JPH02115880A - Printing device - Google Patents

Abstract

PURPOSE:To prevent the unfixation and the yellowing, etc., of printing output by selectively setting the target temperature value of a fixation part after receiving data on paper feeding load. CONSTITUTION:At least two values are set in a control circuit 1 as the target temperature and either of the set target temperature values is selected according to data on motor driving current from a current detection circuit 8. In the case of using paper having average width, thickness and quality, a reference value is selected as the target temperature value in the control circuit 1. On the other hand, in the case of using heavy paper as printing paper, load applied on the tractor 12 of a paper feeding mechanism increases, so that the driving current of a DC motor 7 driving at constant speed increases. The increase of the driving current is detected by a current detection circuit 8. Based on the detected data, a high temperature value is automatically selected as the target temperature value.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a printing device, and particularly to a printing device that uses continuous paper as a printing medium.

[Conventional technology]

As a printing device for printing out information such as information processing equipment, a laser beam is used to project characters and figures onto a photosensitive drum to form an electronic latent image, and this is developed with toner, etc., and the image of this toner, etc. Electrophotographic printing devices that transfer images onto continuous paper are widely used.

In this type of printing device, it is important to fix characters and figures after they are transferred to continuous paper, and to ensure stable fixing that is not affected by differences in paper width, paper thickness, paper surface treatment, etc. requested.

FIG. 2 shows the configuration of an example of a conventional printing device.

In FIG. 2, the continuous printing paper 11 taken out from the hopper 15 has toner images such as characters and figures transferred thereon by a photosensitive drum, a current detector 10, etc., and is conveyed to a fixing section 16 by a tractor 12, where the toner image is transferred. After being fixed, it is stored in the stacker 14. Step motors, AC motors, DC motors, etc. are used to drive the tractor 12, but since highly accurate speed control and position control are required, and high torque is also required at the time of starting, DC motors are the mainstream. It has become.

The continuous printing paper 11 with the toner image attached thereon sent to the fixing section 16 is preheated by a preheater 5, and then the toner image is fixed at a thermocompression bonding section constituted by a roller heater 6 and a pressure roller 13.

The temperatures of the preheater 5 and the roller heater 6 are generally controlled by a temperature control means 17 using a method such as on/off control or PID control in combination with temperature detection means 4 and 4' using a thermistor or the like to maintain a constant target temperature. It is now possible to

[Problem to be solved by the invention]

As explained above, in the fixing section of a conventional printing device, the heater temperature control target is at one point, but since this target temperature is the surface temperature of the play heater 5 and roller heater 6, it is difficult to actually fix the toner. The temperature of the printing paper surface does not necessarily match that of the continuous printing paper 11.
During printing, the paper travels through the fixing section at a constant speed and continuously removes heat from the fixing section, so the surface of the continuous printing paper 11 may vary depending on its width, paper thickness, paper quality, and surface treatment state. The temperatures will vary, and generally wider, thicker sheets with higher surface smoothness tend to have lower temperatures.

For this reason, in printing devices that use various types of printing paper, the pre-heater 5 and roller heater The temperature of part 6 may be set higher.

However, when printing by setting thin continuous paper 11 with a narrow paper width into a printing device with such a high target temperature setting, the temperature of the paper surface will become too high, and in the worst case, the fixation may fail. In some cases, the printing paper may become scorched or yellowed. Furthermore, if the temperature of the fixing section is set to be low in consideration of this, a surface temperature sufficient for fixing may not be obtained for wide or thick paper, resulting in poor fixing.

In this way, the standard for setting the temperature of the fixing unit is determined by taking into account fixing performance (increasing the temperature) and yellowing of the paper (lowering the temperature), and in order to satisfy both, the temperature setting must be intermediate. I had no choice but to take a value (hereinafter referred to as the standard value). In other words, the target temperature at - point cannot fully satisfy the fixing properties and yellowing of various types of continuous paper in printing devices, and depending on the type of continuous printing paper, problems such as non-fixing and yellowing may occur. It had occurred.

For this reason, it is conceivable that the operator could set multiple target temperatures, high and low, and switch settings depending on the paper width, paper thickness, paper quality, etc. of the printing paper being used, but this would make the operation complicated.
Incorrect settings may actually increase accidents.

[Means to solve the problem]

According to the present invention, an electrophotographic printing unit; a fixing unit that heats and fixes images such as characters and figures developed or transferred by the printing unit to the printing paper surface with toner or the like;
In a printing device or the like having a paper feeding mechanism that conveys continuous paper for printing at a predetermined speed through the printing section and the fixing section, a load detection means for detecting a load applied to the paper feeding mechanism, and the fixing section temperature detection means for detecting the temperature of the fixing section; and a control section that receives temperature data detected by the temperature detection means and adjusts the temperature of the fixing section to a set temperature target value, and the control section adjusts the temperature of the fixing section to a set temperature target value. There is obtained a printing device characterized in that the temperature target value has at least two values, and the load detecting means receives paper feed load data and selects and sets one of the temperature target values.

〔Example〕

Next, the present invention will be described in more detail with reference to the drawings showing one embodiment of the present invention.

