JP2001296172A - Liquid detection method and liquid detection device - Google Patents

Abstract

(57) Abstract: An ink detection device for detecting the amount and presence or absence of ink is capable of stably detecting a minute change in the amount of liquid. SOLUTION: A first integration circuit 12 includes a capacitor C1 having a predetermined capacity, and performs an integration operation according to an integration time constant corresponding to the capacity of C1, and a capacitor C2 connected to a detection electrode 8. A second integration circuit 13 that performs an integration operation according to an integration time constant corresponding to the capacitance of C2; a driving circuit 11 that performs an integration operation on both integration circuits 12 and 13; and output signals of both integration circuits 12 and 13 A comparison circuit which compares the integration times indicated by the signals S2 and S3 by comparing the voltages of S2 and S3 to determine whether or not the leading end portion S8 is immersed in the ink is provided. When the leading end portion S8 is immersed in the ink, the capacity of the capacitor C2 increases, and this change in the capacity can be detected by the determination circuit 14, so that a minute change in the ink amount can be detected.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a method and an apparatus for determining the presence or absence and amount of a liquid such as ink used in a printing apparatus.

[0002]

2. Description of the Related Art The function of determining the amount and presence or absence of a liquid such as ink is one of the important basic functions in, for example, offset printing or stencil printing, and affects the reliability of the apparatus. Various types of detection sensors have been considered, such as a float (pendulum) type sensor using liquidity (viscosity), a pressure detection sensor using ink flowing, and a dielectric constant of ink. There are a capacitance detection sensor and a laser or sound wave detection sensor that uses a change in the shape of ink.

[0003] The above-mentioned electrostatic capacitance detection sensor is used to detect a detection needle as a detection electrode connected to one electrode of a capacitor when the amount of accumulated ink exceeds a predetermined amount while facing the ink in the ink reservoir. The tip of the detection needle is disposed so that it can be immersed in the ink, and the tip is immersed in the ink from the state not immersed in the ink (hereinafter also referred to as non-impregnated) (hereinafter also referred to as impregnated). (Hereinafter simply referred to as capacitance). As a method of detecting the change in the capacitance, for example, a method of measuring the absolute value of the capacitance at the time of impregnation, or changing the capacitance change to a change in the oscillation frequency of the oscillation circuit as described in JP-A-58-62520. There is a method of detecting a change in the oscillation frequency.

[0004]

However, the method of detecting a change in capacitance in a conventional capacitance detection sensor is affected by stray capacitance. Unless the difference (variation width) between the capacitance (i.e., the stray capacitance and the capacitance during the impregnation) is large, accurate detection cannot be performed. In order to increase the capacity at the time of impregnation, the detection needle may be formed in a flat plate shape. However, since the floating capacity also increases accordingly, it is not always an effective method, and a problem that the apparatus becomes large occurs. . Further, there is also a problem that a small change in the amount of ink (a minute change in the ink) has a small change width of the capacity, and the minute change in the ink cannot be accurately detected.

[0005] On the other hand, the method described in Japanese Patent Application Laid-Open No. 58-62520 is a method capable of detecting a minute change in ink. It must be high and the capacity during impregnation must be small, but if it is too small the oscillation frequency will be unstable due to the effect of stray capacitance, so the capacity during impregnation will be from several tens of picofarads to nano The actual situation is that the shape and the like of the detection needle are set so as to fall within the farad order range.

However, for example, if the capacity at the time of impregnation is set so as to be in the order of nanofarads to several tens of picofarads for the detection of emulsion ink, the dielectric constant of oil-based ink is smaller than that of emulsion ink. The capacity at the time of impregnation becomes 10 picofarads or less (for example, about 5 picofarads), and the floating capacity (several pico-
0 picofarads), the method described in JP-A-58-62520 can be applied to the detection of minute changes in emulsion ink, but the method described in JP-A-58-62520 can be used to detect minute changes in oil-based ink. Is difficult to apply. Conversely, if the volume at the time of impregnation is set to be about nanofarad order to several tens of picofarads for the detection of oil-based ink, the volume at the time of impregnation becomes larger than the nanofarad order in the case of emulsion ink, It becomes impossible to detect a minute change in ink.

On the other hand, the above-mentioned various sensors other than the capacitance detection sensor have a problem that they are large in size as compared with the capacitance detection sensor and the manufacturing cost is high.

The present invention has been made in view of the above circumstances, and has a low manufacturing cost and a liquid detecting method capable of stably detecting a minute change in the amount of liquid regardless of the type of liquid such as ink. It is intended to provide a device.

[0009]

According to a liquid detecting method of the present invention, a first integration operation is performed according to an integration time constant corresponding to a capacitance of a first capacitor, and the liquid detection method is applied to a liquid in a liquid reservoir portion. A second integration operation is performed according to an integration time constant corresponding to a capacitance of a capacitor connected to a detection electrode provided such that a tip portion can be immersed in the liquid when the liquid accumulation amount becomes equal to or more than a predetermined amount. By comparing the integration time of the first integration operation with the integration time of the second integration operation, it is determined whether or not the tip of the detection electrode is immersed in the liquid. .

Here, the "integration operation" may be any of a charging operation for charging a capacitor and a discharging operation for discharging a capacitor. Further, the charging operation and the discharging operation may be alternately repeated. As described above, in the case where the charging operation and the discharging operation are alternately repeated, the determination may be performed during one or both of the charging operation and the discharging operation. Further, the integration time constant corresponding to the capacitance of each capacitor at this time may be different between the charging operation and the discharging operation.

The term "integration time" means an elapsed time from when charging or discharging is started from a first predetermined voltage to when it reaches a second predetermined voltage.

When comparing the integration time of the first integration operation with the integration time of the second integration operation, the time when the tip of the detection electrode is not immersed in the liquid and the time when it is immersed is not. Any comparison method can be used as long as the change in the integration time of the second integration operation or the change in the integration time of the second integration operation according to the change in the impregnation amount can be detected. For example, the width of each integration time may be detected and compared, or the integrated voltage corresponding to each integration time may be compared.

The term “liquid” is a general term for substances having fluidity, and in the present invention, a gas, a liquid,
It is not limited to a liquid in a narrow sense in the classification of solids, and includes a fluid such as jam, powder, and the like as long as it has fluidity. In short, the present invention determines (detects) the amount and presence or absence of a substance filled in a container or the like through a pipe or the like by using the dielectric constant of the substance.
The substance to be determined may be any substance as long as it can utilize the dielectric constant and has fluidity.

