JPH04190619A - Printer - Google Patents

Abstract

PURPOSE:To prevent abnormal heating, smoking or firing of electronic components by measuring current flowing through a driving section and the duration thereof and detecting an abnormal current for longer than a predetermined time thereby detecting abnormal current at each driving section independently and accurately. CONSTITUTION:An abnormal current detecting section comprises a motor coil 23, a Darlington transistor 22 for driving, a current detecting resistor 24, a reference power supply 25, a comparator 26, a decision unit 28, and the like. When a current flowing through the current detecting resistor 24 exceeds a reference current, output of the comparator 26 is inverted. The decision unit 28 begins to count a reference clock 27 at that time point and when the count reaches a predetermined number N, a decision is made that a predetermined current has flowed for longer than a predetermined time, i.e., an abnormal current is produced, and an abnormal current detection output 29 is inverted. Consequently, power supply is interrupted and each waveform is converged to zero potential.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a printer device that prevents abnormal heat generation by detecting and cutting off abnormal current flowing through the printer device.

[Prior Art] In conventional printer devices, in order to prevent electronic components from generating abnormal heat, smoking, or catching fire due to abnormal current, a fuse or the like is installed in the power supply section to cut off the current when the overall current exceeds a predetermined value. was.

[Problems to be Solved by the Invention] However, with the conventional method, the current that can be detected is the current that flows throughout the entire drive unit, including a plurality of the drive units, and within this rating, the current that flows through each drive unit is Even abnormal currents exceeding the rated current flowing through the parts could not be detected. Therefore, even if the electronic components of the drive unit were to generate heat or smoke due to an abnormal current exceeding their rating, the fuse would not blow.

In addition, a large current normally flows through the drive unit for a period of several microseconds to several hundred milliseconds, but if the current continues to flow for a long time even if the current is smaller than that, it will lead to abnormal heat generation. It must be determined that there is an abnormality when the flow exceeds that level.

An object of the present invention is to provide a printer device that can more accurately detect abnormal current, detect and cut off abnormal current flowing in each individual drive unit, and prevent abnormal heat generation, smoke generation, etc. It is to be.

[Means for Solving the Problems] In order to solve the above problems, the printer device of the present invention detects the current flowing through each of the drive parts, measures time, and stops the current from flowing when a certain predetermined time has passed. It is characterized by having an abnormal current detection section that outputs a signal to the power cutoff section to shut off the power.

[Example] Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing one embodiment of the present invention.

A printing mechanism 8 is composed of actuators such as a paper feed motor 9, a carriage motor 10, and a head solenoid 11. 2 paper feed motor drive units each
It is driven by the carriage motor drive section 3 and the helide solenoid drive section 4. Further, each of the drive units 2, 3, and 4 includes abnormal current detection units 5, 6, and 7, respectively. 14 is a +24v driving power supply, 12 is 5.6
- A power cutoff unit that cuts off the power in response to signals from each abnormal current detection unit 7.

Reference numeral 1 denotes a control unit that controls each of the drive units 2, 3, and 4. 1
3 is a +5V power supply that generates +5V for the logic circuit from a +24V power supply.

FIG. 2 shows a paper feed motor drive section and an abnormal current detection section of a printer device showing an embodiment of the present invention. 23 is a motor coil, 22 is a driving Darlington transistor, and 24 is a current detection resistor. 25 is the reference power supply, 2
6 is a comparator, and when the potential of 24 becomes higher than the reference potential of 25, that is, when the current flowing through 24 becomes larger than the reference current, the output of 26 is inverted.

Furthermore, 27 is a reference clock, and in the judger 28, the reference clock is counted while the output of 26 is inverted, and when the reference clock exceeds a predetermined number, the judger 28 determines that the predetermined current is It is determined that the current has flowed for a predetermined time or longer, that is, it is determined that the current is abnormal, and the abnormal current detection output 29 is output to the power cutoff section.

FIG. 3 shows waveforms of various parts when abnormal current is detected.

31 is the output of the comparator 26, which is inverted when a reference current or more flows through the current detection resistor 24.

The determiner 28 counts the reference clock from this time, and inverts the abnormal current detection output 29 when it reaches a predetermined number N. This output cuts off the power and each waveform converges to zero potential.

FIG. 4 is a block diagram showing a conventional example. A fuse 41 detects an abnormality in the current supplied to each drive unit 42, 43, 44 and +5V power supply unit and cuts it off.

[Effects of the Invention] As described above, according to the present invention, abnormal currents in each drive section are independently and accurately detected and cut off, so that abnormal heat generation, smoke, and ignition of electronic components can be prevented. can.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing one embodiment of a printer device of the present invention. FIG. 2 is an explanatory diagram of a paper feed motor drive section and an abnormal current detection section in a printer device showing an embodiment of the present invention. FIG. 3 is a waveform diagram of each part of an abnormal current detection section showing an embodiment of the present invention. FIG. 4 is a block diagram showing an example of abnormal current detection in a conventional printer device. 1: Control section 2, 3, 4: Drive section 5, 6, 7: Abnormal current detection section 8: Printing mechanism 12: Power cutoff section 14: +24V power supply 22: Drive transistor 24: Current detection resistor 26: Comparator 282 Determiner 29: Abnormal current detection output or higher Applicant Seiko Epson Co., Ltd. agent Patent attorney Kizobe Meiki and 1 other person Figure 1

Claims (1)

[Scope of Claims] A printing mechanism, a drive unit that drives each of a plurality of actuators of the printing mechanism, a control unit that controls the drive unit, and an abnormal current detection unit that detects abnormal current flowing through the drive unit. In a printer device having a power cutoff section that receives the output and cuts off the drive power supplied to the drive section, the abnormal current detection section detects that the abnormal current has flowed for a predetermined period or more. A printer device characterized in that it has a function of detecting.