Referring to FIG. 1, in one embodiment of the present invention, the heaters of the preheater 5 and roller heater 6 constituting the fixing section receive heating current from the heater driver 2. It is detected by a thermistor 4 as a detection means.

The DC motor 7, which is the power source of the paper feed mechanism, receives a drive current from the motor driver 3 and drives the continuous printing paper 11 via the tractor 12. At this time, the magnitude of this drive current is determined by the load detection means. The current detection circuit 8 detects the current.

The control circuit 1 constitutes a control unit similar to the temperature control means 17 together with the motor driver 3, receives temperature detection data from the thermistor 4, compares it with a preset target temperature, and controls the temperature of the preheater 5 and roller heater 6. The heater driver 2 is controlled depending on the temperature to reduce or increase the heating current to match the target temperature. In addition, in the paper feed mechanism, the motor adjusts the feed speed to maintain the running speed at a constant speed regardless of changes in the width, thickness, weight, etc. of the printing paper, as well as small changes in resistance such as paper folds and perforations. It is normal to have a servo mechanism such as this, but it is omitted here.

In addition, at least two thermistors are used as temperature detection means to detect the temperatures of the preheaters and the roller heater 6, and the configuration is such that the heating currents of the preheater 5 and the roller heater 6 are controlled based on the respective detection data. , here represented by thermistor 4.

The difference between the control section of this embodiment and the conventional temperature control means 17 shown in FIG. The configuration is such that one of the target temperature values is selected. In this example, to make it easier to understand, we set two target temperature values for the heater: a reference value and a high temperature value suitable for thick paper that is wider than average paper (hereinafter referred to as heavy paper). I will explain it as if it were.

With the above configuration, the operation in general operating conditions is the same as the conventional example described above, and when using average paper width, paper thickness, and paper quality as printing paper, the target temperature value in control circuit 1 is The reference value is selected. On the other hand, when heavy paper is used as printing paper, the load on the tractor 12 of the paper feeding mechanism increases.
In order to drive this at a constant speed, the drive current of the DC motor 7 increases, and this increase in drive current is detected by the current detection circuit 8. Based on the detection data, the target temperature value in the control circuit 1 is set to a high target temperature. The value is automatically selected and, via the heater driver 2, the heating current of the preheater 5 and the roller heater 6 is increased, and the temperature of the preheater and the roller heater 6 is increased to the target temperature value to reach the printing paper.

Therefore, according to the printing apparatus according to this embodiment, in the case of average printing paper, there is no fear that the fixing temperature is too high and yellowing occurs. Further, even in the case of yellowed paper, fixing failure due to insufficient temperature does not occur.

The function described above uses, for example, a microcomputer as the control circuit 1, stores a target value in advance, receives motor drive current data in the form of a digital value from the converter of the current detection circuit 8, and performs a current control function using a thalistor or the like. It is clear that this can be easily realized by controlling the heater driver 2 held in the hand.

Further, in the above embodiment, the DC motor 7 is used as the power source for the paper feeding mechanism, and the current detection circuit 8 is used as the load detection means to detect the magnitude of the drive current. When using a motor, AC motor, etc., it is sufficient to detect constraint factors for driving them at a constant speed, such as drive pulse width, peak value, current phase, and frequency.

Furthermore, although the target temperature values are set at two points, it is also possible to set the temperature values at three points, light, medium, and heavy, depending on the range of printing paper to be used, and furthermore, the temperature values can be set at three points, depending on the range of printing paper used, and furthermore, the temperature values can be set in conjunction with the load of the paper feeding mechanism. It is also possible to change the target temperature continuously.

〔Effect of the invention〕

As explained above, according to the present invention, by feeding back the current detection of the DC motor, etc. to the temperature constraint target value of the heater, various types of continuous printing paper can be freely used, and print output can be unfixed or unfixed. It has the effect of preventing yellowing, etc.

[Brief explanation of drawings]

FIG. 1 is a block diagram of an embodiment of the present invention, and FIG. 2 is a block diagram of a conventional printing device. 1... Control circuit, 2... Heater driver 3...
・Motor driver, 4... Thermistor, 5... Preheater, 6... Roller heater, 7... DC motor, 8... Current detection circuit, 9... Photosensitive drum, 10
...Developer, 11...Continuous printing paper, 12...Tractor, 13...Pressure roller, 14...Stacker, 15...Hopper 16...Fixing unit, 17
...Temperature control means. Agent Patent Attorney Susumu Uchihara

Claims (1)

[Claims] an electrophotographic printing section, a fixing section that heats and fixes images such as characters and figures developed or transferred onto the printing paper surface by toner or the like by the printing section, and continuous paper for printing through the printing section and the fixing section. In a printing device or the like having a paper feeding mechanism that conveys the paper at a predetermined speed, a load detection means for detecting a load applied to the paper feeding mechanism;
The control unit includes a temperature detection unit that detects the temperature of the fixing unit, and a control unit that receives temperature data detected by the temperature detection unit and adjusts the temperature of the fixing unit to a set temperature target value. has at least two values as the temperature target value, and one of the temperature target values is selected and set upon receiving paper feed load data by the load detection means.