In the liquid detecting method according to the present invention, the first integration operation and the second integration operation are performed at a plurality of different timings, and at each of the plurality of different timings, the integration time of the first integration operation and the second integration operation are different. By comparing the integration time of the operation 2 with the integration time, it is determined whether the tip of the detection electrode is immersed in a liquid having a relatively small dielectric constant or a liquid having a relatively large dielectric constant. It is desirable.

In setting "a plurality of different timings", the integration time based on the second integration operation according to the capacity of the second capacitor when the detection electrode is immersed in the liquid is different at each timing. Any timing may be set as long as it is obtained as a value, and it is possible to determine whether the dielectric constant of the liquid is relatively small or relatively large based on the different values. In the case where the time width for performing the charging operation and the discharging operation is changed, or when the detection is performed by repeating charging and discharging, the time width ratio (so-called duty cycle) of each operation may be changed.

A liquid detecting device according to the present invention includes a device for performing the liquid detecting method, that is, a first capacitor having a predetermined capacity, and an integrating operation according to an integration time constant corresponding to the capacity of the capacitor. The first to do
And a second electrode connected to a detection electrode provided so that the tip can be immersed in the liquid when the accumulated amount of the liquid is equal to or more than a predetermined amount in opposition to the liquid in the liquid reservoir. A second integration circuit including a capacitor and performing an integration operation in accordance with an integration time constant corresponding to a capacitance of the second capacitor; and a drive circuit performing an integration operation on the first integration circuit and the second integration circuit. And the output signal of the first integration circuit and the output signal of the second integration circuit are input, and the integration time indicated by the output signal of the first integration circuit and the integration time indicated by the output signal of the second integration circuit are calculated. A first determination circuit that determines whether or not the tip of the detection electrode is immersed in the liquid by comparison.

In the liquid detection device according to the present invention, the integration time constant of the first integration circuit is substantially equal to the integration time constant corresponding to the capacitance of the second capacitor when the tip of the detection electrode is not immersed in the liquid. It is desirable to set the same.

It is preferable that the liquid detection apparatus according to the present invention further includes a shaping circuit for shaping the waveform of the output signal of the first determination circuit.

Here, "shaping the waveform" means that the output signal of the first determination circuit has a desired waveform or voltage level, and any shaping circuit may be provided. For example, when the first determination circuit outputs a signal having a small pulse width when detecting that the tip of the detection electrode is immersed in the liquid, a circuit for expanding the pulse width is provided. Alternatively, a circuit for detecting the pulse signal may be provided, or a level conversion circuit for performing a level interface between an output signal of the first determination circuit and an input signal level of a subsequent circuit may be provided.

In the liquid detection apparatus according to the present invention, the drive circuit causes the first integration circuit and the second integration circuit to perform integration operations at a plurality of different timings, and a plurality of different timings. Based on the output signal of the first determination circuit obtained in each case, it is determined whether the tip of the detection electrode is immersed in a liquid having a relatively small dielectric constant or a liquid having a relatively large dielectric constant. It is desirable to further include a second determination circuit. Although "based on the output signal of the first determination circuit", it is preferable that the determination is made based on the output signal of the shaping circuit in the case where the shaping circuit is provided. Not even.

[0021]

According to the liquid detecting method and apparatus of the present invention, the first integration operation is performed according to the integration time constant corresponding to the capacitance of the first capacitor, and at the same time, the capacitance of the capacitor connected to the detection electrode is changed. The second integration operation is performed in accordance with the integration time constant corresponding to the first integration operation, and the integration time of the first integration operation is compared with the integration time of the second integration operation. The difference in the capacity of the second capacitor between the non-impregnated state and the impregnated state can be detected as a difference in the integration time of the second integration operation. Also, the difference of this integration time,
That is, since the capacitance change is determined by relative comparison with the integration time of the first integration operation, the amount of the stray capacitance affects both the first integration operation and the second integration operation similarly. As a difference between the integration times of the two integration operations, the stray capacitance can be removed, and as a result, the second capacitor can be removed between the non-impregnated state and the impregnated state without being affected by the stray capacitance. The presence or absence and amount of liquid can be accurately determined based on the difference in the volume of the liquid. In addition, since accurate determination can be performed without being affected by the stray capacitance, a minute change in capacitance, in other words, a minute change in liquid volume can be stably detected.

Further, the first integration operation and the second integration operation are performed at a plurality of different timings. At each of the plurality of different timings, the integration time of the first integration operation and the integration time of the second operation are determined. Is compared, the integration time based on the second integration operation at the time of impregnation is obtained as a different value at each timing. Therefore, based on the value of the different integration time, whether the dielectric constant of the liquid is relatively small or It can be determined whether the liquid is relatively large, and the type of liquid can be determined based on the difference in the dielectric constant. This makes it possible to determine the amount of liquid according to the type of liquid, and as a result, it is possible to stably detect a minute change in the amount of liquid regardless of the type of liquid. Also,
By setting each timing according to the type of liquid, it is possible to identify whether an appropriate liquid (for example, printing ink) tank is loaded or not, thereby preventing trouble due to erroneous loading.

Further, the integration time constant of the first integration circuit is set to the second time when the tip of the detection electrode is not immersed in the liquid.
If the integration time constant is set to be substantially the same as the integration time constant corresponding to the capacitance of the capacitor, the integration time constants of both integration circuits will be substantially the same during non-impregnation, and the integration time constants of both integration circuits will be different values during impregnation. Therefore, it can be easily determined whether or not the tip of the detection electrode is immersed in the liquid based on this difference.

The method and apparatus for detecting a liquid according to the present invention are basically similar to a conventional capacitance detection sensor in that the dielectric constant of a liquid is used.
Compared to the above various sensors except the capacitance detection sensor,
A small and low-cost device can be realized.

[0025]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a schematic structural view of a cylindrical plate cylinder provided with an embodiment of an ink detecting device which is an embodiment of the device for performing the liquid detecting method according to the present invention.

The cylindrical plate cylinder 1 shown in FIG. 1 is used in a stencil printing apparatus, has a porous structure that allows the passage of printing ink, and has a stencil sheet 2 attached to the outer peripheral surface thereof. It has become so. Further, the plate cylinder 1 is driven to rotate around its own central axis in a counterclockwise direction in the figure by a motor (not shown).

