JPH01184162A - Printer - Google Patents

Abstract

PURPOSE:To obtain a stable image by always forming a color in a definite dot size, by mounting a sensor for detecting the difference between the transmissivity of transparent paper and that of opaque paper and a control circuit performing the proper thermal control based upon the detected value of said sensor. CONSTITUTION:The quantity of reflection of paper and that of OHP are detected by a reflection type optical sensor 6 and converted to digital quantities by an A/D converter 7. In the case of the paper, a photocurrent is large because of high reflectivity and, in the case of the OHP, a photocurrent is small because of low reflectivity. By this effect, difference is generated between the digital quantities and a CPU system 8 can confirm the paper and the OHP. On the basis of the data thus confirmed, the CPU system 8 sends a parameter for increasing the power applied to a thermal head 10 when the paper is mounted on a heat control circuit 9 and sends a parameter for reducing the power applied to the thermal head 10 when the OHP is mounted. By this method, a function for altering a control method between the transparent paper and the opaque paper is provided and necessary power to be applied due to difference in image receiving paper is altered to make it possible to always obtain stable image quality.

Description

[Detailed description of the invention] Industrial applications The present invention relates to a printer.

Conventional technology In recent years, color printers have become popular for business use and CAD.
, is used for presentation hard copies mainly in the CAM field.

An example of the conventional color printer mentioned above will be described below with reference to the drawings.

FIG. 2 shows a conventional color printer. In Fig. 2, 1 is the heat-applying tank 2.

A multi-head 2 is a platen roller, 3 is a sheet of paper for printing, 4 is a reflective optical sensor for detecting the presence or absence of paper, and 5 is an ink film to be transferred.

The operation of the printer configured as described above will be described below.

First, the presence or absence of paper is detected by the sensor 4, and if it is determined that there is paper, the thermal head 1 starts printing at the end of use 3 in response to an external command. The paper 3 reciprocates three times, and during this time the ink film 5 is wound up in the direction of the arrow, heat is applied from the thermal head 1, and the paper 3
are transferred in the order of MMC.

Problems to be Solved by the Invention However, in the above configuration, paper with a large surface roughness (generally opaque paper) and ○HP (P) with a small surface roughness are used.
When paper (generally transparent paper) such as ET) is used, changes in the ink transfer wheel of the ink film are observed due to differences in surface roughness. In the case of paper, one dot tends to be multiplied by 9, and in the case of OHP paper, one dot tends to be large.

Page 3 It is conceivable that when changing paper like this, the thermal control can be changed on the printer side depending on the paper type by switching the switch, but if the operator forgets to change the switch, the printer's running system will be affected. This has the problem of causing trouble.

The present invention provides a printer that can solve the above problems.

Means for Solving the Problems In order to solve the above problems, the printer of the present invention includes a sensor that detects the difference in light transmittance between transparent paper and opaque paper;
The printer is equipped with a control circuit that performs appropriate thermal control based on the value of this sensor.

Effect of the Invention With the above-described configuration, the present invention changes the amount of heat applied to the head based on the sensor signal that can distinguish between opaque paper and transparent paper. In addition, for OHPs made of transparent paper with a small surface roughness, the power can be decreased to always produce a constant dot size and obtain a stable image.

Embodiment Hereinafter, a printer according to an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 shows a control circuit of a printer according to the present invention. In FIG. 1, reference numeral 6 denotes a reflective optical sensor, which is placed at the position of the sensor 4 shown in the conventional example. 7 is an A/D converter, 8 is a CPU system, 9 is a control circuit, and 1o is a thermal head. The operation of the printer control circuit configured as described above will be explained.

First, FIG. 1 shows a thermal control circuit of a printer, in which a reflective optical sensor 6 detects the amount of reflection from paper and OHP, and converts this amount of reflection into a photocurrent. Further A
/D converter 7 converts it into a digital quantity. At this time, in the case of paper, the reflective optical sensor 6 has a high reflectance, so the photocurrent is large, and in the case of OHP, the reflectance is low, so the photocurrent is small. This effect causes a difference in the digital amount converted by the pA/D converter 7, allowing the CPU system 8 to recognize whether the paper or OHP is the 5-base type installed in the printer. Based on the information recognized as described above, the CPU system 8 sends a parameter to increase the power applied to the thermal head 1o when paper is attached to the thermal control circuit 9, and also sends a parameter to increase the power applied to the thermal head 1o.
If HP is installed, send parameters to reduce the applied power.

As described above, by providing the reflective optical sensor 6 that detects the reflectance, the A/D converter 7, this information, the CPU system 8 and the thermal control circuit 9 that apply appropriate power to the thermal head 1o. , image quality can be improved due to the difference between paper and OHP.

Further, although the reflection type optical sensor 6 is used in the above embodiment, a transmission type optical sensor may also be used. Further, although the CPU system 8 is used in the above embodiment, the analog value of the reflective optical sensor 6 may also be directly connected to the thermal control circuit 9 and converted into applied power to be applied to the thermal head 10.

Effects of the Invention As described above on page 6, the present invention provides transparent paper by providing a sensor that detects the difference in light transmittance between transparent paper and opaque paper, and a control circuit that performs appropriate heat control based on the value of this sensor. It has a function to change the control method depending on paper and opaque paper, and can always obtain stable image quality by changing the required applied power depending on the difference in image receiving paper.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing a control circuit of a printer according to an embodiment of the present invention, and FIG. 2 is a diagram showing a mechanism of a conventional color printer. 6... Reflective optical sensor, 7... A/
D converter, 8... CPU system, 9...
...Thermal control circuit, 10...Thermal head.

Claims (1)

[Claims] A sensor that detects the difference in light transmittance between transparent paper and opaque paper, and a control that controls heat by controlling the output of this sensor so that the amount of heat applied to the thermal head is greater when the paper is opaque than when it is transparent. Printer with circuit.