JPH0115384B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a liquid temperature control device for controlling the temperature of ink in an inkjet printer or the like.

The device shown in FIG. 1 is known as a control device for controlling the temperature of ink supplied to the head of an inkjet printer. In Figure 1, 1
2 is a head, 2 is a nozzle, and 3 is an ink droplet. Ink supplied to the head 1 is heated by a heater 4 and supplied through a tube (flow path) 5. 6
is the first one that detects the temperature before being heated by the heater 4.
This temperature sensor is installed in a tube (flow path) 5' that supplies ink to the heater 4. 7 is a second temperature detector provided in the heater 4, and 8 is a controller.

The conventional liquid temperature control device configured in this way is
The temperature of the ink before heating is detected by the first temperature detector 6, the temperature of the heated ink is detected by the second temperature detector 7, and the outputs of the first and second temperature detectors 6, 7 are detected. The electric power supplied to the heater 4 is controlled by the voltage difference.

However, this liquid temperature control device uses a power transistor as a substitute for the heater 4 and uses the collector loss when current flows through the power transistor, so it has the disadvantage that the thermal response is very slow. Also, because the power transistor is large in size, it takes a considerable amount of time to heat itself, and the heat transfer member that conveys the temperature to the ink also requires a long time to heat up. There were flaws. If the rise of the heater 4 is slow in this way, it takes a long time for the temperature of the ink flowing to the head 1 to rise, and printing cannot be performed until the temperature stabilizes. Therefore, the heater 4 is usually designed to have a small volume so that the heater 4 can start up quickly. If the rise of the heater 4 is made faster in this way, after the inkjet printer is turned off for a short time as shown by A in FIG.
When restarted, since the head 1 is composed of an electrostrictive vibrator, a support member, and a housing, it takes about 2 to 10 minutes to cool down to the ambient temperature with natural air cooling, but the heater 4 Since it is cooled down in about 30 to 60 seconds compared to Head 1
Since the temperature of the ink flowing to the head 1 becomes higher than the printable temperature range shown by D in FIG. The drawback was that it required a very long waiting time. In this case, head 1
If a temperature sensor is installed in head 1, this problem will not occur, but if a temperature sensor is installed in head 1,
Since the heads 1 are mechanically connected by electric wires, there is a drawback that the direction in which ink is ejected is slightly affected.

In order to eliminate the drawbacks of the above-mentioned conventional example, the present invention provides a head for ejecting recording droplets, a flow path for supplying the recording liquid to the head, and a flow path that is provided in a part of the flow path and that is connected to at least the head. a first heater for heating the recording liquid having a small heat capacity; a first temperature detector for detecting the temperature of the recording liquid flowing into the first heater; and a first temperature detector for detecting the temperature of the recording liquid flowing into the first heater; A second temperature detector for detecting the temperature of the recording liquid, and a heat capacity equivalent to that of the head, which heats the recording liquid by being provided adjacent to an upstream portion of the first temperature detector in the flow path. a second heater comprising: a voltage addition means for adding the output voltage of the first temperature detector and the output voltage of the second temperature sensor; and a preset reference voltage and the output of the voltage addition means. It is characterized by having an error amplifier that amplifies the difference voltage from the voltage, and a voltage supply means for supplying the output voltage of the error amplifier to the first heater via the second heater. The present invention provides a liquid temperature control device that eliminates thermal overshoot of the liquid temperature and shortens printing waiting time when the device is restarted after being turned off for a short time. Hereinafter, embodiments will be described in detail with reference to the drawings.

FIG. 3 shows a configuration diagram of a liquid temperature control device according to an embodiment of the present invention, in which 1 is a head, 2 is a nozzle, 3 is an ink droplet, 4 is a first heater, 5, 5'
is a tube (flow path), 9 is a first temperature sensor, 1
0 is the second temperature detector, 11 is the voltage adder, 12
13 is an error amplifier; 14 is a second heater consisting of an electric heating plate 15, a heat sink 16, and an output power element 17 attached to the tube 5'; First,
The output of the second temperature detectors 9 and 10 is the voltage adder 1
1, and the voltage difference between this added value and the reference voltage V _ref from the reference power supply 12 is amplified by the error amplifier 13, and the voltage is applied to the output power element (second heater) 14 to the first heater 4.
The heater 4 is controlled. Also, the output power element 17
A transistor is used as the power element 1.
7 operates as a heater during steady control,
The second heater 14 is configured to heat the ink through a heat sink 16 and an electric heating plate 15. The heat capacity of the second heater 14 is approximately equal to the heat capacity of the head portion consisting of the head 1 and the nozzle 2, and the heat capacity of the first heater 4 is configured to be very small.