In the plate cylinder 1, an ink supply roller (ink application roller) 3 having a smaller diameter than the ink supply roller 3 is disposed. The plate cylinder 1 is driven to rotate in a counterclockwise direction about its own central axis, that is, the axis 4 by the rotation of the plate cylinder 1 in the figure.

A doctor rod (squeegee roller) is provided in the plate cylinder 1 at a predetermined minute interval t with respect to the outer peripheral surface of the ink supply roller 3 so as to be substantially parallel to the generatrix (axis) of the ink supply roller 3. 5 are arranged.

The outer peripheral surface of the ink supply roller 3 and the doctor rod 5 are positioned on the ink-engaging side between the ink supply roller 3 and the doctor rod 5, that is, on the right side of the doctor rod 5 in the drawing.
Defines an ink reservoir 6 which forms a space with a wedge-shaped cross section that is open at the top. Printing ink is supplied to the ink reservoir 6 through an ink supply pipe 7,
An ink mass Q is formed. This printing ink may be either aqueous or oily,
It has sufficient viscosity to form an ink mass Q as shown.

As shown in FIG. 1, in the vicinity of the ink reservoir 6, an electrostatic sensor having two detection electrodes 8, which are provided so as to face the ink reservoir 6 and hang down toward the ink mass Q, is provided. A capacitive ink detection device 10 is provided. The ink detector 10 electrically determines the amount of print ink in the ink reservoir 6 based on the change in the capacity between the two detection electrodes 8 according to the amount of print ink in the ink reservoir 6. When the detection is performed, that is, when the ink reservoir 6 has a predetermined amount of printing ink or more, the detection electrode 8 is connected to the ink reservoir 6.
A signal indicating that the detection electrode 8 is in an impregnated state is generated by contact with the printing ink of the detection ink. A signal indicating that the detection electrode 8 is in a non-impregnated state is output when the contact is stopped. The signal S5 indicating each state output from the ink detecting device 10 is input to a system microcomputer 20 that controls the entire printing press.

The printing ink of the ink mass Q passes through the gap t between the ink supply roller 3 and the doctor roller 5 with the rotation of the ink supply roller 3, and the ink is supplied while being measured based on the interval dimension. The ink adheres in a layer on the outer peripheral surface of the roller 3 and forms a printing ink layer R having a uniform thickness on the outer peripheral surface. This printing ink layer R is provided on the ink supply roller 3.
Is transferred to a contact area S between the ink supply roller 3 and the inner peripheral surface of the plate cylinder 1, and the contact area S contacts the plate cylinder 1.
Is transferred to the surface of the printing paper P by passing through the plate cylinder 1 and the stencil sheet 2 and being pressed by the ink supply roller 3.

At this time, the amount of printing ink of the ink mass Q is
The printing ink detecting device 10 detects the amount of printing ink supplied from the ink supply pipe 7 to the ink reservoir 6 based on the detected amount. The system microcomputer 20, the ink pump driving circuit 50, and the ink pump driving motor 5
2 are controlled. Note that the system microcomputer 20 also functions as the second determination circuit of the present invention.

Next, the configuration and operation of the ink detecting device 10 will be described in detail. FIG. 2 shows an ink detection device 10.
FIG. 3 to FIG. 6 are diagrams showing details of each circuit constituting the ink detecting apparatus 10, and FIG.
12 to 12 are timing charts for explaining the operation of the ink detecting device 10.

As shown in FIG. 2, the ink detecting device 10 includes a driving circuit 11, a first integration circuit 12 and a second integration circuit 13 driven by the driving circuit 11, a first integration circuit 12 and a second integration circuit. Each output signal S2, S3 of the circuit 13
And a shaping circuit 15 to which the output signal S4 of the determination circuit 14 is input.

As shown in detail in FIG. 3, the drive circuit 11 includes a pulse generation circuit 11a for generating a pulse S0 at a predetermined timing, and an integration circuit 11b for setting an integration start time and an integration stop time. Have been. The pulse generation circuit 11a generates a pulse S0 at a predetermined timing for determining a reference time for detecting the amount of printing ink as shown in (a) of each timing chart. The integrating circuit 11b includes an operational amplifier OPA1, a resistor R
1, capacitor C0, and zener diode ZD1
The pulse S0 generated from the pulse generation circuit 11a is input to the inverting input terminal-of the operational amplifier OPA1 through the resistor R1, and is integrated by the resistor R1 and the capacitor C0, as shown in (b) of each timing chart. Rising and falling dull (with slope)
Generate a reference signal S1. The reference signal S1 is input to the first integration circuit 12 and the second integration circuit 13, and is used as a drive signal for causing the integration circuits 12 and 13 to perform an integration operation.

In FIG. 3, a capacitor C1 (a first capacitor of the present invention) is a capacitor for determining a reference integration time, and a capacitor C2 (a second capacitor of the present invention) determines the capacitance of the printing ink. It represents a capacitance formed by two detection electrodes 8 for measurement. Capacitor C2
Is constituted by two needle-shaped detection electrodes 8 having a sharp tip 8a and arranged opposite to the printing ink in the ink reservoir 6, as shown in FIG. The capacitance is determined by the dielectric constant of the intervening substance. When the ink amount of the ink mass Q in the ink reservoir 6 is equal to or greater than a predetermined amount, the two detection electrodes 8 have their sharp tips 8a in contact with (impregnated with) the ink mass Q. Since the printing ink has a higher dielectric constant than air, the capacitance of the capacitor C2 increases as the ink mass Q increases and the length of the tip 8a immersed in the ink mass Q increases. The shorter the length of immersion in the ink mass Q, the smaller it becomes.

As the structure of the detection electrode 8, a metal needle as shown in FIG. 7A or a metal plate as shown in FIG. 7B may be used. In FIG. 7A, the length x, interval y, thickness, and material of the needle are shown, and in FIG. 7B, the length x, interval y, width z, thickness, and material of the metal plate are those of the printing ink. In accordance with the type and characteristics, it is set so that the determination (detection) described below can be performed stably. For example, when oil-based ink is used as the printing ink, the capacitance between the electrodes when the two detection electrodes 8 are in contact with the ink mass Q may be set to be about several picofarads.

