JPS59218875A - Head driving control system of printer - Google Patents

Abstract

PURPOSE:To perform the uniform control of printing density in a non-contact system, by a method wherein a thermochromic substance is applied to a thermal head and color forming density corresponding to the temp. of said head is detected by an optical sensor while the driving of the thermal head is controlled corresponding to the detected value. CONSTITUTION:A thermochromic substance 2 is applied to the thermal head 1 in a thermal transfer or heat sensitivie color forming type printer and the color forming density thereof is detected in a non-contact system by an optical sensor 3. The temp. of the head 1 is controlled so as to reach a predetermined temp. by a head driving circuit 6 connected to the above mentioned optical sensor 3 through an amplifier 4 and a corrector circuit 5.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to a head drive control system for maintaining print density in a thermal transfer type or thermal recording type printer. During continuous recording, the effect of heat accumulation on the recording head, the polymeric roller, and the ink sheet or heat-sensitive recording paper conveyed to the recording position in between gradually becomes noticeable, resulting in uneven printing of 14 degrees. The problem is that it becomes

For this reason, in the past, a temperature sensor such as a thermistor was embedded in the recording hectare carrier to detect the amount of heat stored in the recording head, and the head drive voltage was changed OT in order to maintain the print density constant according to the detected temperature. However, if such a method is used, the heat distribution state of the head will change due to the temperature sensor attached to the recording medium, and its heat dissipation performance will deteriorate. Purpose The present invention has been made in consideration of the above points, and uses a special sensor to non-contactly detect the heat storage temperature at the recording position in a thermal transfer type or thermal recording type printer to maintain a constant print density. The present invention provides a head drive control method for a printer that controls the drive of a recording head so that the recording head can be maintained at a constant speed.

composition An embodiment of the present invention will be described in detail below.

The printer head drive control system according to the present invention is as follows.

By using a thermochromic material that changes the degree of color development depending on the temperature and detecting the color density with an optical sensor, the heat storage temperature of the recording position of the recording head carrier, platen roller, or ink sheet conveyed between them in the printer can be determined. The present invention is characterized by the provision of special sensor means for non-contact detection. The thermochromic substances used in this spear include electron-donating color-forming organic compounds/bisphenol/alcohol/cetyl myristate mixed systems, poly(N-methylacrylamide) decaaromatic compounds, and Ni complex systems. Are known.

FIG. 1 shows an example of a configuration in which the head drive control is performed by detecting the heat storage temperature of the recording head carrier.
In a thermal transfer printer that drives the head based on recorded data, the back surface of the recording head carrier 1 is coated with a thermochromic substance 2, and
Correspondingly, a reflective optical sensor 3 is provided to detect the color density by photoelectric conversion, and the output of the optical sensor 3 is sent to a correction circuit 5 through an amplifier 4 to determine the heat storage state of the recording head carrier 1 at that time. A correction command corresponding to the determination result is given to the head drive circuit 6 to appropriately adjust the magnitude or pulse width of the pulse drive voltage applied to the recording head. In the figure, 8 indicates a platen roller, 9 indicates a recording paper, 10 indicates an ink sheet, and 11 indicates a separation claw.However, in the structure of this device 5, the recording head carrier 1 is heated. As the temperature rises, the color density of the thermochromic material 2 increases accordingly, and by detecting this density via the optical sensor 3, the correction circuit 5 adjusts the heat storage temperature of the recording head carrier 1 with high precision in a non-contact manner. You will be able to ask for it. Therefore, by performing temperature compensation in which the pulse voltage or pulse width for driving the head is decreased as the determined temperature increases by the correction circuit 5, the state of heat accumulation at the recording position of the printer can be adjusted. It is possible to accurately control the head drive so as to always optimize the print quality regardless of the print speed. At this time, since the heat storage temperature at the recording position of the printer is detected in a non-contact manner using the recording head carrier 1 as an intermediary, the heat distribution state of the head may be changed or the heat dissipation performance may be deteriorated. Nothing like that happens. Second
In the figure, a thermochromic material 202 in the correction circuit 5 is shown.
An example of eclipse detection timing is shown.

Here, in order to appropriately detect the heat storage temperature of the recording head carrier 1, density detection is executed immediately before the valley printing cycle is started.

FIG. 3 shows another embodiment of the present invention, in which the head contact side of the ink sheet 10 is coated with a thermochromic substance, and the ink sheet 10 is coated with a thermochromic substance, and the reflection is applied directly to the recording head carrier 1 on the paper ejection side. A type optical sensor 3 is provided. Further, in this case, a digital control system is incorporated to control the head drive according to the output of the optical sensor 3, and the output of the optical sensor 3 is applied to the AD converter 12 through the amplifier 4 to convert it into a digital signal. , the converted digital signal is compared with the data stored in the memory circuit 13 in which Mazda data of the coloring density of the thermochromic material according to the temperature is stored in advance.
4, and the controller 7 determines the state of heat accumulation at the recording position of the printer from the comparison result and performs head drive control to maintain a constant print density. FIG. 4 shows an example of the timing of detecting the temperature of the thermoclock substance in this case.

Here, ink sheet 1 that has passed the printer's recording position
In order to optimally detect the heat accumulation state of o, the density in the valley of each printing cycle is detected.For Inksee) 100 base material, the coloring density of the thermochromic substance coated on it is accurately detected. In order to be able to do this, it is necessary to use an opaque material such as white so that the density of the ink layer on the surface will not be detected incorrectly.

Furthermore, FIG. 5 shows another embodiment of the present invention, in which the platen roller 8 is a cylindrical body 81 made of transparent heat-resistant tempered glass or glass, and a rubber layer 82 also made of transparent urethane is coated on the surface of the cylindrical body 81 made of transparent heat-resistant tempered glass or glass. The surface of the grating roller 8 is coated with a thermochromic substance, and a reflective (or transmissive) optical sensor 3 is provided inside the platen roller 8 facing the recording head carrier 1. The optical sensor 3 detects the color density of the thermochromic material at the recording position through a transparent platen roller. Although no control system is shown here, a control system having the same configuration as in the case of FIG. 1 or FIG. 3 will be incorporated.

Further, the timing for detecting the concentration of the thermochromic substance is exactly the same as in FIG.

As described above, the printer head drive control method according to the present invention uses a thermochromic material and detects the color density depending on the temperature with an optical sensor, thereby controlling the recording position of a thermal transfer type or thermal recording type printer. This system uses means to non-contactly detect the heat storage temperature at the recording position, and means to control the head drive voltage according to the detected heat storage temperature. This has the excellent advantage that head drive control for holding the head can be performed with high precision.

[Brief explanation of the drawing]

FIG. 1 shows a printer head jl [M tl
FIG. 2 is a time chart showing the concentration detection timing in the same embodiment; FIG. 3 is a diagram showing another embodiment of the present invention; FIG. The figure is a time chart showing the density detection timing in the same embodiment, and FIG. 5 is a diagram showing the configuration of the printer portion according to yet another unknown embodiment. 1... Recording head carrier 2... Thermochromic material 3... Optical sensor 4... Amplifier 5... Correction circuit 6... Head drive circuit 7-... Controller
8...Platen roller 9...Recording paper 10...Ink sheet 12...AD converter 13...Memory circuit 14...Comparator applicant's agent Kiyoshi Torii Figure 1 f 6

Claims (1)

[Claims] A means for non-contact detecting the heat storage temperature at the recording position of a thermal transfer or heat-sensitive recording printer by using a thermochromic substance and detecting the color density depending on the temperature with an optical sensor, and the detected heat storage. A five-turn head movement control system for a printer that includes means for controlling head drive voltage according to temperature.