In the liquid temperature control device of this embodiment configured in this way, when the power is turned on as shown in A of FIG. As shown by curve C in FIG. 4, the temperature of the ink flowing to head 1 is quickly heated to a temperature range that allows printing (see D in FIG. 4). In addition, when the power is turned off and then turned on immediately as shown in A of FIG. 4, the heat storage effect of the second heater 14 causes the heater 4 to become Since the fall in temperature and the fall in ink temperature are the same, the second detector 10 is detecting almost the same temperature as head 1, so the temperature of the ink flowing to head 1 will be greatly exceeded. It is stable without any shoots, and the waiting time is extremely low.

FIG. 5 shows a configuration diagram of a liquid temperature control device according to another embodiment of the present invention. Parts with the same reference numerals as in FIG. 3 indicate the same parts, but in this embodiment,
A heat storage device 20 with a built-in heater 19 is provided as the second heater 18, and the power element 17 and the heat radiator 16, which were replaced by the second heater 14 in FIG. 3, are provided.
are provided outside the tubes 5 and 5' that supply ink.

The liquid temperature control device of this embodiment configured in this way can obtain the same effects as the embodiment of FIG. 3.

FIG. 6 shows a configuration diagram of a liquid temperature control device according to still another embodiment of the present invention, in which a filter 21 for removing ink dust is connected to the tube 5' as a second heater. The case is made of metal or a good thermal conductor, and a heat sink 22 is bonded to the case of the filter 21, so that the heat generated in the power element 17 is transmitted to the ink via the heat sink 22 and the case of the filter 21. . With this configuration, the same effects as the embodiment shown in FIG. 3 can be obtained, and if the heat sink 22 is also used as a support member for the filter 21, the number of parts can be reduced, making it more economical.

As described above, according to the present invention, a first temperature detector that detects the temperature of the ink before heating and a second temperature detector that detects the temperature of the ink after heat radiation are provided before and after the first heater. In addition, a second heater with the same heat capacity as the head was installed in front of the first temperature detector. This method has the advantage of eliminating thermal overshoot of ink and shortening printing waiting time.

[Brief explanation of drawings]

Figure 1 is a configuration diagram of a conventional liquid temperature control device;
1 is an explanatory diagram of the operation of the device shown in FIG. 1, FIG. 3 is a configuration diagram of a liquid temperature control device according to an embodiment of the present invention, FIG. 6 are configuration diagrams of a liquid temperature control device according to another embodiment of the present invention. DESCRIPTION OF SYMBOLS 1... Head, 2... Nozzle, 3... Ink droplet, 4... First heater, 5, 5'... Tube (flow path), 9... First temperature detector, 10... First... 2
Temperature detector, 11... Voltage adder, 12... Reference power supply, 13... Error amplifier, 14, 18... Second heater, 15... Heat transfer plate, 16, 22... Heat sink, 17 ... Power element, 19 ... Heater, 20
...Regenerator, 21...Filter. 30, 30'...
...Voltage supply means.

Claims (1)

[Claims] 1. A head for ejecting recording liquid droplets, a flow path for supplying recording liquid to the head, and a first head for heating the recording liquid, which is provided in a part of the flow path and has a heat capacity smaller than at least that of the head. and a heater of
a first temperature detector that detects the temperature of the recording liquid flowing into the first heater; a second temperature detector that detects the temperature of the recording liquid flowing out from the first heater; a second heater having a heat capacity equivalent to that of the head, the second heater being disposed adjacent to an upstream portion of the first temperature sensor in the path to heat the recording liquid; and an output voltage of the first temperature sensor. and an output voltage of the second temperature detector; an error amplifier that amplifies a differential voltage between a preset reference voltage and the output voltage of the voltage addition means; and an output of the error amplifier. A liquid temperature control device comprising: voltage supply means for supplying voltage to the first heater via the second heater.