As shown in FIG. 4, the first integrating circuit 12 includes an operational amplifier OPA2, resistors R2, R3, and R4.
And a capacitor C1. The second integration circuit 13 includes an operational amplifier O, as shown in detail in FIG.
PA3, resistors R5, R6, R7 and capacitor C2
C3. Capacitor C3 varies the integration time of the integration circuits 12 and 13 (including the stray capacitance).
, The detection electrode 8 not in contact with the ink mass Q (ie, the capacitor C2)
The integration time constant of the second integration circuit 13 determined by the capacitor C3 and the resistance R5 is set to be the same as the integration time constant of the first integration circuit 12 determined by the capacitor C1 and the resistance R2. Thereby, the detection sensitivity to the change in the capacitance of the capacitor C2 can be increased.

As is clear from both figures, both integration circuits 1
2 and 13 have the same basic configuration, but the first integrator 12
The voltage VR is divided by the resistors R3 and R4, the reference voltage Th1 is input to the non-inverting input terminal +, and the second integrating circuit 1
3, the voltage VR is divided by the resistors R6 and R7 at a ratio different from the voltage division ratio of R3 and R4, and the reference voltage Th2 is input to the non-inverting input terminal +. Therefore, both integration circuits 1
Reference numerals 2 and 13 are set so that start times of integration (both charging and discharging) are different according to the output signal S1 of the drive circuit 11. In the present embodiment, when the detection electrode 8 is in contact with the ink
In order for the determination circuit 14 to detect a change in the integration time at the time of the rise of the second integration circuit 13 when the change is made during the impregnation when the contact is made, the setting is made such that Th2 <Th1.

As shown in FIG. 2, the output signal S2 of the first integration circuit 12 and the output signal S3 of the second integration circuit 13 are input to a judgment circuit 14 corresponding to the first judgment circuit of the present invention. The determination circuit 14 compares the level difference between the output signals S2 and S3 to determine the integration time indicated by the output signal S2 of the first integration circuit 12 and the output signal S2 of the second integration circuit 13.
The integration times indicated by 3 are compared.

In this example, the output signal S4 of the determination circuit 14 becomes a low level signal when the output signal S2 of the first integration circuit 12 is higher than the output signal S3 of the second integration circuit 13, and in the opposite case. It becomes a high level signal.

Here, in order to increase the reliability of the comparison operation in the judgment circuit 14, the amplitude relationship between the output signals S2 and S3 of the integration circuits 12 and 13 is determined by the output signal S2.
Low level voltage V2L <low level voltage V3L of output signal S3 and high level voltage V2H of output signal S2
<The high-level voltage V3H of the output signal S3 is satisfied, and no malfunction occurs during the level difference comparison. In this example, the low-level voltages V2L and V3L and the high-level voltages V2H and V3H correspond to the corresponding integration circuits 1 respectively.
2, 13 saturation voltages.

It should be noted that both output signals S2 and S3 are V2L ≒
V3L, V2H ≒ V3H, output signals S2, S
3 does not satisfy the above condition, an appropriate level conversion circuit 1 is connected between one or both of the integration circuits 12 and 13 and the determination circuit 14, as shown in FIG.
6, at the input terminal of the determination circuit 14, the low-level voltage V2L 'of the output signal S2' obtained by level-converting the output signal S2 <the low-level voltage V3L 'of the output signal S3' obtained by level-converting the output signal S3, and Output signal S
It is preferable to satisfy 2 ′ high-level voltage V2H ′ <high-level voltage V3H ′ of output signal S3 ′.

The output signal S4 of the judgment circuit 14 is input to the shaping circuit 15. As shown in detail in FIG. 6, the shaping circuit 15 includes a detection circuit 15a including a capacitor C4, a resistor R12, a diode D1, a resistor R13, and a capacitor C5, and a level conversion circuit 15b. Note that the capacitor C4 and the resistor R12 form a differentiating circuit,
Diode D1, resistor R13, and capacitor C5 form a rectifier circuit. Further, the level conversion circuit 15b
"0" when the input level is lower than the predetermined level,
When the level is higher than the predetermined level, a digital output of "1" is issued. Here, the voltage levels of “0” and “1” correspond to the circuit at the subsequent stage (in this example, the system microcomputer 20).
Voltage input level and interface compatibility.

The output signal S4 of the determination circuit 14 input to the shaping circuit 15 is detected by a detection circuit 15a and then converted into a digital signal S5 of an ON signal "0" and an OFF signal "1" by a level conversion circuit 15b. The data is input to a system microcomputer 20 that controls the entire printing press.

The system microcomputer 20 receives the digital signal S
5, an on / off signal S6 for driving the electric motor 52
Is generated, and the generated on / off signal S6 is input to the ink pump driving circuit 50. The ink pump drive circuit 50 includes:
It controls the energization of the motor 52 for driving the ink supply pump. When the ON signal is given from the system microcomputer 20, in other words, when the digital signal S5 from the ink detector 10 is "0", the motor is controlled. The operation of the system microcomputer 2 causes the ink reservoir 6 to replenish the printing ink from the ink supply pipe 7 by operating the
When the OFF signal is given from 0, in other words, when the digital signal S5 from the ink detecting device 10 is “1”, the motor 52 is stopped.

Next, the operation of the ink detecting device 10 having the above configuration will be described in detail with reference to timing charts 1, 2, 3, and 4 shown in FIGS.

In each of the timing charts 1 to 4,
(A) shows the output signal S0 of the pulse generation circuit 11a,
(B) shows the output signal S1 of the integration circuit 11b. Also,
(C) shows the output signal S2 of the first integration circuit 12,
(D) shows an output signal S3 of the second integration circuit 13,
(E) shows the output signal S4 of the determination circuit 14, and (f) shows the output signal S5 of the shaping circuit 15.

The output signal S0 of the pulse generation circuit 11a is input to the integration circuit 11b and shaped into a signal S1 having a slope according to a design value. In (b) of the timing chart 1, td0 is a delay time (integration time) at the time of rising, and td0 'is a delay time (integration time) at the time of falling.

The non-inverting input terminals of both integrating circuits 12 and 13+
As described above, in the integration circuit 12, the reference voltage Th1
However, the reference voltage Th2 is input to the integration circuit 13, and each of the reference voltages Th1 and Th2 changes when the detection electrode 8 changes from non-impregnation to impregnation.
In order to detect a change in the integration time at the time of the rising edge of No. 3, different voltage values such as Th1> Th2 are set, so that the first integration circuit 12 starts integration after the rising of the output signal S0. Integration start delay time td3 after elapse of delay time td2 and after falling of output signal S0
While the integration is started after the lapse of time, the second integration circuit 13 starts the integration after the lapse of the integration start delay time td1 after the rise of the output signal S0 and after the lapse of the integration start delay time td4 after the fall of the output signal S0. .

