JPH018366Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Technical Field) The present invention relates to a substrate having a conductive path for supplying a driving signal to a heating resistor in a thermal head.

(Prior Art) An example of a thermal head is a heating resistor 10A for recording heat generation, as shown in FIG.
A first substrate (heat generating substrate) 10 such as a ceramic substrate having a heating resistor 10A, and a second substrate (wiring substrate) 11 such as a glass epoxy substrate having a conductive path 11A for supplying a drive signal to the heating resistor 10A. In order to electrically and actively connect these substrates 10 and 11, tape carriers 12, 12-1, 12-2, . . . on which IC chips 12A are mounted are provided.

The second substrate 11 such as a glass epoxy substrate is
It includes a conductive path 11A having a specific wiring pattern for supplying a drive signal to the heat generating resistor 10A. In the conductive path 11A, for example, conductive paths e, e-
2, e-3 is the data derivation path 4 (data out path), and the conductive path f is the data introduction path (data in path).
It is.

By the way, none of the conductive paths 11A of the second substrate 11, such as a glass epoxy substrate of a conventional thermal head, is provided with a terminal for testing. Therefore, testing of the thermal head can only be done after assembly is complete.
If a defective IC chip 12A is discovered after assembly is completed, it is not easy to replace the defective IC chip 12A. After all, if testing cannot be performed until after assembly is completed, there is a problem in that the yield of thermal heads decreases.

(Purpose) The present invention is a wiring board for a thermal head that allows testing to be performed during the assembly process and to test each driving IC one by one, thereby improving yield. The purpose is to provide the following.

(Structure) In the present invention, the heat generating resistor is divided into a plurality of blocks, and the wiring has a conductive path for supplying a drive signal to the heat generating resistor of the heat generating board via a driving IC provided for each block. In the substrate, among the conductive paths, there is a data-in path for introducing an image information signal to the driving IC, and a data-in path for driving one stage preceding the data-in path.
Data-out paths for deriving the signals from the IC are arranged next to each other, and test terminals connected to each adjacent data-in path and data-out path are provided for each block.
The data-in terminal and the test terminal are provided for each IC, and the data-in/data-out test of the driving IC is performed using the data-in terminal and the test terminal.

Examples will be specifically described below.

FIG. 1 shows an embodiment of the present invention, which shows a first substrate such as a ceramic substrate having a heating resistor for recording heat generation, and a conductive path for supplying a drive signal to the heating resistor. a second substrate 21 such as a glass epoxy substrate having 21A;
In order to electrically and actively connect these substrates, tape carriers 22, 22-1 to 22-m are provided on which drive IC chips 22A are mounted. However, since the first substrate is the same as that shown in FIG. 3, illustration thereof is omitted.

The heating resistor is divided into a fixed number of blocks, and each block is provided with one IC chip 22A.

The wiring pattern of the conductive paths 21A on the second substrate 21, such as a glass epoxy substrate, is different from the conventional one shown in FIG. The conductive paths in the wiring pattern are indicated by symbols a to h. For example, conductive paths a to d are signal paths that provide the first to fourth strobe pulses, and conductive paths e and f are ground, clock, and other signal paths. The conductive path g is a data-in path, and the conductive paths h ₁ , h _{2 .} . . are conductive paths that serve both as data-out and data-in to the next stage IC chip.

The conductive paths h ₁ , h ₂ . . . have conductive paths extending from their intermediate portions to the ends 21c of the substrate 21, and wide regions 21d for forming terminals are formed at the ends of the conductive paths. This terminal area 21d is a test terminal.

Further, the ends of each of the wiring patterns a to g of the conductive path 21A extend to the end 21a of the substrate 21, and the width of the entire conductive path 21A is widened near this end 21a. Each conductive path 21 is in contact with the end portion 21a.
A wide area 21b is formed in A to form a terminal. The terminal area of the conductive path g for data-in can be used as a test terminal.

The area indicated by the symbol i on the substrate 21 is an area where the conductive path 21A and the leads A to G of the tape carrier 22 are connected.

Pulses are sequentially applied to the conductive paths a to d that apply strobe pulses over time, and each grouped electrode group is driven by the corresponding pulse.

Data in path g is an image sensor (not shown)
The image information detected by the sensor is sent as a serial digital signal for each pixel. This digital signal is sent to the heating resistor and the next IC via each IC. That is, the image information signal sent from the data-in path g is sent to the data-out path _h1 to be serially arranged via the IC of the tape carrier 22-1. This data out path _h1 also serves as the data in path of the next tape carrier IC. Similarly, conductive paths h ₂ and h ₃
... is also the data-out path of the previous-stage IC and the data-in path of the next-stage IC, so the image information signal is transferred to the tape carriers 22-1 to 22-2.
They are arranged serially along 2-m ICs. In this way, each conductive path g, h ₁ , h ₂ , ... forms a wiring pattern that connects the shift registers in the IC of each tape carrier 22 in series, and therefore the data-in path and the data-out path are adjacent to each other. It forms a suitable conductive path. Moreover, these conductive paths g, h ₁ ,
h ₂ , . . . are formed on the outer portion of the substrate 21.

The data-in terminal g and the test terminal 21d are used for testing the data-in and data-out of the IC 22A during assembly. That is, with the tape carriers 22-1 to 22-m connected to the board 21, a signal is input from the terminal g, and the terminals 21d,
By detecting the signal at 21d,...
It is possible to test whether the shift registers of IC22A, 22A, . . . are normal. Also, terminal g
and the leftmost terminal 21d in the figure, the adjacent terminal 21
By performing a data-in/data-out test between d and 21d, it is possible to test the acceptability of each IC 22A.

Such a substrate 21 can be manufactured as follows. First, as shown in Figure 2,
Extra area 3 in addition to the part 21 that would originally become the substrate
Set it to 0. On these regions 21 and 30, the aforementioned pattern 21A and an electrolytic plating electrode 31 electrically connected thereto are formed by etching. By doing this, all patterns 21
Since A is connected to the common electrode 31 for electrolytic plating, electrolytic plating can be easily formed on the pattern 21A. After such electrolytic plating, area 30 is cut away.

(Effects) The thermal head board of the present invention has test terminals connected to each data-in path and data-out path, so it is possible to test the data-in and data-out of the IC during the assembly process. become able to. Thereby, the yield of thermal heads can be improved.

In addition, since each IC chip has a test terminal, it is possible to test each IC chip, and if a defective IC chip is found, the
Since only the IC chip can be removed, the yield of thermal heads can be further improved.

[Brief explanation of the drawing]

Fig. 1 is a plan view showing a substrate according to an embodiment of the present invention together with a tape carrier, Fig. 2 is a plan view showing how the substrate according to the embodiment of Fig. 1 is manufactured, and Fig. 3 is a plan view showing a conventional thermal head. FIG. 2 is a configuration diagram showing the device. 21... Glass epoxy board, 21A... Conductive path, 21d... Test terminal, 22... Tape carrier, 22A... Drive IC chip, h ₁ , h ₂ , h ₃
...Data in/data out path.

Claims (1)

[Scope of utility model registration request] In a wiring board in which a heat generating resistor is divided into a plurality of blocks and has a conductive path for supplying a drive signal to the heat generating resistor of the heat generating board via a driving IC provided for each block, the conductive path is A data-in path for introducing an image information signal into the driving IC and a data-out path for deriving the signal from the preceding driving IC are arranged next to each other, and each adjacent data-in path and data A test terminal connected to the out path is provided for each drive IC provided for each block,
A board for a thermal head, characterized in that a data-in/data-out test of the driving IC is performed using a data-in terminal and the test terminal.