is used. An ink jet recording apparatus comprising a calculation means for calculating a load inertia moment from a motion equation of a direct current motor and calculating an ink amount in comparison with a load inertia moment when a predetermined amount of ink enters. 4. The constant current circuit comprises an NPN transistor in which the resistor circuit is connected to the emitter, the DC motor is connected to the collector, and a constant voltage power supply is connected to the base. Inkjet recording device. 5. A recording head for recording an image on a recording medium, a carriage equipped with an ink tank for supplying ink to the recording head, a DC motor for reciprocating the carriage in the main scanning direction, and a DC motor for the DC motor. A voltage applying circuit for switching between the first voltage and the second voltage and applying the voltage, and a constant torque for generating a constant motor torque by causing the DC motor to flow a constant current corresponding to the accelerating voltage with the voltage of the voltage applying circuit. A circuit, a clocking means for measuring an acceleration time until the DC motor reaches a predetermined rotation speed, and a first acceleration time from a first acceleration time at a first voltage and a second acceleration time at a second voltage when a power supply voltage is being accelerated. The change in the angular velocity and the change in the second angular velocity are obtained, the load inertia moment is obtained from the equation of motion of the DC motor using the constant motor torque at each voltage, and the predetermined amount of ink is applied. An ink jet recording apparatus comprising: a calculation unit that calculates an ink amount in comparison with a load moment of inertia. 6. The constant torque circuit connects a bridge circuit, in which the DC motor is provided on one side of four sides, to an emitter,
The two points having the same potential of the bridge circuit are used as the input of the first differential amplifier, and the output is set to the voltage of the counter electromotive force of the DC motor according to the amplification factor of the first differential amplifier. 6. An ink jet recording apparatus according to claim 5, further comprising a second differential amplifier having a positive input side as a positive input side, and an NPN type transistor having an output thereof as a base input.