The first integration circuit 12 integrates (charges) after the integration start delay time td2 (> td1) has elapsed.
And the integration operation is continued until the output signal S2 reaches the high-level voltage V2H (integration time tup1). Similarly, the integration (discharge) is started after the integration start delay time td3 (<td4) has elapsed. The integration operation is continued until S2 reaches the low level voltage V2L (integration time tdn1). The second integration circuit 13 starts integration (charging) after the integration start delay time td1 has elapsed, and continues the integration operation until the output signal S3 reaches the high level voltage V3H (integration time tup2). The integration (discharge) is started after the integration start delay time td4 has elapsed, and the integration operation is continued until the output signal S3 reaches the low level voltage V3L (integration time tdn2).

On the other hand, in (a) of each of the timing charts 1 to 4, the output signal S0 of the pulse generation circuit 11a is output.
(The level "1" portion) and t2 (the level "0" portion) are set in accordance with the printing ink and the capacitance generated by the detection electrode 8. Here, t1 is the sum “td1 + t” of the integration start delay time td1 and the integration time tup2 when the second integration circuit 13 rises when the detection electrode 8 is in contact with the ink mass Q.
up2 ”, and t2
Is set to be longer than the sum “td4 + tdn2” of the integration start delay time td4 and the integration time tdn2 when the second integration circuit 13 falls at the time of impregnation. Note that the pulse duty ratio of t1 and t2 (t1 /
(T1 + t2) · 100) is not particularly limited, but is, for example, about 50%.

Note that the detection device 10 can detect
When the maximum value of the capacitance of the capacitor C2 is limited when the detection electrode 8 is in contact with the ink mass Q, that is, when the detectable capacitance change width is limited, t2 is the maximum value of the capacitance of the capacitor C2 to be limited. Td4 + t in value
It is set to be shorter than the value of dn2 (td4 + tdn2) max.

Note that each of the delay times td0 and td0 'is determined by the characteristics of the detection electrode 8, the printing ink,
13. Integration start delay times td1 and td, which are marginal times for obtaining an accurate operation by absorbing the variation of T.13
2, td3, and td4 are times for producing the above-described timing. Therefore, td0, td
If the variation of the elements is small, 0 ′ is set so that a spurious pulse is not generated from the determination circuit 14 when the integration circuits 12 and 13 rise and fall when the detection electrode 8 is not impregnated. tup2 ≦ (td2-td1
+ Tup1) and (td3 + tdn1) ≦ td4 +
As long as tdn2 is satisfied, it is preferable to be as short as possible. As described above, by setting in consideration of the variation range of each component, no adjustment can be performed, and the device can be reduced in cost and high in reliability.

When detecting a change in the capacitance of the capacitor C2 caused by the contact of the detection electrode 8 with the ink mass Q, a small change can be detected by using tup2 << t1, tdn2 << t
It is preferable to set it to 2. Note that such a setting is also effective in expanding the detectable range.

Here, when the detection electrode 8 is not in contact with the ink mass Q when it is not impregnated, the integration time constants of the two integration circuits 12 and 13 are set to be the same as described above. tup1 ≒ tup2 and tdn1 ≒ tdn2. Therefore, during the integration period of the two integration circuits 12, 13, the output signal S3 does not become lower than the output signal S2, and the output signal S2, S3 is a level comparison result of the determination circuit 14. S4 is always at the high level "1" as shown in (e) of the timing chart 1 shown in FIG. This high level output signal S4
Does not pass through the differentiating circuit composed of the capacitor C4 and the resistor R12 of the shaping circuit 15, so that the input of the level converting circuit 15b becomes low level and the output signal S5 of the shaping circuit 15
Is always at the low level “0”.

On the other hand, when the detection electrode 8 is in contact with the ink mass Q in the ink reservoir 6, that is, when a predetermined amount of printing ink is present in the ink reservoir 6, the ink has a high dielectric constant. When the capacitance of the capacitor C2 of the second integration circuit 13 is increasing, the integration time constant of the second integration circuit 13 is increased by an amount corresponding to the increase of the capacitance of the capacitor C2. Since there is no change, tup1 <tup2 and tdn1 <tdn2 may be satisfied. Therefore, when the change in the capacitance of the capacitor C2 is large to some extent, a period in which the output signal S3 becomes lower than the output signal S2 occurs during each cycle of the output signal S0 during the integration period of the two integration circuits 12, 13. S
The output signal S4, which is the result of level comparison between S2 and S3 by the determination circuit 14, is shown in the timing chart 2 shown in FIG.
(E), when the output signal S3 becomes lower than the output signal S2, that is, in (c) and (d) of the timing chart 2, where the rising level of the signal S2 exceeds the rising level of the signal S3. A pulse indicating ink detection, which becomes low level "0" at P1 and becomes high level "1" at P2 where the rising level of signal S3 exceeds high level V2H of signal S2, is generated. This pulse-shaped output signal S4 passes through a differentiating circuit including a capacitor C4 and a resistor R12 of the shaping circuit 15, and is rectified and detected by a rectifying circuit including a diode D1, a resistor R13, and a capacitor C5. The input of the conversion circuit 15b becomes high level, and the shaping circuit 15
Is always at the high level "1".

Accordingly, based on the low level “0” of the output signal S5 when the detection electrode 8 is not impregnated and the high level “1” of the output signal S5 when impregnated, the system microcomputer 20, the ink pump driving circuit 50 and If the supply amount of the printing ink supplied from the ink supply pipe 7 to the ink reservoir 6 is feedback-controlled via the ink pump driving motor 52, the amount of the printing ink filled in the ink reservoir 6 is always adjusted to an appropriate amount. Can be maintained.

Next, the operation when the capacitance of the capacitor C2 detected by the detection electrode 8 during the impregnation is larger than the set detection range will be described with reference to a timing chart 3 shown in FIG. It should be noted that the time axis in FIG. 11 is shown more compressed than in FIG. 9 and FIG.

In this case, the maximum value of the capacitance of the capacitor C2 when the detection electrode 8 comes into contact with the ink mass Q is limited, that is, the detectable capacitance change width is limited. Therefore, t2 should be limited. The value of td4 + tdn2 (td4 + tdn) at the maximum value of the capacitance of the capacitor C2
2) Set to be shorter than max. Also, t1
Is the sum “td1 + tup2” of the integration start delay time td1 and the integration time tup2 when the second integration circuit 13 rises when the detection electrode 8 is in contact with the ink mass Q.
Set to be longer than Although the condition relating to the setting of t1 is not an essential condition, in order to increase the speed at which the output signal S5 converges to a high level (see later), it is necessary to set t1 (exactly, until the start of the discharge start at t2). It is preferable that the output signal S3 reaches a high level during the period), and it is better that the above condition is satisfied.
Further, in this example, since the integration time constants at the time of rising and at the time of falling are the same, as a result, the pulse duty ratio of t1 and t2 is 50% or more, that is, t1> t2
Will be set to Note that the pulse generation circuit 11a is provided with the system microcomputer 2 so that the pulse duty ratios of t1 and t2 can be changed and set as described above.
It is preferable that the pulse duty ratio of t1 and t2 of the output signal S0 be freely programmable by a command S7 of 0.

When the capacity of the capacitor C2 of the second integrating circuit 13 exceeds the range shown in the timing chart 2 and exceeds the detectable range, the integration time constants at the time of rising and falling are very large. Become. At this time,
Since the condition of t1> t2 is set, a sufficient discharge time cannot be secured and tup2> tdn2, so that the low level voltage V3L of the output signal S3 of the second integration circuit 13 is
Eventually, the voltage settles to the voltage V3Lmax obtained by subtracting the amount discharged during the discharge period (the integration time tdn2 in the cycle) from the high level voltage V3H during the fall, and the rise at the time of charging starts from the voltage V3Lmax. Will repeatedly charge and discharge between the voltage V3Lmax and the high-level voltage V3H.

At this time, when the capacity of the ink is sufficiently larger than the capacity of the normal ink, for example, the type of the ink is different and the capacity of the ink is 2
When the capacity is of the order of magnitude (several nF), the output signal S3 is fixed at a substantially high level during the period of repeated charging and discharging, and the output signal S3 does not become lower than the output signal S2. As a result, both output signals S2,
As shown in (e) of the timing chart 3 shown in FIG. 11, a low level pulse is generated at the beginning of the measurement of the output signal S4, which is a result of comparing the level of S3 by the determination circuit 14, but the high level signal “S3” is eventually output. 1 ". Since the high-level output signal S4 does not pass through the differentiating circuit including the capacitor C4 and the resistor R12 of the shaping circuit 15, the input of the level conversion circuit 15b becomes low. As a result, the output signal S5 of the shaping circuit 15
Is set to a high level when a pulse output is output to the output signal S4, but is fixed to a low level “0” when the output signal S4 is fixed to a high level. This makes it possible to detect that the detection electrode 8 has come into contact with the ink mass Q and that the capacitance of the capacitor C2 has exceeded the detectable range.

However, the output signal S5 is at low level "0".
Is the same as the above-described state at the time of non-impregnation in which the detection electrode 8 is not in contact with the ink mass Q. This means
In the ink detection device 10 according to the above embodiment,
When the output signal S5 becomes high level “1”,
The detection electrode 8 is in contact with the ink mass Q and the capacitance of the capacitor C2 is within the detectable range, in other words, the ink reservoir 6
It can be determined that the appropriate amount of the printing ink has been filled, but when the output signal S5 becomes low level “0”,
Whether the detection electrode 8 is not in contact with the ink mass Q,
Alternatively, it is difficult to accurately determine whether the detection electrode 8 is in contact with the ink mass Q and the capacitance of the capacitor C2 exceeds the detectable range.

The following two states can be considered as a state where the detection electrode 8 contacts the ink mass Q and the capacitance of the capacitor C2 exceeds the detectable range. The first state is an overfilled state in which the dielectric constant of the printing ink is relatively small, such as oil-based ink, and the detection electrode 8 is impregnated to the deep part of the ink mass Q. The second state is, for example, an emulsion state. The detection electrode 8 is in contact with the ink mass Q of the printing ink having a relatively large dielectric constant, such as ink, in other words, an inappropriate printing ink is being used.

In the first state, the capacity of the capacitor C2 increases as the amount of ink increases.
If it is detected that the detection electrode 8 has come into contact with the ink mass Q and the supply amount of the printing ink supplied from the ink supply pipe 7 to the ink reservoir 6 is controlled, the capacity of the capacitor C2 exceeds the detectable range. Is usually not reached rapidly, it is possible to determine whether the printing ink in the ink reservoir 6 is in the unfilled state or the overfilled state by monitoring the change state of the output signal S5. It is.

On the other hand, in the case of the second state, the detection electrode 8
Since the output signal S5 suddenly goes to the low level "0" when touches the ink mass Q, the pulse or the output signal S5 generated in the output signal S3 when the detection electrode 8 comes into contact with the ink mass Q suddenly becomes low. Unless the moment of “0” is detected, it is difficult to determine whether the proper printing ink is in an unfilled state, an overfilled state, or whether an inappropriate printing ink is used. is there.

Therefore, it is necessary to accurately determine whether the detection electrode 8 is not in contact with the ink mass Q or whether it is in contact with the ink mass Q and the capacitance of the capacitor C2 exceeds the detectable range. As a method, the pulse generation circuit 11
Change the setting of the pulse timing of the output signal S0 issued from a. For example, as shown in the timing chart 4 of FIG. 12, the pulse duty ratio of t1 and t2 is set to 50% or less to expand the detectable range and If the low-level voltage V3L of the output signal S3 of the two-integration circuit 13 reaches the low-level saturation voltage within the period of t2,
The rise at the time of charging starts from the low-level saturation voltage, and even in a state where an inappropriate printing ink having a large dielectric constant is used, the output signal S3 is different from the output signal S2 as in FIG. The state in which the detection electrode 8 contacts the ink mass Q can be detected when the output signal S5 becomes high level "1".

Therefore, in the ink printing apparatus 10 to which the present invention is applied, two kinds of pulse timings as shown in FIGS. 11 and 12 are used so as to correspond to the range of the capacitance value detected by the detection electrode 8. The system microcomputer 2 which performs detection and functions as a second determination circuit of the present invention based on each output signal S5 at each pulse timing
By making a determination based on 0, as shown in FIG. 13, it is possible to detect an oil-based low-impedance (low-permittivity) printing ink, and to determine whether ink is present, that is, whether the printing ink is in a non-filled state or not. It can also be determined whether an appropriate amount of ink has been filled or an inappropriate ink has been filled. In the above example, a printing ink having a relatively high dielectric constant is regarded as an inappropriate ink. However, it goes without saying that a printing ink having a relatively low dielectric constant can be determined as an inappropriate ink. . Further, by performing detection at three or more types of pulse timings, it is possible to classify the difference in dielectric constant, that is, the difference in ink type more finely.

In the description of FIG. 11, it is assumed that the ink capacity is sufficiently larger than the normal ink capacity, and the signal S3 does not become lower than the signal S2 during the period of repeated charging and discharging. Is smaller, the signal S3 becomes lower than the signal S2 as shown in FIG.
At the rise of the signal S4, a pulse having a very small width is output as the signal S4, and a detection error may occur. In this case, the above problems can be solved by adjusting the offset amount of the signal S3, lowering the high level of the signal S2, and shortening the period t2, but new problems such as an increase in the dead area due to these changes. This is not always preferable, since it may also occur.

Next, an embodiment will be described in which a detection error does not occur not only when the capacitance difference is large but also when the capacitance difference is small.

FIG. 15 is a circuit block diagram showing a main part of another embodiment of the ink detecting apparatus, and FIG. 16 is a timing chart for explaining the operation. In the digital output in FIG. 16, the L (low) level is indicated by “0” and the H (high) level is indicated by “1”.

The difference from the above embodiment lies in the judgment circuit.
The first and second integration circuits 12 and 13 use the same ones as in the above embodiment. The determination circuit 14 of this embodiment has two comparators (level comparators) 72 and 73 and an EX-OR gate 74 as shown in FIG.
The output signal S2 of the first integration circuit 12 is supplied to the comparator 72.
Is input and compared with the reference voltage TH3, and when the signal S2 is higher than the reference voltage TH3, the output S72 of the comparator 72 becomes L. The output signal S3 of the second integration circuit 13 is input to the comparator 73 and is compared with the reference voltage TH3. When the signal S3 is higher than the reference voltage TH3, the output S73 of the comparator 73 becomes L. The outputs S72, S of the comparators 72, 73
73 is input to the EX-OR gate 74. Each of the comparators 72 and 73 can perform a stable level comparison because the reference operation point of the comparison operation is fixed.

At the time of non-impregnation when the detection electrode 8 is not in contact with the ink mass Q, the outputs S72 and S73 of the comparators have the same output waveform as shown in FIG. The output S74 becomes L. As shown in the figure, the output S74 may generate edge noise at the edges of the signals S72 and S73 due to the variation. However, when the edge noise becomes a problem, a noise removing circuit may be provided.

On the other hand, when the detection electrode 8 contacts the ink mass Q, as shown in FIG. 16B, the L level timing of the output S73 is changed to the output S72 in accordance with the size of the ink capacity.
In contrast, or when the capacity is extremely large, it remains at H, and a pulse (active H) having a width corresponding to the magnitude of the ink capacity is output to the output S74.

Therefore, by detecting the pulse width of the output S74 by, for example, a microcomputer, the presence or absence of ink and the difference in ink capacity (dielectric constant), that is, the ink type can be detected without changing the pulse timings t1 and t2. become able to.

As shown in FIG. 17, instead of the EX-OR gate 74, a mask circuit 75 for outputting a mask signal S75 (active H) of a predetermined width based on the falling edge of the output S72, and a mask signal S75 The AND gate 76 to which the signal S73 is input, the pulse comparison circuit 77 to which the output signal S76 of the AND gate 76 and the mask signal S75 are input to detect the difference between the two signals, and the shaping circuit 15 to which the output signal S76 is input May be provided. As the pulse comparison circuit 77, for example, EX-O
It is preferable to use an R gate or a latch.

FIG. 18 is a timing chart for explaining the operation of the determination circuit shown in FIG. A pulse (active H) having a width only until the signal S73 falls within the mask period Tm is output from the AND gate 76,
The output signal S76 of the AND gate 76 is input to the shaping circuit 15 similarly to the signal S4 of the above-described embodiment. When the output signal S76 has a pulse output, the presence of ink can be detected.

From the pulse comparison circuit 77, an output S77 that is H when the two input signals S75 and S76 are the same and L when they are different is obtained. When the output S77 is H, it indicates that the ink capacity is larger than the mask width Tm. Therefore, by repeating the detection while sequentially changing the mask width Tm so as to increase, the ink capacity can be separated, that is, the ink type can be determined.

Further, by providing the mask circuit 75, the stability against detection errors due to edge noise or the like can be improved.

FIG. 19 is a block diagram (A) showing another configuration example in which the ink capacity is classified by appropriately changing the mask width Tm, a timing chart (B) for explaining the operation thereof, and a judgment table. (C).

In this case, a mask circuit 81 for outputting a mask signal S81 which is triggered by the falling edge of the output signal S72 and becomes H level after a relatively short time ta has elapsed and returns to L level immediately before the fall of the output signal S72, Signal S72
The mask circuit 82 outputs a mask signal S82 which is triggered by the falling edge of the output signal S72 and becomes H level just before the rising edge of the output signal S72 and returns to the L level just before the falling edge of the output signal S72, and the output signal S73 of the comparator 73 is masked. Latches 83 and 84 for latching at the rising edges of the signals S81 and S82 are provided.

The mask circuits 81 and 82 also function to reduce detection errors due to variations, and the mask circuit 8
The rising timing of the output S81 of 1 may be determined according to the minimum detection value of the ink capacity, and the rising timing of the output S81 of the mask circuit 82 may be determined according to the detectable range of the ink capacity.

Further, several stages of a mask circuit having a rising edge within each rising period of the mask circuits 81 and 82 and a latch for latching the output signal S73 of the comparator 73 at the rising edge of the mask signal which is the output thereof are provided. Is also good.

FIG. 19C shows a determination table in a case where a mask circuit and latches are provided for a total of four stages. According to the configuration shown in FIG. 19, as shown in FIG. 19C, even if the pulse timings t1 and t2 are not changed, not only the presence or absence of ink but also the magnitude of the ink capacity, that is, the ink type is finely classified. Since the shaping circuit 15 is not required, the circuit configuration is simple and the number of elements is small. Further, there is an effect that all the parts after the comparator can be constituted by digital circuits.
Furthermore, if the mask timing is configured to be program-controllable, the mask circuit and the latch circuit are each one.
Can be made more compact.

Although the preferred embodiment of the ink detecting apparatus to which the liquid detecting method and apparatus according to the present invention has been described, the present invention is not necessarily limited to the above-described embodiment.

For example, in the above description, the change in the integration time caused by the contact of the detection electrode 8 with the ink mass
The two integrating circuits 12 and 13 are started substantially simultaneously, and the output signal S of the determination circuit 14 is set at the time of the charging operation, that is, at the time of the rising of the output signals S2 and S3 of the integrating circuits 12 and 13.
4 has been described as being detected by detecting the pulse generated in the integration circuits 12 and 13 as long as the change in the integration time can be detected.
May not be started at substantially the same time, and by changing the integration start delay time of each of the integration circuits 12 and 13, the discharge operation, that is, each of the integration circuits 12 and 13 may be changed.
The change in the integration time can be detected by detecting a pulse generated in the output signal S4 of the determination circuit 14 when the output signals S2 and S3 of the 13 fall.

In the above description, the change in the integration time caused by the contact of the detection electrode 8 with the ink mass Q is detected by comparing the level difference between the output signals S2 and S3 of the integration circuits 12 and 13. However, the present invention is not limited to this, and the tip portion 8a of the detection electrode 8 is not impregnated in the ink mass Q and is not impregnated.
Any comparison circuit may be used as long as the change in the integration time of the integration circuit 13 or the change in the integration time of the second integration circuit 13 in accordance with the change in the impregnation amount is detected.

In the above description, the two detection electrodes 8
Has been described as detecting the capacitance of the capacitor C2 formed between the two electrodes.
As described in No. 20, the number of detection electrodes 8 is one, and the capacity of a capacitor C2 formed between the detection electrodes 8 and the ink supply roller 3 and the doctor roller 5 facing the detection electrodes 8 is determined by printing in the ink reservoir 6. The amount of print ink stored in the ink reservoir 6 may be electrically detected based on a change in accordance with the amount of ink stored.

Further, in the above description, the integration circuit 12,
Although 13 is configured using an operational amplifier, it goes without saying that the circuit can be realized by another device such as a transistor.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a cylindrical plate cylinder provided with an embodiment of an ink detection device to which a liquid detection method according to the present invention is applied.

FIG. 2 is a circuit block diagram of an embodiment of an ink detection device.

FIG. 3 is a circuit diagram showing details of a drive circuit.

FIG. 4 is a circuit diagram showing details of a first integration circuit;

FIG. 5 is a circuit diagram showing details of a second integration circuit;

FIG. 6 is a circuit diagram showing details of a shaping circuit;

FIGS. 7A and 7B show an example of the structure of a detection electrode;
(B)

FIG. 8 is a diagram showing an example in which a level conversion circuit is provided between each integration circuit and a determination circuit;

FIG. 9 is a timing chart illustrating the operation of the ink detection device.

FIG. 10 is a timing chart illustrating the operation of the ink detection device.

FIG. 11 is a timing chart illustrating the operation of the ink detection device.

FIG. 12 is a timing chart illustrating the operation of the ink detection device.

FIG. 13 is a view for explaining a determination method in consideration of a difference in dielectric constant.

FIG. 14 is a timing chart for explaining a detection error when the ink capacity difference is small.

FIG. 15 is a circuit block diagram illustrating a main part of another embodiment of the ink detection device.

16 is a timing chart illustrating the operation of the configuration shown in FIG.

FIG. 17 is a block diagram showing another configuration example of the determination circuit;

18 is a diagram illustrating the operation of the determination circuit shown in FIG.

FIG. 19 is a diagram illustrating another configuration example of a determination circuit and its operation.

[Explanation of symbols]

REFERENCE SIGNS LIST 1 plate cylinder 2 stencil sheet 3 ink supply roller 5 doctor rod 6 ink reservoir 7 ink supply tube 8 detection electrode 10 ink detection device 11 drive circuit 12 first integration circuit 13 second integration circuit 14 determination circuit (first determination circuit) 15 Shaping circuit 16 Level conversion circuit 20 System microcomputer (also functions as a second determination circuit) C1 First capacitor C2 Second capacitor P Printing paper Q Ink block R Printing ink layer

Claims (6)

[Claims] 1. A first integration operation is performed according to an integration time constant corresponding to a capacitance of a first capacitor,
Corresponding to the capacitance of the second capacitor connected to the detection electrode provided so that the tip can be immersed in the liquid when the amount of the liquid facing the liquid in the liquid reservoir becomes a predetermined amount or more. A second integration operation according to the integration time constant to be performed, and comparing the integration time of the first integration operation with the integration time of the second operation to determine whether the tip is immersed in the liquid. Determining whether the liquid is present or not. 2. The method according to claim 1, wherein the first integration operation and the second integration operation are performed at different timings, and at each of the different timings, the integration time of the first integration operation and the second integration operation are determined. Comparing with the integration time of the operation, it is determined whether the tip is immersed in a liquid having a relatively small dielectric constant or a liquid having a relatively large dielectric constant. 2. The liquid detection method according to 1. 3. A first integration circuit including a first capacitor having a predetermined capacity and performing an integration operation in accordance with an integration time constant corresponding to the capacity of the first capacitor; A second capacitor connected to a detection electrode provided so that the tip can be immersed in the liquid when the amount of pool of the liquid is equal to or more than a predetermined amount,
A second integration circuit that performs an integration operation in accordance with an integration time constant corresponding to a capacitance of the second capacitor; and a drive circuit that performs the integration operation on the first integration circuit and the second integration circuit. An output signal of the first integration circuit and an output signal of the second integration circuit are input, and an integration time indicated by an output signal of the first integration circuit and an integration indicated by an output signal of the second integration circuit. A first determination circuit that determines whether the tip is immersed in the liquid by comparing time. 4. The integration time constant of the first integration circuit is set to be substantially the same as the integration time constant corresponding to the capacitance of the second capacitor when the tip of the detection electrode is not immersed in the liquid. The liquid detecting device according to claim 3, wherein the liquid detecting device is used. 5. The apparatus according to claim 3, further comprising a shaping circuit for shaping a waveform of an output signal of the first determination circuit.
Or the liquid detection device according to 4. 6. The driving circuit causes the first integration circuit and the second integration circuit to perform the integration operation at a plurality of different timings, and obtains the integration operation at each of the different timings. A second determination for determining whether the tip is immersed in a liquid having a relatively small dielectric constant or a liquid having a relatively large dielectric constant based on the output signal of the first determination circuit. The liquid detection device according to any one of claims 3 to 5, further comprising a circuit.